AuroraMiddleware/qt5base-lts
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Avoid glyph rendering with FT when not needed

Browse Source 
If we only need to access the font metrics (like in scenegraph) for
layout, we don't need to render glyphs with FreeType at all.

Increase cached linearAdvance to 22 bits so that no overflow will
happen: FreeType returns 16.16 fixed point linearHoriAdvance, but
QFixed is 26.6, we store

    glyph->linearAdvance = linearHoriAdvance >> 10

Apparently 'short' is not enough since it's only 16 bits.

Change-Id: Id14eafa19f01a687de11997526281f9e7e860482
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@nokia.com>
This commit is contained in:
Jiang Jiang 2012-03-02 14:22:10 +01:00 committed by Qt by Nokia
parent ac300a166f
commit 295ec32a74
2 changed files with 25 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
src/gui/text/qfontengine_ft.cpp
View File

@ -835,7 +835,7 @@ QFontEngineFT::Glyph *QFontEngineFT::loadGlyph(QGlyphSet *set, uint glyph,
}
Glyph *g = set ? set->getGlyph(glyph, subPixelPosition) : 0;
if (g && g->format == format)
if (g && g->format == format && (fetchMetricsOnly || g->data))
return g;
QFontEngineFT::GlyphInfo info;
@ -877,10 +877,28 @@ QFontEngineFT::Glyph *QFontEngineFT::loadGlyph(QGlyphSet *set, uint glyph,
if (err != FT_Err_Ok)
qWarning("load glyph failed err=%x face=%p, glyph=%d", err, face, glyph);
if ((!set || set->outline_drawing) && fetchMetricsOnly)
return 0;
FT_GlyphSlot slot = face->glyph;
if ((set && set->outline_drawing) || fetchMetricsOnly) {
g = new Glyph;
g->data = 0;
g->linearAdvance = slot->linearHoriAdvance >> 10;
int left = FLOOR(slot->metrics.horiBearingX);
int right = CEIL(slot->metrics.horiBearingX + slot->metrics.width);
int top = CEIL(slot->metrics.horiBearingY);
int bottom = FLOOR(slot->metrics.horiBearingY - slot->metrics.height);
g->width = TRUNC(right-left);
g->height = TRUNC(top-bottom);
g->x = TRUNC(left);
g->y = TRUNC(top);
g->advance = TRUNC(ROUND(slot->advance.x));
g->format = format;
if (set)
set->setGlyph(glyph, subPixelPosition, g);
return g;
}
if (embolden) Q_FT_GLYPHSLOT_EMBOLDEN(slot);
if (obliquen) {
Q_FT_GLYPHSLOT_OBLIQUE(slot);
@ -1870,7 +1888,7 @@ QImage QFontEngineFT::alphaMapForGlyph(glyph_t g, QFixed subPixelPosition)
lockFace();
Glyph *glyph = loadGlyphFor(g, subPixelPosition, antialias ? Format_A8 : Format_Mono);
if (!glyph) {
if (!glyph || !glyph->data) {
unlockFace();
return QFontEngine::alphaMapForGlyph(g);
}
@ -1907,7 +1925,7 @@ QImage QFontEngineFT::alphaRGBMapForGlyph(glyph_t g, QFixed subPixelPosition, co
lockFace();
Glyph *glyph = loadGlyphFor(g, subPixelPosition, Format_A32);
if (!glyph) {
if (!glyph || !glyph->data) {
unlockFace();
return QFontEngine::alphaRGBMapForGlyph(g, subPixelPosition, t);
}

2
src/gui/text/qfontengine_ft_p.h
View File

@ -144,7 +144,7 @@ public:
/* we don't cache glyphs that are too large anyway, so we can make this struct rather small */
struct Glyph {
~Glyph();
short linearAdvance;
int linearAdvance : 22; // 16.6
unsigned char width;
unsigned char height;
signed char x;