diff -r 000000000000 -r 6474c204b198 gfx/gl/ScopedGLHelpers.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/gl/ScopedGLHelpers.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,249 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef SCOPEDGLHELPERS_H_
+#define SCOPEDGLHELPERS_H_
+
+#include "GLContext.h"
+
+namespace mozilla {
+namespace gl {
+
+//RAII via CRTP!
+template <class Derived>
+struct ScopedGLWrapper
+{
+private:
+    bool mIsUnwrapped;
+
+protected:
+    GLContext* const mGL;
+
+    ScopedGLWrapper(GLContext* gl)
+        : mIsUnwrapped(false)
+        , mGL(gl)
+    {
+        MOZ_ASSERT(&ScopedGLWrapper<Derived>::Unwrap == &Derived::Unwrap);
+        MOZ_ASSERT(&Derived::UnwrapImpl);
+        MOZ_ASSERT(mGL->IsCurrent());
+    }
+
+    virtual ~ScopedGLWrapper() {
+        if (!mIsUnwrapped)
+            Unwrap();
+    }
+
+public:
+    void Unwrap() {
+        MOZ_ASSERT(!mIsUnwrapped);
+
+        Derived* derived = static_cast<Derived*>(this);
+        derived->UnwrapImpl();
+
+        mIsUnwrapped = true;
+    }
+};
+
+// Wraps glEnable/Disable.
+struct ScopedGLState
+    : public ScopedGLWrapper<ScopedGLState>
+{
+    friend struct ScopedGLWrapper<ScopedGLState>;
+
+protected:
+    const GLenum mCapability;
+    bool mOldState;
+
+public:
+    // Use |newState = true| to enable, |false| to disable.
+    ScopedGLState(GLContext* aGL, GLenum aCapability, bool aNewState);
+    // variant that doesn't change state; simply records existing state to be
+    // restored by the destructor
+    ScopedGLState(GLContext* aGL, GLenum aCapability);
+
+protected:
+    void UnwrapImpl();
+};
+
+// Saves and restores with GetUserBoundFB and BindUserFB.
+struct ScopedBindFramebuffer
+    : public ScopedGLWrapper<ScopedBindFramebuffer>
+{
+    friend struct ScopedGLWrapper<ScopedBindFramebuffer>;
+
+protected:
+    GLuint mOldFB;
+
+private:
+    void Init();
+
+public:
+    explicit ScopedBindFramebuffer(GLContext* aGL);
+    ScopedBindFramebuffer(GLContext* aGL, GLuint aNewFB);
+
+protected:
+    void UnwrapImpl();
+};
+
+struct ScopedBindTextureUnit
+    : public ScopedGLWrapper<ScopedBindTextureUnit>
+{
+    friend struct ScopedGLWrapper<ScopedBindTextureUnit>;
+
+protected:
+    GLenum mOldTexUnit;
+
+public:
+    ScopedBindTextureUnit(GLContext* aGL, GLenum aTexUnit);
+
+protected:
+    void UnwrapImpl();
+};
+
+
+struct ScopedTexture
+    : public ScopedGLWrapper<ScopedTexture>
+{
+    friend struct ScopedGLWrapper<ScopedTexture>;
+
+protected:
+    GLuint mTexture;
+
+public:
+    ScopedTexture(GLContext* aGL);
+    GLuint Texture() { return mTexture; }
+
+protected:
+    void UnwrapImpl();
+};
+
+
+struct ScopedBindTexture
+    : public ScopedGLWrapper<ScopedBindTexture>
+{
+    friend struct ScopedGLWrapper<ScopedBindTexture>;
+
+protected:
+    GLuint mOldTex;
+    GLenum mTarget;
+
+private:
+    void Init(GLenum aTarget);
+
+public:
+    ScopedBindTexture(GLContext* aGL, GLuint aNewTex,
+                      GLenum aTarget = LOCAL_GL_TEXTURE_2D);
+
+protected:
+    void UnwrapImpl();
+};
+
+
+struct ScopedBindRenderbuffer
+    : public ScopedGLWrapper<ScopedBindRenderbuffer>
+{
+    friend struct ScopedGLWrapper<ScopedBindRenderbuffer>;
+
+protected:
+    GLuint mOldRB;
+
+private:
+    void Init();
+
+public:
+    explicit ScopedBindRenderbuffer(GLContext* aGL);
+
+    ScopedBindRenderbuffer(GLContext* aGL, GLuint aNewRB);
+
+protected:
+    void UnwrapImpl();
+};
+
+
+struct ScopedFramebufferForTexture
+    : public ScopedGLWrapper<ScopedFramebufferForTexture>
+{
+    friend struct ScopedGLWrapper<ScopedFramebufferForTexture>;
+
+protected:
+    bool mComplete; // True if the framebuffer we create is complete.
+    GLuint mFB;
+
+public:
+    ScopedFramebufferForTexture(GLContext* aGL, GLuint aTexture,
+                                GLenum aTarget = LOCAL_GL_TEXTURE_2D);
+
+    bool IsComplete() const {
+        return mComplete;
+    }
+
+    GLuint FB() const {
+        MOZ_ASSERT(IsComplete());
+        return mFB;
+    }
+
+protected:
+    void UnwrapImpl();
+};
+
+struct ScopedFramebufferForRenderbuffer
+    : public ScopedGLWrapper<ScopedFramebufferForRenderbuffer>
+{
+    friend struct ScopedGLWrapper<ScopedFramebufferForRenderbuffer>;
+
+protected:
+    bool mComplete; // True if the framebuffer we create is complete.
+    GLuint mFB;
+
+public:
+    ScopedFramebufferForRenderbuffer(GLContext* aGL, GLuint aRB);
+
+    bool IsComplete() const {
+        return mComplete;
+    }
+
+    GLuint FB() const {
+        return mFB;
+    }
+
+protected:
+    void UnwrapImpl();
+};
+
+struct ScopedViewportRect
+    : public ScopedGLWrapper<ScopedViewportRect>
+{
+    friend struct ScopedGLWrapper<ScopedViewportRect>;
+
+protected:
+    GLint mSavedViewportRect[4];
+
+public:
+    ScopedViewportRect(GLContext* aGL, GLint x, GLint y, GLsizei width, GLsizei height);
+
+protected:
+    void UnwrapImpl();
+};
+
+struct ScopedScissorRect
+    : public ScopedGLWrapper<ScopedScissorRect>
+{
+    friend struct ScopedGLWrapper<ScopedScissorRect>;
+
+protected:
+    GLint mSavedScissorRect[4];
+
+public:
+    ScopedScissorRect(GLContext* aGL, GLint x, GLint y, GLsizei width, GLsizei height);
+    explicit ScopedScissorRect(GLContext* aGL);
+
+protected:
+    void UnwrapImpl();
+};
+
+} /* namespace gl */
+} /* namespace mozilla */
+
+#endif /* SCOPEDGLHELPERS_H_ */