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Draw perspective text as paths.

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Perspective glyphs can vary in screen size so it's unclear which SDF
level is best, and even if we choose one for an entire subrun it's
possible that a given glyph will have artifacts if it's too big.
Instead we fall back to paths.

Bug: skia:9515
Change-Id: I88f03b25651df0222459f5dbd03eee9465b97487
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/247437
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
This commit is contained in:
Jim Van Verth 2019-10-09 15:11:56 -04:00 committed by Skia Commit-Bot
parent 7951a0da32
commit 76826fc91c
3 changed files with 31 additions and 34 deletions
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1
src/core/SkStrikeSpec.cpp
View File

@ -181,6 +181,7 @@ SkStrikeSpec::MakeSDFT(const SkFont& font, const SkPaint& paint,
const SkSurfaceProps& surfaceProps, const SkMatrix& deviceMatrix,
const GrTextContext::Options& options) {
SkStrikeSpec storage;
SkASSERT(!deviceMatrix.hasPerspective());
SkPaint dfPaint = GrTextContext::InitDistanceFieldPaint(paint);
SkFont dfFont = GrTextContext::InitDistanceFieldFont(

58
src/gpu/text/GrTextContext.cpp
View File

@ -95,24 +95,8 @@ bool GrTextContext::CanDrawAsDistanceFields(const SkPaint& paint, const SkFont&
const SkSurfaceProps& props,
bool contextSupportsDistanceFieldText,
const Options& options) {
if (!viewMatrix.hasPerspective()) {
SkScalar maxScale = viewMatrix.getMaxScale();
SkScalar scaledTextSize = maxScale * font.getSize();
// Hinted text looks far better at small resolutions
// Scaling up beyond 2x yields undesireable artifacts
if (scaledTextSize < options.fMinDistanceFieldFontSize ||
scaledTextSize > options.fMaxDistanceFieldFontSize) {
return false;
}
bool useDFT = props.isUseDeviceIndependentFonts();
#if SK_FORCE_DISTANCE_FIELD_TEXT
useDFT = true;
#endif
if (!useDFT && scaledTextSize < kLargeDFFontSize) {
return false;
}
if (viewMatrix.hasPerspective()) {
return false;
}
// mask filters modify alpha, which doesn't translate well to distance
@ -125,24 +109,38 @@ bool GrTextContext::CanDrawAsDistanceFields(const SkPaint& paint, const SkFont&
return false;
}
SkScalar maxScale = viewMatrix.getMaxScale();
SkScalar scaledTextSize = maxScale * font.getSize();
// Hinted text looks far better at small resolutions
// Scaling up beyond 2x yields undesirable artifacts
if (scaledTextSize < options.fMinDistanceFieldFontSize ||
scaledTextSize > options.fMaxDistanceFieldFontSize) {
return false;
}
bool useDFT = props.isUseDeviceIndependentFonts();
#if SK_FORCE_DISTANCE_FIELD_TEXT
useDFT = true;
#endif
if (!useDFT && scaledTextSize < kLargeDFFontSize) {
return false;
}
return true;
}
SkScalar scaled_text_size(const SkScalar textSize, const SkMatrix& viewMatrix) {
SkASSERT(!viewMatrix.hasPerspective());
SkScalar scaledTextSize = textSize;
if (viewMatrix.hasPerspective()) {
// for perspective, we simply force to the medium size
// TODO: compute a size based on approximate screen area
scaledTextSize = kMediumDFFontLimit;
} else {
SkScalar maxScale = viewMatrix.getMaxScale();
// if we have non-unity scale, we need to choose our base text size
// based on the SkPaint's text size multiplied by the max scale factor
// TODO: do we need to do this if we're scaling down (i.e. maxScale < 1)?
if (maxScale > 0 && !SkScalarNearlyEqual(maxScale, SK_Scalar1)) {
scaledTextSize *= maxScale;
}
SkScalar maxScale = viewMatrix.getMaxScale();
// if we have non-unity scale, we need to choose our base text size
// based on the SkPaint's text size multiplied by the max scale factor
// TODO: do we need to do this if we're scaling down (i.e. maxScale < 1)?
if (maxScale > 0 && !SkScalarNearlyEqual(maxScale, SK_Scalar1)) {
scaledTextSize *= maxScale;
}
return scaledTextSize;

6
tests/SkRemoteGlyphCacheTest.cpp
View File

@ -678,10 +678,8 @@ DEF_GPUTEST_FOR_RENDERING_CONTEXTS(SkRemoteGlyphCache_DrawTextAsDFT, reporter, c
SkPaint paint;
SkFont font;
// A perspective transform forces fallback to dft.
SkMatrix matrix = SkMatrix::I();
matrix[SkMatrix::kMPersp0] = 0.5f;
REPORTER_ASSERT(reporter, matrix.hasPerspective());
// A scale transform forces fallback to dft.
SkMatrix matrix = SkMatrix::MakeScale(16);
SkSurfaceProps surfaceProps(0, kUnknown_SkPixelGeometry);
GrTextContext::Options options;
GrTextContext::SanitizeOptions(&options);