sRGB support in Ganesh. Several pieces:

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 877 matching lines @@
         case kAlpha_8_GrPixelConfig:
             return 1;
         case kRGB_565_GrPixelConfig:
         case kRGBA_4444_GrPixelConfig:
         case kAlpha_half_GrPixelConfig:
         case kRGBA_half_GrPixelConfig:
             return 2;
         case kRGBA_8888_GrPixelConfig:
         case kBGRA_8888_GrPixelConfig:
         case kSRGBA_8888_GrPixelConfig:
+        case kSBGRA_8888_GrPixelConfig:
         case kRGBA_float_GrPixelConfig:
             return 4;
         default:
             return 0;
     }
 }
 
 static inline GrGLenum check_alloc_error(const GrSurfaceDesc& desc,
                                          const GrGLInterface* interface) {
     if (SkToBool(desc.fFlags & kCheckAllocation_GrSurfaceFlag)) {
@@ skipping 1183 matching lines @@
     if (blendInfo.fWriteColor) {
         // 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);
 
+    GrGLRenderTarget* glRT = static_cast<GrGLRenderTarget*>(pipeline.getRenderTarget());
+    GrSRGBPolicy srgbPolicy = GrPixelConfigSRGBPolicy(glRT->config());
+
     int numTextureAccesses = textureAccesses.count();
     for (int i = 0; i < numTextureAccesses; i++) {
-        this->bindTexture(i, textureAccesses[i]->getParams(),
+        this->bindTexture(i, textureAccesses[i]->getParams(), srgbPolicy,
                           static_cast<GrGLTexture*>(textureAccesses[i]->getTexture()));
     }
 
-    GrGLRenderTarget* glRT = static_cast<GrGLRenderTarget*>(pipeline.getRenderTarget());
     this->flushStencil(pipeline.getStencil());
     this->flushScissor(pipeline.getScissorState(), glRT->getViewport(), glRT->origin());
     this->flushHWAAState(glRT, pipeline.isHWAntialiasState(), !pipeline.getStencil().isDisabled());
 
     // This must come after textures are flushed because a texture may need
     // to be msaa-resolved (which will modify bound FBO state).
     this->flushRenderTarget(glRT, nullptr);
 
     return true;
 }
@@ skipping 456 matching lines @@
         if (readConfig == kBGRA_8888_GrPixelConfig &&
             this->glCaps().isConfigRenderable(kRGBA_8888_GrPixelConfig, false) &&
             this->readPixelsSupported(kRGBA_8888_GrPixelConfig, kRGBA_8888_GrPixelConfig)) {
             // We're trying to read BGRA but it's not supported. If RGBA is renderable and
             // we can read it back, then do a swizzling draw to a RGBA and read it back (which
             // will effectively be BGRA).
             tempDrawInfo->fTempSurfaceDesc.fConfig = kRGBA_8888_GrPixelConfig;
             tempDrawInfo->fSwizzle = GrSwizzle::BGRA();
             tempDrawInfo->fReadConfig = kRGBA_8888_GrPixelConfig;
             ElevateDrawPreference(drawPreference, kRequireDraw_DrawPreference);
+        } else if (readConfig == kSBGRA_8888_GrPixelConfig &&
+            this->glCaps().isConfigRenderable(kSRGBA_8888_GrPixelConfig, false) &&
+            this->readPixelsSupported(kSRGBA_8888_GrPixelConfig, kSRGBA_8888_GrPixelConfig)) {
+            // We're trying to read sBGRA but it's not supported. If sRGBA is renderable and
+            // we can read it back, then do a swizzling draw to a sRGBA and read it back (which
+            // will effectively be sBGRA).
+            tempDrawInfo->fTempSurfaceDesc.fConfig = kSRGBA_8888_GrPixelConfig;
+            tempDrawInfo->fSwizzle = GrSwizzle::BGRA();
+            tempDrawInfo->fReadConfig = kSRGBA_8888_GrPixelConfig;
+            ElevateDrawPreference(drawPreference, kRequireDraw_DrawPreference);

[Brian Osman, 2016/03/11 17:15:24]

This block of code may make no sense, given how sBGRA is implemented.

         } else if (readConfig == kAlpha_8_GrPixelConfig) {
             // onReadPixels implements a fallback for cases where we are want to read kAlpha_8,
             // it's unsupported, but 32bit RGBA reads are supported.
             // Don't attempt to do any srgb conversions since we only care about alpha.
             GrPixelConfig cpuTempConfig = kRGBA_8888_GrPixelConfig;
             if (GrPixelConfigIsSRGB(srcSurface->config())) {
                 cpuTempConfig = kSRGBA_8888_GrPixelConfig;
             }
             if (!this->readPixelsSupported(srcSurface, cpuTempConfig)) {
                 // If we can't read RGBA from the src try to draw to a kRGBA_8888 (or kSRGBA_8888)
@@ skipping 672 matching lines @@
   the generated shader code. This potentially allows greater reuse of cached shaders. */
 static void get_tex_param_swizzle(GrPixelConfig config,
                                   const GrGLCaps& caps,
                                   GrGLenum* glSwizzle) {
     const GrSwizzle& swizzle = caps.configSwizzle(config);
     for (int i = 0; i < 4; ++i) {
         glSwizzle[i] = get_component_enum_from_char(swizzle.c_str()[i]);
     }
 }
 
-void GrGLGpu::bindTexture(int unitIdx, const GrTextureParams& params, GrGLTexture* texture) {
+void GrGLGpu::bindTexture(int unitIdx, const GrTextureParams& params, GrSRGBPolicy srgbPolicy,
+                          GrGLTexture* texture) {
     SkASSERT(texture);
 
 #ifdef SK_DEBUG
     if (!this->caps()->npotTextureTileSupport()) {
         const bool tileX = SkShader::kClamp_TileMode != params.getTileModeX();
         const bool tileY = SkShader::kClamp_TileMode != params.getTileModeY();
         if (tileX || tileY) {
             const int w = texture->width();
             const int h = texture->height();
             SkASSERT(SkIsPow2(w) && SkIsPow2(h));
@@ skipping 15 matching lines @@
         this->setTextureUnit(unitIdx);
         GL_CALL(BindTexture(target, texture->textureID()));
         fHWBoundTextureUniqueIDs[unitIdx] = textureID;
     }
 
     ResetTimestamp timestamp;
     const GrGLTexture::TexParams& oldTexParams = texture->getCachedTexParams(&timestamp);
     bool setAll = timestamp < this->getResetTimestamp();
     GrGLTexture::TexParams newTexParams;
 
+    if (this->caps()->srgbSupport()) {
+        static GrGLenum glSRGBDecodeModes[] = {
+            GR_GL_DECODE_EXT,       // kUnknown_GrSRGBPolicy
+            GR_GL_DECODE_EXT,       // kAllowSRGB_GrSRGBPolicy
+            GR_GL_SKIP_DECODE_EXT   // kSuppressSRGB_GrSRGBPolicy
+        };
+
+        // By default, the decision to allow SRGB decode is based on the destination config.
+        // A texture can override that by specifying a value in GrTextureParams.
+        if (kUnknown_GrSRGBPolicy != params.srgbPolicy()) {
+            srgbPolicy = params.srgbPolicy();
+        }
+
+        SkASSERT(srgbPolicy >= kAllowSRGB_GrSRGBPolicy && srgbPolicy <= kSuppressSRGB_GrSRGBPolicy);
+        newTexParams.fSRGBDecode = glSRGBDecodeModes[srgbPolicy];
+        if (setAll || newTexParams.fSRGBDecode != oldTexParams.fSRGBDecode) {
+            this->setTextureUnit(unitIdx);
+            GL_CALL(TexParameteri(target, GR_GL_TEXTURE_SRGB_DECODE_EXT, newTexParams.fSRGBDecode));
+        }
+    }
+
     static GrGLenum glMinFilterModes[] = {
         GR_GL_NEAREST,
         GR_GL_LINEAR,
         GR_GL_LINEAR_MIPMAP_LINEAR
     };
     static GrGLenum glMagFilterModes[] = {
         GR_GL_NEAREST,
         GR_GL_LINEAR,
         GR_GL_LINEAR
     };
@@ skipping 647 matching lines @@
 
 void GrGLGpu::copySurfaceAsDraw(GrSurface* dst,
                                 GrSurface* src,
                                 const SkIRect& srcRect,
                                 const SkIPoint& dstPoint) {
     int w = srcRect.width();
     int h = srcRect.height();
 
     GrGLTexture* srcTex = static_cast<GrGLTexture*>(src->asTexture());
     GrTextureParams params(SkShader::kClamp_TileMode, GrTextureParams::kNone_FilterMode);
-    this->bindTexture(0, params, srcTex);
+    this->bindTexture(0, params, kAllowSRGB_GrSRGBPolicy, srcTex);
 
     GrGLIRect dstVP;
     this->bindSurfaceFBOForCopy(dst, GR_GL_FRAMEBUFFER, &dstVP, kDst_TempFBOTarget);
     this->flushViewport(dstVP);
     fHWBoundRenderTargetUniqueID = SK_InvalidUniqueID;
 
     SkIRect dstRect = SkIRect::MakeXYWH(dstPoint.fX, dstPoint.fY, w, h);
 
     int progIdx = TextureTargetToCopyProgramIdx(srcTex->target());
 
@@ skipping 362 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;
 }