lcd blits for sRGB

include/core/SkXfermode.h

Index: include/core/SkXfermode.h
diff --git a/include/core/SkXfermode.h b/include/core/SkXfermode.h
index 21d77f874768bcf03ef28607285377b55ab2b045..3b0f49d22e12a70a2210b82cfd0e736ae55f6cb5 100644
--- a/include/core/SkXfermode.h
+++ b/include/core/SkXfermode.h
@@ -248,6 +248,16 @@ public:
     static U64Proc1 GetU64Proc1(Mode, uint32_t flags);
     static U64ProcN GetU64ProcN(Mode, uint32_t flags);
 
+    enum LCDFlags {
+        kSrcIsOpaque_LCDFlag    = 1 << 0,   // else src(s) may have alpha < 1
+        kSrcIsSingle_LCDFlag    = 1 << 1,   // else src[count]
+        kDstIsLinearInt_LCDFlag = 1 << 2,   // else srgb/half-float

[mtklein, 2016/02/18 16:10:20]

Ah,

  IsLinearInt -> u32 == 8888, u64 = 16161616
 !IsLinearInt -> u32 == sRGB, u64 = hhhh

?

Guess this is so confusing because 3 of the destination options are int,
3 of the options are linear.

+    };
+    typedef void (*LCD32Proc)(uint32_t* dst, const SkPM4f* src, int count, const uint16_t lcd[]);
+    typedef void (*LCD64Proc)(uint64_t* dst, const SkPM4f* src, int count, const uint16_t lcd[]);
+    static LCD32Proc GetLCD32Proc(uint32_t flags);
+    static LCD64Proc GetLCD64Proc(uint32_t) { return nullptr; }
+
 protected:
     SkXfermode() {}
     /** The default implementation of xfer32/xfer16/xferA8 in turn call this