float components in xfermodes

include/core/SkXfermode.h

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkXfermode_DEFINED
@@ skipping 211 matching lines @@
             }
             return true;
         }
         return xfermode->asXPFactory(xpf);
     }
 
     SK_TO_STRING_PUREVIRT()
     SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
     SK_DEFINE_FLATTENABLE_TYPE(SkXfermode)
 
+    enum PM4fFlags {

[mtklein, 2016/02/01 22:53:52]

We may want to split these up / mark these as required and optional. 
SrcIsOpaque is an optional optimization.  DstIsSRGB is required for correctness.
 Seems a little weird to treat them the same.

[reed1, 2016/02/02 14:20:54]

I combined them just for convenience. Happy to consider other organizations.

+        kSrcIsOpaque_PM4fFlag  = 1 << 0,
+        kDstIsSRGB_PM4fFlag    = 1 << 1,
+    };
+    struct PM4fState {
+        const SkXfermode* fXfer;
+        uint32_t          fFlags;
+    };
+    typedef void (*PM4fProc1)(const PM4fState&, uint32_t dst[], const SkPM4f& src,
+                              int count, const SkAlpha coverage[]);
+    typedef void (*PM4fProcN)(const PM4fState&, uint32_t dst[], const SkPM4f src[],
+                              int count, const SkAlpha coverage[]);
+    static PM4fProc1 GetPM4fProc1(Mode, uint32_t flags);
+    static PM4fProcN GetPM4fProcN(Mode, uint32_t flags);
+    virtual PM4fProc1 getPM4fProc1(uint32_t flags) const;
+    virtual PM4fProcN getPM4fProcN(uint32_t flags) const;
+
 protected:
     SkXfermode() {}
     /** The default implementation of xfer32/xfer16/xferA8 in turn call this
         method, 1 color at a time (upscaled to a SkPMColor). The default
         implementation of this method just returns dst. If performance is
         important, your subclass should override xfer32/xfer16/xferA8 directly.
 
         This method will not be called directly by the client, so it need not
         be implemented if your subclass has overridden xfer32/xfer16/xferA8
     */
     virtual SkPMColor xferColor(SkPMColor src, SkPMColor dst) const;
 
 private:
     enum {
         kModeCount = kLastMode + 1
     };
 
     // TODO(benjaminwagner): This is crazy, but it fixes the Google3 Android build. :-(
     virtual void doNothing() const;
 
     typedef SkFlattenable INHERITED;
 };
 
 #endif