michael@0: /*
michael@0:  * Copyright © 2002 Keith Packard, member of The XFree86 Project, Inc.
michael@0:  * Copyright © 2004 Keith Packard
michael@0:  *
michael@0:  * Permission to use, copy, modify, distribute, and sell this software and its
michael@0:  * documentation for any purpose is hereby granted without fee, provided that
michael@0:  * the above copyright notice appear in all copies and that both that
michael@0:  * copyright notice and this permission notice appear in supporting
michael@0:  * documentation, and that the name of Keith Packard not be used in
michael@0:  * advertising or publicity pertaining to distribution of the software without
michael@0:  * specific, written prior permission.  Keith Packard makes no
michael@0:  * representations about the suitability of this software for any purpose.  It
michael@0:  * is provided "as is" without express or implied warranty.
michael@0:  *
michael@0:  * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
michael@0:  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
michael@0:  * EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
michael@0:  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
michael@0:  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
michael@0:  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
michael@0:  * PERFORMANCE OF THIS SOFTWARE.
michael@0:  */
michael@0: 
michael@0: #ifdef HAVE_CONFIG_H
michael@0: #include <config.h>
michael@0: #endif
michael@0: 
michael@0: #include <stdio.h>
michael@0: #include <stdlib.h>
michael@0: #include "pixman-private.h"
michael@0: 
michael@0: /*
michael@0:  * Compute the smallest value greater than or equal to y which is on a
michael@0:  * grid row.
michael@0:  */
michael@0: 
michael@0: PIXMAN_EXPORT pixman_fixed_t
michael@0: pixman_sample_ceil_y (pixman_fixed_t y, int n)
michael@0: {
michael@0:     pixman_fixed_t f = pixman_fixed_frac (y);
michael@0:     pixman_fixed_t i = pixman_fixed_floor (y);
michael@0: 
michael@0:     f = DIV (f - Y_FRAC_FIRST (n) + (STEP_Y_SMALL (n) - pixman_fixed_e), STEP_Y_SMALL (n)) * STEP_Y_SMALL (n) +
michael@0: 	Y_FRAC_FIRST (n);
michael@0:     
michael@0:     if (f > Y_FRAC_LAST (n))
michael@0:     {
michael@0: 	if (pixman_fixed_to_int (i) == 0x7fff)
michael@0: 	{
michael@0: 	    f = 0xffff; /* saturate */
michael@0: 	}
michael@0: 	else
michael@0: 	{
michael@0: 	    f = Y_FRAC_FIRST (n);
michael@0: 	    i += pixman_fixed_1;
michael@0: 	}
michael@0:     }
michael@0:     return (i | f);
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * Compute the largest value strictly less than y which is on a
michael@0:  * grid row.
michael@0:  */
michael@0: PIXMAN_EXPORT pixman_fixed_t
michael@0: pixman_sample_floor_y (pixman_fixed_t y,
michael@0:                        int            n)
michael@0: {
michael@0:     pixman_fixed_t f = pixman_fixed_frac (y);
michael@0:     pixman_fixed_t i = pixman_fixed_floor (y);
michael@0: 
michael@0:     f = DIV (f - pixman_fixed_e - Y_FRAC_FIRST (n), STEP_Y_SMALL (n)) * STEP_Y_SMALL (n) +
michael@0: 	Y_FRAC_FIRST (n);
michael@0: 
michael@0:     if (f < Y_FRAC_FIRST (n))
michael@0:     {
michael@0: 	if (pixman_fixed_to_int (i) == 0x8000)
michael@0: 	{
michael@0: 	    f = 0; /* saturate */
michael@0: 	}
michael@0: 	else
michael@0: 	{
michael@0: 	    f = Y_FRAC_LAST (n);
michael@0: 	    i -= pixman_fixed_1;
michael@0: 	}
michael@0:     }
michael@0:     return (i | f);
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * Step an edge by any amount (including negative values)
michael@0:  */
michael@0: PIXMAN_EXPORT void
michael@0: pixman_edge_step (pixman_edge_t *e,
michael@0:                   int            n)
michael@0: {
michael@0:     pixman_fixed_48_16_t ne;
michael@0: 
michael@0:     e->x += n * e->stepx;
michael@0: 
michael@0:     ne = e->e + n * (pixman_fixed_48_16_t) e->dx;
michael@0: 
michael@0:     if (n >= 0)
michael@0:     {
michael@0: 	if (ne > 0)
michael@0: 	{
michael@0: 	    int nx = (ne + e->dy - 1) / e->dy;
michael@0: 	    e->e = ne - nx * (pixman_fixed_48_16_t) e->dy;
michael@0: 	    e->x += nx * e->signdx;
michael@0: 	}
michael@0:     }
michael@0:     else
michael@0:     {
michael@0: 	if (ne <= -e->dy)
michael@0: 	{
michael@0: 	    int nx = (-ne) / e->dy;
michael@0: 	    e->e = ne + nx * (pixman_fixed_48_16_t) e->dy;
michael@0: 	    e->x -= nx * e->signdx;
michael@0: 	}
michael@0:     }
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * A private routine to initialize the multi-step
michael@0:  * elements of an edge structure
michael@0:  */
michael@0: static void
michael@0: _pixman_edge_multi_init (pixman_edge_t * e,
michael@0:                          int             n,
michael@0:                          pixman_fixed_t *stepx_p,
michael@0:                          pixman_fixed_t *dx_p)
michael@0: {
michael@0:     pixman_fixed_t stepx;
michael@0:     pixman_fixed_48_16_t ne;
michael@0: 
michael@0:     ne = n * (pixman_fixed_48_16_t) e->dx;
michael@0:     stepx = n * e->stepx;
michael@0: 
michael@0:     if (ne > 0)
michael@0:     {
michael@0: 	int nx = ne / e->dy;
michael@0: 	ne -= nx * (pixman_fixed_48_16_t)e->dy;
michael@0: 	stepx += nx * e->signdx;
michael@0:     }
michael@0: 
michael@0:     *dx_p = ne;
michael@0:     *stepx_p = stepx;
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * Initialize one edge structure given the line endpoints and a
michael@0:  * starting y value
michael@0:  */
michael@0: PIXMAN_EXPORT void
michael@0: pixman_edge_init (pixman_edge_t *e,
michael@0:                   int            n,
michael@0:                   pixman_fixed_t y_start,
michael@0:                   pixman_fixed_t x_top,
michael@0:                   pixman_fixed_t y_top,
michael@0:                   pixman_fixed_t x_bot,
michael@0:                   pixman_fixed_t y_bot)
michael@0: {
michael@0:     pixman_fixed_t dx, dy;
michael@0: 
michael@0:     e->x = x_top;
michael@0:     e->e = 0;
michael@0:     dx = x_bot - x_top;
michael@0:     dy = y_bot - y_top;
michael@0:     e->dy = dy;
michael@0:     e->dx = 0;
michael@0: 
michael@0:     if (dy)
michael@0:     {
michael@0: 	if (dx >= 0)
michael@0: 	{
michael@0: 	    e->signdx = 1;
michael@0: 	    e->stepx = dx / dy;
michael@0: 	    e->dx = dx % dy;
michael@0: 	    e->e = -dy;
michael@0: 	}
michael@0: 	else
michael@0: 	{
michael@0: 	    e->signdx = -1;
michael@0: 	    e->stepx = -(-dx / dy);
michael@0: 	    e->dx = -dx % dy;
michael@0: 	    e->e = 0;
michael@0: 	}
michael@0: 
michael@0: 	_pixman_edge_multi_init (e, STEP_Y_SMALL (n),
michael@0: 				 &e->stepx_small, &e->dx_small);
michael@0: 
michael@0: 	_pixman_edge_multi_init (e, STEP_Y_BIG (n),
michael@0: 				 &e->stepx_big, &e->dx_big);
michael@0:     }
michael@0:     pixman_edge_step (e, y_start - y_top);
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * Initialize one edge structure given a line, starting y value
michael@0:  * and a pixel offset for the line
michael@0:  */
michael@0: PIXMAN_EXPORT void
michael@0: pixman_line_fixed_edge_init (pixman_edge_t *            e,
michael@0:                              int                        n,
michael@0:                              pixman_fixed_t             y,
michael@0:                              const pixman_line_fixed_t *line,
michael@0:                              int                        x_off,
michael@0:                              int                        y_off)
michael@0: {
michael@0:     pixman_fixed_t x_off_fixed = pixman_int_to_fixed (x_off);
michael@0:     pixman_fixed_t y_off_fixed = pixman_int_to_fixed (y_off);
michael@0:     const pixman_point_fixed_t *top, *bot;
michael@0: 
michael@0:     if (line->p1.y <= line->p2.y)
michael@0:     {
michael@0: 	top = &line->p1;
michael@0: 	bot = &line->p2;
michael@0:     }
michael@0:     else
michael@0:     {
michael@0: 	top = &line->p2;
michael@0: 	bot = &line->p1;
michael@0:     }
michael@0:     
michael@0:     pixman_edge_init (e, n, y,
michael@0:                       top->x + x_off_fixed,
michael@0:                       top->y + y_off_fixed,
michael@0:                       bot->x + x_off_fixed,
michael@0:                       bot->y + y_off_fixed);
michael@0: }
michael@0: 
michael@0: PIXMAN_EXPORT void
michael@0: pixman_add_traps (pixman_image_t *     image,
michael@0:                   int16_t              x_off,
michael@0:                   int16_t              y_off,
michael@0:                   int                  ntrap,
michael@0:                   const pixman_trap_t *traps)
michael@0: {
michael@0:     int bpp;
michael@0:     int height;
michael@0: 
michael@0:     pixman_fixed_t x_off_fixed;
michael@0:     pixman_fixed_t y_off_fixed;
michael@0:     pixman_edge_t l, r;
michael@0:     pixman_fixed_t t, b;
michael@0: 
michael@0:     _pixman_image_validate (image);
michael@0:     
michael@0:     height = image->bits.height;
michael@0:     bpp = PIXMAN_FORMAT_BPP (image->bits.format);
michael@0: 
michael@0:     x_off_fixed = pixman_int_to_fixed (x_off);
michael@0:     y_off_fixed = pixman_int_to_fixed (y_off);
michael@0: 
michael@0:     while (ntrap--)
michael@0:     {
michael@0: 	t = traps->top.y + y_off_fixed;
michael@0: 	if (t < 0)
michael@0: 	    t = 0;
michael@0: 	t = pixman_sample_ceil_y (t, bpp);
michael@0: 
michael@0: 	b = traps->bot.y + y_off_fixed;
michael@0: 	if (pixman_fixed_to_int (b) >= height)
michael@0: 	    b = pixman_int_to_fixed (height) - 1;
michael@0: 	b = pixman_sample_floor_y (b, bpp);
michael@0: 
michael@0: 	if (b >= t)
michael@0: 	{
michael@0: 	    /* initialize edge walkers */
michael@0: 	    pixman_edge_init (&l, bpp, t,
michael@0: 	                      traps->top.l + x_off_fixed,
michael@0: 	                      traps->top.y + y_off_fixed,
michael@0: 	                      traps->bot.l + x_off_fixed,
michael@0: 	                      traps->bot.y + y_off_fixed);
michael@0: 
michael@0: 	    pixman_edge_init (&r, bpp, t,
michael@0: 	                      traps->top.r + x_off_fixed,
michael@0: 	                      traps->top.y + y_off_fixed,
michael@0: 	                      traps->bot.r + x_off_fixed,
michael@0: 	                      traps->bot.y + y_off_fixed);
michael@0: 
michael@0: 	    pixman_rasterize_edges (image, &l, &r, t, b);
michael@0: 	}
michael@0: 
michael@0: 	traps++;
michael@0:     }
michael@0: }
michael@0: 
michael@0: #if 0
michael@0: static void
michael@0: dump_image (pixman_image_t *image,
michael@0:             const char *    title)
michael@0: {
michael@0:     int i, j;
michael@0: 
michael@0:     if (!image->type == BITS)
michael@0: 	printf ("%s is not a regular image\n", title);
michael@0: 
michael@0:     if (!image->bits.format == PIXMAN_a8)
michael@0: 	printf ("%s is not an alpha mask\n", title);
michael@0: 
michael@0:     printf ("\n\n\n%s: \n", title);
michael@0: 
michael@0:     for (i = 0; i < image->bits.height; ++i)
michael@0:     {
michael@0: 	uint8_t *line =
michael@0: 	    (uint8_t *)&(image->bits.bits[i * image->bits.rowstride]);
michael@0: 
michael@0: 	for (j = 0; j < image->bits.width; ++j)
michael@0: 	    printf ("%c", line[j] ? '#' : ' ');
michael@0: 
michael@0: 	printf ("\n");
michael@0:     }
michael@0: }
michael@0: #endif
michael@0: 
michael@0: PIXMAN_EXPORT void
michael@0: pixman_add_trapezoids (pixman_image_t *          image,
michael@0:                        int16_t                   x_off,
michael@0:                        int                       y_off,
michael@0:                        int                       ntraps,
michael@0:                        const pixman_trapezoid_t *traps)
michael@0: {
michael@0:     int i;
michael@0: 
michael@0: #if 0
michael@0:     dump_image (image, "before");
michael@0: #endif
michael@0: 
michael@0:     for (i = 0; i < ntraps; ++i)
michael@0:     {
michael@0: 	const pixman_trapezoid_t *trap = &(traps[i]);
michael@0: 
michael@0: 	if (!pixman_trapezoid_valid (trap))
michael@0: 	    continue;
michael@0: 
michael@0: 	pixman_rasterize_trapezoid (image, trap, x_off, y_off);
michael@0:     }
michael@0: 
michael@0: #if 0
michael@0:     dump_image (image, "after");
michael@0: #endif
michael@0: }
michael@0: 
michael@0: PIXMAN_EXPORT void
michael@0: pixman_rasterize_trapezoid (pixman_image_t *          image,
michael@0:                             const pixman_trapezoid_t *trap,
michael@0:                             int                       x_off,
michael@0:                             int                       y_off)
michael@0: {
michael@0:     int bpp;
michael@0:     int height;
michael@0: 
michael@0:     pixman_fixed_t y_off_fixed;
michael@0:     pixman_edge_t l, r;
michael@0:     pixman_fixed_t t, b;
michael@0: 
michael@0:     return_if_fail (image->type == BITS);
michael@0: 
michael@0:     _pixman_image_validate (image);
michael@0:     
michael@0:     if (!pixman_trapezoid_valid (trap))
michael@0: 	return;
michael@0: 
michael@0:     height = image->bits.height;
michael@0:     bpp = PIXMAN_FORMAT_BPP (image->bits.format);
michael@0: 
michael@0:     y_off_fixed = pixman_int_to_fixed (y_off);
michael@0: 
michael@0:     t = trap->top + y_off_fixed;
michael@0:     if (t < 0)
michael@0: 	t = 0;
michael@0:     t = pixman_sample_ceil_y (t, bpp);
michael@0: 
michael@0:     b = trap->bottom + y_off_fixed;
michael@0:     if (pixman_fixed_to_int (b) >= height)
michael@0: 	b = pixman_int_to_fixed (height) - 1;
michael@0:     b = pixman_sample_floor_y (b, bpp);
michael@0:     
michael@0:     if (b >= t)
michael@0:     {
michael@0: 	/* initialize edge walkers */
michael@0: 	pixman_line_fixed_edge_init (&l, bpp, t, &trap->left, x_off, y_off);
michael@0: 	pixman_line_fixed_edge_init (&r, bpp, t, &trap->right, x_off, y_off);
michael@0: 
michael@0: 	pixman_rasterize_edges (image, &l, &r, t, b);
michael@0:     }
michael@0: }
michael@0: 
michael@0: static const pixman_bool_t zero_src_has_no_effect[PIXMAN_N_OPERATORS] =
michael@0: {
michael@0:     FALSE,	/* Clear		0			0    */
michael@0:     FALSE,	/* Src			1			0    */
michael@0:     TRUE,	/* Dst			0			1    */
michael@0:     TRUE,	/* Over			1			1-Aa */
michael@0:     TRUE,	/* OverReverse		1-Ab			1    */
michael@0:     FALSE,	/* In			Ab			0    */
michael@0:     FALSE,	/* InReverse		0			Aa   */
michael@0:     FALSE,	/* Out			1-Ab			0    */
michael@0:     TRUE,	/* OutReverse		0			1-Aa */
michael@0:     TRUE,	/* Atop			Ab			1-Aa */
michael@0:     FALSE,	/* AtopReverse		1-Ab			Aa   */
michael@0:     TRUE,	/* Xor			1-Ab			1-Aa */
michael@0:     TRUE,	/* Add			1			1    */
michael@0: };
michael@0: 
michael@0: static pixman_bool_t
michael@0: get_trap_extents (pixman_op_t op, pixman_image_t *dest,
michael@0: 		  const pixman_trapezoid_t *traps, int n_traps,
michael@0: 		  pixman_box32_t *box)
michael@0: {
michael@0:     int i;
michael@0: 
michael@0:     /* When the operator is such that a zero source has an
michael@0:      * effect on the underlying image, we have to
michael@0:      * composite across the entire destination
michael@0:      */
michael@0:     if (!zero_src_has_no_effect [op])
michael@0:     {
michael@0: 	box->x1 = 0;
michael@0: 	box->y1 = 0;
michael@0: 	box->x2 = dest->bits.width;
michael@0: 	box->y2 = dest->bits.height;
michael@0: 	return TRUE;
michael@0:     }
michael@0:     
michael@0:     box->x1 = INT32_MAX;
michael@0:     box->y1 = INT32_MAX;
michael@0:     box->x2 = INT32_MIN;
michael@0:     box->y2 = INT32_MIN;
michael@0: 	
michael@0:     for (i = 0; i < n_traps; ++i)
michael@0:     {
michael@0: 	const pixman_trapezoid_t *trap = &(traps[i]);
michael@0: 	int y1, y2;
michael@0: 	    
michael@0: 	if (!pixman_trapezoid_valid (trap))
michael@0: 	    continue;
michael@0: 	    
michael@0: 	y1 = pixman_fixed_to_int (trap->top);
michael@0: 	if (y1 < box->y1)
michael@0: 	    box->y1 = y1;
michael@0: 	    
michael@0: 	y2 = pixman_fixed_to_int (pixman_fixed_ceil (trap->bottom));
michael@0: 	if (y2 > box->y2)
michael@0: 	    box->y2 = y2;
michael@0: 	    
michael@0: #define EXTEND_MIN(x)							\
michael@0: 	if (pixman_fixed_to_int ((x)) < box->x1)			\
michael@0: 	    box->x1 = pixman_fixed_to_int ((x));
michael@0: #define EXTEND_MAX(x)							\
michael@0: 	if (pixman_fixed_to_int (pixman_fixed_ceil ((x))) > box->x2)	\
michael@0: 	    box->x2 = pixman_fixed_to_int (pixman_fixed_ceil ((x)));
michael@0: 	    
michael@0: #define EXTEND(x)							\
michael@0: 	EXTEND_MIN(x);							\
michael@0: 	EXTEND_MAX(x);
michael@0: 	    
michael@0: 	EXTEND(trap->left.p1.x);
michael@0: 	EXTEND(trap->left.p2.x);
michael@0: 	EXTEND(trap->right.p1.x);
michael@0: 	EXTEND(trap->right.p2.x);
michael@0:     }
michael@0: 	
michael@0:     if (box->x1 >= box->x2 || box->y1 >= box->y2)
michael@0: 	return FALSE;
michael@0: 
michael@0:     return TRUE;
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * pixman_composite_trapezoids()
michael@0:  *
michael@0:  * All the trapezoids are conceptually rendered to an infinitely big image.
michael@0:  * The (0, 0) coordinates of this image are then aligned with the (x, y)
michael@0:  * coordinates of the source image, and then both images are aligned with
michael@0:  * the (x, y) coordinates of the destination. Then these three images are
michael@0:  * composited across the entire destination.
michael@0:  */
michael@0: PIXMAN_EXPORT void
michael@0: pixman_composite_trapezoids (pixman_op_t		op,
michael@0: 			     pixman_image_t *		src,
michael@0: 			     pixman_image_t *		dst,
michael@0: 			     pixman_format_code_t	mask_format,
michael@0: 			     int			x_src,
michael@0: 			     int			y_src,
michael@0: 			     int			x_dst,
michael@0: 			     int			y_dst,
michael@0: 			     int			n_traps,
michael@0: 			     const pixman_trapezoid_t *	traps)
michael@0: {
michael@0:     int i;
michael@0: 
michael@0:     return_if_fail (PIXMAN_FORMAT_TYPE (mask_format) == PIXMAN_TYPE_A);
michael@0:     
michael@0:     if (n_traps <= 0)
michael@0: 	return;
michael@0: 
michael@0:     _pixman_image_validate (src);
michael@0:     _pixman_image_validate (dst);
michael@0: 
michael@0:     if (op == PIXMAN_OP_ADD &&
michael@0: 	(src->common.flags & FAST_PATH_IS_OPAQUE)		&&
michael@0: 	(mask_format == dst->common.extended_format_code)	&&
michael@0: 	!(dst->common.have_clip_region))
michael@0:     {
michael@0: 	for (i = 0; i < n_traps; ++i)
michael@0: 	{
michael@0: 	    const pixman_trapezoid_t *trap = &(traps[i]);
michael@0: 	    
michael@0: 	    if (!pixman_trapezoid_valid (trap))
michael@0: 		continue;
michael@0: 	    
michael@0: 	    pixman_rasterize_trapezoid (dst, trap, x_dst, y_dst);
michael@0: 	}
michael@0:     }
michael@0:     else
michael@0:     {
michael@0: 	pixman_image_t *tmp;
michael@0: 	pixman_box32_t box;
michael@0: 	int i;
michael@0: 
michael@0: 	if (!get_trap_extents (op, dst, traps, n_traps, &box))
michael@0: 	    return;
michael@0: 	
michael@0: 	if (!(tmp = pixman_image_create_bits (
michael@0: 		  mask_format, box.x2 - box.x1, box.y2 - box.y1, NULL, -1)))
michael@0: 	    return;
michael@0: 	
michael@0: 	for (i = 0; i < n_traps; ++i)
michael@0: 	{
michael@0: 	    const pixman_trapezoid_t *trap = &(traps[i]);
michael@0: 	    
michael@0: 	    if (!pixman_trapezoid_valid (trap))
michael@0: 		continue;
michael@0: 	    
michael@0: 	    pixman_rasterize_trapezoid (tmp, trap, - box.x1, - box.y1);
michael@0: 	}
michael@0: 	
michael@0: 	pixman_image_composite (op, src, tmp, dst,
michael@0: 				x_src + box.x1, y_src + box.y1,
michael@0: 				0, 0,
michael@0: 				x_dst + box.x1, y_dst + box.y1,
michael@0: 				box.x2 - box.x1, box.y2 - box.y1);
michael@0: 	
michael@0: 	pixman_image_unref (tmp);
michael@0:     }
michael@0: }
michael@0: 
michael@0: static int
michael@0: greater_y (const pixman_point_fixed_t *a, const pixman_point_fixed_t *b)
michael@0: {
michael@0:     if (a->y == b->y)
michael@0: 	return a->x > b->x;
michael@0:     return a->y > b->y;
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * Note that the definition of this function is a bit odd because
michael@0:  * of the X coordinate space (y increasing downwards).
michael@0:  */
michael@0: static int
michael@0: clockwise (const pixman_point_fixed_t *ref,
michael@0: 	   const pixman_point_fixed_t *a,
michael@0: 	   const pixman_point_fixed_t *b)
michael@0: {
michael@0:     pixman_point_fixed_t	ad, bd;
michael@0: 
michael@0:     ad.x = a->x - ref->x;
michael@0:     ad.y = a->y - ref->y;
michael@0:     bd.x = b->x - ref->x;
michael@0:     bd.y = b->y - ref->y;
michael@0: 
michael@0:     return ((pixman_fixed_32_32_t) bd.y * ad.x -
michael@0: 	    (pixman_fixed_32_32_t) ad.y * bd.x) < 0;
michael@0: }
michael@0: 
michael@0: static void
michael@0: triangle_to_trapezoids (const pixman_triangle_t *tri, pixman_trapezoid_t *traps)
michael@0: {
michael@0:     const pixman_point_fixed_t *top, *left, *right, *tmp;
michael@0: 
michael@0:     top = &tri->p1;
michael@0:     left = &tri->p2;
michael@0:     right = &tri->p3;
michael@0: 
michael@0:     if (greater_y (top, left))
michael@0:     {
michael@0: 	tmp = left;
michael@0: 	left = top;
michael@0: 	top = tmp;
michael@0:     }
michael@0: 
michael@0:     if (greater_y (top, right))
michael@0:     {
michael@0: 	tmp = right;
michael@0: 	right = top;
michael@0: 	top = tmp;
michael@0:     }
michael@0: 
michael@0:     if (clockwise (top, right, left))
michael@0:     {
michael@0: 	tmp = right;
michael@0: 	right = left;
michael@0: 	left = tmp;
michael@0:     }
michael@0:     
michael@0:     /*
michael@0:      * Two cases:
michael@0:      *
michael@0:      *		+		+
michael@0:      *	       / \             / \
michael@0:      *	      /   \           /	  \
michael@0:      *	     /     +         +	   \
michael@0:      *      /    --           --    \
michael@0:      *     /   --               --   \
michael@0:      *    / ---                   --- \
michael@0:      *	 +--                         --+
michael@0:      */
michael@0: 
michael@0:     traps->top = top->y;
michael@0:     traps->left.p1 = *top;
michael@0:     traps->left.p2 = *left;
michael@0:     traps->right.p1 = *top;
michael@0:     traps->right.p2 = *right;
michael@0: 
michael@0:     if (right->y < left->y)
michael@0: 	traps->bottom = right->y;
michael@0:     else
michael@0: 	traps->bottom = left->y;
michael@0: 
michael@0:     traps++;
michael@0: 
michael@0:     *traps = *(traps - 1);
michael@0:     
michael@0:     if (right->y < left->y)
michael@0:     {
michael@0: 	traps->top = right->y;
michael@0: 	traps->bottom = left->y;
michael@0: 	traps->right.p1 = *right;
michael@0: 	traps->right.p2 = *left;
michael@0:     }
michael@0:     else
michael@0:     {
michael@0: 	traps->top = left->y;
michael@0: 	traps->bottom = right->y;
michael@0: 	traps->left.p1 = *left;
michael@0: 	traps->left.p2 = *right;
michael@0:     }
michael@0: }
michael@0: 
michael@0: static pixman_trapezoid_t *
michael@0: convert_triangles (int n_tris, const pixman_triangle_t *tris)
michael@0: {
michael@0:     pixman_trapezoid_t *traps;
michael@0:     int i;
michael@0: 
michael@0:     if (n_tris <= 0)
michael@0: 	return NULL;
michael@0:     
michael@0:     traps = pixman_malloc_ab (n_tris, 2 * sizeof (pixman_trapezoid_t));
michael@0:     if (!traps)
michael@0: 	return NULL;
michael@0: 
michael@0:     for (i = 0; i < n_tris; ++i)
michael@0: 	triangle_to_trapezoids (&(tris[i]), traps + 2 * i);
michael@0: 
michael@0:     return traps;
michael@0: }
michael@0: 
michael@0: PIXMAN_EXPORT void
michael@0: pixman_composite_triangles (pixman_op_t			op,
michael@0: 			    pixman_image_t *		src,
michael@0: 			    pixman_image_t *		dst,
michael@0: 			    pixman_format_code_t	mask_format,
michael@0: 			    int				x_src,
michael@0: 			    int				y_src,
michael@0: 			    int				x_dst,
michael@0: 			    int				y_dst,
michael@0: 			    int				n_tris,
michael@0: 			    const pixman_triangle_t *	tris)
michael@0: {
michael@0:     pixman_trapezoid_t *traps;
michael@0: 
michael@0:     if ((traps = convert_triangles (n_tris, tris)))
michael@0:     {
michael@0: 	pixman_composite_trapezoids (op, src, dst, mask_format,
michael@0: 				     x_src, y_src, x_dst, y_dst,
michael@0: 				     n_tris * 2, traps);
michael@0: 	
michael@0: 	free (traps);
michael@0:     }
michael@0: }
michael@0: 
michael@0: PIXMAN_EXPORT void
michael@0: pixman_add_triangles (pixman_image_t          *image,
michael@0: 		      int32_t	               x_off,
michael@0: 		      int32_t	               y_off,
michael@0: 		      int	               n_tris,
michael@0: 		      const pixman_triangle_t *tris)
michael@0: {
michael@0:     pixman_trapezoid_t *traps;
michael@0: 
michael@0:     if ((traps = convert_triangles (n_tris, tris)))
michael@0:     {
michael@0: 	pixman_add_trapezoids (image, x_off, y_off,
michael@0: 			       n_tris * 2, traps);
michael@0: 
michael@0: 	free (traps);
michael@0:     }
michael@0: }