michael@0: /*
michael@0:  * Copyright 2013 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #include "SkPaintPriv.h"
michael@0: 
michael@0: #include "SkBitmap.h"
michael@0: #include "SkColorFilter.h"
michael@0: #include "SkPaint.h"
michael@0: #include "SkShader.h"
michael@0: 
michael@0: bool isPaintOpaque(const SkPaint* paint,
michael@0:                    const SkBitmap* bmpReplacesShader) {
michael@0:     // TODO: SkXfermode should have a virtual isOpaque method, which would
michael@0:     // make it possible to test modes that do not have a Coeff representation.
michael@0: 
michael@0:     if (!paint) {
michael@0:         return bmpReplacesShader ? bmpReplacesShader->isOpaque() : true;
michael@0:     }
michael@0: 
michael@0:     SkXfermode::Coeff srcCoeff, dstCoeff;
michael@0:     if (SkXfermode::AsCoeff(paint->getXfermode(), &srcCoeff, &dstCoeff)){
michael@0:         if (SkXfermode::kDA_Coeff == srcCoeff || SkXfermode::kDC_Coeff == srcCoeff ||
michael@0:             SkXfermode::kIDA_Coeff == srcCoeff || SkXfermode::kIDC_Coeff == srcCoeff) {
michael@0:             return false;
michael@0:         }
michael@0:         switch (dstCoeff) {
michael@0:         case SkXfermode::kZero_Coeff:
michael@0:             return true;
michael@0:         case SkXfermode::kISA_Coeff:
michael@0:             if (paint->getAlpha() != 255) {
michael@0:                 break;
michael@0:             }
michael@0:             if (bmpReplacesShader) {
michael@0:                 if (!bmpReplacesShader->isOpaque()) {
michael@0:                     break;
michael@0:                 }
michael@0:             } else if (paint->getShader() && !paint->getShader()->isOpaque()) {
michael@0:                 break;
michael@0:             }
michael@0:             if (paint->getColorFilter() &&
michael@0:                 ((paint->getColorFilter()->getFlags() &
michael@0:                 SkColorFilter::kAlphaUnchanged_Flag) == 0)) {
michael@0:                 break;
michael@0:             }
michael@0:             return true;
michael@0:         case SkXfermode::kSA_Coeff:
michael@0:             if (paint->getAlpha() != 0) {
michael@0:                 break;
michael@0:             }
michael@0:             if (paint->getColorFilter() &&
michael@0:                 ((paint->getColorFilter()->getFlags() &
michael@0:                 SkColorFilter::kAlphaUnchanged_Flag) == 0)) {
michael@0:                 break;
michael@0:             }
michael@0:             return true;
michael@0:         case SkXfermode::kSC_Coeff:
michael@0:             if (paint->getColor() != 0) { // all components must be 0
michael@0:                 break;
michael@0:             }
michael@0:             if (bmpReplacesShader || paint->getShader()) {
michael@0:                 break;
michael@0:             }
michael@0:             if (paint->getColorFilter() && (
michael@0:                 (paint->getColorFilter()->getFlags() &
michael@0:                 SkColorFilter::kAlphaUnchanged_Flag) == 0)) {
michael@0:                 break;
michael@0:             }
michael@0:             return true;
michael@0:         default:
michael@0:             break;
michael@0:         }
michael@0:     }
michael@0:     return false;
michael@0: }