skia2/include/gpu/GrBuffer.h
csmartdalton 485a12003a Add resource provider flag to avoid client-side buffers
On some platforms, a newly-created buffer was liable to be CPU backed.
This would break code that expected a VBO (aka instanced rendering).
This change adds an optional flag to GrResourceProvider that requires
a buffer to be created in GPU memory.

It also moves the CPU backing logic into Gr land in order to properly
cache real VBOs on platforms that prefer client-side buffers.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2143333002

Review-Url: https://codereview.chromium.org/2143333002
2016-07-13 10:16:32 -07:00

137 lines
4.2 KiB
C++

/*
* Copyright 2016 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrBuffer_DEFINED
#define GrBuffer_DEFINED
#include "GrGpuResource.h"
class GrGpu;
class GrBuffer : public GrGpuResource {
public:
/**
* Creates a client-side buffer.
*/
static SK_WARN_UNUSED_RESULT GrBuffer* CreateCPUBacked(GrGpu*, size_t sizeInBytes, GrBufferType,
const void* data = nullptr);
/**
* Computes a scratch key for a GPU-side buffer with a "dynamic" access pattern. (Buffers with
* "static" and "stream" patterns are disqualified by nature from being cached and reused.)
*/
static void ComputeScratchKeyForDynamicVBO(size_t size, GrBufferType, GrScratchKey*);
GrAccessPattern accessPattern() const { return fAccessPattern; }
size_t sizeInBytes() const { return fSizeInBytes; }
/**
* Returns true if the buffer is a wrapper around a CPU array. If true it
* indicates that map will always succeed and will be free.
*/
bool isCPUBacked() const { return SkToBool(fCPUData); }
size_t baseOffset() const { return reinterpret_cast<size_t>(fCPUData); }
/**
* Maps the buffer to be written by the CPU.
*
* The previous content of the buffer is invalidated. It is an error
* to draw from the buffer while it is mapped. It may fail if the backend
* doesn't support mapping the buffer. If the buffer is CPU backed then
* it will always succeed and is a free operation. Once a buffer is mapped,
* subsequent calls to map() are ignored.
*
* Note that buffer mapping does not go through GrContext and therefore is
* not serialized with other operations.
*
* @return a pointer to the data or nullptr if the map fails.
*/
void* map() {
if (!fMapPtr) {
this->onMap();
}
return fMapPtr;
}
/**
* Unmaps the buffer.
*
* The pointer returned by the previous map call will no longer be valid.
*/
void unmap() {
SkASSERT(fMapPtr);
this->onUnmap();
fMapPtr = nullptr;
}
/**
* Returns the same ptr that map() returned at time of map or nullptr if the
* is not mapped.
*
* @return ptr to mapped buffer data or nullptr if buffer is not mapped.
*/
void* mapPtr() const { return fMapPtr; }
/**
Queries whether the buffer has been mapped.
@return true if the buffer is mapped, false otherwise.
*/
bool isMapped() const { return SkToBool(fMapPtr); }
/**
* Updates the buffer data.
*
* The size of the buffer will be preserved. The src data will be
* placed at the beginning of the buffer and any remaining contents will
* be undefined. srcSizeInBytes must be <= to the buffer size.
*
* The buffer must not be mapped.
*
* Note that buffer updates do not go through GrContext and therefore are
* not serialized with other operations.
*
* @return returns true if the update succeeds, false otherwise.
*/
bool updateData(const void* src, size_t srcSizeInBytes) {
SkASSERT(!this->isMapped());
SkASSERT(srcSizeInBytes <= fSizeInBytes);
return this->onUpdateData(src, srcSizeInBytes);
}
~GrBuffer() override {
sk_free(fCPUData);
}
protected:
GrBuffer(GrGpu*, size_t sizeInBytes, GrBufferType, GrAccessPattern);
void* fMapPtr;
private:
/**
* Internal constructor to make a CPU-backed buffer.
*/
GrBuffer(GrGpu*, size_t sizeInBytes, GrBufferType, void* cpuData);
virtual void onMap() { SkASSERT(this->isCPUBacked()); fMapPtr = fCPUData; }
virtual void onUnmap() { SkASSERT(this->isCPUBacked()); }
virtual bool onUpdateData(const void* src, size_t srcSizeInBytes);
size_t onGpuMemorySize() const override { return fSizeInBytes; } // TODO: zero for cpu backed?
void computeScratchKey(GrScratchKey* key) const override;
size_t fSizeInBytes;
GrAccessPattern fAccessPattern;
void* fCPUData;
GrBufferType fIntendedType;
typedef GrGpuResource INHERITED;
};
#endif