skia: add ability to load command_buffer_gles2

src/views/win/SkOSWindow_win.cpp

Index: src/views/win/SkOSWindow_win.cpp
diff --git a/src/views/win/SkOSWindow_win.cpp b/src/views/win/SkOSWindow_win.cpp
index b0bb76ca19cc05071a108a6902cce64b5e4fee2e..e4609fb4103c6030d31b6e9683933beaa1942aed 100644
--- a/src/views/win/SkOSWindow_win.cpp
+++ b/src/views/win/SkOSWindow_win.cpp
@@ -30,7 +30,17 @@
         (IFACE)->fFunctions.f##X;                               \
     } while (false)
 
-#endif
+#endif // SK_ANGLE
+
+#if SK_COMMAND_BUFFER
+#include "gl/command_buffer/SkCommandBufferGLContext.h"
+
+#define COMMAND_BUFFER_GL_CALL(IFACE, X)                                 \
+    do {                                                        \
+        (IFACE)->fFunctions.f##X;                               \
+    } while (false)
+
+#endif // SK_COMMAND_BUFFER
 
 #define WM_EVENT_CALLBACK (WM_USER+0)
 
@@ -53,6 +63,10 @@ SkOSWindow::SkOSWindow(const void* winInit) {
     fContext = EGL_NO_CONTEXT;
     fSurface = EGL_NO_SURFACE;
 #endif
+#if SK_COMMAND_BUFFER
+    fCommandBuffer = nullptr;
+#endif // SK_COMMAND_BUFFER
+
     fHGLRC = NULL;
 #endif
     fAttached = kNone_BackEndType;
@@ -80,6 +94,10 @@ SkOSWindow::~SkOSWindow() {
         fDisplay = EGL_NO_DISPLAY;
     }
 #endif // SK_ANGLE
+#if SK_COMMAND_BUFFER
+    delete fCommandBuffer;
+#endif // SK_COMMAND_BUFFER
+
 #endif // SK_SUPPORT_GPU
     this->closeWindow();
 }
@@ -530,6 +548,50 @@ void SkOSWindow::presentANGLE() {
     eglSwapBuffers(fDisplay, fSurface);
 }
 #endif // SK_ANGLE
+
+#if SK_COMMAND_BUFFER
+
+bool SkOSWindow::attachCommandBuffer(int msaaSampleCount, AttachmentInfo* info) {
+    if (!fCommandBuffer) {
+        fCommandBuffer = SkCommandBufferGLContext::Create((HWND)fHWND, msaaSampleCount);
+        if (!fCommandBuffer)
+            return false;
+    
+        SkAutoTUnref<const GrGLInterface> intf(GrGLCreateCommandBufferInterface());
+        if (intf) {
+            COMMAND_BUFFER_GL_CALL(intf, ClearStencil(0));
+            COMMAND_BUFFER_GL_CALL(intf, ClearColor(0, 0, 0, 0));
+            COMMAND_BUFFER_GL_CALL(intf, StencilMask(0xffffffff));
+            COMMAND_BUFFER_GL_CALL(intf, Clear(GL_STENCIL_BUFFER_BIT |GL_COLOR_BUFFER_BIT));
+        }
+    }
+
+    if (fCommandBuffer->makeCurrent()) {
+        info->fStencilBits = fCommandBuffer->getStencilBits();
+        info->fSampleCount = fCommandBuffer->getSampleCount();
+
+        SkAutoTUnref<const GrGLInterface> intf(GrGLCreateCommandBufferInterface());
+
+        if (intf ) {
+            COMMAND_BUFFER_GL_CALL(intf, Viewport(0, 0,
+                                         SkScalarRoundToInt(this->width()),
+                                         SkScalarRoundToInt(this->height())));
+        }
+        return true;
+    }
+    return false;
+}
+
+void SkOSWindow::detachCommandBuffer() {
+    delete fCommandBuffer;
+    fCommandBuffer = nullptr;
+}
+
+void SkOSWindow::presentCommandBuffer() {
+    fCommandBuffer->presentCommandBuffer();
+}
+#endif // SK_COMMAND_BUFFER
+
 #endif // SK_SUPPORT_GPU
 
 // return true on success
@@ -554,6 +616,11 @@ bool SkOSWindow::attach(SkBackEndTypes attachType, int msaaSampleCount, Attachme
         result = attachANGLE(msaaSampleCount, info);
         break;
 #endif // SK_ANGLE
+#if SK_COMMAND_BUFFER
+    case kCommandBuffer_BackEndType:
+        result = attachCommandBuffer(msaaSampleCount, info);
+        break;
+#endif // SK_COMMAND_BUFFER
 #endif // SK_SUPPORT_GPU
     default:
         SkASSERT(false);
@@ -582,6 +649,11 @@ void SkOSWindow::detach() {
         detachANGLE();
         break;
 #endif // SK_ANGLE
+#if SK_COMMAND_BUFFER
+    case kCommandBuffer_BackEndType:
+        detachCommandBuffer();
+        break;
+#endif // SK_COMMAND_BUFFER
 #endif // SK_SUPPORT_GPU
     default:
         SkASSERT(false);
@@ -604,6 +676,11 @@ void SkOSWindow::present() {
         presentANGLE();
         break;
 #endif // SK_ANGLE
+#if SK_COMMAND_BUFFER
+    case kCommandBuffer_BackEndType:
+        presentCommandBuffer();
+        break;
+#endif // SK_COMMAND_BUFFER
 #endif // SK_SUPPORT_GPU
     default:
         SkASSERT(false);