Swizzle shader output and blend when using GL_RED to implement kAlpha_8_GrPixelConfig

src/gpu/gl/GrGLGpu.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 "GrGLGpu.h"
 #include "GrGLGLSL.h"
@@ skipping 1552 matching lines @@
         return false;
     }
 
     GrGLuint programID = program->programID();
     if (fHWProgramID != programID) {
         GL_CALL(UseProgram(programID));
         fHWProgramID = programID;
     }
 
     if (blendInfo.fWriteColor) {
-        this->flushBlend(blendInfo);
+        // Swizzle the blend to match what the shader will output.
+        const GrSwizzle& swizzle = this->glCaps().glslCaps()->configOutputSwizzle(
+            args.fPipeline->getRenderTarget()->config());
+        this->flushBlend(blendInfo, swizzle);
     }
 
     SkSTArray<8, const GrTextureAccess*> textureAccesses;
     program->setData(*args.fPrimitiveProcessor, pipeline, &textureAccesses);
 
     int numTextureAccesses = textureAccesses.count();
     for (int i = 0; i < numTextureAccesses; i++) {
         this->bindTexture(i, textureAccesses[i]->getParams(),
                           static_cast<GrGLTexture*>(textureAccesses[i]->getTexture()));
     }
@@ skipping 59 matching lines @@
                              reinterpret_cast<GrGLvoid*>(vertexOffsetInBytes + offset));
             offset += attrib.fOffset;
         }
         attribState->disableUnusedArrays(this, usedAttribArraysMask);
     }
 }
 
 void GrGLGpu::buildProgramDesc(GrProgramDesc* desc,
                                const GrPrimitiveProcessor& primProc,
                                const GrPipeline& pipeline) const {
-    if (!GrGLProgramDescBuilder::Build(desc, primProc, pipeline, this)) {
+    if (!GrGLProgramDescBuilder::Build(desc, primProc, pipeline, *this->glCaps().glslCaps())) {
         SkDEBUGFAIL("Failed to generate GL program descriptor");
     }
 }
 
 void GrGLGpu::bindBuffer(GrGLuint id, GrGLenum type) {
     this->handleDirtyContext();
     if (GR_GL_ARRAY_BUFFER == type) {
         this->bindVertexBuffer(id);
     } else if (GR_GL_ELEMENT_ARRAY_BUFFER == type) {
         this->bindIndexBufferAndDefaultVertexArray(id);
@@ skipping 724 matching lines @@
             }
         } else {
             if (kNo_TriState != fMSAAEnabled) {
                 GL_CALL(Disable(GR_GL_MULTISAMPLE));
                 fMSAAEnabled = kNo_TriState;
             }
         }
     }
 }
 
-void GrGLGpu::flushBlend(const GrXferProcessor::BlendInfo& blendInfo) {
+void GrGLGpu::flushBlend(const GrXferProcessor::BlendInfo& blendInfo, const GrSwizzle& swizzle) {
     // Any optimization to disable blending should have already been applied and
     // tweaked the equation to "add" or "subtract", and the coeffs to (1, 0).
 
     GrBlendEquation equation = blendInfo.fEquation;
     GrBlendCoeff srcCoeff = blendInfo.fSrcBlend;
     GrBlendCoeff dstCoeff = blendInfo.fDstBlend;
     bool blendOff = (kAdd_GrBlendEquation == equation || kSubtract_GrBlendEquation == equation) &&
                     kOne_GrBlendCoeff == srcCoeff && kZero_GrBlendCoeff == dstCoeff;
     if (blendOff) {
         if (kNo_TriState != fHWBlendState.fEnabled) {
@@ skipping 32 matching lines @@
     }
 
     if (fHWBlendState.fSrcCoeff != srcCoeff ||
         fHWBlendState.fDstCoeff != dstCoeff) {
         GL_CALL(BlendFunc(gXfermodeCoeff2Blend[srcCoeff],
                           gXfermodeCoeff2Blend[dstCoeff]));
         fHWBlendState.fSrcCoeff = srcCoeff;
         fHWBlendState.fDstCoeff = dstCoeff;
     }
 
-    GrColor blendConst = blendInfo.fBlendConstant;
-    if ((BlendCoeffReferencesConstant(srcCoeff) ||
-         BlendCoeffReferencesConstant(dstCoeff)) &&
-        (!fHWBlendState.fConstColorValid || fHWBlendState.fConstColor != blendConst)) {
-        GrGLfloat c[4];
-        GrColorToRGBAFloat(blendConst, c);
-        GL_CALL(BlendColor(c[0], c[1], c[2], c[3]));
-        fHWBlendState.fConstColor = blendConst;
-        fHWBlendState.fConstColorValid = true;
+    if ((BlendCoeffReferencesConstant(srcCoeff) || BlendCoeffReferencesConstant(dstCoeff))) {
+        GrColor blendConst = blendInfo.fBlendConstant;
+        blendConst = swizzle.applyTo(blendConst);
+        if (!fHWBlendState.fConstColorValid || fHWBlendState.fConstColor != blendConst) {
+            GrGLfloat c[4];
+            GrColorToRGBAFloat(blendConst, c);
+            GL_CALL(BlendColor(c[0], c[1], c[2], c[3]));
+            fHWBlendState.fConstColor = blendConst;
+            fHWBlendState.fConstColorValid = true;
+        }
     }
 }
 
 static inline GrGLenum tile_to_gl_wrap(SkShader::TileMode tm) {
     static const GrGLenum gWrapModes[] = {
         GR_GL_CLAMP_TO_EDGE,
         GR_GL_REPEAT,
         GR_GL_MIRRORED_REPEAT
     };
     GR_STATIC_ASSERT(SkShader::kTileModeCount == SK_ARRAY_COUNT(gWrapModes));
@@ skipping 363 matching lines @@
     desc->fConfig = src->config();
     desc->fOrigin = src->origin();
     desc->fFlags = kNone_GrSurfaceFlags;
     return true;
 }
 
 bool GrGLGpu::onCopySurface(GrSurface* dst,
                             GrSurface* src,
                             const SkIRect& srcRect,
                             const SkIPoint& dstPoint) {
+    // None of our copy methods can handle a swizzle. TODO: Make copySurfaceAsDraw handle the
+    // swizzle.
+    if (this->glCaps().glslCaps()->configOutputSwizzle(src->config()) !=
+        this->glCaps().glslCaps()->configOutputSwizzle(dst->config())) {
+        return false;
+    }
     if (src->asTexture() && dst->asRenderTarget()) {
         this->copySurfaceAsDraw(dst, src, srcRect, dstPoint);
         return true;
     }
     
     if (can_copy_texsubimage(dst, src, this)) {
         this->copySurfaceAsCopyTexSubImage(dst, src, srcRect, dstPoint);
         return true;
     }
 
@@ skipping 204 matching lines @@
         1, 0,
     };
     GL_ALLOC_CALL(this->glInterface(),
                   BufferData(GR_GL_ARRAY_BUFFER,
                              (GrGLsizeiptr) sizeof(vdata),
                              vdata,  // data ptr
                              GR_GL_STATIC_DRAW));
 }
 
 void GrGLGpu::drawDebugWireRect(GrRenderTarget* rt, const SkIRect& rect, GrColor color) {
+    // TODO: This should swizzle the output to match dst's config, though it is a debugging
+    // visualization.
+
     this->handleDirtyContext();
     if (!fWireRectProgram.fProgram) {
         this->createWireRectProgram();
     }
 
     int w = rt->width();
     int h = rt->height();
 
     // Compute the edges of the rectangle (top,left,right,bottom) in NDC space. Must consider
     // whether the render target is flipped or not.
@@ skipping 30 matching lines @@
     GrGLAttribArrayState* attribs =
         fHWGeometryState.bindArrayAndBufferToDraw(this, fWireRectArrayBuffer);
     attribs->set(this, 0, fWireRectArrayBuffer, 2, GR_GL_FLOAT, false, 2 * sizeof(GrGLfloat), 0);
     attribs->disableUnusedArrays(this, 0x1);
 
     GL_CALL(Uniform4fv(fWireRectProgram.fRectUniform, 1, edges));
     GL_CALL(Uniform4fv(fWireRectProgram.fColorUniform, 1, channels));
 
     GrXferProcessor::BlendInfo blendInfo;
     blendInfo.reset();
-    this->flushBlend(blendInfo);
+    this->flushBlend(blendInfo, GrSwizzle::RGBA());
     this->flushColorWrite(true);
     this->flushDrawFace(GrPipelineBuilder::kBoth_DrawFace);
     this->flushHWAAState(glRT, false);
     this->disableScissor();
     GrStencilSettings stencil;
     stencil.setDisabled();
     this->flushStencil(stencil);
 
     GL_CALL(DrawArrays(GR_GL_LINE_LOOP, 0, 4));
 }
@@ skipping 50 matching lines @@
         sy1 = 1.f - sy1;
     }
 
     GL_CALL(Uniform4f(fCopyPrograms[progIdx].fPosXformUniform, dx1 - dx0, dy1 - dy0, dx0, dy0));
     GL_CALL(Uniform4f(fCopyPrograms[progIdx].fTexCoordXformUniform,
                       sx1 - sx0, sy1 - sy0, sx0, sy0));
     GL_CALL(Uniform1i(fCopyPrograms[progIdx].fTextureUniform, 0));
 
     GrXferProcessor::BlendInfo blendInfo;
     blendInfo.reset();
-    this->flushBlend(blendInfo);
+    this->flushBlend(blendInfo, GrSwizzle::RGBA());
     this->flushColorWrite(true);
     this->flushDrawFace(GrPipelineBuilder::kBoth_DrawFace);
     this->flushHWAAState(dstRT, false);
     this->disableScissor();
     GrStencilSettings stencil;
     stencil.setDisabled();
     this->flushStencil(stencil);
 
     GL_CALL(DrawArrays(GR_GL_TRIANGLE_STRIP, 0, 4));
 }
@@ skipping 245 matching lines @@
             this->setVertexArrayID(gpu, 0);
         }
         int attrCount = gpu->glCaps().maxVertexAttributes();
         if (fDefaultVertexArrayAttribState.count() != attrCount) {
             fDefaultVertexArrayAttribState.resize(attrCount);
         }
         attribState = &fDefaultVertexArrayAttribState;
     }
     return attribState;
 }