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add optional decolorization value for lcd text

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git-svn-id: http://skia.googlecode.com/svn/trunk@1358 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
reed@google.com 2011-05-17 20:52:46 +00:00
parent 1fbb30051a
commit c518134fa2
1 changed files with 23 additions and 1 deletions
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24
src/ports/SkFontHost_FreeType.cpp
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@ -72,6 +72,13 @@
using namespace skia_advanced_typeface_metrics_utils;
// SK_FREETYPE_LCD_LERP should be 0...256, where 0 means no color reduction
// and 256 means 100% color reduction (e.g. gray)
//
#ifndef SK_FREETYPE_LCD_LERP
#define SK_FREETYPE_LCD_LERP 128
#endif
//////////////////////////////////////////////////////////////////////////
struct SkFaceRec;
@ -979,6 +986,21 @@ extern void CopyFreetypeBitmapToVerticalLCDMask(const SkGlyph& dest, const FT_Bi
using namespace skia_freetype_support;
#endif
static int lerp(int start, int end, int percent) {
return start + ((end - start) * percent >> 8);
}
static uint16_t packTriple(unsigned r, unsigned g, unsigned b) {
if (SK_FREETYPE_LCD_LERP) {
SkASSERT((unsigned)SK_FREETYPE_LCD_LERP <= 256);
unsigned sum = r + 2 * g + b >> 2;
r = lerp(r, sum, SK_FREETYPE_LCD_LERP);
g = lerp(g, sum, SK_FREETYPE_LCD_LERP);
b = lerp(b, sum, SK_FREETYPE_LCD_LERP);
}
return SkPackRGB16(r >> 3, g >> 2, b >> 3);
}
static void copyFT2LCD16(const SkGlyph& glyph, const FT_Bitmap& bitmap) {
SkASSERT(glyph.fWidth * 3 == bitmap.width - 6);
SkASSERT(glyph.fHeight == bitmap.rows);
@ -991,7 +1013,7 @@ static void copyFT2LCD16(const SkGlyph& glyph, const FT_Bitmap& bitmap) {
for (int y = 0; y < glyph.fHeight; y++) {
const uint8_t* triple = src;
for (int x = 0; x < width; x++) {
dst[x] = SkPackRGB16(triple[0] >> 3, triple[1] >> 2, triple[2] >> 3);
dst[x] = packTriple(triple[0], triple[1], triple[2]);
triple += 3;
}
src += bitmap.pitch;