michael@0: 
michael@0: /*
michael@0:  * Copyright 2006 The Android Open Source Project
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: 
michael@0: #include "SkComposeShader.h"
michael@0: #include "SkColorFilter.h"
michael@0: #include "SkColorPriv.h"
michael@0: #include "SkColorShader.h"
michael@0: #include "SkReadBuffer.h"
michael@0: #include "SkWriteBuffer.h"
michael@0: #include "SkXfermode.h"
michael@0: #include "SkString.h"
michael@0: 
michael@0: ///////////////////////////////////////////////////////////////////////////////
michael@0: 
michael@0: SkComposeShader::SkComposeShader(SkShader* sA, SkShader* sB, SkXfermode* mode) {
michael@0:     fShaderA = sA;  sA->ref();
michael@0:     fShaderB = sB;  sB->ref();
michael@0:     // mode may be null
michael@0:     fMode = mode;
michael@0:     SkSafeRef(mode);
michael@0: }
michael@0: 
michael@0: SkComposeShader::SkComposeShader(SkReadBuffer& buffer) :
michael@0:     INHERITED(buffer) {
michael@0:     fShaderA = buffer.readShader();
michael@0:     if (NULL == fShaderA) {
michael@0:         fShaderA = SkNEW_ARGS(SkColorShader, (0));
michael@0:     }
michael@0:     fShaderB = buffer.readShader();
michael@0:     if (NULL == fShaderB) {
michael@0:         fShaderB = SkNEW_ARGS(SkColorShader, (0));
michael@0:     }
michael@0:     fMode = buffer.readXfermode();
michael@0: }
michael@0: 
michael@0: SkComposeShader::~SkComposeShader() {
michael@0:     SkSafeUnref(fMode);
michael@0:     fShaderB->unref();
michael@0:     fShaderA->unref();
michael@0: }
michael@0: 
michael@0: class SkAutoAlphaRestore {
michael@0: public:
michael@0:     SkAutoAlphaRestore(SkPaint* paint, uint8_t newAlpha) {
michael@0:         fAlpha = paint->getAlpha();
michael@0:         fPaint = paint;
michael@0:         paint->setAlpha(newAlpha);
michael@0:     }
michael@0: 
michael@0:     ~SkAutoAlphaRestore() {
michael@0:         fPaint->setAlpha(fAlpha);
michael@0:     }
michael@0: private:
michael@0:     SkPaint*    fPaint;
michael@0:     uint8_t     fAlpha;
michael@0: };
michael@0: #define SkAutoAlphaRestore(...) SK_REQUIRE_LOCAL_VAR(SkAutoAlphaRestore)
michael@0: 
michael@0: void SkComposeShader::flatten(SkWriteBuffer& buffer) const {
michael@0:     this->INHERITED::flatten(buffer);
michael@0:     buffer.writeFlattenable(fShaderA);
michael@0:     buffer.writeFlattenable(fShaderB);
michael@0:     buffer.writeFlattenable(fMode);
michael@0: }
michael@0: 
michael@0: /*  We call setContext on our two worker shaders. However, we
michael@0:     always let them see opaque alpha, and if the paint really
michael@0:     is translucent, then we apply that after the fact.
michael@0: 
michael@0:     We need to keep the calls to setContext/endContext balanced, since if we
michael@0:     return false, our endContext() will not be called.
michael@0:  */
michael@0: bool SkComposeShader::setContext(const SkBitmap& device,
michael@0:                                  const SkPaint& paint,
michael@0:                                  const SkMatrix& matrix) {
michael@0:     if (!this->INHERITED::setContext(device, paint, matrix)) {
michael@0:         return false;
michael@0:     }
michael@0: 
michael@0:     // we preconcat our localMatrix (if any) with the device matrix
michael@0:     // before calling our sub-shaders
michael@0: 
michael@0:     SkMatrix tmpM;
michael@0: 
michael@0:     tmpM.setConcat(matrix, this->getLocalMatrix());
michael@0: 
michael@0:     SkAutoAlphaRestore  restore(const_cast<SkPaint*>(&paint), 0xFF);
michael@0: 
michael@0:     bool setContextA = fShaderA->setContext(device, paint, tmpM);
michael@0:     bool setContextB = fShaderB->setContext(device, paint, tmpM);
michael@0:     if (!setContextA || !setContextB) {
michael@0:         if (setContextB) {
michael@0:             fShaderB->endContext();
michael@0:         }
michael@0:         else if (setContextA) {
michael@0:             fShaderA->endContext();
michael@0:         }
michael@0:         this->INHERITED::endContext();
michael@0:         return false;
michael@0:     }
michael@0:     return true;
michael@0: }
michael@0: 
michael@0: void SkComposeShader::endContext() {
michael@0:     fShaderB->endContext();
michael@0:     fShaderA->endContext();
michael@0:     this->INHERITED::endContext();
michael@0: }
michael@0: 
michael@0: // larger is better (fewer times we have to loop), but we shouldn't
michael@0: // take up too much stack-space (each element is 4 bytes)
michael@0: #define TMP_COLOR_COUNT     64
michael@0: 
michael@0: void SkComposeShader::shadeSpan(int x, int y, SkPMColor result[], int count) {
michael@0:     SkShader*   shaderA = fShaderA;
michael@0:     SkShader*   shaderB = fShaderB;
michael@0:     SkXfermode* mode = fMode;
michael@0:     unsigned    scale = SkAlpha255To256(this->getPaintAlpha());
michael@0: 
michael@0:     SkPMColor   tmp[TMP_COLOR_COUNT];
michael@0: 
michael@0:     if (NULL == mode) {   // implied SRC_OVER
michael@0:         // TODO: when we have a good test-case, should use SkBlitRow::Proc32
michael@0:         // for these loops
michael@0:         do {
michael@0:             int n = count;
michael@0:             if (n > TMP_COLOR_COUNT) {
michael@0:                 n = TMP_COLOR_COUNT;
michael@0:             }
michael@0: 
michael@0:             shaderA->shadeSpan(x, y, result, n);
michael@0:             shaderB->shadeSpan(x, y, tmp, n);
michael@0: 
michael@0:             if (256 == scale) {
michael@0:                 for (int i = 0; i < n; i++) {
michael@0:                     result[i] = SkPMSrcOver(tmp[i], result[i]);
michael@0:                 }
michael@0:             } else {
michael@0:                 for (int i = 0; i < n; i++) {
michael@0:                     result[i] = SkAlphaMulQ(SkPMSrcOver(tmp[i], result[i]),
michael@0:                                             scale);
michael@0:                 }
michael@0:             }
michael@0: 
michael@0:             result += n;
michael@0:             x += n;
michael@0:             count -= n;
michael@0:         } while (count > 0);
michael@0:     } else {    // use mode for the composition
michael@0:         do {
michael@0:             int n = count;
michael@0:             if (n > TMP_COLOR_COUNT) {
michael@0:                 n = TMP_COLOR_COUNT;
michael@0:             }
michael@0: 
michael@0:             shaderA->shadeSpan(x, y, result, n);
michael@0:             shaderB->shadeSpan(x, y, tmp, n);
michael@0:             mode->xfer32(result, tmp, n, NULL);
michael@0: 
michael@0:             if (256 == scale) {
michael@0:                 for (int i = 0; i < n; i++) {
michael@0:                     result[i] = SkAlphaMulQ(result[i], scale);
michael@0:                 }
michael@0:             }
michael@0: 
michael@0:             result += n;
michael@0:             x += n;
michael@0:             count -= n;
michael@0:         } while (count > 0);
michael@0:     }
michael@0: }
michael@0: 
michael@0: #ifndef SK_IGNORE_TO_STRING
michael@0: void SkComposeShader::toString(SkString* str) const {
michael@0:     str->append("SkComposeShader: (");
michael@0: 
michael@0:     str->append("ShaderA: ");
michael@0:     fShaderA->toString(str);
michael@0:     str->append(" ShaderB: ");
michael@0:     fShaderB->toString(str);
michael@0:     str->append(" Xfermode: ");
michael@0:     fMode->toString(str);
michael@0: 
michael@0:     this->INHERITED::toString(str);
michael@0: 
michael@0:     str->append(")");
michael@0: }
michael@0: #endif