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bug 571724 - check for missing hhea table; fall back to platform if unable to use harfbuzz with the given font. r=jdaggett

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This commit is contained in:
Jonathan Kew 2010-06-16 07:37:37 +01:00
parent dc22443c80
commit f702826779
1 changed files with 51 additions and 45 deletions
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96
gfx/thebes/src/gfxHarfBuzzShaper.cpp
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@ -77,15 +77,9 @@ gfxHarfBuzzShaper::gfxHarfBuzzShaper(gfxFont *aFont)
gfxHarfBuzzShaper::~gfxHarfBuzzShaper()
{
if (mCmapTable) {
hb_blob_destroy(mCmapTable);
}
if (mHmtxTable) {
hb_blob_destroy(mHmtxTable);
}
if (mHBFace) {
hb_face_destroy(mHBFace);
}
hb_blob_destroy(mCmapTable);
hb_blob_destroy(mHmtxTable);
hb_face_destroy(mHBFace);
}
/*
@ -125,26 +119,11 @@ gfxHarfBuzzShaper::GetGlyph(hb_codepoint_t unicode,
NS_ASSERTION(mFont->GetFontEntry()->HasCmapTable(),
"we cannot be using this font!");
if (!mCmapTable) {
mCmapTable = mFont->GetFontTable(TRUETYPE_TAG('c','m','a','p'));
if (!mCmapTable) {
NS_WARNING("failed to load cmap, glyphs will be missing");
return 0;
}
}
NS_ASSERTION(mCmapTable && (mCmapFormat > 0) && (mSubtableOffset > 0),
"cmap data not correctly set up, expect disaster");
const PRUint8* data = (const PRUint8*)hb_blob_lock(mCmapTable);
if (mCmapFormat < 0) {
PRBool symbol;
mCmapFormat =
gfxFontUtils::FindPreferredSubtable(data,
hb_blob_get_length(mCmapTable),
&mSubtableOffset,
&mUVSTableOffset,
&symbol);
}
hb_codepoint_t gid;
switch (mCmapFormat) {
case 4:
@ -226,25 +205,8 @@ gfxHarfBuzzShaper::GetGlyphMetrics(gfxContext *aContext,
// font did not implement GetHintedGlyphWidth, so get an unhinted value
// directly from the font tables
if (mNumLongMetrics == 0) {
mNumLongMetrics = -1;
// read this from the hhea table without caching the blob
hb_blob_t *hheaTable = mFont->GetFontTable(TRUETYPE_TAG('h','h','e','a'));
if (hb_blob_get_length(hheaTable) >= sizeof(HMetricsHeader)) {
const HMetricsHeader* hhea = reinterpret_cast<const HMetricsHeader*>
(hb_blob_lock(hheaTable));
mNumLongMetrics = hhea->numberOfHMetrics;
hb_blob_unlock(hheaTable);
}
hb_blob_destroy(hheaTable);
mHmtxTable = mFont->GetFontTable(TRUETYPE_TAG('h','m','t','x'));
}
if (mNumLongMetrics < 1) {
return;
}
NS_ASSERTION((mNumLongMetrics > 0) && mHmtxTable != nsnull,
"font is lacking metrics, we shouldn't be here");
if (glyph >= mNumLongMetrics) {
glyph = mNumLongMetrics - 1;
@ -342,6 +304,8 @@ gfxHarfBuzzShaper::InitTextRun(gfxContext *aContext,
mFont->SetupCairoFont(aContext);
if (!mHBFace) {
// set up the harfbuzz face etc the first time we use the font
if (!sHBFontFuncs) {
// static function callback pointers, initialized by the first
// harfbuzz shaper used
@ -366,6 +330,48 @@ gfxHarfBuzzShaper::InitTextRun(gfxContext *aContext,
}
mHBFace = hb_face_create_for_tables(HBGetTable, nsnull, this);
// get the cmap table and find offset to our subtable
mCmapTable = mFont->GetFontTable(TRUETYPE_TAG('c','m','a','p'));
if (!mCmapTable) {
NS_WARNING("failed to load cmap, glyphs will be missing");
return PR_FALSE;
}
const PRUint8* data = (const PRUint8*)hb_blob_lock(mCmapTable);
PRBool symbol;
mCmapFormat =
gfxFontUtils::FindPreferredSubtable(data,
hb_blob_get_length(mCmapTable),
&mSubtableOffset,
&mUVSTableOffset,
&symbol);
hb_blob_unlock(mCmapTable);
if (!mUseHintedWidths) {
// if font doesn't implement hinted widths, we will be reading
// the hmtx table directly;
// read mNumLongMetrics from hhea table without caching its blob,
// and preload/cache the hmtx table
hb_blob_t *hheaTable =
mFont->GetFontTable(TRUETYPE_TAG('h','h','e','a'));
if (hheaTable &&
hb_blob_get_length(hheaTable) >= sizeof(HMetricsHeader)) {
const HMetricsHeader* hhea =
reinterpret_cast<const HMetricsHeader*>
(hb_blob_lock(hheaTable));
mNumLongMetrics = hhea->numberOfHMetrics;
hb_blob_unlock(hheaTable);
mHmtxTable =
mFont->GetFontTable(TRUETYPE_TAG('h','m','t','x'));
}
hb_blob_destroy(hheaTable);
}
}
if (mCmapFormat <= 0 || (!mUseHintedWidths && !mHmtxTable)) {
// unable to shape with this font
return PR_FALSE;
}
FontCallbackData fcd(this, aContext);