Make SkOSWindow return the sample count and stencil bit count for its GL context.

Review URL: https://codereview.chromium.org/12437010

git-svn-id: http://skia.googlecode.com/svn/trunk@7995 2bbb7eff-a529-9590-31e7-b0007b416f81

17 files changed, 152 insertions, 50 deletions

diff --git a/experimental/iOSSampleApp/Shared/SkUIView.h b/experimental/iOSSampleApp/Shared/SkUIView.h
index a3d05e37db..45c4df0abd 100644
--- a/experimental/iOSSampleApp/Shared/SkUIView.h
+++ b/experimental/iOSSampleApp/Shared/SkUIView.h
@@ -11,8 +11,8 @@
 #import <OpenGLES/ES2/glext.h>
 #import <QuartzCore/QuartzCore.h>
 #import <UIKit/UIKit.h>
-#include "SkWindow.h"
-class SkOSWindow;
+#include "SkOSWindow_ios.h"
+
 class SkEvent;
 @class SkUIView;
 
@@ -43,4 +43,6 @@ class SkEvent;
 - (void)onUpdateMenu:(SkOSMenu*)menu;
 - (void)postInvalWithRect:(const SkIRect*)rectOrNil;
 - (BOOL)onHandleEvent:(const SkEvent&)event;
+- (void)getAttachmentInfo:(SkOSWindow::AttachmentInfo*)info;
+
 @end
diff --git a/experimental/iOSSampleApp/Shared/SkUIView.mm b/experimental/iOSSampleApp/Shared/SkUIView.mm
index 835e970666..10b55183c3 100644
--- a/experimental/iOSSampleApp/Shared/SkUIView.mm
+++ b/experimental/iOSSampleApp/Shared/SkUIView.mm
@@ -93,6 +93,12 @@
     return false;
 }
 
+- (void)getAttachmentInfo:(SkOSWindow::AttachmentInfo*)info {
+    // we don't have a GL context.
+    info->fSampleCount = 0;
+    info->fStencilBits = 0;
+}
+
 #include "SkOSMenu.h"
 - (void)onAddMenu:(const SkOSMenu*)menu {
     [self.fOptionsDelegate view:self didAddMenu:menu];
diff --git a/experimental/iOSSampleApp/SkSampleUIView.h b/experimental/iOSSampleApp/SkSampleUIView.h
index 9bb195621d..a1009b84da 100644
--- a/experimental/iOSSampleApp/SkSampleUIView.h
+++ b/experimental/iOSSampleApp/SkSampleUIView.h
@@ -43,4 +43,6 @@ struct FPSState;
 
 - (void)setSkTitle:(const char*)title;
 - (void)postInvalWithRect:(const SkIRect*)rectOrNil;
+- (void)getAttachmentInfo:(SkOSWindow::AttachmentInfo*)info;
+
 @end
diff --git a/experimental/iOSSampleApp/SkSampleUIView.mm b/experimental/iOSSampleApp/SkSampleUIView.mm
index 2ed5402ba6..9fc95bd152 100644
--- a/experimental/iOSSampleApp/SkSampleUIView.mm
+++ b/experimental/iOSSampleApp/SkSampleUIView.mm
@@ -61,8 +61,8 @@ public:
                 SkASSERT(false);
                 break;
         }
-        
-        bool result = win->attach(fBackend, msaaSampleCount);
+        SkOSWindow::AttachmentInfo info;
+        bool result = win->attach(fBackend, msaaSampleCount, &info);
         if (!result) {
             SkDebugf("Failed to initialize GL");
             return;
@@ -165,7 +165,9 @@ public:
     virtual void windowSizeChanged(SampleWindow* win) SK_OVERRIDE {
 #if SK_SUPPORT_GPU
         if (NULL != fCurContext) {
-            win->attach(fBackend, fMSAASampleCount);
+            SkOSWindow::AttachmentInfo info;
+
+            win->attach(fBackend, fMSAASampleCount, &info);
             
             glBindFramebuffer(GL_FRAMEBUFFER, fLayerFBO);
             GrBackendRenderTargetDesc desc;
@@ -173,9 +175,9 @@ public:
             desc.fHeight = SkScalarRound(win->height());
             desc.fConfig = kSkia8888_GrPixelConfig;
             desc.fRenderTargetHandle = fLayerFBO;
-            glGetIntegerv(GL_SAMPLES, &desc.fSampleCnt);
-            glGetIntegerv(GL_STENCIL_BITS, &desc.fStencilBits);
-            
+            desc.fSampleCnt = info.fSampleCount;
+            desc.fStencilBits = info.fStencilBits;
+
             SkSafeUnref(fCurRenderTarget);
             fCurRenderTarget = fCurContext->wrapBackendRenderTarget(desc);
         }
@@ -480,4 +482,14 @@ static FPSState gFPS;
     }
 }
 
+- (void)getAttachmentInfo:(SkOSWindow::AttachmentInfo*)info {
+    glBindRenderbuffer(GL_RENDERBUFFER, fGL.fRenderbuffer);
+    glGetRenderbufferParameteriv(GL_RENDERBUFFER,
+                                 GL_RENDERBUFFER_STENCIL_SIZE,
+                                 &info->fStencilBits);
+    glGetRenderbufferParameteriv(GL_RENDERBUFFER,
+                                 GL_RENDERBUFFER_SAMPLES_APPLE,
+                                 &info->fSampleCount);
+}
+
 @end
diff --git a/include/views/SkOSWindow_Android.h b/include/views/SkOSWindow_Android.h
index ca9b7708f1..77c156cd23 100644
--- a/include/views/SkOSWindow_Android.h
+++ b/include/views/SkOSWindow_Android.h
@@ -24,7 +24,15 @@ public:
         kNativeGL_BackEndType,
     };
 
-    bool attach(SkBackEndTypes /* attachType */, int /* msaaSampleCount */) {
+    struct AttachmentInfo {
+        int fSampleCount;
+        int fStencilBits;
+    };
+
+    bool attach(SkBackEndTypes /* attachType */, int /* msaaSampleCount */, AttachmentInfo* info) {
+        // These are the values requested in SkiaSampleView.java
+        info->fSampleCount = 0;
+        info->fStencilBits = 8;
         return true;
     }
     void detach() {}
diff --git a/include/views/SkOSWindow_Mac.h b/include/views/SkOSWindow_Mac.h
index aa52021607..5dea2fc12e 100644
--- a/include/views/SkOSWindow_Mac.h
+++ b/include/views/SkOSWindow_Mac.h
@@ -26,8 +26,13 @@ public:
 #endif
     };
 
+    struct AttachmentInfo {
+        int fSampleCount;
+        int fStencilBits;
+    };
+
     void    detach();
-    bool    attach(SkBackEndTypes attachType, int msaaSampleCount);
+    bool    attach(SkBackEndTypes attachType, int msaaSampleCount, AttachmentInfo*);
     void    present();
 
 protected:
diff --git a/include/views/SkOSWindow_NaCl.h b/include/views/SkOSWindow_NaCl.h
index 52514cab71..22960236d3 100644
--- a/include/views/SkOSWindow_NaCl.h
+++ b/include/views/SkOSWindow_NaCl.h
@@ -24,7 +24,14 @@ public:
         kNativeGL_BackEndType,
     };
 
-    bool attach(SkBackEndTypes /* attachType */, int /* msaaSampleCount */) {
+    struct AttachmentInfo {
+        int fSampleCount;
+        int fStencilBits;
+    };
+
+    bool attach(SkBackEndTypes /* attachType */, int /* msaaSampleCount */, AttachmentInfo* info) {
+        info->fSampleCount = 0;
+        info->fStencilBits = 0;
         return true;
     }
     void detach() {}
diff --git a/include/views/SkOSWindow_Unix.h b/include/views/SkOSWindow_Unix.h
index f1a4698668..89265a4367 100644
--- a/include/views/SkOSWindow_Unix.h
+++ b/include/views/SkOSWindow_Unix.h
@@ -39,7 +39,12 @@ public:
         kNativeGL_BackEndType,
     };
 
-    bool attach(SkBackEndTypes attachType, int msaaSampleCount);
+    struct AttachmentInfo {
+        int fSampleCount;
+        int fStencilBits;
+    };
+
+    bool attach(SkBackEndTypes attachType, int msaaSampleCount, AttachmentInfo*);
     void detach();
     void present();
 
@@ -61,7 +66,7 @@ private:
     void mapWindowAndWait();
 
     void closeWindow();
-    void initWindow(int newMSAASampleCount);
+    void initWindow(int newMSAASampleCount, AttachmentInfo* info);
 
     SkUnixWindow fUnixWindow;
 
diff --git a/include/views/SkOSWindow_Win.h b/include/views/SkOSWindow_Win.h
index ff289bd6a6..6b5977ce3f 100644
--- a/include/views/SkOSWindow_Win.h
+++ b/include/views/SkOSWindow_Win.h
@@ -37,7 +37,12 @@ public:
 #endif // SK_SUPPORT_GPU
     };
 
-    bool attach(SkBackEndTypes attachType, int msaaSampleCount);
+    struct AttachmentInfo {
+        int fSampleCount;
+        int fStencilBits;
+    };
+
+    bool attach(SkBackEndTypes attachType, int msaaSampleCount, AttachmentInfo*);
     void detach();
     void present();
 
@@ -70,6 +75,7 @@ private:
     EGLDisplay          fDisplay;
     EGLContext          fContext;
     EGLSurface          fSurface;
+    EGLConfig           fConfig;
 #endif // SK_ANGLE
 #endif // SK_SUPPORT_GPU
 
@@ -78,12 +84,12 @@ private:
     SkBackEndTypes      fAttached;
 
 #if SK_SUPPORT_GPU
-    bool attachGL(int msaaSampleCount);
+    bool attachGL(int msaaSampleCount, AttachmentInfo* info);
     void detachGL();
     void presentGL();
 
 #if SK_ANGLE
-    bool attachANGLE(int msaaSampleCount);
+    bool attachANGLE(int msaaSampleCount, AttachmentInfo* info);
     void detachANGLE();
     void presentANGLE();
 #endif // SK_ANGLE
diff --git a/include/views/SkOSWindow_iOS.h b/include/views/SkOSWindow_iOS.h
index 1dd3997dfe..1984900ded 100755
--- a/include/views/SkOSWindow_iOS.h
+++ b/include/views/SkOSWindow_iOS.h
@@ -21,8 +21,13 @@ public:
         kNativeGL_BackEndType,
     };
 
+    struct AttachmentInfo {
+        int fSampleCount;
+        int fStencilBits;
+    };
+
     void    detach();
-    bool    attach(SkBackEndTypes attachType, int msaaSampleCount);
+    bool    attach(SkBackEndTypes attachType, int msaaSampleCount, AttachmentInfo*);
     void    present();
 
 protected:
diff --git a/samplecode/SampleApp.cpp b/samplecode/SampleApp.cpp
index 6266085d78..badc7c01e8 100644
--- a/samplecode/SampleApp.cpp
+++ b/samplecode/SampleApp.cpp
@@ -188,8 +188,8 @@ public:
                 SkASSERT(false);
                 break;
         }
-
-        bool result = win->attach(fBackend, msaaSampleCount);
+        AttachmentInfo attachmentInfo;
+        bool result = win->attach(fBackend, msaaSampleCount, &attachmentInfo);
         if (!result) {
             SkDebugf("Failed to initialize GL");
             return;
@@ -289,15 +289,16 @@ public:
     virtual void windowSizeChanged(SampleWindow* win) {
 #if SK_SUPPORT_GPU
         if (fCurContext) {
-            win->attach(fBackend, fMSAASampleCount);
+            AttachmentInfo attachmentInfo;
+            win->attach(fBackend, fMSAASampleCount, &attachmentInfo);
 
             GrBackendRenderTargetDesc desc;
             desc.fWidth = SkScalarRound(win->width());
             desc.fHeight = SkScalarRound(win->height());
             desc.fConfig = kSkia8888_GrPixelConfig;
             desc.fOrigin = kBottomLeft_GrSurfaceOrigin;
-            GR_GL_GetIntegerv(fCurIntf, GR_GL_SAMPLES, &desc.fSampleCnt);
-            GR_GL_GetIntegerv(fCurIntf, GR_GL_STENCIL_BITS, &desc.fStencilBits);
+            desc.fSampleCnt = attachmentInfo.fSampleCount;
+            desc.fStencilBits = attachmentInfo.fStencilBits;
             GrGLint buffer;
             GR_GL_GetIntegerv(fCurIntf, GR_GL_FRAMEBUFFER_BINDING, &buffer);
             desc.fRenderTargetHandle = buffer;
diff --git a/src/views/ios/SkOSWindow_iOS.mm b/src/views/ios/SkOSWindow_iOS.mm
index 94579aa14b..04a219b6a7 100755
--- a/src/views/ios/SkOSWindow_iOS.mm
+++ b/src/views/ios/SkOSWindow_iOS.mm
@@ -51,7 +51,9 @@ void SkOSWindow::onUpdateMenu(SkOSMenu* menu) {
 }
 
 bool SkOSWindow::attach(SkBackEndTypes /* attachType */,
-                        int /* msaaSampleCount */) {
+                        int /* msaaSampleCount */,
+                        AttachmentInfo* info) {
+    [(SkUIView*)fHWND getAttachmentInfo:info];
     bool success = true;
     return success;
 }
diff --git a/src/views/mac/SkNSView.h b/src/views/mac/SkNSView.h
index 109a9982cc..dfc81ea5bd 100644
--- a/src/views/mac/SkNSView.h
+++ b/src/views/mac/SkNSView.h
@@ -46,7 +46,7 @@ class SkEvent;
 - (void)postInvalWithRect:(const SkIRect*)rectOrNil;
 - (BOOL)onHandleEvent:(const SkEvent&)event;
 
-- (bool)attach:(SkOSWindow::SkBackEndTypes)attachType withMSAASampleCount:(int) sampleCount;
+- (bool)attach:(SkOSWindow::SkBackEndTypes)attachType withMSAASampleCount:(int) sampleCount andGetInfo:(SkOSWindow::AttachmentInfo*) info;
 - (void)detach;
 - (void)present;
 @end
diff --git a/src/views/mac/SkNSView.mm b/src/views/mac/SkNSView.mm
index fc82ac4949..2d796e46b6 100644
--- a/src/views/mac/SkNSView.mm
+++ b/src/views/mac/SkNSView.mm
@@ -291,7 +291,6 @@ CGLContextObj createGLContext(int msaaSampleCount) {
     if (!npix) {
         CGLChoosePixelFormat(attributes, &format, &npix);
     }
-    
     CGLContextObj ctx;
     CGLCreateContext(format, NULL, &ctx);
     CGLDestroyPixelFormat(format);
@@ -314,7 +313,8 @@ CGLContextObj createGLContext(int msaaSampleCount) {
     }
 }
 - (bool)attach:(SkOSWindow::SkBackEndTypes)attachType
-        withMSAASampleCount:(int) sampleCount {
+        withMSAASampleCount:(int) sampleCount
+        andGetInfo:(SkOSWindow::AttachmentInfo*) info {
     if (nil == fGLContext) {
         CGLContextObj ctx = createGLContext(sampleCount);
         fGLContext = [[NSOpenGLContext alloc] initWithCGLContextObj:ctx];
@@ -324,9 +324,11 @@ CGLContextObj createGLContext(int msaaSampleCount) {
         }
         [fGLContext setView:self];
     }
-    
+
     [fGLContext makeCurrentContext];
-    
+    CGLPixelFormatObj format = CGLGetPixelFormat((CGLContextObj)[fGLContext CGLContextObj]);
+    CGLDescribePixelFormat(format, 0, kCGLPFASamples, &info->fSampleCount);
+    CGLDescribePixelFormat(format, 0, kCGLPFAStencilSize, &info->fStencilBits);
     glViewport(0, 0, (int) self.bounds.size.width, (int) self.bounds.size.width);
     glClearColor(0, 0, 0, 0);
     glClearStencil(0);
diff --git a/src/views/mac/SkOSWindow_Mac.mm b/src/views/mac/SkOSWindow_Mac.mm
index 01c8677f4d..b0f006a884 100644
--- a/src/views/mac/SkOSWindow_Mac.mm
+++ b/src/views/mac/SkOSWindow_Mac.mm
@@ -65,8 +65,8 @@ void SkOSWindow::onUpdateMenu(const SkOSMenu* menu) {
     [(SkNSView*)fHWND onUpdateMenu:menu];
 }
 
-bool SkOSWindow::attach(SkBackEndTypes attachType, int sampleCount) {
-    return [(SkNSView*)fHWND attach:attachType withMSAASampleCount:sampleCount];
+bool SkOSWindow::attach(SkBackEndTypes attachType, int sampleCount, AttachmentInfo* info) {
+    return [(SkNSView*)fHWND attach:attachType withMSAASampleCount:sampleCount andGetInfo:info];
 }
 
 void SkOSWindow::detach() {
diff --git a/src/views/unix/SkOSWindow_Unix.cpp b/src/views/unix/SkOSWindow_Unix.cpp
index 7da04bdc7c..f6e32e42f2 100644
--- a/src/views/unix/SkOSWindow_Unix.cpp
+++ b/src/views/unix/SkOSWindow_Unix.cpp
@@ -37,7 +37,7 @@ SkOSWindow::SkOSWindow(void* unused)
     , fMSAASampleCount(0) {
     fUnixWindow.fDisplay = NULL;
     fUnixWindow.fGLContext = NULL;
-    this->initWindow(0);
+    this->initWindow(0, NULL);
     this->resize(WIDTH, HEIGHT);
 }
 
@@ -59,12 +59,21 @@ void SkOSWindow::closeWindow() {
     }
 }
 
-void SkOSWindow::initWindow(int requestedMSAASampleCount) {
+void SkOSWindow::initWindow(int requestedMSAASampleCount, AttachmentInfo* info) {
     if (fMSAASampleCount != requestedMSAASampleCount) {
         this->closeWindow();
     }
     // presence of fDisplay means we already have a window
     if (NULL != fUnixWindow.fDisplay) {
+        if (NULL != info) {
+            if (NULL != fVi) {
+                glXGetConfig(fUnixWindow.fDisplay, fVi, GLX_SAMPLES_ARB, &info->fSampleCount);
+                glXGetConfig(fUnixWindow.fDisplay, fVi, GLX_STENCIL_SIZE, &info->fStencilBits);
+            } else {
+                info->fSampleCount = 0;
+                info->fStencilBits = 0;
+            }
+        }
         return;
     }
     fUnixWindow.fDisplay = XOpenDisplay(NULL);
@@ -101,6 +110,10 @@ void SkOSWindow::initWindow(int requestedMSAASampleCount) {
     }
 
     if (fVi) {
+        if (NULL != info) {
+            glXGetConfig(dsp, fVi, GLX_SAMPLES_ARB, &info->fSampleCount);
+            glXGetConfig(dsp, fVi, GLX_STENCIL_SIZE, &info->fStencilBits);
+        }
         Colormap colorMap = XCreateColormap(dsp,
                                             RootWindow(dsp, fVi->screen),
                                             fVi->visual,
@@ -119,6 +132,10 @@ void SkOSWindow::initWindow(int requestedMSAASampleCount) {
                                          CWEventMask | CWColormap,
                                          &swa);
     } else {
+        if (NULL != info) {
+            info->fSampleCount = 0;
+            info->fStencilBits = 0;
+        }
         // Create a simple window instead.  We will not be able to show GL
         fUnixWindow.fWin = XCreateSimpleWindow(dsp,
                                                DefaultRootWindow(dsp),
@@ -250,8 +267,9 @@ void SkOSWindow::mapWindowAndWait() {
 
 }
 
-bool SkOSWindow::attach(SkBackEndTypes /* attachType */, int msaaSampleCount) {
-    this->initWindow(msaaSampleCount);
+bool SkOSWindow::attach(SkBackEndTypes, int msaaSampleCount, AttachmentInfo* info) {
+    this->initWindow(msaaSampleCount, info);
+
     if (NULL == fUnixWindow.fDisplay) {
         return false;
     }
diff --git a/src/views/win/SkOSWindow_win.cpp b/src/views/win/SkOSWindow_win.cpp
index 620bd7189c..1d247b24eb 100644
--- a/src/views/win/SkOSWindow_win.cpp
+++ b/src/views/win/SkOSWindow_win.cpp
@@ -324,7 +324,7 @@ void SkEvent::SignalQueueTimer(SkMSec delay)
 
 #if SK_SUPPORT_GPU
 
-bool SkOSWindow::attachGL(int msaaSampleCount) {
+bool SkOSWindow::attachGL(int msaaSampleCount, AttachmentInfo* info) {
     HDC dc = GetDC((HWND)fHWND);
     if (NULL == fHGLRC) {
         fHGLRC = SkCreateWGLContext(dc, msaaSampleCount, false);
@@ -337,8 +337,27 @@ bool SkOSWindow::attachGL(int msaaSampleCount) {
         glClear(GL_STENCIL_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
     }
     if (wglMakeCurrent(dc, (HGLRC)fHGLRC)) {
-        glViewport(0, 0, SkScalarRound(this->width()),
-                   SkScalarRound(this->height()));
+        // use DescribePixelFormat to get the stencil bit depth.
+        int pixelFormat = GetPixelFormat(dc);
+        PIXELFORMATDESCRIPTOR pfd;
+        DescribePixelFormat(dc, pixelFormat, sizeof(pfd), &pfd);
+        info->fStencilBits = pfd.cStencilBits;
+
+        // Get sample count if the MSAA WGL extension is present
+        SkWGLExtensions extensions;
+        if (extensions.hasExtension(dc, "WGL_ARB_multisample")) {
+            static const int kSampleCountAttr = SK_WGL_SAMPLES;
+            extensions.getPixelFormatAttribiv(dc,
+                                              pixelFormat,
+                                              0,
+                                              1,
+                                              &kSampleCountAttr,
+                                              &info->fSampleCount);
+        } else {
+            info->fSampleCount = 0;
+        }
+
+        glViewport(0, 0, SkScalarRound(this->width()), SkScalarRound(this->height()));
         return true;
     }
     return false;
@@ -360,7 +379,8 @@ bool create_ANGLE(EGLNativeWindowType hWnd,
                   int msaaSampleCount,
                   EGLDisplay* eglDisplay,
                   EGLContext* eglContext,
-                  EGLSurface* eglSurface) {
+                  EGLSurface* eglSurface,
+                  EGLConfig* eglConfig) {
     static const EGLint contextAttribs[] = {
         EGL_CONTEXT_CLIENT_VERSION, 2,
         EGL_NONE, EGL_NONE
@@ -395,7 +415,6 @@ bool create_ANGLE(EGLNativeWindowType hWnd,
     }
 
     // Choose config
-    EGLConfig config;
     bool foundConfig = false;
     if (msaaSampleCount) {
         static const int kConfigAttribListCnt =
@@ -410,21 +429,19 @@ bool create_ANGLE(EGLNativeWindowType hWnd,
         msaaConfigAttribList[kConfigAttribListCnt + 1] = EGL_SAMPLES;
         msaaConfigAttribList[kConfigAttribListCnt + 2] = msaaSampleCount;
         msaaConfigAttribList[kConfigAttribListCnt + 3] = EGL_NONE;
-        if (eglChooseConfig(display, configAttribList,
-                                   &config, 1, &numConfigs)) {
+        if (eglChooseConfig(display, configAttribList, eglConfig, 1, &numConfigs)) {
             SkASSERT(numConfigs > 0);
             foundConfig = true;
         }
     }
     if (!foundConfig) {
-        if (!eglChooseConfig(display, configAttribList,
-                                    &config, 1, &numConfigs)) {
+        if (!eglChooseConfig(display, configAttribList, eglConfig, 1, &numConfigs)) {
            return false;
         }
     }
 
     // Create a surface
-    EGLSurface surface = eglCreateWindowSurface(display, config,
+    EGLSurface surface = eglCreateWindowSurface(display, *eglConfig,
                                                 (EGLNativeWindowType)hWnd,
                                                 surfaceAttribList);
     if (surface == EGL_NO_SURFACE) {
@@ -432,7 +449,7 @@ bool create_ANGLE(EGLNativeWindowType hWnd,
     }
 
     // Create a GL context
-    EGLContext context = eglCreateContext(display, config,
+    EGLContext context = eglCreateContext(display, *eglConfig,
                                           EGL_NO_CONTEXT,
                                           contextAttribs );
     if (context == EGL_NO_CONTEXT ) {
@@ -450,13 +467,14 @@ bool create_ANGLE(EGLNativeWindowType hWnd,
     return true;
 }
 
-bool SkOSWindow::attachANGLE(int msaaSampleCount) {
+bool SkOSWindow::attachANGLE(int msaaSampleCount, AttachmentInfo* info) {
     if (EGL_NO_DISPLAY == fDisplay) {
         bool bResult = create_ANGLE((HWND)fHWND,
                                     msaaSampleCount,
                                     &fDisplay,
                                     &fContext,
-                                    &fSurface);
+                                    &fSurface,
+                                    &fConfig);
         if (false == bResult) {
             return false;
         }
@@ -470,6 +488,9 @@ bool SkOSWindow::attachANGLE(int msaaSampleCount) {
         }
     }
     if (eglMakeCurrent(fDisplay, fSurface, fSurface, fContext)) {
+        eglGetConfigAttrib(fDisplay, fConfig, EGL_STENCIL_SIZE, &info->fStencilBits);
+        eglGetConfigAttrib(fDisplay, fConfig, EGL_SAMPLES, &info->fSampleCount);
+
         SkAutoTUnref<const GrGLInterface> intf(GrGLCreateANGLEInterface());
 
         if (intf ) {
@@ -507,7 +528,7 @@ void SkOSWindow::presentANGLE() {
 #endif // SK_SUPPORT_GPU
 
 // return true on success
-bool SkOSWindow::attach(SkBackEndTypes attachType, int msaaSampleCount) {
+bool SkOSWindow::attach(SkBackEndTypes attachType, int msaaSampleCount, AttachmentInfo* info) {
 
     // attach doubles as "windowResize" so we need to allo
     // already bound states to pass through again
@@ -521,11 +542,11 @@ bool SkOSWindow::attach(SkBackEndTypes attachType, int msaaSampleCount) {
         break;
 #if SK_SUPPORT_GPU
     case kNativeGL_BackEndType:
-        result = attachGL(msaaSampleCount);
+        result = attachGL(msaaSampleCount, info);
         break;
 #if SK_ANGLE
     case kANGLE_BackEndType:
-        result = attachANGLE(msaaSampleCount);
+        result = attachANGLE(msaaSampleCount, info);
         break;
 #endif // SK_ANGLE
 #endif // SK_SUPPORT_GPU