SkARGB4444_Blitter::SkARGB4444_Blitter(const SkBitmap& device,
const SkPaint& paint) : INHERITED(device) {
// cache premultiplied versions in 4444
SkPMColor c = SkPreMultiplyColor(paint.getColor());
fPMColor16 = SkPixel32ToPixel4444(c);
if (paint.isDither()) {
fPMColor16Other = SkDitherPixel32To4444(c);
} else {
fPMColor16Other = fPMColor16;
}
// cache raw versions in 4444
fRawColor16 = SkPackARGB4444(0xFF >> 4, SkColorGetR(c) >> 4,
SkColorGetG(c) >> 4, SkColorGetB(c) >> 4);
if (paint.isDither()) {
fRawColor16Other = SkDitherARGB32To4444(0xFF, SkColorGetR(c),
SkColorGetG(c), SkColorGetB(c));
} else {
fRawColor16Other = fRawColor16;
}
fScale16 = SkAlpha15To16(SkGetPackedA4444(fPMColor16Other));
if (16 == fScale16) {
// force the original to also be opaque
fPMColor16 |= (0xF << SK_A4444_SHIFT);
}
}
SkARGB4444_Blitter::SkARGB4444_Blitter(const SkBitmap& device, const SkPaint& paint)
: INHERITED(device)
{
// cache premultiplied versions in 4444
SkPMColor c = SkPreMultiplyColor(paint.getColor());
fPMColor16 = SkPixel32ToPixel4444(c);
if (paint.isDither()) {
fPMColor16Other = SkDitherPixel32To4444(c);
} else {
fPMColor16Other = fPMColor16;
}
// cache raw versions in 4444
fRawColor16 = SkPackARGB4444(0xFF >> 4, SkColorGetR(c) >> 4,
SkColorGetG(c) >> 4, SkColorGetB(c) >> 4);
if (paint.isDither()) {
fRawColor16Other = SkDitherARGB32To4444(0xFF, SkColorGetR(c),
SkColorGetG(c), SkColorGetB(c));
} else {
fRawColor16Other = fRawColor16;
}
#if 0 /// don't think this assertion is true, but need it be?
// our dithered color will be the same or more opaque than the original
// so use dithered to compute our scale
SkASSERT(SkGetPackedA4444(fPMColor16Other) >= SkGetPackedA4444(fPMColor16));
#endif
fScale16 = SkAlpha15To16(SkGetPackedA4444(fPMColor16Other));
if (16 == fScale16) {
// force the original to also be opaque
fPMColor16 |= (0xF << SK_A4444_SHIFT);
}
}
static inline SkPMColor SkBlendARGB4444(SkPMColor16 src, SkPMColor16 dst,
U8CPU aa) {
SkASSERT((unsigned)aa <= 255);
unsigned src_scale = SkAlpha255To256(aa) >> 4;
unsigned dst_scale = SkAlpha15To16(15 - SkAlphaMul4(SkGetPackedA4444(src), src_scale));
uint32_t src32 = SkExpand_4444(src) * src_scale;
uint32_t dst32 = SkExpand_4444(dst) * dst_scale;
return SkCompact_4444((src32 + dst32) >> 4);
}
