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Fix error handling in DirectWrite with tiny text.

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If there is an error while trying to determine the metrics,
we need to bail instead of potentially using uninitialized data.

R=reed@google.com, mtklein@google.com

Author: bungeman@google.com

Review URL: https://codereview.chromium.org/511783003
This commit is contained in:
bungeman 2014-08-28 11:42:29 -07:00 committed by Commit bot
parent 63b9dc8247
commit 683a37692b
2 changed files with 64 additions and 44 deletions
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100
src/ports/SkScalerContext_win_dw.cpp
View File

@ -398,10 +398,10 @@ void SkScalerContext_DW::generateAdvance(SkGlyph* glyph) {
glyph->fAdvanceY = SkScalarToFixed(vecs[0].fY);
}
void SkScalerContext_DW::getBoundingBox(SkGlyph* glyph,
DWRITE_RENDERING_MODE renderingMode,
DWRITE_TEXTURE_TYPE textureType,
RECT* bbox)
HRESULT SkScalerContext_DW::getBoundingBox(SkGlyph* glyph,
DWRITE_RENDERING_MODE renderingMode,
DWRITE_TEXTURE_TYPE textureType,
RECT* bbox)
{
//Measure raster size.
fXform.dx = SkFixedToFloat(glyph->getSubXFixed());
@ -426,50 +426,70 @@ void SkScalerContext_DW::getBoundingBox(SkGlyph* glyph,
run.glyphOffsets = &offset;
SkTScopedComPtr<IDWriteGlyphRunAnalysis> glyphRunAnalysis;
HRVM(fTypeface->fFactory->CreateGlyphRunAnalysis(
&run,
1.0f, // pixelsPerDip,
&fXform,
renderingMode,
fMeasuringMode,
0.0f, // baselineOriginX,
0.0f, // baselineOriginY,
&glyphRunAnalysis),
"Could not create glyph run analysis.");
HRM(fTypeface->fFactory->CreateGlyphRunAnalysis(
&run,
1.0f, // pixelsPerDip,
&fXform,
renderingMode,
fMeasuringMode,
0.0f, // baselineOriginX,
0.0f, // baselineOriginY,
&glyphRunAnalysis),
"Could not create glyph run analysis.");
HRVM(glyphRunAnalysis->GetAlphaTextureBounds(textureType, bbox),
"Could not get texture bounds.");
HRM(glyphRunAnalysis->GetAlphaTextureBounds(textureType, bbox),
"Could not get texture bounds.");
return S_OK;
}
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.
/** GetAlphaTextureBounds succeeds but sometimes returns empty bounds like
* { 0x80000000, 0x80000000, 0x80000000, 0x80000000 }
* for small, but not quite zero, sized glyphs.
* Only set as non-empty if the returned bounds are non-empty.
*/
static bool glyph_check_and_set_bounds(SkGlyph* glyph, const RECT& bbox) {
if (bbox.left >= bbox.right || bbox.top >= bbox.bottom) {
return false;
}
glyph->fWidth = SkToU16(bbox.right - bbox.left);
glyph->fHeight = SkToU16(bbox.bottom - bbox.top);
glyph->fLeft = SkToS16(bbox.left);
glyph->fTop = SkToS16(bbox.top);
return true;
}
void SkScalerContext_DW::generateMetrics(SkGlyph* glyph) {
glyph->fWidth = 0;
glyph->fHeight = 0;
glyph->fLeft = 0;
glyph->fTop = 0;
this->generateAdvance(glyph);
RECT bbox;
HRVM(this->getBoundingBox(glyph, fRenderingMode, fTextureType, &bbox),
"Requested bounding box could not be determined.");
if (glyph_check_and_set_bounds(glyph, bbox)) {
return;
}
// 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 (DWRITE_TEXTURE_CLEARTYPE_3x1 == fTextureType) {
HRVM(this->getBoundingBox(glyph,
DWRITE_RENDERING_MODE_ALIASED,
DWRITE_TEXTURE_ALIASED_1x1,
&bbox),
"Fallback bounding box could not be determined.");
if (glyph_check_and_set_bounds(glyph, bbox)) {
glyph->fForceBW = 1;
}
}
// TODO: handle the case where a request for DWRITE_TEXTURE_ALIASED_1x1
// fails, and try DWRITE_TEXTURE_CLEARTYPE_3x1.
}
void SkScalerContext_DW::generateFontMetrics(SkPaint::FontMetrics* metrics) {

8
src/ports/SkScalerContext_win_dw.h
View File

@ -37,10 +37,10 @@ private:
DWRITE_RENDERING_MODE renderingMode,
DWRITE_TEXTURE_TYPE textureType);
void getBoundingBox(SkGlyph* glyph,
DWRITE_RENDERING_MODE renderingMode,
DWRITE_TEXTURE_TYPE textureType,
RECT* bbox);
HRESULT 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. */