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DirectWrite to use aliased if ClearType is empty.
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Some CJK fonts with some versions of DirectWrite return valid
data for bitmaps, but not for cleartype data.

For reference, two screenshots. M37 Stable and then with this patch:

https://imgur.com/9pf3rB9,EiTb6Li

See https://code.google.com/p/chromium/issues/detail?id=396624#c10 for
content of test html file.

[email protected], [email protected], [email protected], [email protected], [email protected]
BUG=chromium:407945

Review URL: https://codereview.chromium.org/504343007
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Ben Wagner committed Aug 27, 2014
1 parent 56fa442 commit b2f7fce
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Showing 3 changed files with 58 additions and 15 deletions.
2 changes: 2 additions & 0 deletions src/core/SkGlyph.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -32,13 +32,15 @@ struct SkGlyph {
void* fDistanceField;
uint8_t fMaskFormat;
int8_t fRsbDelta, fLsbDelta; // used by auto-kerning
int8_t fForceBW;

void init(uint32_t id) {
fID = id;
fImage = NULL;
fPath = NULL;
fDistanceField = NULL;
fMaskFormat = MASK_FORMAT_UNKNOWN;
fForceBW = 0;
}

/**
Expand Down
62 changes: 48 additions & 14 deletions src/ports/SkScalerContext_win_dw.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -398,11 +398,11 @@ void SkScalerContext_DW::generateAdvance(SkGlyph* glyph) {
glyph->fAdvanceY = SkScalarToFixed(vecs[0].fY);
}

void SkScalerContext_DW::generateMetrics(SkGlyph* glyph) {
glyph->fWidth = 0;

this->generateAdvance(glyph);

void SkScalerContext_DW::getBoundingBox(SkGlyph* glyph,
DWRITE_RENDERING_MODE renderingMode,
DWRITE_TEXTURE_TYPE textureType,
RECT* bbox)
{
//Measure raster size.
fXform.dx = SkFixedToFloat(glyph->getSubXFixed());
fXform.dy = SkFixedToFloat(glyph->getSubYFixed());
Expand Down Expand Up @@ -430,16 +430,41 @@ void SkScalerContext_DW::generateMetrics(SkGlyph* glyph) {
&run,
1.0f, // pixelsPerDip,
&fXform,
fRenderingMode,
renderingMode,
fMeasuringMode,
0.0f, // baselineOriginX,
0.0f, // baselineOriginY,
&glyphRunAnalysis),
"Could not create glyph run analysis.");

RECT bbox;
HRVM(glyphRunAnalysis->GetAlphaTextureBounds(fTextureType, &bbox),
HRVM(glyphRunAnalysis->GetAlphaTextureBounds(textureType, bbox),
"Could not get texture bounds.");
}

void SkScalerContext_DW::generateMetrics(SkGlyph* glyph) {
glyph->fWidth = 0;

this->generateAdvance(glyph);

RECT bbox;
this->getBoundingBox(glyph, fRenderingMode, fTextureType, &bbox);

// GetAlphaTextureBounds succeeds but returns an empty RECT if there are no
// glyphs of the specified texture type. When this happens, try with the
// alternate texture type.
if (bbox.left == bbox.right || bbox.top == bbox.bottom) {
if (DWRITE_TEXTURE_CLEARTYPE_3x1 == fTextureType) {
this->getBoundingBox(glyph,
DWRITE_RENDERING_MODE_ALIASED,
DWRITE_TEXTURE_ALIASED_1x1,
&bbox);
if (bbox.left != bbox.right && bbox.top != bbox.bottom) {
glyph->fForceBW = 1;
}
}
// TODO: handle the case where a request for DWRITE_TEXTURE_ALIASED_1x1
// fails, and try DWRITE_TEXTURE_CLEARTYPE_3x1.
}

glyph->fWidth = SkToU16(bbox.right - bbox.left);
glyph->fHeight = SkToU16(bbox.bottom - bbox.top);
Expand Down Expand Up @@ -602,9 +627,12 @@ static void rgb_to_lcd32(const uint8_t* SK_RESTRICT src, const SkGlyph& glyph,
}
}

const void* SkScalerContext_DW::drawDWMask(const SkGlyph& glyph) {
const void* SkScalerContext_DW::drawDWMask(const SkGlyph& glyph,
DWRITE_RENDERING_MODE renderingMode,
DWRITE_TEXTURE_TYPE textureType)
{
int sizeNeeded = glyph.fWidth * glyph.fHeight;
if (DWRITE_RENDERING_MODE_ALIASED != fRenderingMode) {
if (DWRITE_RENDERING_MODE_ALIASED != renderingMode) {
sizeNeeded *= 3;
}
if (sizeNeeded > fBits.count()) {
Expand Down Expand Up @@ -639,7 +667,7 @@ const void* SkScalerContext_DW::drawDWMask(const SkGlyph& glyph) {
HRNM(fTypeface->fFactory->CreateGlyphRunAnalysis(&run,
1.0f, // pixelsPerDip,
&fXform,
fRenderingMode,
renderingMode,
fMeasuringMode,
0.0f, // baselineOriginX,
0.0f, // baselineOriginY,
Expand All @@ -653,7 +681,7 @@ const void* SkScalerContext_DW::drawDWMask(const SkGlyph& glyph) {
bbox.top = glyph.fTop;
bbox.right = glyph.fLeft + glyph.fWidth;
bbox.bottom = glyph.fTop + glyph.fHeight;
HRNM(glyphRunAnalysis->CreateAlphaTexture(fTextureType,
HRNM(glyphRunAnalysis->CreateAlphaTexture(textureType,
&bbox,
fBits.begin(),
sizeNeeded),
Expand All @@ -663,15 +691,21 @@ const void* SkScalerContext_DW::drawDWMask(const SkGlyph& glyph) {

void SkScalerContext_DW::generateImage(const SkGlyph& glyph) {
//Create the mask.
const void* bits = this->drawDWMask(glyph);
DWRITE_RENDERING_MODE renderingMode = fRenderingMode;
DWRITE_TEXTURE_TYPE textureType = fTextureType;
if (glyph.fForceBW) {
renderingMode = DWRITE_RENDERING_MODE_ALIASED;
textureType = DWRITE_TEXTURE_ALIASED_1x1;
}
const void* bits = this->drawDWMask(glyph, renderingMode, textureType);
if (!bits) {
sk_bzero(glyph.fImage, glyph.computeImageSize());
return;
}

//Copy the mask into the glyph.
const uint8_t* src = (const uint8_t*)bits;
if (DWRITE_RENDERING_MODE_ALIASED == fRenderingMode) {
if (DWRITE_RENDERING_MODE_ALIASED == renderingMode) {
bilevel_to_bw(src, glyph);
const_cast<SkGlyph&>(glyph).fMaskFormat = SkMask::kBW_Format;
} else if (!isLCD(fRec)) {
Expand Down
9 changes: 8 additions & 1 deletion src/ports/SkScalerContext_win_dw.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,14 @@ class SkScalerContext_DW : public SkScalerContext {
virtual void generateFontMetrics(SkPaint::FontMetrics*) SK_OVERRIDE;

private:
const void* drawDWMask(const SkGlyph& glyph);
const void* drawDWMask(const SkGlyph& glyph,
DWRITE_RENDERING_MODE renderingMode,
DWRITE_TEXTURE_TYPE textureType);

void getBoundingBox(SkGlyph* glyph,
DWRITE_RENDERING_MODE renderingMode,
DWRITE_TEXTURE_TYPE textureType,
RECT* bbox);

SkTDArray<uint8_t> fBits;
/** The total matrix without the text height scale. */