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Fix line heights to properly scale to requested size for color-bitmapped SFNTs.

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This commit is contained in:
wolfbeast 2018-03-27 21:26:25 +02:00 • committed by Roy Tam
commit 2653da27b3
1 changed files with 23 additions and 7 deletions
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30
gfx/thebes/gfxFT2Utils.cpp
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@ -10,6 +10,10 @@
#include FT_TRUETYPE_TABLES_H
#include <algorithm>
#ifndef FT_FACE_FLAG_COLOR
#define FT_FACE_FLAG_COLOR ( 1L << 14 )
#endif
#ifdef HAVE_FONTCONFIG_FCFREETYPE_H
#include <fontconfig/fcfreetype.h>
#endif
@ -53,7 +57,7 @@ gfxFT2LockedFace::GetMetrics(gfxFont::Metrics* aMetrics,
if (MOZ_UNLIKELY(!mFace)) {
// No face. This unfortunate situation might happen if the font
// file is (re)moved at the wrong time.
const gfxFloat emHeight = mGfxFont->GetStyle()->size;
const gfxFloat emHeight = mGfxFont->GetAdjustedSize();
aMetrics->emHeight = emHeight;
aMetrics->maxAscent = aMetrics->emAscent = 0.8 * emHeight;
aMetrics->maxDescent = aMetrics->emDescent = 0.2 * emHeight;
@ -80,6 +84,11 @@ gfxFT2LockedFace::GetMetrics(gfxFont::Metrics* aMetrics,
const FT_Size_Metrics& ftMetrics = mFace->size->metrics;
aMetrics->maxAscent = FLOAT_FROM_26_6(ftMetrics.ascender);
aMetrics->maxDescent = -FLOAT_FROM_26_6(ftMetrics.descender);
aMetrics->maxAdvance = FLOAT_FROM_26_6(ftMetrics.max_advance);
gfxFloat lineHeight = FLOAT_FROM_26_6(ftMetrics.height);
gfxFloat emHeight;
// Scale for vertical design metric conversion: pixels per design unit.
// If this remains at 0.0, we can't use metrics from OS/2 etc.
@ -103,6 +112,19 @@ gfxFT2LockedFace::GetMetrics(gfxFont::Metrics* aMetrics,
const TT_Header* head =
static_cast<TT_Header*>(FT_Get_Sfnt_Table(mFace, ft_sfnt_head));
if (head) {
// Even if the font is not explicitly scalable, if the face has
// color bitmaps, it should be treated as scalable and scaled to
// the desired size. Metrics based on y_ppem need to be rescaled
// for the adjusted size. This makes metrics agree with the
// scales we pass to Cairo for Fontconfig fonts.
if (mFace->face_flags & FT_FACE_FLAG_COLOR) {
emHeight = mGfxFont->GetAdjustedSize();
gfxFloat adjustScale = emHeight / ftMetrics.y_ppem;
aMetrics->maxAscent *= adjustScale;
aMetrics->maxDescent *= adjustScale;
aMetrics->maxAdvance *= adjustScale;
lineHeight *= adjustScale;
}
gfxFloat emUnit = head->Units_Per_EM;
yScale = emHeight / emUnit;
}
@ -111,11 +133,6 @@ gfxFT2LockedFace::GetMetrics(gfxFont::Metrics* aMetrics,
TT_OS2 *os2 =
static_cast<TT_OS2*>(FT_Get_Sfnt_Table(mFace, ft_sfnt_os2));
aMetrics->maxAscent = FLOAT_FROM_26_6(ftMetrics.ascender);
aMetrics->maxDescent = -FLOAT_FROM_26_6(ftMetrics.descender);
aMetrics->maxAdvance = FLOAT_FROM_26_6(ftMetrics.max_advance);
gfxFloat lineHeight;
if (os2 && os2->sTypoAscender && yScale > 0.0) {
aMetrics->emAscent = os2->sTypoAscender * yScale;
aMetrics->emDescent = -os2->sTypoDescender * yScale;
@ -142,7 +159,6 @@ gfxFT2LockedFace::GetMetrics(gfxFont::Metrics* aMetrics,
} else {
aMetrics->emAscent = aMetrics->maxAscent;
aMetrics->emDescent = aMetrics->maxDescent;
lineHeight = FLOAT_FROM_26_6(ftMetrics.height);
}
cairo_text_extents_t extents;