gecko-dev/dom/canvas/WebGLElementArrayCache.h

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3.3 KiB
C++

/* -*- 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 WEBGLELEMENTARRAYCACHE_H
#define WEBGLELEMENTARRAYCACHE_H
#include "mozilla/MemoryReporting.h"
#include "mozilla/Scoped.h"
#include "nsTArray.h"
#include <stdint.h>
#include "nscore.h"
#include "GLDefs.h"
namespace mozilla {
template<typename T>
struct WebGLElementArrayCacheTree;
/*
* WebGLElementArrayCache implements WebGL element array buffer validation for drawElements.
*
* Its exposes methods meant to be called by WebGL method implementations:
* - Validate, to be called by WebGLContext::DrawElements, is where we use the cache
* - BufferData and BufferSubData, to be called by eponymous WebGL methods, are how
* data is fed into the cache
*
* Most of the implementation is hidden in the auxilary class template, WebGLElementArrayCacheTree.
* Refer to its code for design comments.
*/
class WebGLElementArrayCache {
public:
bool BufferData(const void* ptr, size_t byteLength);
bool BufferSubData(size_t pos, const void* ptr, size_t updateByteSize);
bool Validate(GLenum type, uint32_t maxAllowed, size_t first, size_t count,
uint32_t* out_upperBound);
template<typename T>
T Element(size_t i) const { return Elements<T>()[i]; }
WebGLElementArrayCache();
~WebGLElementArrayCache();
size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
bool BeenUsedWithMultipleTypes() const;
private:
/*
* Returns true if a drawElements call with the given parameters should succeed,
* false otherwise.
*
* In other words, this returns true if all entries in the element array at positions
*
* first .. first+count-1
*
* are less than or equal to maxAllowed.
*
* Input parameters:
* maxAllowed: maximum value to be allowed in the specificied portion of the element array.
* first: start of the portion of the element array to consume.
* count: number of entries from the element array to consume.
*
* Output parameter:
* out_upperBound: upon success, is set to the actual maximum value in the specified range,
* which is then guaranteed to be less than or equal to maxAllowed.
* upon failure, is set to the first value in the specified range, that
* is greater than maxAllowed.
*/
template<typename T>
bool Validate(uint32_t maxAllowed, size_t first, size_t count,
uint32_t* out_upperBound);
template<typename T>
const T* Elements() const { return reinterpret_cast<const T*>(mBytes.Elements()); }
template<typename T>
T* Elements() { return reinterpret_cast<T*>(mBytes.Elements()); }
bool UpdateTrees(size_t firstByte, size_t lastByte);
template<typename T>
friend struct WebGLElementArrayCacheTree;
template<typename T>
friend struct TreeForType;
FallibleTArray<uint8_t> mBytes;
ScopedDeletePtr<WebGLElementArrayCacheTree<uint8_t>> mUint8Tree;
ScopedDeletePtr<WebGLElementArrayCacheTree<uint16_t>> mUint16Tree;
ScopedDeletePtr<WebGLElementArrayCacheTree<uint32_t>> mUint32Tree;
};
} // end namespace mozilla
#endif // WEBGLELEMENTARRAYCACHE_H