Use Offscreen Surface for Split Screen

tools/viewer/sk_app/WindowContext.cpp

Index: tools/viewer/sk_app/WindowContext.cpp
diff --git a/tools/viewer/sk_app/WindowContext.cpp b/tools/viewer/sk_app/WindowContext.cpp
index 41bbd14576b37f604c8f65d7001b8de076932553..44fd91458f9326b8a9c9d233ebd151a4bd042f65 100755
--- a/tools/viewer/sk_app/WindowContext.cpp
+++ b/tools/viewer/sk_app/WindowContext.cpp
@@ -21,12 +21,14 @@
 
 namespace sk_app {
 
-sk_sp<SkSurface> WindowContext::createRenderSurface(sk_sp<GrRenderTarget> rt, int colorBits) {
+sk_sp<SkSurface> WindowContext::createRenderSurface(
+        sk_sp<GrRenderTarget> rt, int colorBits, bool offscreen, bool sRGB) {
     auto flags = (fSurfaceProps.flags() & ~SkSurfaceProps::kGammaCorrect_Flag) |
-                 (GrPixelConfigIsSRGB(fPixelConfig) ? SkSurfaceProps::kGammaCorrect_Flag : 0);
+                 (GrPixelConfigIsSRGB(fPixelConfig) || sRGB ?
+                  SkSurfaceProps::kGammaCorrect_Flag : 0);
     SkSurfaceProps props(flags, fSurfaceProps.pixelGeometry());
 
-    if (!this->isGpuContext() || colorBits > 24 ||
+    if (!this->isGpuContext() || colorBits > 24 || offscreen ||
         kRGBA_F16_SkColorType == fDisplayParams.fColorType) {
         // If we're rendering to F16, we need an off-screen surface - the current render
         // target is most likely the wrong format.
@@ -35,10 +37,17 @@ sk_sp<SkSurface> WindowContext::createRenderSurface(sk_sp<GrRenderTarget> rt, in
         // need an off-screen surface. 10-bit, in particular, has strange gamma behavior.
         SkImageInfo info = SkImageInfo::Make(fWidth, fHeight,
                                              fDisplayParams.fColorType,
-                                             kUnknown_SkAlphaType,
-                                             fDisplayParams.fProfileType);
-        return SkSurface::MakeRenderTarget(fContext, SkBudgeted::kNo, info,
-                                           fDisplayParams.fMSAASampleCount, &props);
+                                             // kUnknown_SkAlphaType won't pass
+                                             // CheckAlphaTypeAndGetFlags
+                                             kOpaque_SkAlphaType,

[Brian Osman, 2016/06/15 15:32:03]

kOpaque is probably okay, although kPremul is probably better. (I think that our
GMs generally don't rely on destination alpha, but there's no hard-and-fast
rule).

[liyuqian, 2016/06/15 16:43:12]

Done. Ok, I'll change both kOpaque to kPremul.

+                                             sRGB ? kSRGB_SkColorProfileType
+                                                  : fDisplayParams.fProfileType);
+        if (this->isGpuContext()) {
+            return SkSurface::MakeRenderTarget(fContext, SkBudgeted::kNo, info,
+                                               fDisplayParams.fMSAASampleCount, &props);
+        } else {
+            return SkSurface::MakeRaster(info, &props);
+        }
     } else {
         return SkSurface::MakeRenderTargetDirect(rt.get(), &props);
     }