Add an option to create unpremultiplied bitmaps.

src/core/SkColor.cpp

 
 /*
  * 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.
  */
 
 
 #include "SkColor.h"
 #include "SkColorPriv.h"
 
 SkPMColor SkPreMultiplyARGB(U8CPU a, U8CPU r, U8CPU g, U8CPU b) {
     return SkPremultiplyARGBInline(a, r, g, b);
 }
 
 SkPMColor SkPreMultiplyColor(SkColor c) {
     return SkPremultiplyARGBInline(SkColorGetA(c), SkColorGetR(c),
                                    SkColorGetG(c), SkColorGetB(c));
 }
 
+/**
+ *  Interprets c as an unpremultiplied color, and returns the
+ *  premultiplied equivalent.
+ */
+SkPMColor SkPreMultiplyUnPMColor(SkPMColor c) {

[reed1, 2013/06/13 19:33:07]

Since there is no header for this method, and it is pretty trivial (and there is
only one correct way to impl it), I propose we just copy/paste it into the two
testing/sample files that use it for now.

[scroggo, 2013/06/13 20:10:40]

Done.

+    U8CPU a = SkGetPackedA32(c);
+    U8CPU r = SkGetPackedR32(c);
+    U8CPU g = SkGetPackedG32(c);
+    U8CPU b = SkGetPackedB32(c);
+    return SkPreMultiplyARGB(a, r, g, b);
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 static inline SkScalar ByteToScalar(U8CPU x) {
     SkASSERT(x <= 255);
     return SkIntToScalar(x) / 255;
 }
 
 static inline SkScalar ByteDivToScalar(int numer, U8CPU denom) {
     // cast to keep the answer signed
     return SkIntToScalar(numer) / (int)denom;
@@ skipping 72 matching lines @@
     switch (hx >> 16) {
         case 0: r = v; g = t; b = p; break;
         case 1: r = q; g = v; b = p; break;
         case 2: r = p; g = v; b = t; break;
         case 3: r = p; g = q; b = v; break;
         case 4: r = t;  g = p; b = v; break;
         default: r = v; g = p; b = q; break;
     }
     return SkColorSetARGB(a, r, g, b);
 }