Add support for GL_EXT_raster_multisample

src/gpu/gl/GrGLCaps.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrGLCaps.h"
 
@@ skipping 288 matching lines @@
      * GrCaps fields
      **************************************************************************/
 
     // We need dual source blending and the ability to disable multisample in order to support mixed
     // samples in every corner case.
     if (fMultisampleDisableSupport &&
         glslCaps->dualSourceBlendingSupport() &&
         fShaderCaps->pathRenderingSupport()) {
         fUsesMixedSamples = ctxInfo.hasExtension("GL_NV_framebuffer_mixed_samples") ||
                 ctxInfo.hasExtension("GL_CHROMIUM_framebuffer_mixed_samples");
-        // Workaround NVIDIA bug related to glInvalidateFramebuffer and mixed samples.
-        if (fUsesMixedSamples && (kNVIDIA_GrGLDriver == ctxInfo.driver() ||
-                                  kChromium_GrGLDriver == ctxInfo.driver())) {
-            fDiscardRenderTargetSupport = false;
-            fInvalidateFBType = kNone_InvalidateFBType;
+        if (fUsesMixedSamples) {
+            if (kNVIDIA_GrGLDriver == ctxInfo.driver() ||
+                kChromium_GrGLDriver == ctxInfo.driver()) {
+                // Workaround NVIDIA bug related to glInvalidateFramebuffer and mixed samples.
+                fDiscardRenderTargetSupport = false;
+                fInvalidateFBType = kNone_InvalidateFBType;
+            }
+            // Raster multisample is only useful to us when coverage modulation is also supported,
+            // as defined by mixed samples.
+            fRasterMultisampleSupport = ctxInfo.hasExtension("GL_EXT_raster_multisample");
+            if (fRasterMultisampleSupport) {
+                GR_GL_GetIntegerv(gli, GR_GL_MAX_RASTER_SAMPLES, &fMaxRasterSamples);
+            }
         }
     }
 
     // fUsesMixedSamples must be set before calling initFSAASupport.
     this->initFSAASupport(ctxInfo, gli);
     this->initBlendEqationSupport(ctxInfo);
     this->initStencilFormats(ctxInfo);
 
     if (kGL_GrGLStandard == standard) {
         // we could also look for GL_ATI_separate_stencil extension or
@@ skipping 1311 matching lines @@
         for (int j = 0; j < kExternalFormatUsageCnt; ++j) {
             SkASSERT(defaultEntry.fFormats.fExternalFormat[j] !=
                      fConfigTable[i].fFormats.fExternalFormat[j]);
         }
         SkASSERT(defaultEntry.fFormats.fExternalType != fConfigTable[i].fFormats.fExternalType);
     }
 #endif
 }
 
 void GrGLCaps::onApplyOptionsOverrides(const GrContextOptions& options) {}