don't draw unpremul alpha (yet)

src/core/SkBitmapProcState.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkBitmapProcState.h"
 #include "SkColorPriv.h"
 #include "SkFilterProc.h"
@@ skipping 463 matching lines @@
     // shader will perform.
 
     fMatrixProc = this->chooseMatrixProc(trivialMatrix);
     // TODO(dominikg): SkASSERT(fMatrixProc) instead? chooseMatrixProc never returns NULL.
     if (NULL == fMatrixProc) {
         return false;
     }
 
     ///////////////////////////////////////////////////////////////////////
 
+    const SkAlphaType at = fBitmap->alphaType();
+
     // No need to do this if we're doing HQ sampling; if filter quality is
     // still set to HQ by the time we get here, then we must have installed
     // the shader procs above and can skip all this.
 
     if (fFilterLevel < SkPaint::kHigh_FilterLevel) {
 
         int index = 0;
         if (fAlphaScale < 256) {  // note: this distinction is not used for D16
             index |= 1;
         }
         if (fInvType <= (SkMatrix::kTranslate_Mask | SkMatrix::kScale_Mask)) {
             index |= 2;
         }
         if (fFilterLevel > SkPaint::kNone_FilterLevel) {
             index |= 4;
         }
         // bits 3,4,5 encoding the source bitmap format
         switch (fBitmap->colorType()) {
             case kN32_SkColorType:
+                if (kPremul_SkAlphaType != at && kOpaque_SkAlphaType != at) {
+                    return false;
+                }
                 index |= 0;
                 break;
             case kRGB_565_SkColorType:
                 index |= 8;
                 break;
             case kIndex_8_SkColorType:
+                if (kPremul_SkAlphaType != at && kOpaque_SkAlphaType != at) {
+                    return false;
+                }
                 index |= 16;
                 break;
             case kARGB_4444_SkColorType:
+                if (kPremul_SkAlphaType != at && kOpaque_SkAlphaType != at) {
+                    return false;
+                }
                 index |= 24;
                 break;
             case kAlpha_8_SkColorType:
                 index |= 32;
                 fPaintPMColor = SkPreMultiplyColor(paint.getColor());
                 break;
             default:
                 // TODO(dominikg): Should we ever get here? SkASSERT(false) instead?
                 return false;
         }
@@ skipping 507 matching lines @@
     } else {
         size >>= 2;
     }
 
     if (fFilterLevel != SkPaint::kNone_FilterLevel) {
         size >>= 1;
     }
 
     return size;
 }