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 ecac2cc0047b44ab2d189dbd4e223148ff3cba40..ba04e7eace9837bd267a6f220346bfaba6d8c74c 100755
--- a/tools/viewer/sk_app/WindowContext.cpp
+++ b/tools/viewer/sk_app/WindowContext.cpp
@@ -21,24 +21,41 @@
 
 namespace sk_app {
 
+sk_sp<SkSurface> WindowContext::createOffscreenSurface(bool forceSRGB) {
+    return createSurface(nullptr, 0, true, forceSRGB);
+}
+
 sk_sp<SkSurface> WindowContext::createRenderSurface(sk_sp<GrRenderTarget> rt, int colorBits) {
+    return createSurface(rt, colorBits, false, false);
+}
+
+sk_sp<SkSurface> WindowContext::createSurface(
+        sk_sp<GrRenderTarget> rt, int colorBits, bool offscreen, bool forceSRGB) {
     auto flags = (fSurfaceProps.flags() & ~SkSurfaceProps::kGammaCorrect_Flag) |
-                 (GrPixelConfigIsSRGB(fPixelConfig) ? SkSurfaceProps::kGammaCorrect_Flag : 0);
+                 (GrPixelConfigIsSRGB(fPixelConfig) || forceSRGB ?
+                  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.
         //
         // If we're rendering raster data or using a deep (10-bit or higher) surface, we probably
         // need an off-screen surface. 10-bit, in particular, has strange gamma behavior.
-        SkImageInfo info = SkImageInfo::Make(fWidth, fHeight,
-                                             fDisplayParams.fColorType,
-                                             kUnknown_SkAlphaType,
-                                             fDisplayParams.fColorSpace);
-        return SkSurface::MakeRenderTarget(fContext, SkBudgeted::kNo, info,
-                                           fDisplayParams.fMSAASampleCount, &props);
+        SkImageInfo info = SkImageInfo::Make(
+            fWidth, fHeight,
+            fDisplayParams.fColorType,
+            kPremul_SkAlphaType,
+            forceSRGB ? SkColorSpace::NewNamed(SkColorSpace::kSRGB_Named)
+                      : fDisplayParams.fColorSpace
+        );
+        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);
     }