The Tor Browser: content/canvas/src/WebGLObjectModel.h@deefc01c0e14 (annotated)

content/canvas/src/WebGLObjectModel.h@deefc01c0e14 (annotated)

content/canvas/src/WebGLObjectModel.h

Thu, 15 Jan 2015 21:03:48 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 15 Jan 2015 21:03:48 +0100
branch: TOR_BUG_9701
changeset 11: deefc01c0e14
permissions: -rw-r--r--

Integrate friendly tips from Tor colleagues to make (or not) 4.5 alpha 3;
This includes removal of overloaded (but unused) methods, and addition of
a overlooked call to DataStruct::SetData(nsISupports, uint32_t, bool.)

 /* -*- Mode: C++; tab-width: 4; 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 WEBGLOBJECTMODEL_H_
 #define WEBGLOBJECTMODEL_H_
 #include "nsCycleCollectionNoteChild.h"
 #include "nsICanvasRenderingContextInternal.h"
 #include "WebGLTypes.h"
 namespace mozilla {
 class WebGLBuffer;
 class WebGLContext;
 /* Each WebGL object class WebGLFoo wants to:
  *  - inherit WebGLRefCountedObject<WebGLFoo>
  *  - implement a Delete() method
  *  - have its destructor call DeleteOnce()
  *
  * This base class provides two features to WebGL object types:
  * 1. support for OpenGL object reference counting
  * 2. support for OpenGL deletion statuses
  *
  ***** 1. OpenGL object reference counting *****
  *
  * WebGL objects such as WebGLTexture's really have two different refcounts:
  * the XPCOM refcount, that is directly exposed to JavaScript, and the OpenGL
  * refcount.
  *
  * For example, when in JavaScript one does: var newname = existingTexture;
  * that increments the XPCOM refcount, but doesn't affect the OpenGL refcount.
  * When one attaches the texture to a framebuffer object, that does increment
  * its OpenGL refcount (and also its XPCOM refcount, to prevent the regular
  * XPCOM refcounting mechanism from destroying objects prematurely).
  *
  * The actual OpenGL refcount is opaque to us (it's internal to the OpenGL
  * implementation) but is affects the WebGL semantics that we have to implement:
  * for example, a WebGLTexture that is attached to a WebGLFramebuffer must not
  * be actually deleted, even if deleteTexture has been called on it, and even
  * if JavaScript doesn't have references to it anymore. We can't just rely on
  * OpenGL to keep alive the underlying OpenGL texture for us, for a variety of
  * reasons, most importantly: we'd need to know when OpenGL objects are actually
  * deleted, and OpenGL doesn't notify us about that, so we would have to query
  * status very often with glIsXxx calls which isn't practical.
  *
  * This means that we have to keep track of the OpenGL refcount ourselves,
  * in addition to the XPCOM refcount.
  *
  * This class implements such a refcount, see the mWebGLRefCnt
  * member. In order to avoid name clashes (with regular XPCOM refcounting)
  * in the derived class, we prefix members with 'WebGL', whence the names
  * WebGLAddRef, WebGLRelease, etc.
  *
  * In practice, WebGLAddRef and WebGLRelease are only called from the
  * WebGLRefPtr class.
  *
  ***** 2. OpenGL deletion statuses *****
  *
  * In OpenGL, an object can go through 3 different deletion statuses during its
  * lifetime, which correspond to the 3 enum values for DeletionStatus in this class:
  *  - the Default status, which it has from its creation to when the
  *    suitable glDeleteXxx function is called on it;
  *  - the DeleteRequested status, which is has from when the suitable glDeleteXxx
  *    function is called on it to when it is no longer referenced by other OpenGL
  *    objects. For example, a texture that is attached to a non-current FBO
  *    will enter that status when glDeleteTexture is called on it. For objects
  *    with that status, GL_DELETE_STATUS queries return true, but glIsXxx
  *    functions still return true.
  *  - the Deleted status, which is the status of objects on which the
  *    suitable glDeleteXxx function has been called, and that are not referenced
  *    by other OpenGL objects.
  *
  * This state is stored in the mDeletionStatus member of this class.
  *
  * When the GL refcount hits zero, if the status is DeleteRequested then we call
  * the Delete() method on the derived class and the status becomes Deleted. This is
  * what the MaybeDelete() function does.
  *
  * The DeleteOnce() function implemented here is a helper to ensure that we don't
  * call Delete() twice on the same object. Since the derived class' destructor
  * needs to call DeleteOnce() which calls Delete(), we can't allow either to be
  * virtual. Strictly speaking, we could let them be virtual if the derived class
  * were final, but that would be impossible to enforce and would lead to strange
  * bugs if it were subclassed.
  *
  * This WebGLRefCountedObject class takes the Derived type
  * as template parameter, as a means to allow DeleteOnce to call Delete()
  * on the Derived class, without either method being virtual. This is a common
  * C++ pattern known as the "curiously recursive template pattern (CRTP)".
  */
 template<typename Derived>
 class WebGLRefCountedObject
 {
 public:
     enum DeletionStatus { Default, DeleteRequested, Deleted };
     WebGLRefCountedObject()
       : mDeletionStatus(Default)
     { }
     ~WebGLRefCountedObject() {
         MOZ_ASSERT(mWebGLRefCnt == 0, "destroying WebGL object still referenced by other WebGL objects");
         MOZ_ASSERT(mDeletionStatus == Deleted, "Derived class destructor must call DeleteOnce()");
     }
     // called by WebGLRefPtr
     void WebGLAddRef() {
         ++mWebGLRefCnt;
     }
     // called by WebGLRefPtr
     void WebGLRelease() {
         MOZ_ASSERT(mWebGLRefCnt > 0, "releasing WebGL object with WebGL refcnt already zero");
         --mWebGLRefCnt;
         MaybeDelete();
     }
     // this is the function that WebGL.deleteXxx() functions want to call
     void RequestDelete() {
         if (mDeletionStatus == Default)
             mDeletionStatus = DeleteRequested;
         MaybeDelete();
     }
     bool IsDeleted() const {
         return mDeletionStatus == Deleted;
     }
     bool IsDeleteRequested() const {
         return mDeletionStatus != Default;
     }
     void DeleteOnce() {
         if (mDeletionStatus != Deleted) {
             static_cast<Derived*>(this)->Delete();
             mDeletionStatus = Deleted;
         }
     }
 private:
     void MaybeDelete() {
         if (mWebGLRefCnt == 0 &&
             mDeletionStatus == DeleteRequested)
         {
             DeleteOnce();
         }
     }
 protected:
     nsAutoRefCnt mWebGLRefCnt;
     DeletionStatus mDeletionStatus;
 };
 /* This WebGLRefPtr class is meant to be used for references between WebGL objects.
  * For example, a WebGLProgram holds WebGLRefPtr's to the WebGLShader's attached
  * to it.
  *
  * Why the need for a separate refptr class? The only special thing that WebGLRefPtr
  * does is that it increments and decrements the WebGL refcount of
  * WebGLRefCountedObject's, in addition to incrementing and decrementing the
  * usual XPCOM refcount.
  *
  * This means that by using a WebGLRefPtr instead of a nsRefPtr, you ensure that
  * the WebGL refcount is incremented, which means that the object will be kept
  * alive by this reference even if the matching webgl.deleteXxx() function is
  * called on it.
  */
 template<typename T>
 class WebGLRefPtr
 {
 public:
     WebGLRefPtr()
         : mRawPtr(0)
     { }
     WebGLRefPtr(const WebGLRefPtr<T>& aSmartPtr)
         : mRawPtr(aSmartPtr.mRawPtr)
     {
         AddRefOnPtr(mRawPtr);
     }
     WebGLRefPtr(T *aRawPtr)
         : mRawPtr(aRawPtr)
     {
         AddRefOnPtr(mRawPtr);
     }
     ~WebGLRefPtr() {
         ReleasePtr(mRawPtr);
     }
     WebGLRefPtr<T>&
     operator=(const WebGLRefPtr<T>& rhs)
     {
         assign_with_AddRef(rhs.mRawPtr);
         return *this;
     }
     WebGLRefPtr<T>&
     operator=(T* rhs)
     {
         assign_with_AddRef(rhs);
         return *this;
     }
     T* get() const {
         return static_cast<T*>(mRawPtr);
     }
     operator T*() const {
         return get();
     }
     T* operator->() const {
         MOZ_ASSERT(mRawPtr != 0, "You can't dereference a nullptr WebGLRefPtr with operator->()!");
         return get();
     }
     T& operator*() const {
         MOZ_ASSERT(mRawPtr != 0, "You can't dereference a nullptr WebGLRefPtr with operator*()!");
         return *get();
     }
 private:
     static void AddRefOnPtr(T* rawPtr) {
         if (rawPtr) {
             rawPtr->WebGLAddRef();
             rawPtr->AddRef();
         }
     }
     static void ReleasePtr(T* rawPtr) {
         if (rawPtr) {
             rawPtr->WebGLRelease(); // must be done first before Release(), as Release() might actually destroy the object
             rawPtr->Release();
         }
     }
     void assign_with_AddRef(T* rawPtr) {
         AddRefOnPtr(rawPtr);
         assign_assuming_AddRef(rawPtr);
     }
     void assign_assuming_AddRef(T* newPtr) {
         T* oldPtr = mRawPtr;
         mRawPtr = newPtr;
         ReleasePtr(oldPtr);
     }
 protected:
     T *mRawPtr;
 };
 // This class is a mixin for objects that are tied to a specific
 // context (which is to say, all of them).  They provide initialization
 // as well as comparison with the current context.
 class WebGLContextBoundObject
 {
 public:
     WebGLContextBoundObject(WebGLContext *context);
     bool IsCompatibleWithContext(WebGLContext *other);
     WebGLContext *Context() const { return mContext; }
 protected:
     WebGLContext *mContext;
     uint32_t mContextGeneration;
 };
 // this class is a mixin for GL objects that have dimensions
 // that we need to track.
 class WebGLRectangleObject
 {
 public:
     WebGLRectangleObject()
         : mWidth(0), mHeight(0) { }
     WebGLRectangleObject(GLsizei width, GLsizei height)
         : mWidth(width), mHeight(height) { }
     GLsizei Width() const { return mWidth; }
     void width(GLsizei value) { mWidth = value; }
     GLsizei Height() const { return mHeight; }
     void height(GLsizei value) { mHeight = value; }
     void setDimensions(GLsizei width, GLsizei height) {
         mWidth = width;
         mHeight = height;
     }
     void setDimensions(WebGLRectangleObject *rect) {
         if (rect) {
             mWidth = rect->Width();
             mHeight = rect->Height();
         } else {
             mWidth = 0;
             mHeight = 0;
         }
     }
     bool HasSameDimensionsAs(const WebGLRectangleObject& other) const {
         return Width() == other.Width() && Height() == other.Height();
     }
 protected:
     GLsizei mWidth;
     GLsizei mHeight;
 };
 }// namespace mozilla
 template <typename T>
 inline void
 ImplCycleCollectionUnlink(mozilla::WebGLRefPtr<T>& aField)
 {
   aField = nullptr;
 }
 template <typename T>
 inline void
 ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
                             mozilla::WebGLRefPtr<T>& aField,
                             const char* aName,
                             uint32_t aFlags = 0)
 {
   CycleCollectionNoteChild(aCallback, aField.get(), aName, aFlags);
 }
 #endif

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content/canvas/src/WebGLObjectModel.h@deefc01c0e14 (annotated)

content/canvas/src/WebGLObjectModel.h