Add "sample locations" feature to GrProcessor

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"
 #include "GrGLStencilAttachment.h"
@@ skipping 3765 matching lines @@
                             dstGLRect.fBottom,
                             dstGLRect.fLeft + dstGLRect.fWidth,
                             dstGLRect.fBottom + dstGLRect.fHeight,
                             GR_GL_COLOR_BUFFER_BIT, GR_GL_NEAREST));
     this->unbindTextureFBOForCopy(GR_GL_DRAW_FRAMEBUFFER, dst);
     this->unbindTextureFBOForCopy(GR_GL_READ_FRAMEBUFFER, src);
     this->didWriteToSurface(dst, &dstRect);
     return true;
 }
 
+void GrGLGpu::onGetMultisampleSpecs(GrRenderTarget* rt,
+                                    const GrStencilSettings& stencil,
+                                    int* effectiveSampleCnt,
+                                    SamplePattern* pattern) {
+    SkASSERT(!rt->hasMixedSamples() || rt->renderTargetPriv().getStencilAttachment() ||
+             stencil.isDisabled());
+
+    this->flushStencil(stencil);
+    this->flushHWAAState(rt, true, !stencil.isDisabled());
+    this->flushRenderTarget(static_cast<GrGLRenderTarget*>(rt), &SkIRect::EmptyIRect());
+
+    if (0 != this->caps()->maxRasterSamples()) {
+        GR_GL_GetIntegerv(this->glInterface(), GR_GL_EFFECTIVE_RASTER_SAMPLES, effectiveSampleCnt);
+    } else {
+        GR_GL_GetIntegerv(this->glInterface(), GR_GL_SAMPLES, effectiveSampleCnt);
+    }
+    if (this->caps()->sampleLocationsSupport()) {
+        pattern->reset(*effectiveSampleCnt);
+        for (int i = 0; i < *effectiveSampleCnt; ++i) {
+            GrGLfloat pos[2];
+            GL_CALL(GetMultisamplefv(GR_GL_SAMPLE_POSITION, i, pos));
+            // OpenGL pixel space and Skia device space have inverted y directions.
+            (*pattern)[i].set(pos[0], 1 - pos[1]);
+        }
+    }
+}
+
 void GrGLGpu::xferBarrier(GrRenderTarget* rt, GrXferBarrierType type) {
     SkASSERT(type);
     switch (type) {
         case kTexture_GrXferBarrierType: {
             GrGLRenderTarget* glrt = static_cast<GrGLRenderTarget*>(rt);
             if (glrt->textureFBOID() != glrt->renderFBOID()) {
                 // The render target uses separate storage so no need for glTextureBarrier.
                 // FIXME: The render target will resolve automatically when its texture is bound,
                 // but we could resolve only the bounds that will be read if we do it here instead.
                 return;
@@ skipping 156 matching lines @@
         if (GR_GL_TEXTURE_EXTERNAL == glTexture->target() ||
             GR_GL_TEXTURE_RECTANGLE == glTexture->target()) {
             copyParams->fFilter = GrTextureParams::kNone_FilterMode;
             copyParams->fWidth = texture->width();
             copyParams->fHeight = texture->height();
             return true;
         }
     }
     return false;
 }