The Tor Browser: gfx/skia/trunk/src/core/SkMatrixUtils.h@b8a032363ba2

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

     1 /*

     2  * Copyright 2013 Google Inc.

     3  *

     4  * Use of this source code is governed by a BSD-style license that can be

     5  * found in the LICENSE file.

     6  */

     8 #ifndef SkMatrixUtils_DEFINED

     9 #define SkMatrixUtils_DEFINED

    11 #include "SkMatrix.h"

    13 /**

    14  *  Number of subpixel bits used in skia's bilerp.

    15  *  See SkBitmapProcState_procs.h and SkBitmapProcState_filter.h

    16  */

    17 #define kSkSubPixelBitsForBilerp   4

    19 /**

    20  *  Given a matrix and width/height, return true if the computed dst-rect would

    21  *  align such that there is a 1-to-1 coorspondence between src and dst pixels.

    22  *  This can be called by drawing code to see if drawBitmap can be turned into

    23  *  drawSprite (which is faster).

    24  *

    25  *  The src-rect is defined to be { 0, 0, width, height }

    26  *

    27  *  The "closeness" test is based on the subpixelBits parameter. Pass 0 for

    28  *  round-to-nearest behavior (e.g. nearest neighbor sampling). Pass the number

    29  *  of subpixel-bits to simulate filtering.

    30  */

    31 bool SkTreatAsSprite(const SkMatrix&, int width, int height,

    32                      unsigned subpixelBits);

    34 /**

    35  *  Calls SkTreatAsSprite() with default subpixelBits value to match Skia's

    36  *  filter-bitmap implementation (i.e. kSkSubPixelBitsForBilerp).

    37  */

    38 static inline bool SkTreatAsSpriteFilter(const SkMatrix& matrix,

    39                                          int width, int height) {

    40     return SkTreatAsSprite(matrix, width, height, kSkSubPixelBitsForBilerp);

    41 }

    43 /** Decomposes the upper-left 2x2 of the matrix into a rotation (represented by

    44     the cosine and sine of the rotation angle), followed by a non-uniform scale,

    45     followed by another rotation. If there is a reflection, one of the scale

    46     factors will be negative.

    47     Returns true if successful. Returns false if the matrix is degenerate.

    48     */

    49 bool SkDecomposeUpper2x2(const SkMatrix& matrix,

    50                          SkPoint* rotation1,

    51                          SkPoint* scale,

    52                          SkPoint* rotation2);

    54 #endif

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