The Tor Browser: gfx/cairo/libpixman/src/pixman-region.c@b8a032363ba2 (annotated)

gfx/cairo/libpixman/src/pixman-region.c@b8a032363ba2 (annotated)

gfx/cairo/libpixman/src/pixman-region.c

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /*
  * Copyright 1987, 1988, 1989, 1998  The Open Group
  *
  * Permission to use, copy, modify, distribute, and sell this software and its
  * documentation for any purpose is hereby granted without fee, provided that
  * the above copyright notice appear in all copies and that both that
  * copyright notice and this permission notice appear in supporting
  * documentation.
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
  * OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  *
  * Except as contained in this notice, the name of The Open Group shall not be
  * used in advertising or otherwise to promote the sale, use or other dealings
  * in this Software without prior written authorization from The Open Group.
  *
  * Copyright 1987, 1988, 1989 by
  * Digital Equipment Corporation, Maynard, Massachusetts.
  *
  *                    All Rights Reserved
  *
  * Permission to use, copy, modify, and distribute this software and its
  * documentation for any purpose and without fee is hereby granted,
  * provided that the above copyright notice appear in all copies and that
  * both that copyright notice and this permission notice appear in
  * supporting documentation, and that the name of Digital not be
  * used in advertising or publicity pertaining to distribution of the
  * software without specific, written prior permission.
  *
  * DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
  * ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
  * DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
  * ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
  * WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
  * ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  * SOFTWARE.
  *
  * Copyright © 1998 Keith Packard
  *
  * Permission to use, copy, modify, distribute, and sell this software and its
  * documentation for any purpose is hereby granted without fee, provided that
  * the above copyright notice appear in all copies and that both that
  * copyright notice and this permission notice appear in supporting
  * documentation, and that the name of Keith Packard not be used in
  * advertising or publicity pertaining to distribution of the software without
  * specific, written prior permission.  Keith Packard makes no
  * representations about the suitability of this software for any purpose.  It
  * is provided "as is" without express or implied warranty.
  *
  * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  * EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  * PERFORMANCE OF THIS SOFTWARE.
  */
 #include <stdlib.h>
 #include <limits.h>
 #include <string.h>
 #include <stdio.h>
 #include "pixman-private.h"
 #define PIXREGION_NIL(reg) ((reg)->data && !(reg)->data->numRects)
 /* not a region */
 #define PIXREGION_NAR(reg)      ((reg)->data == pixman_broken_data)
 #define PIXREGION_NUMRECTS(reg) ((reg)->data ? (reg)->data->numRects : 1)
 #define PIXREGION_SIZE(reg) ((reg)->data ? (reg)->data->size : 0)
 #define PIXREGION_RECTS(reg) \
     ((reg)->data ? (box_type_t *)((reg)->data + 1) \
      : &(reg)->extents)
 #define PIXREGION_BOXPTR(reg) ((box_type_t *)((reg)->data + 1))
 #define PIXREGION_BOX(reg, i) (&PIXREGION_BOXPTR (reg)[i])
 #define PIXREGION_TOP(reg) PIXREGION_BOX (reg, (reg)->data->numRects)
 #define PIXREGION_END(reg) PIXREGION_BOX (reg, (reg)->data->numRects - 1)
 #define GOOD_RECT(rect) ((rect)->x1 < (rect)->x2 && (rect)->y1 < (rect)->y2)
 #define BAD_RECT(rect) ((rect)->x1 > (rect)->x2 || (rect)->y1 > (rect)->y2)
 #ifdef DEBUG
 #define GOOD(reg)							\
     do									\
     {									\
 	if (!PREFIX (_selfcheck (reg)))					\
 	    _pixman_log_error (FUNC, "Malformed region " # reg);	\
     } while (0)
 #else
 #define GOOD(reg)
 #endif
 static const box_type_t PREFIX (_empty_box_) = { 0, 0, 0, 0 };
 static const region_data_type_t PREFIX (_empty_data_) = { 0, 0 };
 #if defined (__llvm__) && !defined (__clang__)
 static const volatile region_data_type_t PREFIX (_broken_data_) = { 0, 0 };
 #else
 static const region_data_type_t PREFIX (_broken_data_) = { 0, 0 };
 #endif
 static box_type_t *pixman_region_empty_box =
     (box_type_t *)&PREFIX (_empty_box_);
 static region_data_type_t *pixman_region_empty_data =
     (region_data_type_t *)&PREFIX (_empty_data_);
 static region_data_type_t *pixman_broken_data =
     (region_data_type_t *)&PREFIX (_broken_data_);
 static pixman_bool_t
 pixman_break (region_type_t *region);
 /*
  * The functions in this file implement the Region abstraction used extensively
  * throughout the X11 sample server. A Region is simply a set of disjoint
  * (non-overlapping) rectangles, plus an "extent" rectangle which is the
  * smallest single rectangle that contains all the non-overlapping rectangles.
  *
  * A Region is implemented as a "y-x-banded" array of rectangles.  This array
  * imposes two degrees of order.  First, all rectangles are sorted by top side
  * y coordinate first (y1), and then by left side x coordinate (x1).
  *
  * Furthermore, the rectangles are grouped into "bands".  Each rectangle in a
  * band has the same top y coordinate (y1), and each has the same bottom y
  * coordinate (y2).  Thus all rectangles in a band differ only in their left
  * and right side (x1 and x2).  Bands are implicit in the array of rectangles:
  * there is no separate list of band start pointers.
  *
  * The y-x band representation does not minimize rectangles.  In particular,
  * if a rectangle vertically crosses a band (the rectangle has scanlines in
  * the y1 to y2 area spanned by the band), then the rectangle may be broken
  * down into two or more smaller rectangles stacked one atop the other.
  *
  *  -----------				    -----------
  *  |         |				    |         |		    band 0
  *  |         |  --------		    -----------  --------
  *  |         |  |      |  in y-x banded    |         |  |      |   band 1
  *  |         |  |      |  form is	    |         |  |      |
  *  -----------  |      |		    -----------  --------
  *               |      |				 |      |   band 2
  *               --------				 --------
  *
  * An added constraint on the rectangles is that they must cover as much
  * horizontal area as possible: no two rectangles within a band are allowed
  * to touch.
  *
  * Whenever possible, bands will be merged together to cover a greater vertical
  * distance (and thus reduce the number of rectangles). Two bands can be merged
  * only if the bottom of one touches the top of the other and they have
  * rectangles in the same places (of the same width, of course).
  *
  * Adam de Boor wrote most of the original region code.  Joel McCormack
  * substantially modified or rewrote most of the core arithmetic routines, and
  * added pixman_region_validate in order to support several speed improvements
  * to pixman_region_validate_tree.  Bob Scheifler changed the representation
  * to be more compact when empty or a single rectangle, and did a bunch of
  * gratuitous reformatting. Carl Worth did further gratuitous reformatting
  * while re-merging the server and client region code into libpixregion.
  * Soren Sandmann did even more gratuitous reformatting.
  */
 /*  true iff two Boxes overlap */
 #define EXTENTCHECK(r1, r2)	   \
     (!( ((r1)->x2 <= (r2)->x1)  || \
         ((r1)->x1 >= (r2)->x2)  || \
         ((r1)->y2 <= (r2)->y1)  || \
         ((r1)->y1 >= (r2)->y2) ) )
 /* true iff (x,y) is in Box */
 #define INBOX(r, x, y)	\
     ( ((r)->x2 >  x) && \
       ((r)->x1 <= x) && \
       ((r)->y2 >  y) && \
       ((r)->y1 <= y) )
 /* true iff Box r1 contains Box r2 */
 #define SUBSUMES(r1, r2)	\
     ( ((r1)->x1 <= (r2)->x1) && \
       ((r1)->x2 >= (r2)->x2) && \
       ((r1)->y1 <= (r2)->y1) && \
       ((r1)->y2 >= (r2)->y2) )
 static size_t
 PIXREGION_SZOF (size_t n)
 {
     size_t size = n * sizeof(box_type_t);
     if (n > UINT32_MAX / sizeof(box_type_t))
 	return 0;
     if (sizeof(region_data_type_t) > UINT32_MAX - size)
 	return 0;
     return size + sizeof(region_data_type_t);
 }
 static region_data_type_t *
 alloc_data (size_t n)
 {
     size_t sz = PIXREGION_SZOF (n);
     if (!sz)
 	return NULL;
     return malloc (sz);
 }
 #define FREE_DATA(reg) if ((reg)->data && (reg)->data->size) free ((reg)->data)
 #define RECTALLOC_BAIL(region, n, bail)					\
     do									\
     {									\
 	if (!(region)->data ||						\
 	    (((region)->data->numRects + (n)) > (region)->data->size))	\
 	{								\
 	    if (!pixman_rect_alloc (region, n))				\
 		goto bail;						\
 	}								\
     } while (0)
 #define RECTALLOC(region, n)						\
     do									\
     {									\
 	if (!(region)->data ||						\
 	    (((region)->data->numRects + (n)) > (region)->data->size))	\
 	{								\
 	    if (!pixman_rect_alloc (region, n)) {			\
 		return FALSE;						\
 	    }								\
 	}								\
     } while (0)
 #define ADDRECT(next_rect, nx1, ny1, nx2, ny2)      \
     do						    \
     {						    \
 	next_rect->x1 = nx1;                        \
 	next_rect->y1 = ny1;                        \
 	next_rect->x2 = nx2;                        \
 	next_rect->y2 = ny2;                        \
 	next_rect++;                                \
     }						    \
     while (0)
 #define NEWRECT(region, next_rect, nx1, ny1, nx2, ny2)			\
     do									\
     {									\
 	if (!(region)->data ||						\
 	    ((region)->data->numRects == (region)->data->size))		\
 	{								\
 	    if (!pixman_rect_alloc (region, 1))				\
 		return FALSE;						\
 	    next_rect = PIXREGION_TOP (region);				\
 	}								\
 	ADDRECT (next_rect, nx1, ny1, nx2, ny2);			\
 	region->data->numRects++;					\
 	critical_if_fail (region->data->numRects <= region->data->size);		\
     } while (0)
 #define DOWNSIZE(reg, numRects)						\
     do									\
     {									\
 	if (((numRects) < ((reg)->data->size >> 1)) &&			\
 	    ((reg)->data->size > 50))					\
 	{								\
 	    region_data_type_t * new_data;				\
 	    size_t data_size = PIXREGION_SZOF (numRects);		\
 									\
 	    if (!data_size)						\
 	    {								\
 		new_data = NULL;					\
 	    }								\
 	    else							\
 	    {								\
 		new_data = (region_data_type_t *)			\
 		    realloc ((reg)->data, data_size);			\
 	    }								\
 									\
 	    if (new_data)						\
 	    {								\
 		new_data->size = (numRects);				\
 		(reg)->data = new_data;					\
 	    }								\
 	}								\
     } while (0)
 PIXMAN_EXPORT pixman_bool_t
 PREFIX (_equal) (region_type_t *reg1, region_type_t *reg2)
 {
     int i;
     box_type_t *rects1;
     box_type_t *rects2;
     if (reg1->extents.x1 != reg2->extents.x1)
 	return FALSE;
     if (reg1->extents.x2 != reg2->extents.x2)
 	return FALSE;
     if (reg1->extents.y1 != reg2->extents.y1)
 	return FALSE;
     if (reg1->extents.y2 != reg2->extents.y2)
 	return FALSE;
     if (PIXREGION_NUMRECTS (reg1) != PIXREGION_NUMRECTS (reg2))
 	return FALSE;
     rects1 = PIXREGION_RECTS (reg1);
     rects2 = PIXREGION_RECTS (reg2);
     for (i = 0; i != PIXREGION_NUMRECTS (reg1); i++)
     {
 	if (rects1[i].x1 != rects2[i].x1)
 	    return FALSE;
 	if (rects1[i].x2 != rects2[i].x2)
 	    return FALSE;
 	if (rects1[i].y1 != rects2[i].y1)
 	    return FALSE;
 	if (rects1[i].y2 != rects2[i].y2)
 	    return FALSE;
     }
     return TRUE;
 }
 int
 PREFIX (_print) (region_type_t *rgn)
 {
     int num, size;
     int i;
     box_type_t * rects;
     num = PIXREGION_NUMRECTS (rgn);
     size = PIXREGION_SIZE (rgn);
     rects = PIXREGION_RECTS (rgn);
     fprintf (stderr, "num: %d size: %d\n", num, size);
     fprintf (stderr, "extents: %d %d %d %d\n",
              rgn->extents.x1,
 	     rgn->extents.y1,
 	     rgn->extents.x2,
 	     rgn->extents.y2);
     for (i = 0; i < num; i++)
     {
 	fprintf (stderr, "%d %d %d %d \n",
 	         rects[i].x1, rects[i].y1, rects[i].x2, rects[i].y2);
     }
     fprintf (stderr, "\n");
     return(num);
 }
 PIXMAN_EXPORT void
 PREFIX (_init) (region_type_t *region)
 {
     region->extents = *pixman_region_empty_box;
     region->data = pixman_region_empty_data;
 }
 PIXMAN_EXPORT void
 PREFIX (_init_rect) (region_type_t *	region,
                      int		x,
 		     int		y,
 		     unsigned int	width,
 		     unsigned int	height)
 {
     region->extents.x1 = x;
     region->extents.y1 = y;
     region->extents.x2 = x + width;
     region->extents.y2 = y + height;
     if (!GOOD_RECT (&region->extents))
     {
         if (BAD_RECT (&region->extents))
             _pixman_log_error (FUNC, "Invalid rectangle passed");
         PREFIX (_init) (region);
         return;
     }
     region->data = NULL;
 }
 PIXMAN_EXPORT void
 PREFIX (_init_with_extents) (region_type_t *region, box_type_t *extents)
 {
     if (!GOOD_RECT (extents))
     {
         if (BAD_RECT (extents))
             _pixman_log_error (FUNC, "Invalid rectangle passed");
         PREFIX (_init) (region);
         return;
     }
     region->extents = *extents;
     region->data = NULL;
 }
 PIXMAN_EXPORT void
 PREFIX (_fini) (region_type_t *region)
 {
     GOOD (region);
     FREE_DATA (region);
 }
 PIXMAN_EXPORT int
 PREFIX (_n_rects) (region_type_t *region)
 {
     return PIXREGION_NUMRECTS (region);
 }
 PIXMAN_EXPORT box_type_t *
 PREFIX (_rectangles) (region_type_t *region,
                       int               *n_rects)
 {
     if (n_rects)
 	*n_rects = PIXREGION_NUMRECTS (region);
     return PIXREGION_RECTS (region);
 }
 static pixman_bool_t
 pixman_break (region_type_t *region)
 {
     FREE_DATA (region);
     region->extents = *pixman_region_empty_box;
     region->data = pixman_broken_data;
     return FALSE;
 }
 static pixman_bool_t
 pixman_rect_alloc (region_type_t * region,
                    int             n)
 {
     region_data_type_t *data;
     if (!region->data)
     {
 	n++;
 	region->data = alloc_data (n);
 	if (!region->data)
 	    return pixman_break (region);
 	region->data->numRects = 1;
 	*PIXREGION_BOXPTR (region) = region->extents;
     }
     else if (!region->data->size)
     {
 	region->data = alloc_data (n);
 	if (!region->data)
 	    return pixman_break (region);
 	region->data->numRects = 0;
     }
     else
     {
 	size_t data_size;
 	if (n == 1)
 	{
 	    n = region->data->numRects;
 	    if (n > 500) /* XXX pick numbers out of a hat */
 		n = 250;
 	}
 	n += region->data->numRects;
 	data_size = PIXREGION_SZOF (n);
 	if (!data_size)
 	{
 	    data = NULL;
 	}
 	else
 	{
 	    data = (region_data_type_t *)
 		realloc (region->data, PIXREGION_SZOF (n));
 	}
 	if (!data)
 	    return pixman_break (region);
 	region->data = data;
     }
     region->data->size = n;
     return TRUE;
 }
 PIXMAN_EXPORT pixman_bool_t
 PREFIX (_copy) (region_type_t *dst, region_type_t *src)
 {
     GOOD (dst);
     GOOD (src);
     if (dst == src)
 	return TRUE;
     dst->extents = src->extents;
     if (!src->data || !src->data->size)
     {
 	FREE_DATA (dst);
 	dst->data = src->data;
 	return TRUE;
     }
     if (!dst->data || (dst->data->size < src->data->numRects))
     {
 	FREE_DATA (dst);
 	dst->data = alloc_data (src->data->numRects);
 	if (!dst->data)
 	    return pixman_break (dst);
 	dst->data->size = src->data->numRects;
     }
     dst->data->numRects = src->data->numRects;
     memmove ((char *)PIXREGION_BOXPTR (dst), (char *)PIXREGION_BOXPTR (src),
              dst->data->numRects * sizeof(box_type_t));
     return TRUE;
 }
 /*======================================================================
  *	    Generic Region Operator
  *====================================================================*/
 /*-
  *-----------------------------------------------------------------------
  * pixman_coalesce --
  *	Attempt to merge the boxes in the current band with those in the
  *	previous one.  We are guaranteed that the current band extends to
  *      the end of the rects array.  Used only by pixman_op.
  *
  * Results:
  *	The new index for the previous band.
  *
  * Side Effects:
  *	If coalescing takes place:
  *	    - rectangles in the previous band will have their y2 fields
  *	      altered.
  *	    - region->data->numRects will be decreased.
  *
  *-----------------------------------------------------------------------
  */
 static inline int
 pixman_coalesce (region_type_t * region,      /* Region to coalesce		 */
 		 int             prev_start,  /* Index of start of previous band */
 		 int             cur_start)   /* Index of start of current band  */
 {
     box_type_t *prev_box;       /* Current box in previous band	     */
     box_type_t *cur_box;        /* Current box in current band       */
     int numRects;               /* Number rectangles in both bands   */
     int y2;                     /* Bottom of current band	     */
     /*
      * Figure out how many rectangles are in the band.
      */
     numRects = cur_start - prev_start;
     critical_if_fail (numRects == region->data->numRects - cur_start);
     if (!numRects) return cur_start;
     /*
      * The bands may only be coalesced if the bottom of the previous
      * matches the top scanline of the current.
      */
     prev_box = PIXREGION_BOX (region, prev_start);
     cur_box = PIXREGION_BOX (region, cur_start);
     if (prev_box->y2 != cur_box->y1) return cur_start;
     /*
      * Make sure the bands have boxes in the same places. This
      * assumes that boxes have been added in such a way that they
      * cover the most area possible. I.e. two boxes in a band must
      * have some horizontal space between them.
      */
     y2 = cur_box->y2;
     do
     {
 	if ((prev_box->x1 != cur_box->x1) || (prev_box->x2 != cur_box->x2))
 	    return (cur_start);
 	prev_box++;
 	cur_box++;
 	numRects--;
     }
     while (numRects);
     /*
      * The bands may be merged, so set the bottom y of each box
      * in the previous band to the bottom y of the current band.
      */
     numRects = cur_start - prev_start;
     region->data->numRects -= numRects;
     do
     {
 	prev_box--;
 	prev_box->y2 = y2;
 	numRects--;
     }
     while (numRects);
     return prev_start;
 }
 /* Quicky macro to avoid trivial reject procedure calls to pixman_coalesce */
 #define COALESCE(new_reg, prev_band, cur_band)                          \
     do									\
     {									\
 	if (cur_band - prev_band == new_reg->data->numRects - cur_band)	\
 	    prev_band = pixman_coalesce (new_reg, prev_band, cur_band);	\
 	else								\
 	    prev_band = cur_band;					\
     } while (0)
 /*-
  *-----------------------------------------------------------------------
  * pixman_region_append_non_o --
  *	Handle a non-overlapping band for the union and subtract operations.
  *      Just adds the (top/bottom-clipped) rectangles into the region.
  *      Doesn't have to check for subsumption or anything.
  *
  * Results:
  *	None.
  *
  * Side Effects:
  *	region->data->numRects is incremented and the rectangles overwritten
  *	with the rectangles we're passed.
  *
  *-----------------------------------------------------------------------
  */
 static inline pixman_bool_t
 pixman_region_append_non_o (region_type_t * region,
 			    box_type_t *    r,
 			    box_type_t *    r_end,
 			    int             y1,
 			    int             y2)
 {
     box_type_t *next_rect;
     int new_rects;
     new_rects = r_end - r;
     critical_if_fail (y1 < y2);
     critical_if_fail (new_rects != 0);
     /* Make sure we have enough space for all rectangles to be added */
     RECTALLOC (region, new_rects);
     next_rect = PIXREGION_TOP (region);
     region->data->numRects += new_rects;
     do
     {
 	critical_if_fail (r->x1 < r->x2);
 	ADDRECT (next_rect, r->x1, y1, r->x2, y2);
 	r++;
     }
     while (r != r_end);
     return TRUE;
 }
 #define FIND_BAND(r, r_band_end, r_end, ry1)			     \
     do								     \
     {								     \
 	ry1 = r->y1;						     \
 	r_band_end = r + 1;					     \
 	while ((r_band_end != r_end) && (r_band_end->y1 == ry1)) {   \
 	    r_band_end++;					     \
 	}							     \
     } while (0)
 #define APPEND_REGIONS(new_reg, r, r_end)				\
     do									\
     {									\
 	int new_rects;							\
 	if ((new_rects = r_end - r)) {					\
 	    RECTALLOC_BAIL (new_reg, new_rects, bail);			\
 	    memmove ((char *)PIXREGION_TOP (new_reg), (char *)r,	\
 		     new_rects * sizeof(box_type_t));			\
 	    new_reg->data->numRects += new_rects;			\
 	}								\
     } while (0)
 /*-
  *-----------------------------------------------------------------------
  * pixman_op --
  *	Apply an operation to two regions. Called by pixman_region_union, pixman_region_inverse,
  *	pixman_region_subtract, pixman_region_intersect....  Both regions MUST have at least one
  *      rectangle, and cannot be the same object.
  *
  * Results:
  *	TRUE if successful.
  *
  * Side Effects:
  *	The new region is overwritten.
  *	overlap set to TRUE if overlap_func ever returns TRUE.
  *
  * Notes:
  *	The idea behind this function is to view the two regions as sets.
  *	Together they cover a rectangle of area that this function divides
  *	into horizontal bands where points are covered only by one region
  *	or by both. For the first case, the non_overlap_func is called with
  *	each the band and the band's upper and lower extents. For the
  *	second, the overlap_func is called to process the entire band. It
  *	is responsible for clipping the rectangles in the band, though
  *	this function provides the boundaries.
  *	At the end of each band, the new region is coalesced, if possible,
  *	to reduce the number of rectangles in the region.
  *
  *-----------------------------------------------------------------------
  */
 typedef pixman_bool_t (*overlap_proc_ptr) (region_type_t *region,
 					   box_type_t *   r1,
 					   box_type_t *   r1_end,
 					   box_type_t *   r2,
 					   box_type_t *   r2_end,
 					   int            y1,
 					   int            y2);
 static pixman_bool_t
 pixman_op (region_type_t *  new_reg,               /* Place to store result	    */
 	   region_type_t *  reg1,                  /* First region in operation     */
 	   region_type_t *  reg2,                  /* 2d region in operation        */
 	   overlap_proc_ptr overlap_func,          /* Function to call for over-
 						    * lapping bands		    */
 	   int              append_non1,           /* Append non-overlapping bands
 						    * in region 1 ?
 						    */
 	   int              append_non2            /* Append non-overlapping bands
 						    * in region 2 ?
 						    */
     )
 {
     box_type_t *r1;                 /* Pointer into first region     */
     box_type_t *r2;                 /* Pointer into 2d region	     */
     box_type_t *r1_end;             /* End of 1st region	     */
     box_type_t *r2_end;             /* End of 2d region		     */
     int ybot;                       /* Bottom of intersection	     */
     int ytop;                       /* Top of intersection	     */
     region_data_type_t *old_data;   /* Old data for new_reg	     */
     int prev_band;                  /* Index of start of
 				     * previous band in new_reg       */
     int cur_band;                   /* Index of start of current
 				     * band in new_reg		     */
     box_type_t * r1_band_end;       /* End of current band in r1     */
     box_type_t * r2_band_end;       /* End of current band in r2     */
     int top;                        /* Top of non-overlapping band   */
     int bot;                        /* Bottom of non-overlapping band*/
     int r1y1;                       /* Temps for r1->y1 and r2->y1   */
     int r2y1;
     int new_size;
     int numRects;
     /*
      * Break any region computed from a broken region
      */
     if (PIXREGION_NAR (reg1) || PIXREGION_NAR (reg2))
 	return pixman_break (new_reg);
     /*
      * Initialization:
      *	set r1, r2, r1_end and r2_end appropriately, save the rectangles
      * of the destination region until the end in case it's one of
      * the two source regions, then mark the "new" region empty, allocating
      * another array of rectangles for it to use.
      */
     r1 = PIXREGION_RECTS (reg1);
     new_size = PIXREGION_NUMRECTS (reg1);
     r1_end = r1 + new_size;
     numRects = PIXREGION_NUMRECTS (reg2);
     r2 = PIXREGION_RECTS (reg2);
     r2_end = r2 + numRects;
     critical_if_fail (r1 != r1_end);
     critical_if_fail (r2 != r2_end);
     old_data = (region_data_type_t *)NULL;
     if (((new_reg == reg1) && (new_size > 1)) ||
         ((new_reg == reg2) && (numRects > 1)))
     {
         old_data = new_reg->data;
         new_reg->data = pixman_region_empty_data;
     }
     /* guess at new size */
     if (numRects > new_size)
 	new_size = numRects;
     new_size <<= 1;
     if (!new_reg->data)
 	new_reg->data = pixman_region_empty_data;
     else if (new_reg->data->size)
 	new_reg->data->numRects = 0;
     if (new_size > new_reg->data->size)
     {
         if (!pixman_rect_alloc (new_reg, new_size))
         {
             free (old_data);
             return FALSE;
 	}
     }
     /*
      * Initialize ybot.
      * In the upcoming loop, ybot and ytop serve different functions depending
      * on whether the band being handled is an overlapping or non-overlapping
      * band.
      *  In the case of a non-overlapping band (only one of the regions
      * has points in the band), ybot is the bottom of the most recent
      * intersection and thus clips the top of the rectangles in that band.
      * ytop is the top of the next intersection between the two regions and
      * serves to clip the bottom of the rectangles in the current band.
      *	For an overlapping band (where the two regions intersect), ytop clips
      * the top of the rectangles of both regions and ybot clips the bottoms.
      */
     ybot = MIN (r1->y1, r2->y1);
     /*
      * prev_band serves to mark the start of the previous band so rectangles
      * can be coalesced into larger rectangles. qv. pixman_coalesce, above.
      * In the beginning, there is no previous band, so prev_band == cur_band
      * (cur_band is set later on, of course, but the first band will always
      * start at index 0). prev_band and cur_band must be indices because of
      * the possible expansion, and resultant moving, of the new region's
      * array of rectangles.
      */
     prev_band = 0;
     do
     {
         /*
 	 * This algorithm proceeds one source-band (as opposed to a
 	 * destination band, which is determined by where the two regions
 	 * intersect) at a time. r1_band_end and r2_band_end serve to mark the
 	 * rectangle after the last one in the current band for their
 	 * respective regions.
 	 */
         critical_if_fail (r1 != r1_end);
         critical_if_fail (r2 != r2_end);
         FIND_BAND (r1, r1_band_end, r1_end, r1y1);
         FIND_BAND (r2, r2_band_end, r2_end, r2y1);
         /*
 	 * First handle the band that doesn't intersect, if any.
 	 *
 	 * Note that attention is restricted to one band in the
 	 * non-intersecting region at once, so if a region has n
 	 * bands between the current position and the next place it overlaps
 	 * the other, this entire loop will be passed through n times.
 	 */
         if (r1y1 < r2y1)
         {
             if (append_non1)
             {
                 top = MAX (r1y1, ybot);
                 bot = MIN (r1->y2, r2y1);
                 if (top != bot)
                 {
                     cur_band = new_reg->data->numRects;
                     if (!pixman_region_append_non_o (new_reg, r1, r1_band_end, top, bot))
 			goto bail;
                     COALESCE (new_reg, prev_band, cur_band);
 		}
 	    }
             ytop = r2y1;
 	}
         else if (r2y1 < r1y1)
         {
             if (append_non2)
             {
                 top = MAX (r2y1, ybot);
                 bot = MIN (r2->y2, r1y1);
                 if (top != bot)
                 {
                     cur_band = new_reg->data->numRects;
                     if (!pixman_region_append_non_o (new_reg, r2, r2_band_end, top, bot))
 			goto bail;
                     COALESCE (new_reg, prev_band, cur_band);
 		}
 	    }
             ytop = r1y1;
 	}
         else
         {
             ytop = r1y1;
 	}
         /*
 	 * Now see if we've hit an intersecting band. The two bands only
 	 * intersect if ybot > ytop
 	 */
         ybot = MIN (r1->y2, r2->y2);
         if (ybot > ytop)
         {
             cur_band = new_reg->data->numRects;
             if (!(*overlap_func)(new_reg,
                                  r1, r1_band_end,
                                  r2, r2_band_end,
                                  ytop, ybot))
 	    {
 		goto bail;
 	    }
             COALESCE (new_reg, prev_band, cur_band);
 	}
         /*
 	 * If we've finished with a band (y2 == ybot) we skip forward
 	 * in the region to the next band.
 	 */
         if (r1->y2 == ybot)
 	    r1 = r1_band_end;
         if (r2->y2 == ybot)
 	    r2 = r2_band_end;
     }
     while (r1 != r1_end && r2 != r2_end);
     /*
      * Deal with whichever region (if any) still has rectangles left.
      *
      * We only need to worry about banding and coalescing for the very first
      * band left.  After that, we can just group all remaining boxes,
      * regardless of how many bands, into one final append to the list.
      */
     if ((r1 != r1_end) && append_non1)
     {
         /* Do first non_overlap1Func call, which may be able to coalesce */
         FIND_BAND (r1, r1_band_end, r1_end, r1y1);
         cur_band = new_reg->data->numRects;
         if (!pixman_region_append_non_o (new_reg,
                                          r1, r1_band_end,
                                          MAX (r1y1, ybot), r1->y2))
 	{
 	    goto bail;
 	}
         COALESCE (new_reg, prev_band, cur_band);
         /* Just append the rest of the boxes  */
         APPEND_REGIONS (new_reg, r1_band_end, r1_end);
     }
     else if ((r2 != r2_end) && append_non2)
     {
         /* Do first non_overlap2Func call, which may be able to coalesce */
         FIND_BAND (r2, r2_band_end, r2_end, r2y1);
 	cur_band = new_reg->data->numRects;
         if (!pixman_region_append_non_o (new_reg,
                                          r2, r2_band_end,
                                          MAX (r2y1, ybot), r2->y2))
 	{
 	    goto bail;
 	}
         COALESCE (new_reg, prev_band, cur_band);
         /* Append rest of boxes */
         APPEND_REGIONS (new_reg, r2_band_end, r2_end);
     }
     free (old_data);
     if (!(numRects = new_reg->data->numRects))
     {
         FREE_DATA (new_reg);
         new_reg->data = pixman_region_empty_data;
     }
     else if (numRects == 1)
     {
         new_reg->extents = *PIXREGION_BOXPTR (new_reg);
         FREE_DATA (new_reg);
         new_reg->data = (region_data_type_t *)NULL;
     }
     else
     {
         DOWNSIZE (new_reg, numRects);
     }
     return TRUE;
 bail:
     free (old_data);
     return pixman_break (new_reg);
 }
 /*-
  *-----------------------------------------------------------------------
  * pixman_set_extents --
  *	Reset the extents of a region to what they should be. Called by
  *	pixman_region_subtract and pixman_region_intersect as they can't
  *      figure it out along the way or do so easily, as pixman_region_union can.
  *
  * Results:
  *	None.
  *
  * Side Effects:
  *	The region's 'extents' structure is overwritten.
  *
  *-----------------------------------------------------------------------
  */
 static void
 pixman_set_extents (region_type_t *region)
 {
     box_type_t *box, *box_end;
     if (!region->data)
 	return;
     if (!region->data->size)
     {
         region->extents.x2 = region->extents.x1;
         region->extents.y2 = region->extents.y1;
         return;
     }
     box = PIXREGION_BOXPTR (region);
     box_end = PIXREGION_END (region);
     /*
      * Since box is the first rectangle in the region, it must have the
      * smallest y1 and since box_end is the last rectangle in the region,
      * it must have the largest y2, because of banding. Initialize x1 and
      * x2 from  box and box_end, resp., as good things to initialize them
      * to...
      */
     region->extents.x1 = box->x1;
     region->extents.y1 = box->y1;
     region->extents.x2 = box_end->x2;
     region->extents.y2 = box_end->y2;
     critical_if_fail (region->extents.y1 < region->extents.y2);
     while (box <= box_end)
     {
         if (box->x1 < region->extents.x1)
 	    region->extents.x1 = box->x1;
         if (box->x2 > region->extents.x2)
 	    region->extents.x2 = box->x2;
         box++;
     }
     critical_if_fail (region->extents.x1 < region->extents.x2);
 }
 /*======================================================================
  *	    Region Intersection
  *====================================================================*/
 /*-
  *-----------------------------------------------------------------------
  * pixman_region_intersect_o --
  *	Handle an overlapping band for pixman_region_intersect.
  *
  * Results:
  *	TRUE if successful.
  *
  * Side Effects:
  *	Rectangles may be added to the region.
  *
  *-----------------------------------------------------------------------
  */
 /*ARGSUSED*/
 static pixman_bool_t
 pixman_region_intersect_o (region_type_t *region,
                            box_type_t *   r1,
                            box_type_t *   r1_end,
                            box_type_t *   r2,
                            box_type_t *   r2_end,
                            int            y1,
                            int            y2)
 {
     int x1;
     int x2;
     box_type_t *        next_rect;
     next_rect = PIXREGION_TOP (region);
     critical_if_fail (y1 < y2);
     critical_if_fail (r1 != r1_end && r2 != r2_end);
     do
     {
         x1 = MAX (r1->x1, r2->x1);
         x2 = MIN (r1->x2, r2->x2);
         /*
 	 * If there's any overlap between the two rectangles, add that
 	 * overlap to the new region.
 	 */
         if (x1 < x2)
 	    NEWRECT (region, next_rect, x1, y1, x2, y2);
         /*
 	 * Advance the pointer(s) with the leftmost right side, since the next
 	 * rectangle on that list may still overlap the other region's
 	 * current rectangle.
 	 */
         if (r1->x2 == x2)
         {
             r1++;
 	}
         if (r2->x2 == x2)
         {
             r2++;
 	}
     }
     while ((r1 != r1_end) && (r2 != r2_end));
     return TRUE;
 }
 PIXMAN_EXPORT pixman_bool_t
 PREFIX (_intersect) (region_type_t *     new_reg,
                      region_type_t *        reg1,
                      region_type_t *        reg2)
 {
     GOOD (reg1);
     GOOD (reg2);
     GOOD (new_reg);
     /* check for trivial reject */
     if (PIXREGION_NIL (reg1) || PIXREGION_NIL (reg2) ||
         !EXTENTCHECK (&reg1->extents, &reg2->extents))
     {
         /* Covers about 20% of all cases */
         FREE_DATA (new_reg);
         new_reg->extents.x2 = new_reg->extents.x1;
         new_reg->extents.y2 = new_reg->extents.y1;
         if (PIXREGION_NAR (reg1) || PIXREGION_NAR (reg2))
         {
             new_reg->data = pixman_broken_data;
             return FALSE;
 	}
         else
 	{
 	    new_reg->data = pixman_region_empty_data;
 	}
     }
     else if (!reg1->data && !reg2->data)
     {
         /* Covers about 80% of cases that aren't trivially rejected */
         new_reg->extents.x1 = MAX (reg1->extents.x1, reg2->extents.x1);
         new_reg->extents.y1 = MAX (reg1->extents.y1, reg2->extents.y1);
         new_reg->extents.x2 = MIN (reg1->extents.x2, reg2->extents.x2);
         new_reg->extents.y2 = MIN (reg1->extents.y2, reg2->extents.y2);
         FREE_DATA (new_reg);
 	new_reg->data = (region_data_type_t *)NULL;
     }
     else if (!reg2->data && SUBSUMES (&reg2->extents, &reg1->extents))
     {
         return PREFIX (_copy) (new_reg, reg1);
     }
     else if (!reg1->data && SUBSUMES (&reg1->extents, &reg2->extents))
     {
         return PREFIX (_copy) (new_reg, reg2);
     }
     else if (reg1 == reg2)
     {
         return PREFIX (_copy) (new_reg, reg1);
     }
     else
     {
         /* General purpose intersection */
         if (!pixman_op (new_reg, reg1, reg2, pixman_region_intersect_o, FALSE, FALSE))
 	    return FALSE;
         pixman_set_extents (new_reg);
     }
     GOOD (new_reg);
     return(TRUE);
 }
 #define MERGERECT(r)							\
     do									\
     {									\
         if (r->x1 <= x2)						\
 	{								\
             /* Merge with current rectangle */				\
             if (x2 < r->x2)						\
 		x2 = r->x2;						\
 	}								\
 	else								\
 	{								\
             /* Add current rectangle, start new one */			\
             NEWRECT (region, next_rect, x1, y1, x2, y2);		\
             x1 = r->x1;							\
             x2 = r->x2;							\
 	}								\
         r++;								\
     } while (0)
 /*======================================================================
  *	    Region Union
  *====================================================================*/
 /*-
  *-----------------------------------------------------------------------
  * pixman_region_union_o --
  *	Handle an overlapping band for the union operation. Picks the
  *	left-most rectangle each time and merges it into the region.
  *
  * Results:
  *	TRUE if successful.
  *
  * Side Effects:
  *	region is overwritten.
  *	overlap is set to TRUE if any boxes overlap.
  *
  *-----------------------------------------------------------------------
  */
 static pixman_bool_t
 pixman_region_union_o (region_type_t *region,
 		       box_type_t *   r1,
 		       box_type_t *   r1_end,
 		       box_type_t *   r2,
 		       box_type_t *   r2_end,
 		       int            y1,
 		       int            y2)
 {
     box_type_t *next_rect;
     int x1;            /* left and right side of current union */
     int x2;
     critical_if_fail (y1 < y2);
     critical_if_fail (r1 != r1_end && r2 != r2_end);
     next_rect = PIXREGION_TOP (region);
     /* Start off current rectangle */
     if (r1->x1 < r2->x1)
     {
         x1 = r1->x1;
         x2 = r1->x2;
         r1++;
     }
     else
     {
         x1 = r2->x1;
         x2 = r2->x2;
         r2++;
     }
     while (r1 != r1_end && r2 != r2_end)
     {
         if (r1->x1 < r2->x1)
 	    MERGERECT (r1);
 	else
 	    MERGERECT (r2);
     }
     /* Finish off whoever (if any) is left */
     if (r1 != r1_end)
     {
         do
         {
             MERGERECT (r1);
 	}
         while (r1 != r1_end);
     }
     else if (r2 != r2_end)
     {
         do
         {
             MERGERECT (r2);
 	}
         while (r2 != r2_end);
     }
     /* Add current rectangle */
     NEWRECT (region, next_rect, x1, y1, x2, y2);
     return TRUE;
 }
 PIXMAN_EXPORT pixman_bool_t
 PREFIX(_intersect_rect) (region_type_t *dest,
 			 region_type_t *source,
 			 int x, int y,
 			 unsigned int width,
 			 unsigned int height)
 {
     region_type_t region;
     region.data = NULL;
     region.extents.x1 = x;
     region.extents.y1 = y;
     region.extents.x2 = x + width;
     region.extents.y2 = y + height;
     return PREFIX(_intersect) (dest, source, &region);
 }
 /* Convenience function for performing union of region with a
  * single rectangle
  */
 PIXMAN_EXPORT pixman_bool_t
 PREFIX (_union_rect) (region_type_t *dest,
                       region_type_t *source,
                       int            x,
 		      int            y,
                       unsigned int   width,
 		      unsigned int   height)
 {
     region_type_t region;
     region.extents.x1 = x;
     region.extents.y1 = y;
     region.extents.x2 = x + width;
     region.extents.y2 = y + height;
     if (!GOOD_RECT (&region.extents))
     {
         if (BAD_RECT (&region.extents))
             _pixman_log_error (FUNC, "Invalid rectangle passed");
 	return PREFIX (_copy) (dest, source);
     }
     region.data = NULL;
     return PREFIX (_union) (dest, source, &region);
 }
 PIXMAN_EXPORT pixman_bool_t
 PREFIX (_union) (region_type_t *new_reg,
                  region_type_t *reg1,
                  region_type_t *reg2)
 {
     /* Return TRUE if some overlap
      * between reg1, reg2
      */
     GOOD (reg1);
     GOOD (reg2);
     GOOD (new_reg);
     /*  checks all the simple cases */
     /*
      * Region 1 and 2 are the same
      */
     if (reg1 == reg2)
         return PREFIX (_copy) (new_reg, reg1);
     /*
      * Region 1 is empty
      */
     if (PIXREGION_NIL (reg1))
     {
         if (PIXREGION_NAR (reg1))
 	    return pixman_break (new_reg);
         if (new_reg != reg2)
 	    return PREFIX (_copy) (new_reg, reg2);
 	return TRUE;
     }
     /*
      * Region 2 is empty
      */
     if (PIXREGION_NIL (reg2))
     {
         if (PIXREGION_NAR (reg2))
 	    return pixman_break (new_reg);
 	if (new_reg != reg1)
 	    return PREFIX (_copy) (new_reg, reg1);
 	return TRUE;
     }
     /*
      * Region 1 completely subsumes region 2
      */
     if (!reg1->data && SUBSUMES (&reg1->extents, &reg2->extents))
     {
         if (new_reg != reg1)
 	    return PREFIX (_copy) (new_reg, reg1);
 	return TRUE;
     }
     /*
      * Region 2 completely subsumes region 1
      */
     if (!reg2->data && SUBSUMES (&reg2->extents, &reg1->extents))
     {
         if (new_reg != reg2)
 	    return PREFIX (_copy) (new_reg, reg2);
 	return TRUE;
     }
     if (!pixman_op (new_reg, reg1, reg2, pixman_region_union_o, TRUE, TRUE))
 	return FALSE;
     new_reg->extents.x1 = MIN (reg1->extents.x1, reg2->extents.x1);
     new_reg->extents.y1 = MIN (reg1->extents.y1, reg2->extents.y1);
     new_reg->extents.x2 = MAX (reg1->extents.x2, reg2->extents.x2);
     new_reg->extents.y2 = MAX (reg1->extents.y2, reg2->extents.y2);
     GOOD (new_reg);
     return TRUE;
 }
 /*======================================================================
  *	    Batch Rectangle Union
  *====================================================================*/
 #define EXCHANGE_RECTS(a, b)	\
     {                           \
         box_type_t t;		\
         t = rects[a];           \
         rects[a] = rects[b];    \
         rects[b] = t;           \
     }
 static void
 quick_sort_rects (
     box_type_t rects[],
     int        numRects)
 {
     int y1;
     int x1;
     int i, j;
     box_type_t *r;
     /* Always called with numRects > 1 */
     do
     {
         if (numRects == 2)
         {
             if (rects[0].y1 > rects[1].y1 ||
                 (rects[0].y1 == rects[1].y1 && rects[0].x1 > rects[1].x1))
 	    {
 		EXCHANGE_RECTS (0, 1);
 	    }
             return;
 	}
         /* Choose partition element, stick in location 0 */
         EXCHANGE_RECTS (0, numRects >> 1);
         y1 = rects[0].y1;
         x1 = rects[0].x1;
         /* Partition array */
         i = 0;
         j = numRects;
         do
         {
             r = &(rects[i]);
             do
             {
                 r++;
                 i++;
 	    }
 	    while (i != numRects && (r->y1 < y1 || (r->y1 == y1 && r->x1 < x1)));
 	    r = &(rects[j]);
             do
             {
                 r--;
                 j--;
 	    }
             while (y1 < r->y1 || (y1 == r->y1 && x1 < r->x1));
             if (i < j)
 		EXCHANGE_RECTS (i, j);
 	}
         while (i < j);
         /* Move partition element back to middle */
         EXCHANGE_RECTS (0, j);
         /* Recurse */
         if (numRects - j - 1 > 1)
 	    quick_sort_rects (&rects[j + 1], numRects - j - 1);
         numRects = j;
     }
     while (numRects > 1);
 }
 /*-
  *-----------------------------------------------------------------------
  * pixman_region_validate --
  *
  *      Take a ``region'' which is a non-y-x-banded random collection of
  *      rectangles, and compute a nice region which is the union of all the
  *      rectangles.
  *
  * Results:
  *	TRUE if successful.
  *
  * Side Effects:
  *      The passed-in ``region'' may be modified.
  *	overlap set to TRUE if any retangles overlapped,
  *      else FALSE;
  *
  * Strategy:
  *      Step 1. Sort the rectangles into ascending order with primary key y1
  *		and secondary key x1.
  *
  *      Step 2. Split the rectangles into the minimum number of proper y-x
  *		banded regions.  This may require horizontally merging
  *		rectangles, and vertically coalescing bands.  With any luck,
  *		this step in an identity transformation (ala the Box widget),
  *		or a coalescing into 1 box (ala Menus).
  *
  *	Step 3. Merge the separate regions down to a single region by calling
  *		pixman_region_union.  Maximize the work each pixman_region_union call does by using
  *		a binary merge.
  *
  *-----------------------------------------------------------------------
  */
 static pixman_bool_t
 validate (region_type_t * badreg)
 {
     /* Descriptor for regions under construction  in Step 2. */
     typedef struct
     {
         region_type_t reg;
         int prev_band;
         int cur_band;
     } region_info_t;
     region_info_t stack_regions[64];
     int numRects;                   /* Original numRects for badreg	    */
     region_info_t *ri;              /* Array of current regions		    */
     int num_ri;                     /* Number of entries used in ri	    */
     int size_ri;                    /* Number of entries available in ri    */
     int i;                          /* Index into rects			    */
     int j;                          /* Index into ri			    */
     region_info_t *rit;             /* &ri[j]				    */
     region_type_t *reg;             /* ri[j].reg			    */
     box_type_t *box;                /* Current box in rects		    */
     box_type_t *ri_box;             /* Last box in ri[j].reg		    */
     region_type_t *hreg;            /* ri[j_half].reg			    */
     pixman_bool_t ret = TRUE;
     if (!badreg->data)
     {
         GOOD (badreg);
         return TRUE;
     }
     numRects = badreg->data->numRects;
     if (!numRects)
     {
         if (PIXREGION_NAR (badreg))
 	    return FALSE;
         GOOD (badreg);
         return TRUE;
     }
     if (badreg->extents.x1 < badreg->extents.x2)
     {
         if ((numRects) == 1)
         {
             FREE_DATA (badreg);
             badreg->data = (region_data_type_t *) NULL;
 	}
         else
         {
             DOWNSIZE (badreg, numRects);
 	}
         GOOD (badreg);
 	return TRUE;
     }
     /* Step 1: Sort the rects array into ascending (y1, x1) order */
     quick_sort_rects (PIXREGION_BOXPTR (badreg), numRects);
     /* Step 2: Scatter the sorted array into the minimum number of regions */
     /* Set up the first region to be the first rectangle in badreg */
     /* Note that step 2 code will never overflow the ri[0].reg rects array */
     ri = stack_regions;
     size_ri = sizeof (stack_regions) / sizeof (stack_regions[0]);
     num_ri = 1;
     ri[0].prev_band = 0;
     ri[0].cur_band = 0;
     ri[0].reg = *badreg;
     box = PIXREGION_BOXPTR (&ri[0].reg);
     ri[0].reg.extents = *box;
     ri[0].reg.data->numRects = 1;
     badreg->extents = *pixman_region_empty_box;
     badreg->data = pixman_region_empty_data;
     /* Now scatter rectangles into the minimum set of valid regions.  If the
      * next rectangle to be added to a region would force an existing rectangle
      * in the region to be split up in order to maintain y-x banding, just
      * forget it.  Try the next region.  If it doesn't fit cleanly into any
      * region, make a new one.
      */
     for (i = numRects; --i > 0;)
     {
         box++;
         /* Look for a region to append box to */
         for (j = num_ri, rit = ri; --j >= 0; rit++)
         {
             reg = &rit->reg;
             ri_box = PIXREGION_END (reg);
             if (box->y1 == ri_box->y1 && box->y2 == ri_box->y2)
             {
                 /* box is in same band as ri_box.  Merge or append it */
                 if (box->x1 <= ri_box->x2)
                 {
                     /* Merge it with ri_box */
                     if (box->x2 > ri_box->x2)
 			ri_box->x2 = box->x2;
 		}
                 else
                 {
                     RECTALLOC_BAIL (reg, 1, bail);
                     *PIXREGION_TOP (reg) = *box;
                     reg->data->numRects++;
 		}
                 goto next_rect;   /* So sue me */
 	    }
             else if (box->y1 >= ri_box->y2)
             {
                 /* Put box into new band */
                 if (reg->extents.x2 < ri_box->x2)
 		    reg->extents.x2 = ri_box->x2;
                 if (reg->extents.x1 > box->x1)
 		    reg->extents.x1 = box->x1;
                 COALESCE (reg, rit->prev_band, rit->cur_band);
                 rit->cur_band = reg->data->numRects;
                 RECTALLOC_BAIL (reg, 1, bail);
                 *PIXREGION_TOP (reg) = *box;
                 reg->data->numRects++;
                 goto next_rect;
 	    }
             /* Well, this region was inappropriate.  Try the next one. */
 	} /* for j */
         /* Uh-oh.  No regions were appropriate.  Create a new one. */
         if (size_ri == num_ri)
         {
             size_t data_size;
             /* Oops, allocate space for new region information */
             size_ri <<= 1;
             data_size = size_ri * sizeof(region_info_t);
             if (data_size / size_ri != sizeof(region_info_t))
 		goto bail;
             if (ri == stack_regions)
             {
                 rit = malloc (data_size);
                 if (!rit)
 		    goto bail;
                 memcpy (rit, ri, num_ri * sizeof (region_info_t));
 	    }
             else
             {
                 rit = (region_info_t *) realloc (ri, data_size);
                 if (!rit)
 		    goto bail;
 	    }
             ri = rit;
             rit = &ri[num_ri];
 	}
         num_ri++;
         rit->prev_band = 0;
         rit->cur_band = 0;
         rit->reg.extents = *box;
         rit->reg.data = (region_data_type_t *)NULL;
 	/* MUST force allocation */
         if (!pixman_rect_alloc (&rit->reg, (i + num_ri) / num_ri))
 	    goto bail;
     next_rect: ;
     } /* for i */
     /* Make a final pass over each region in order to COALESCE and set
      * extents.x2 and extents.y2
      */
     for (j = num_ri, rit = ri; --j >= 0; rit++)
     {
         reg = &rit->reg;
         ri_box = PIXREGION_END (reg);
         reg->extents.y2 = ri_box->y2;
         if (reg->extents.x2 < ri_box->x2)
 	    reg->extents.x2 = ri_box->x2;
         COALESCE (reg, rit->prev_band, rit->cur_band);
 	if (reg->data->numRects == 1) /* keep unions happy below */
         {
             FREE_DATA (reg);
             reg->data = (region_data_type_t *)NULL;
 	}
     }
     /* Step 3: Union all regions into a single region */
     while (num_ri > 1)
     {
         int half = num_ri / 2;
         for (j = num_ri & 1; j < (half + (num_ri & 1)); j++)
         {
             reg = &ri[j].reg;
             hreg = &ri[j + half].reg;
             if (!pixman_op (reg, reg, hreg, pixman_region_union_o, TRUE, TRUE))
 		ret = FALSE;
             if (hreg->extents.x1 < reg->extents.x1)
 		reg->extents.x1 = hreg->extents.x1;
             if (hreg->extents.y1 < reg->extents.y1)
 		reg->extents.y1 = hreg->extents.y1;
             if (hreg->extents.x2 > reg->extents.x2)
 		reg->extents.x2 = hreg->extents.x2;
             if (hreg->extents.y2 > reg->extents.y2)
 		reg->extents.y2 = hreg->extents.y2;
             FREE_DATA (hreg);
 	}
         num_ri -= half;
 	if (!ret)
 	    goto bail;
     }
     *badreg = ri[0].reg;
     if (ri != stack_regions)
 	free (ri);
     GOOD (badreg);
     return ret;
 bail:
     for (i = 0; i < num_ri; i++)
 	FREE_DATA (&ri[i].reg);
     if (ri != stack_regions)
 	free (ri);
     return pixman_break (badreg);
 }
 /*======================================================================
  *                Region Subtraction
  *====================================================================*/
 /*-
  *-----------------------------------------------------------------------
  * pixman_region_subtract_o --
  *	Overlapping band subtraction. x1 is the left-most point not yet
  *	checked.
  *
  * Results:
  *	TRUE if successful.
  *
  * Side Effects:
  *	region may have rectangles added to it.
  *
  *-----------------------------------------------------------------------
  */
 /*ARGSUSED*/
 static pixman_bool_t
 pixman_region_subtract_o (region_type_t * region,
 			  box_type_t *    r1,
 			  box_type_t *    r1_end,
 			  box_type_t *    r2,
 			  box_type_t *    r2_end,
 			  int             y1,
 			  int             y2)
 {
     box_type_t *        next_rect;
     int x1;
     x1 = r1->x1;
     critical_if_fail (y1 < y2);
     critical_if_fail (r1 != r1_end && r2 != r2_end);
     next_rect = PIXREGION_TOP (region);
     do
     {
         if (r2->x2 <= x1)
         {
             /*
 	     * Subtrahend entirely to left of minuend: go to next subtrahend.
 	     */
             r2++;
 	}
         else if (r2->x1 <= x1)
         {
             /*
 	     * Subtrahend preceeds minuend: nuke left edge of minuend.
 	     */
             x1 = r2->x2;
             if (x1 >= r1->x2)
             {
                 /*
 		 * Minuend completely covered: advance to next minuend and
 		 * reset left fence to edge of new minuend.
 		 */
                 r1++;
                 if (r1 != r1_end)
 		    x1 = r1->x1;
 	    }
             else
             {
                 /*
 		 * Subtrahend now used up since it doesn't extend beyond
 		 * minuend
 		 */
                 r2++;
 	    }
 	}
         else if (r2->x1 < r1->x2)
         {
             /*
 	     * Left part of subtrahend covers part of minuend: add uncovered
 	     * part of minuend to region and skip to next subtrahend.
 	     */
             critical_if_fail (x1 < r2->x1);
             NEWRECT (region, next_rect, x1, y1, r2->x1, y2);
             x1 = r2->x2;
             if (x1 >= r1->x2)
             {
                 /*
 		 * Minuend used up: advance to new...
 		 */
                 r1++;
                 if (r1 != r1_end)
 		    x1 = r1->x1;
 	    }
             else
             {
                 /*
 		 * Subtrahend used up
 		 */
                 r2++;
 	    }
 	}
         else
         {
             /*
 	     * Minuend used up: add any remaining piece before advancing.
 	     */
             if (r1->x2 > x1)
 		NEWRECT (region, next_rect, x1, y1, r1->x2, y2);
             r1++;
 	    if (r1 != r1_end)
 		x1 = r1->x1;
 	}
     }
     while ((r1 != r1_end) && (r2 != r2_end));
     /*
      * Add remaining minuend rectangles to region.
      */
     while (r1 != r1_end)
     {
         critical_if_fail (x1 < r1->x2);
         NEWRECT (region, next_rect, x1, y1, r1->x2, y2);
         r1++;
         if (r1 != r1_end)
 	    x1 = r1->x1;
     }
     return TRUE;
 }
 /*-
  *-----------------------------------------------------------------------
  * pixman_region_subtract --
  *	Subtract reg_s from reg_m and leave the result in reg_d.
  *	S stands for subtrahend, M for minuend and D for difference.
  *
  * Results:
  *	TRUE if successful.
  *
  * Side Effects:
  *	reg_d is overwritten.
  *
  *-----------------------------------------------------------------------
  */
 PIXMAN_EXPORT pixman_bool_t
 PREFIX (_subtract) (region_type_t *reg_d,
                     region_type_t *reg_m,
                     region_type_t *reg_s)
 {
     GOOD (reg_m);
     GOOD (reg_s);
     GOOD (reg_d);
     /* check for trivial rejects */
     if (PIXREGION_NIL (reg_m) || PIXREGION_NIL (reg_s) ||
         !EXTENTCHECK (&reg_m->extents, &reg_s->extents))
     {
         if (PIXREGION_NAR (reg_s))
 	    return pixman_break (reg_d);
         return PREFIX (_copy) (reg_d, reg_m);
     }
     else if (reg_m == reg_s)
     {
         FREE_DATA (reg_d);
         reg_d->extents.x2 = reg_d->extents.x1;
         reg_d->extents.y2 = reg_d->extents.y1;
         reg_d->data = pixman_region_empty_data;
         return TRUE;
     }
     /* Add those rectangles in region 1 that aren't in region 2,
        do yucky substraction for overlaps, and
        just throw away rectangles in region 2 that aren't in region 1 */
     if (!pixman_op (reg_d, reg_m, reg_s, pixman_region_subtract_o, TRUE, FALSE))
 	return FALSE;
     /*
      * Can't alter reg_d's extents before we call pixman_op because
      * it might be one of the source regions and pixman_op depends
      * on the extents of those regions being unaltered. Besides, this
      * way there's no checking against rectangles that will be nuked
      * due to coalescing, so we have to examine fewer rectangles.
      */
     pixman_set_extents (reg_d);
     GOOD (reg_d);
     return TRUE;
 }
 /*======================================================================
  *	    Region Inversion
  *====================================================================*/
 /*-
  *-----------------------------------------------------------------------
  * pixman_region_inverse --
  *	Take a region and a box and return a region that is everything
  *	in the box but not in the region. The careful reader will note
  *	that this is the same as subtracting the region from the box...
  *
  * Results:
  *	TRUE.
  *
  * Side Effects:
  *	new_reg is overwritten.
  *
  *-----------------------------------------------------------------------
  */
 PIXMAN_EXPORT pixman_bool_t
 PREFIX (_inverse) (region_type_t *new_reg,  /* Destination region */
 		   region_type_t *reg1,     /* Region to invert */
 		   box_type_t *   inv_rect) /* Bounding box for inversion */
 {
     region_type_t inv_reg; /* Quick and dirty region made from the
 			    * bounding box */
     GOOD (reg1);
     GOOD (new_reg);
     /* check for trivial rejects */
     if (PIXREGION_NIL (reg1) || !EXTENTCHECK (inv_rect, &reg1->extents))
     {
         if (PIXREGION_NAR (reg1))
 	    return pixman_break (new_reg);
         new_reg->extents = *inv_rect;
         FREE_DATA (new_reg);
         new_reg->data = (region_data_type_t *)NULL;
         return TRUE;
     }
     /* Add those rectangles in region 1 that aren't in region 2,
      * do yucky substraction for overlaps, and
      * just throw away rectangles in region 2 that aren't in region 1
      */
     inv_reg.extents = *inv_rect;
     inv_reg.data = (region_data_type_t *)NULL;
     if (!pixman_op (new_reg, &inv_reg, reg1, pixman_region_subtract_o, TRUE, FALSE))
 	return FALSE;
     /*
      * Can't alter new_reg's extents before we call pixman_op because
      * it might be one of the source regions and pixman_op depends
      * on the extents of those regions being unaltered. Besides, this
      * way there's no checking against rectangles that will be nuked
      * due to coalescing, so we have to examine fewer rectangles.
      */
     pixman_set_extents (new_reg);
     GOOD (new_reg);
     return TRUE;
 }
 /* In time O(log n), locate the first box whose y2 is greater than y.
  * Return @end if no such box exists.
  */
 static box_type_t *
 find_box_for_y (box_type_t *begin, box_type_t *end, int y)
 {
     box_type_t *mid;
     if (end == begin)
 	return end;
     if (end - begin == 1)
     {
 	if (begin->y2 > y)
 	    return begin;
 	else
 	    return end;
     }
     mid = begin + (end - begin) / 2;
     if (mid->y2 > y)
     {
 	/* If no box is found in [begin, mid], the function
 	 * will return @mid, which is then known to be the
 	 * correct answer.
 	 */
 	return find_box_for_y (begin, mid, y);
     }
     else
     {
 	return find_box_for_y (mid, end, y);
     }
 }
 /*
  *   rect_in(region, rect)
  *   This routine takes a pointer to a region and a pointer to a box
  *   and determines if the box is outside/inside/partly inside the region.
  *
  *   The idea is to travel through the list of rectangles trying to cover the
  *   passed box with them. Anytime a piece of the rectangle isn't covered
  *   by a band of rectangles, part_out is set TRUE. Any time a rectangle in
  *   the region covers part of the box, part_in is set TRUE. The process ends
  *   when either the box has been completely covered (we reached a band that
  *   doesn't overlap the box, part_in is TRUE and part_out is false), the
  *   box has been partially covered (part_in == part_out == TRUE -- because of
  *   the banding, the first time this is true we know the box is only
  *   partially in the region) or is outside the region (we reached a band
  *   that doesn't overlap the box at all and part_in is false)
  */
 PIXMAN_EXPORT pixman_region_overlap_t
 PREFIX (_contains_rectangle) (region_type_t *  region,
 			      box_type_t *     prect)
 {
     box_type_t *     pbox;
     box_type_t *     pbox_end;
     int part_in, part_out;
     int numRects;
     int x, y;
     GOOD (region);
     numRects = PIXREGION_NUMRECTS (region);
     /* useful optimization */
     if (!numRects || !EXTENTCHECK (&region->extents, prect))
 	return(PIXMAN_REGION_OUT);
     if (numRects == 1)
     {
         /* We know that it must be PIXMAN_REGION_IN or PIXMAN_REGION_PART */
         if (SUBSUMES (&region->extents, prect))
 	    return(PIXMAN_REGION_IN);
         else
 	    return(PIXMAN_REGION_PART);
     }
     part_out = FALSE;
     part_in = FALSE;
     /* (x,y) starts at upper left of rect, moving to the right and down */
     x = prect->x1;
     y = prect->y1;
     /* can stop when both part_out and part_in are TRUE, or we reach prect->y2 */
     for (pbox = PIXREGION_BOXPTR (region), pbox_end = pbox + numRects;
 	 pbox != pbox_end;
 	 pbox++)
     {
 	/* getting up to speed or skipping remainder of band */
 	if (pbox->y2 <= y)
 	{
 	    if ((pbox = find_box_for_y (pbox, pbox_end, y)) == pbox_end)
 		break;
 	}
         if (pbox->y1 > y)
         {
             part_out = TRUE;     /* missed part of rectangle above */
             if (part_in || (pbox->y1 >= prect->y2))
 		break;
             y = pbox->y1;       /* x guaranteed to be == prect->x1 */
 	}
         if (pbox->x2 <= x)
 	    continue;           /* not far enough over yet */
         if (pbox->x1 > x)
         {
             part_out = TRUE;     /* missed part of rectangle to left */
             if (part_in)
 		break;
 	}
         if (pbox->x1 < prect->x2)
         {
             part_in = TRUE;      /* definitely overlap */
             if (part_out)
 		break;
 	}
         if (pbox->x2 >= prect->x2)
         {
             y = pbox->y2;       /* finished with this band */
             if (y >= prect->y2)
 		break;
             x = prect->x1;      /* reset x out to left again */
 	}
         else
         {
             /*
 	     * Because boxes in a band are maximal width, if the first box
 	     * to overlap the rectangle doesn't completely cover it in that
 	     * band, the rectangle must be partially out, since some of it
 	     * will be uncovered in that band. part_in will have been set true
 	     * by now...
 	     */
             part_out = TRUE;
             break;
 	}
     }
     if (part_in)
     {
         if (y < prect->y2)
 	    return PIXMAN_REGION_PART;
         else
 	    return PIXMAN_REGION_IN;
     }
     else
     {
         return PIXMAN_REGION_OUT;
     }
 }
 /* PREFIX(_translate) (region, x, y)
  * translates in place
  */
 PIXMAN_EXPORT void
 PREFIX (_translate) (region_type_t *region, int x, int y)
 {
     overflow_int_t x1, x2, y1, y2;
     int nbox;
     box_type_t * pbox;
     GOOD (region);
     region->extents.x1 = x1 = region->extents.x1 + x;
     region->extents.y1 = y1 = region->extents.y1 + y;
     region->extents.x2 = x2 = region->extents.x2 + x;
     region->extents.y2 = y2 = region->extents.y2 + y;
     if (((x1 - PIXMAN_REGION_MIN) | (y1 - PIXMAN_REGION_MIN) | (PIXMAN_REGION_MAX - x2) | (PIXMAN_REGION_MAX - y2)) >= 0)
     {
         if (region->data && (nbox = region->data->numRects))
         {
             for (pbox = PIXREGION_BOXPTR (region); nbox--; pbox++)
             {
                 pbox->x1 += x;
                 pbox->y1 += y;
                 pbox->x2 += x;
                 pbox->y2 += y;
 	    }
 	}
         return;
     }
     if (((x2 - PIXMAN_REGION_MIN) | (y2 - PIXMAN_REGION_MIN) | (PIXMAN_REGION_MAX - x1) | (PIXMAN_REGION_MAX - y1)) <= 0)
     {
         region->extents.x2 = region->extents.x1;
         region->extents.y2 = region->extents.y1;
         FREE_DATA (region);
         region->data = pixman_region_empty_data;
         return;
     }
     if (x1 < PIXMAN_REGION_MIN)
 	region->extents.x1 = PIXMAN_REGION_MIN;
     else if (x2 > PIXMAN_REGION_MAX)
 	region->extents.x2 = PIXMAN_REGION_MAX;
     if (y1 < PIXMAN_REGION_MIN)
 	region->extents.y1 = PIXMAN_REGION_MIN;
     else if (y2 > PIXMAN_REGION_MAX)
 	region->extents.y2 = PIXMAN_REGION_MAX;
     if (region->data && (nbox = region->data->numRects))
     {
         box_type_t * pbox_out;
         for (pbox_out = pbox = PIXREGION_BOXPTR (region); nbox--; pbox++)
         {
             pbox_out->x1 = x1 = pbox->x1 + x;
             pbox_out->y1 = y1 = pbox->y1 + y;
             pbox_out->x2 = x2 = pbox->x2 + x;
             pbox_out->y2 = y2 = pbox->y2 + y;
             if (((x2 - PIXMAN_REGION_MIN) | (y2 - PIXMAN_REGION_MIN) |
                  (PIXMAN_REGION_MAX - x1) | (PIXMAN_REGION_MAX - y1)) <= 0)
             {
                 region->data->numRects--;
                 continue;
 	    }
             if (x1 < PIXMAN_REGION_MIN)
 		pbox_out->x1 = PIXMAN_REGION_MIN;
             else if (x2 > PIXMAN_REGION_MAX)
 		pbox_out->x2 = PIXMAN_REGION_MAX;
             if (y1 < PIXMAN_REGION_MIN)
 		pbox_out->y1 = PIXMAN_REGION_MIN;
             else if (y2 > PIXMAN_REGION_MAX)
 		pbox_out->y2 = PIXMAN_REGION_MAX;
             pbox_out++;
 	}
         if (pbox_out != pbox)
         {
             if (region->data->numRects == 1)
             {
                 region->extents = *PIXREGION_BOXPTR (region);
                 FREE_DATA (region);
                 region->data = (region_data_type_t *)NULL;
 	    }
             else
 	    {
 		pixman_set_extents (region);
 	    }
 	}
     }
     GOOD (region);
 }
 PIXMAN_EXPORT void
 PREFIX (_reset) (region_type_t *region, box_type_t *box)
 {
     GOOD (region);
     critical_if_fail (GOOD_RECT (box));
     region->extents = *box;
     FREE_DATA (region);
     region->data = NULL;
 }
 PIXMAN_EXPORT void
 PREFIX (_clear) (region_type_t *region)
 {
     GOOD (region);
     FREE_DATA (region);
     region->extents = *pixman_region_empty_box;
     region->data = pixman_region_empty_data;
 }
 /* box is "return" value */
 PIXMAN_EXPORT int
 PREFIX (_contains_point) (region_type_t * region,
                           int x, int y,
                           box_type_t * box)
 {
     box_type_t *pbox, *pbox_end;
     int numRects;
     GOOD (region);
     numRects = PIXREGION_NUMRECTS (region);
     if (!numRects || !INBOX (&region->extents, x, y))
 	return(FALSE);
     if (numRects == 1)
     {
         if (box)
 	    *box = region->extents;
         return(TRUE);
     }
     pbox = PIXREGION_BOXPTR (region);
     pbox_end = pbox + numRects;
     pbox = find_box_for_y (pbox, pbox_end, y);
     for (;pbox != pbox_end; pbox++)
     {
         if ((y < pbox->y1) || (x < pbox->x1))
 	    break;              /* missed it */
         if (x >= pbox->x2)
 	    continue;           /* not there yet */
         if (box)
 	    *box = *pbox;
         return(TRUE);
     }
     return(FALSE);
 }
 PIXMAN_EXPORT int
 PREFIX (_not_empty) (region_type_t * region)
 {
     GOOD (region);
     return(!PIXREGION_NIL (region));
 }
 PIXMAN_EXPORT box_type_t *
 PREFIX (_extents) (region_type_t * region)
 {
     GOOD (region);
     return(&region->extents);
 }
 /*
  * Clip a list of scanlines to a region.  The caller has allocated the
  * space.  FSorted is non-zero if the scanline origins are in ascending order.
  *
  * returns the number of new, clipped scanlines.
  */
 PIXMAN_EXPORT pixman_bool_t
 PREFIX (_selfcheck) (region_type_t *reg)
 {
     int i, numRects;
     if ((reg->extents.x1 > reg->extents.x2) ||
         (reg->extents.y1 > reg->extents.y2))
     {
 	return FALSE;
     }
     numRects = PIXREGION_NUMRECTS (reg);
     if (!numRects)
     {
 	return ((reg->extents.x1 == reg->extents.x2) &&
 	        (reg->extents.y1 == reg->extents.y2) &&
 	        (reg->data->size || (reg->data == pixman_region_empty_data)));
     }
     else if (numRects == 1)
     {
 	return (!reg->data);
     }
     else
     {
         box_type_t * pbox_p, * pbox_n;
         box_type_t box;
         pbox_p = PIXREGION_RECTS (reg);
         box = *pbox_p;
         box.y2 = pbox_p[numRects - 1].y2;
         pbox_n = pbox_p + 1;
         for (i = numRects; --i > 0; pbox_p++, pbox_n++)
         {
             if ((pbox_n->x1 >= pbox_n->x2) ||
                 (pbox_n->y1 >= pbox_n->y2))
 	    {
 		return FALSE;
 	    }
             if (pbox_n->x1 < box.x1)
 		box.x1 = pbox_n->x1;
             if (pbox_n->x2 > box.x2)
 		box.x2 = pbox_n->x2;
             if ((pbox_n->y1 < pbox_p->y1) ||
                 ((pbox_n->y1 == pbox_p->y1) &&
                  ((pbox_n->x1 < pbox_p->x2) || (pbox_n->y2 != pbox_p->y2))))
 	    {
 		return FALSE;
 	    }
 	}
         return ((box.x1 == reg->extents.x1) &&
                 (box.x2 == reg->extents.x2) &&
                 (box.y1 == reg->extents.y1) &&
                 (box.y2 == reg->extents.y2));
     }
 }
 PIXMAN_EXPORT pixman_bool_t
 PREFIX (_init_rects) (region_type_t *region,
                       const box_type_t *boxes, int count)
 {
     box_type_t *rects;
     int displacement;
     int i;
     /* if it's 1, then we just want to set the extents, so call
      * the existing method. */
     if (count == 1)
     {
         PREFIX (_init_rect) (region,
                              boxes[0].x1,
                              boxes[0].y1,
                              boxes[0].x2 - boxes[0].x1,
                              boxes[0].y2 - boxes[0].y1);
         return TRUE;
     }
     PREFIX (_init) (region);
     /* if it's 0, don't call pixman_rect_alloc -- 0 rectangles is
      * a special case, and causing pixman_rect_alloc would cause
      * us to leak memory (because the 0-rect case should be the
      * static pixman_region_empty_data data).
      */
     if (count == 0)
 	return TRUE;
     if (!pixman_rect_alloc (region, count))
 	return FALSE;
     rects = PIXREGION_RECTS (region);
     /* Copy in the rects */
     memcpy (rects, boxes, sizeof(box_type_t) * count);
     region->data->numRects = count;
     /* Eliminate empty and malformed rectangles */
     displacement = 0;
     for (i = 0; i < count; ++i)
     {
         box_type_t *box = &rects[i];
         if (box->x1 >= box->x2 || box->y1 >= box->y2)
 	    displacement++;
         else if (displacement)
 	    rects[i - displacement] = rects[i];
     }
     region->data->numRects -= displacement;
     /* If eliminating empty rectangles caused there
      * to be only 0 or 1 rectangles, deal with that.
      */
     if (region->data->numRects == 0)
     {
         FREE_DATA (region);
         PREFIX (_init) (region);
         return TRUE;
     }
     if (region->data->numRects == 1)
     {
         region->extents = rects[0];
         FREE_DATA (region);
         region->data = NULL;
         GOOD (region);
         return TRUE;
     }
     /* Validate */
     region->extents.x1 = region->extents.x2 = 0;
     return validate (region);
 }
 #define READ(_ptr) (*(_ptr))
 static inline box_type_t *
 bitmap_addrect (region_type_t *reg,
                 box_type_t *r,
                 box_type_t **first_rect,
                 int rx1, int ry1,
                 int rx2, int ry2)
 {
     if ((rx1 < rx2) && (ry1 < ry2) &&
 	(!(reg->data->numRects &&
 	   ((r-1)->y1 == ry1) && ((r-1)->y2 == ry2) &&
 	   ((r-1)->x1 <= rx1) && ((r-1)->x2 >= rx2))))
     {
 	if (reg->data->numRects == reg->data->size)
 	{
 	    if (!pixman_rect_alloc (reg, 1))
 		return NULL;
 	    *first_rect = PIXREGION_BOXPTR(reg);
 	    r = *first_rect + reg->data->numRects;
 	}
 	r->x1 = rx1;
 	r->y1 = ry1;
 	r->x2 = rx2;
 	r->y2 = ry2;
 	reg->data->numRects++;
 	if (r->x1 < reg->extents.x1)
 	    reg->extents.x1 = r->x1;
 	if (r->x2 > reg->extents.x2)
 	    reg->extents.x2 = r->x2;
 	r++;
     }
     return r;
 }
 /* Convert bitmap clip mask into clipping region.
  * First, goes through each line and makes boxes by noting the transitions
  * from 0 to 1 and 1 to 0.
  * Then it coalesces the current line with the previous if they have boxes
  * at the same X coordinates.
  * Stride is in number of uint32_t per line.
  */
 PIXMAN_EXPORT void
 PREFIX (_init_from_image) (region_type_t *region,
                            pixman_image_t *image)
 {
     uint32_t mask0 = 0xffffffff & ~SCREEN_SHIFT_RIGHT(0xffffffff, 1);
     box_type_t *first_rect, *rects, *prect_line_start;
     box_type_t *old_rect, *new_rect;
     uint32_t *pw, w, *pw_line, *pw_line_end;
     int	irect_prev_start, irect_line_start;
     int	h, base, rx1 = 0, crects;
     int	ib;
     pixman_bool_t in_box, same;
     int width, height, stride;
     PREFIX(_init) (region);
     critical_if_fail (region->data);
     return_if_fail (image->type == BITS);
     return_if_fail (image->bits.format == PIXMAN_a1);
     pw_line = pixman_image_get_data (image);
     width = pixman_image_get_width (image);
     height = pixman_image_get_height (image);
     stride = pixman_image_get_stride (image) / 4;
     first_rect = PIXREGION_BOXPTR(region);
     rects = first_rect;
     region->extents.x1 = width - 1;
     region->extents.x2 = 0;
     irect_prev_start = -1;
     for (h = 0; h < height; h++)
     {
         pw = pw_line;
         pw_line += stride;
         irect_line_start = rects - first_rect;
         /* If the Screen left most bit of the word is set, we're starting in
          * a box */
         if (READ(pw) & mask0)
         {
             in_box = TRUE;
             rx1 = 0;
         }
         else
         {
             in_box = FALSE;
         }
         /* Process all words which are fully in the pixmap */
         pw_line_end = pw + (width >> 5);
         for (base = 0; pw < pw_line_end; base += 32)
         {
             w = READ(pw++);
             if (in_box)
             {
                 if (!~w)
                     continue;
             }
             else
             {
                 if (!w)
                     continue;
             }
             for (ib = 0; ib < 32; ib++)
             {
                 /* If the Screen left most bit of the word is set, we're
                  * starting a box */
                 if (w & mask0)
                 {
                     if (!in_box)
                     {
                         rx1 = base + ib;
                         /* start new box */
                         in_box = TRUE;
                     }
                 }
                 else
                 {
                     if (in_box)
                     {
                         /* end box */
                         rects = bitmap_addrect (region, rects, &first_rect,
                                                 rx1, h, base + ib, h + 1);
                         if (rects == NULL)
                             goto error;
                         in_box = FALSE;
                     }
                 }
                 /* Shift the word VISUALLY left one. */
                 w = SCREEN_SHIFT_LEFT(w, 1);
             }
         }
         if (width & 31)
         {
             /* Process final partial word on line */
              w = READ(pw++);
             for (ib = 0; ib < (width & 31); ib++)
             {
                 /* If the Screen left most bit of the word is set, we're
                  * starting a box */
                 if (w & mask0)
                 {
                     if (!in_box)
                     {
                         rx1 = base + ib;
                         /* start new box */
                         in_box = TRUE;
                     }
                 }
                 else
                 {
                     if (in_box)
                     {
                         /* end box */
                         rects = bitmap_addrect(region, rects, &first_rect,
 					       rx1, h, base + ib, h + 1);
 			if (rects == NULL)
 			    goto error;
                         in_box = FALSE;
                     }
                 }
                 /* Shift the word VISUALLY left one. */
                 w = SCREEN_SHIFT_LEFT(w, 1);
             }
         }
         /* If scanline ended with last bit set, end the box */
         if (in_box)
         {
             rects = bitmap_addrect(region, rects, &first_rect,
 				   rx1, h, base + (width & 31), h + 1);
 	    if (rects == NULL)
 		goto error;
         }
         /* if all rectangles on this line have the same x-coords as
          * those on the previous line, then add 1 to all the previous  y2s and
          * throw away all the rectangles from this line
          */
         same = FALSE;
         if (irect_prev_start != -1)
         {
             crects = irect_line_start - irect_prev_start;
             if (crects != 0 &&
                 crects == ((rects - first_rect) - irect_line_start))
             {
                 old_rect = first_rect + irect_prev_start;
                 new_rect = prect_line_start = first_rect + irect_line_start;
                 same = TRUE;
                 while (old_rect < prect_line_start)
                 {
                     if ((old_rect->x1 != new_rect->x1) ||
                         (old_rect->x2 != new_rect->x2))
                     {
                           same = FALSE;
                           break;
                     }
                     old_rect++;
                     new_rect++;
                 }
                 if (same)
                 {
                     old_rect = first_rect + irect_prev_start;
                     while (old_rect < prect_line_start)
                     {
                         old_rect->y2 += 1;
                         old_rect++;
                     }
                     rects -= crects;
                     region->data->numRects -= crects;
                 }
             }
         }
         if(!same)
             irect_prev_start = irect_line_start;
     }
     if (!region->data->numRects)
     {
         region->extents.x1 = region->extents.x2 = 0;
     }
     else
     {
         region->extents.y1 = PIXREGION_BOXPTR(region)->y1;
         region->extents.y2 = PIXREGION_END(region)->y2;
         if (region->data->numRects == 1)
         {
             free (region->data);
             region->data = NULL;
         }
     }
  error:
     return;
 }

The Tor Browser / annotate

gfx/cairo/libpixman/src/pixman-region.c@b8a032363ba2 (annotated)

gfx/cairo/libpixman/src/pixman-region.c