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tdf#103403: Wrong glyph advances with Graphite

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Always create HarfBuzz font at the UPEM size and scale HarfBuzz output
with the desired size instead. This theoretically means we loss any
size-specific adjustments in the font but in practice very few fonts do
this and in general modern APIs prefer stable glyph positioning across
font sizes.

Change-Id: Idf396eec5e241cc5fb9d0db698f2c081b7de29e3
This commit is contained in:
Khaled Hosny
2016-11-01 02:15:23 +02:00
parent 86abe3cb3d
commit e31f7f4c87
2 changed files with 34 additions and 37 deletions
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2
vcl/inc/CommonSalLayout.hxx
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@@ -55,7 +55,7 @@ class CommonSalLayout : public GenericSalLayout
OString msLanguage;
std::vector<hb_feature_t> maFeatures;
hb_font_t* getHbFont();
void getScale(double* nXScale, double* nYScale);
public:
#if defined(_WIN32)

69
vcl/source/gdi/CommonSalLayout.cxx
View File

@@ -80,31 +80,28 @@ static hb_blob_t* getFontTable(hb_face_t* /*face*/, hb_tag_t nTableTag, void* pU
static hb_font_t* createHbFont(hb_face_t* pHbFace)
{
hb_font_t* pHbFont = hb_font_create(pHbFace);
unsigned int nUPEM = hb_face_get_upem(pHbFace);
hb_font_set_scale(pHbFont, nUPEM, nUPEM);
hb_ot_font_set_funcs(pHbFont);
hb_face_destroy(pHbFace);
return pHbFont;
}
// We cache and re-use the HarfBuzz font for different layout instances, so we
// need sure to set the correct scale (font size) before using the font.
hb_font_t* CommonSalLayout::getHbFont()
void CommonSalLayout::getScale(double* nXScale, double* nYScale)
{
unsigned int nXScale = mrFontSelData.mnWidth << 6;
unsigned int nYScale = mrFontSelData.mnHeight << 6;
hb_face_t* pHbFace = hb_font_get_face(mpHbFont);
unsigned int nUPEM = hb_face_get_upem(pHbFace);
double nHeight(mrFontSelData.mnHeight);
double nWidth(mrFontSelData.mnWidth ? mrFontSelData.mnWidth : nHeight);
if (nYScale)
*nYScale = nHeight / nUPEM;
#if defined(_WIN32)
// HACK to get stretched/shrunken text. TODO: Get rid of HACK
if (nXScale)
nXScale = double(nXScale) * 1.812;
#endif
if (!nXScale)
nXScale = nYScale;
hb_font_set_ppem(mpHbFont, nXScale, nYScale);
hb_font_set_scale(mpHbFont, nXScale, nYScale);
return mpHbFont;
*nXScale = nWidth / nUPEM;
}
#if !HB_VERSION_ATLEAST(1, 1, 0)
@@ -182,8 +179,6 @@ CommonSalLayout::CommonSalLayout(HDC hDC, WinFontInstance& rWinFontInstance, con
mpHbFont = createHbFont(pHbFace);
rWinFontFace.SetHbFont(mpHbFont);
hb_face_destroy(pHbFace);
}
}
@@ -206,8 +201,6 @@ CommonSalLayout::CommonSalLayout(const CoreTextStyle& rCoreTextStyle)
mpHbFont = createHbFont(pHbFace);
rCoreTextStyle.SetHbFont(mpHbFont);
hb_face_destroy(pHbFace);
}
}
@@ -223,8 +216,6 @@ CommonSalLayout::CommonSalLayout(FreetypeFont& rFreetypeFont)
mpHbFont = createHbFont(pHbFace);
mrFreetypeFont.SetHbFont(mpHbFont);
hb_face_destroy(pHbFace);
}
}
#endif
@@ -370,8 +361,7 @@ static int GetVerticalFlagsForScript(UScriptCode aScript)
bool CommonSalLayout::LayoutText(ImplLayoutArgs& rArgs)
{
hb_font_t* pHbFont = getHbFont();
hb_face_t* pHbFace = hb_font_get_face(pHbFont);
hb_face_t* pHbFace = hb_font_get_face(mpHbFont);
hb_script_t aHbScript = HB_SCRIPT_INVALID;
int nGlyphCapacity = 2 * (rArgs.mnEndCharPos - rArgs.mnMinCharPos);
@@ -401,6 +391,10 @@ bool CommonSalLayout::LayoutText(ImplLayoutArgs& rArgs)
ParseFeatures(mrFontSelData.maTargetName);
double nXScale = 0;
double nYScale = 0;
getScale(&nXScale, &nYScale);
Point aCurrPos(0, 0);
while (true)
{
@@ -485,7 +479,7 @@ bool CommonSalLayout::LayoutText(ImplLayoutArgs& rArgs)
hb_segment_properties_t aHbProps;
hb_buffer_get_segment_properties(pHbBuffer, &aHbProps);
hb_shape_plan_t* pHbPlan = hb_shape_plan_create_cached(pHbFace, &aHbProps, maFeatures.data(), maFeatures.size(), pHbShapers);
bool ok = hb_shape_plan_execute(pHbPlan, pHbFont, pHbBuffer, maFeatures.data(), maFeatures.size());
bool ok = hb_shape_plan_execute(pHbPlan, mpHbFont, pHbBuffer, maFeatures.data(), maFeatures.size());
assert(ok);
(void) ok;
hb_buffer_set_content_type(pHbBuffer, HB_BUFFER_CONTENT_TYPE_GLYPHS);
@@ -543,7 +537,7 @@ bool CommonSalLayout::LayoutText(ImplLayoutArgs& rArgs)
if (bDiacritic)
nGlyphFlags |= GlyphItem::IS_DIACRITIC;
int32_t nAdvance, nXOffset, nYOffset;
DeviceCoordinate nAdvance, nXOffset, nYOffset;
if (bVertical)
{
int nVertFlag;
@@ -556,15 +550,15 @@ bool CommonSalLayout::LayoutText(ImplLayoutArgs& rArgs)
nVertFlag = GF_ROTL;
#endif
nGlyphIndex |= nVertFlag;
nAdvance = -pHbPositions[i].y_advance >> 6;
nXOffset = pHbPositions[i].y_offset >> 6;
nYOffset = -pHbPositions[i].x_offset >> 6;
nAdvance = -pHbPositions[i].y_advance * nYScale;
nXOffset = pHbPositions[i].y_offset * nYScale;
nYOffset = -pHbPositions[i].x_offset * nXScale;
}
else
{
nAdvance = pHbPositions[i].x_advance >> 6;
nXOffset = pHbPositions[i].x_offset >> 6;
nYOffset = pHbPositions[i].y_offset >> 6;
nAdvance = pHbPositions[i].x_advance * nXScale;
nXOffset = pHbPositions[i].x_offset * nXScale;
nYOffset = pHbPositions[i].y_offset * nYScale;
}
Point aNewPos = Point(aCurrPos.X() + nXOffset, -(aCurrPos.Y() + nYOffset));
@@ -649,9 +643,12 @@ void CommonSalLayout::ApplyDXArray(ImplLayoutArgs& rArgs)
if (rArgs.mnFlags & SalLayoutFlags::KashidaJustification)
{
// Find Kashida glyph width and index.
hb_font_t* pHbFont = getHbFont();
if (hb_font_get_glyph(pHbFont, 0x0640, 0, &nKashidaIndex))
nKashidaWidth = hb_font_get_glyph_h_advance(pHbFont, nKashidaIndex) / 64;
if (hb_font_get_glyph(mpHbFont, 0x0640, 0, &nKashidaIndex))
{
double nXScale = 0;
getScale(&nXScale, nullptr);
nKashidaWidth = hb_font_get_glyph_h_advance(mpHbFont, nKashidaIndex) * nXScale;
}
bKashidaJustify = nKashidaWidth != 0;
}