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use forward matrix to determine if we can ignore scale part of a matrix

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Review URL: https://codereview.chromium.org/14018020

git-svn-id: http://skia.googlecode.com/svn/trunk@8700 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
reed@google.com 2013-04-16 17:14:45 +00:00
parent 0a6465949e
commit 19c4e6eb5e
1 changed files with 25 additions and 27 deletions
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52
src/core/SkBitmapProcState.cpp
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@ -30,36 +30,39 @@ extern void Clamp_SI8_opaque_D32_filter_DX_shaderproc_neon(const SkBitmapProcSt
///////////////////////////////////////////////////////////////////////////////
// true iff the matrix contains, at most, scale and translate elements
static bool matrix_only_scale_translate(const SkMatrix& m) {
return m.getType() <= SkMatrix::kScale_Mask | SkMatrix::kTranslate_Mask;
}
/**
* For the purposes of drawing bitmaps, if a matrix is "almost" translate
* go ahead and treat it as if it were, so that subsequent code can go fast.
*/
static bool just_trans_clamp(const SkMatrix& matrix, const SkBitmap& bitmap) {
SkMatrix::TypeMask mask = matrix.getType();
SkASSERT(matrix_only_scale_translate(matrix));
if (mask & (SkMatrix::kAffine_Mask | SkMatrix::kPerspective_Mask)) {
return false;
}
if (mask & SkMatrix::kScale_Mask) {
SkScalar sx = matrix[SkMatrix::kMScaleX];
SkScalar sy = matrix[SkMatrix::kMScaleY];
int w = bitmap.width();
int h = bitmap.height();
int sw = SkScalarRound(SkScalarMul(sx, SkIntToScalar(w)));
int sh = SkScalarRound(SkScalarMul(sy, SkIntToScalar(h)));
return sw == w && sh == h;
if (matrix.getType() & SkMatrix::kScale_Mask) {
SkRect src, dst;
bitmap.getBounds(&src);
matrix.mapRect(&dst, src);
// Now round all 4 edges to device space, and then compare the device
// width/height to the original. Note: we must map all 4 and subtract
// rather than map the "width" and compare, since we care about the
// phase (in pixel space) that any translate in the matrix might impart.
SkIRect idst;
dst.round(&idst);
return idst.width() == bitmap.width() && idst.height() == bitmap.height();
}
// if we got here, we're either kTranslate_Mask or identity
return true;
}
static bool just_trans_general(const SkMatrix& matrix) {
SkMatrix::TypeMask mask = matrix.getType();
SkASSERT(matrix_only_scale_translate(matrix));
if (mask & (SkMatrix::kAffine_Mask | SkMatrix::kPerspective_Mask)) {
return false;
}
if (mask & SkMatrix::kScale_Mask) {
if (matrix.getType() & SkMatrix::kScale_Mask) {
const SkScalar tol = SK_Scalar1 / 32768;
if (!SkScalarNearlyZero(matrix[SkMatrix::kMScaleX] - SK_Scalar1, tol)) {
@ -120,16 +123,11 @@ bool SkBitmapProcState::chooseProcs(const SkMatrix& inv, const SkPaint& paint) {
}
// wack our matrix to exactly no-scale, if we're really close to begin with
{
bool fixupMatrix = clamp_clamp ?
just_trans_clamp(*m, *fBitmap) : just_trans_general(*m);
if (fixupMatrix) {
// If we can be treated just like translate, construct that inverse
// such that we landed in the proper place. Given that m may have
// some slight scale, we have to invert it to compute this new
// matrix.
SkMatrix forward;
if (m->invert(&forward)) {
if (matrix_only_scale_translate(*m)) {
SkMatrix forward;
if (m->invert(&forward)) {
if (clamp_clamp ? just_trans_clamp(forward, *fBitmap)
: just_trans_general(forward)) {
SkScalar tx = -SkScalarRoundToScalar(forward.getTranslateX());
SkScalar ty = -SkScalarRoundToScalar(forward.getTranslateY());
fUnitInvMatrix.setTranslate(tx, ty);