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Enable patent-free LCD rendering with FreeType 2.8.1

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Use the FreeType LCD rendering path with 2.8.1 even when it has lcd-
filtering disabled. This gives us proper subpixel rendering even with
a freetype build with the patented lcd-filtering code disabled.

The code is also simplified by removing the long pointless
ifdefs for 10+ year old versions of freetype.

Change-Id: I487e465317cb984b6e33c7bcc497f27cf29f9bcd
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
This commit is contained in:
Allan Sandfeld Jensen 2017-09-20 10:23:01 +02:00
parent 467cede61e
commit f0096a2bd3
1 changed files with 11 additions and 16 deletions
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27
src/platformsupport/fontdatabases/freetype/qfontengine_ft.cpp
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@ -66,11 +66,7 @@
#include FT_TYPE1_TABLES_H
#include FT_GLYPH_H
#include FT_MODULE_H
#if defined(FT_LCD_FILTER_H)
#include FT_LCD_FILTER_H
#define QT_USE_FREETYPE_LCDFILTER
#endif
#if defined(FT_CONFIG_OPTIONS_H)
#include FT_CONFIG_OPTIONS_H
@ -125,12 +121,13 @@ class QtFreetypeData
{
public:
QtFreetypeData()
: library(0)
: library(0), hasPatentFreeLcdRendering(false)
{ }
~QtFreetypeData();
FT_Library library;
QHash<QFontEngine::FaceId, QFreetypeFace *> faces;
bool hasPatentFreeLcdRendering;
};
QtFreetypeData::~QtFreetypeData()
@ -164,6 +161,11 @@ QtFreetypeData *qt_getFreetypeData()
FT_Bool no_darkening = false;
FT_Property_Set(freetypeData->library, "cff", "no-stem-darkening", &no_darkening);
#endif
// FreeType has since 2.8.1 a patent free alternative to LCD-filtering.
FT_Int amajor, aminor = 0, apatch = 0;
FT_Library_Version(freetypeData->library, &amajor, &aminor, &apatch);
if (QT_VERSION_CHECK(amajor, aminor, apatch) >= QT_VERSION_CHECK(2, 8, 1))
freetypeData->hasPatentFreeLcdRendering = true;
}
return freetypeData;
}
@ -775,10 +777,7 @@ QFontEngineFT::QFontEngineFT(const QFontDef &fd)
default_load_flags = FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH;
default_hint_style = ftInitialDefaultHintStyle;
subpixelType = Subpixel_None;
lcdFilterType = 0;
#if defined(FT_LCD_FILTER_H)
lcdFilterType = (int)((quintptr) FT_LCD_FILTER_DEFAULT);
#endif
defaultFormat = Format_None;
embeddedbitmap = false;
const QByteArray env = qgetenv("QT_NO_FT_CACHE");
@ -1165,14 +1164,14 @@ QFontEngineFT::Glyph *QFontEngineFT::loadGlyph(QGlyphSet *set, uint glyph,
int glyph_buffer_size = 0;
QScopedArrayPointer<uchar> glyph_buffer;
#if defined(QT_USE_FREETYPE_LCDFILTER)
bool useFreetypeRenderGlyph = false;
if (slot->format == FT_GLYPH_FORMAT_OUTLINE && (hsubpixel || vfactor != 1)) {
err = FT_Library_SetLcdFilter(slot->library, (FT_LcdFilter)lcdFilterType);
if (err == FT_Err_Ok)
// We use FT_Render_Glyph if freetype has support for lcd-filtering
// or is version 2.8.1 or higher and can do without.
if (err == FT_Err_Ok || qt_getFreetypeData()->hasPatentFreeLcdRendering)
useFreetypeRenderGlyph = true;
}
if (useFreetypeRenderGlyph) {
err = FT_Render_Glyph(slot, hsubpixel ? FT_RENDER_MODE_LCD : FT_RENDER_MODE_LCD_V);
@ -1193,9 +1192,7 @@ QFontEngineFT::Glyph *QFontEngineFT::loadGlyph(QGlyphSet *set, uint glyph,
convertRGBToARGB(slot->bitmap.buffer, (uint *)glyph_buffer.data(), info.width, info.height, slot->bitmap.pitch, subpixelType != Subpixel_RGB, false);
else if (vfactor != 1)
convertRGBToARGB_V(slot->bitmap.buffer, (uint *)glyph_buffer.data(), info.width, info.height, slot->bitmap.pitch, subpixelType != Subpixel_VRGB, false);
} else
#endif
{
} else {
int left = slot->metrics.horiBearingX;
int right = slot->metrics.horiBearingX + slot->metrics.width;
int top = slot->metrics.horiBearingY;
@ -1262,9 +1259,7 @@ QFontEngineFT::Glyph *QFontEngineFT::loadGlyph(QGlyphSet *set, uint glyph,
Q_ASSERT(antialias);
uchar *convoluted = new uchar[bitmap_buffer_size];
bool useLegacyLcdFilter = false;
#if defined(FC_LCD_FILTER) && defined(FT_LCD_FILTER_H)
useLegacyLcdFilter = (lcdFilterType == FT_LCD_FILTER_LEGACY);
#endif
uchar *buffer = bitmap.buffer;
if (!useLegacyLcdFilter) {
convoluteBitmap(bitmap.buffer, convoluted, bitmap.width, info.height, bitmap.pitch);