skia2/include/gpu/GrBuffer.h
cdalton 74b8d32332 Implement texel buffers
Adds a mechanism for processors to add buffer accesses and implements
them in the GL backend.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1870893002

Review URL: https://codereview.chromium.org/1870893002
2016-04-11 14:47:28 -07:00

142 lines
4.7 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:
/**
* Computes a scratch key for a buffer with a "dynamic" access pattern. (Buffers with "static"
* and "stream" access patterns are disqualified by nature from being cached and reused.)
*/
static void ComputeScratchKeyForDynamicBuffer(size_t size, GrBufferType intendedType,
GrScratchKey* key) {
static const GrScratchKey::ResourceType kType = GrScratchKey::GenerateResourceType();
GrScratchKey::Builder builder(key, kType, 1 + (sizeof(size_t) + 3) / 4);
// TODO: There's not always reason to cache a buffer by type. In some (all?) APIs it's just
// a chunk of memory we can use/reuse for any type of data. We really only need to
// differentiate between the "read" types (e.g. kGpuToCpu_BufferType) and "draw" types.
builder[0] = intendedType;
builder[1] = (uint32_t)size;
if (sizeof(size_t) > 4) {
builder[2] = (uint32_t)((uint64_t)size >> 32);
}
}
GrAccessPattern accessPattern() const { return fAccessPattern; }
/**
* 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 fCPUBacked; }
/**
* 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 <= fGpuMemorySize);
return this->onUpdateData(src, srcSizeInBytes);
}
protected:
GrBuffer(GrGpu* gpu, size_t gpuMemorySize, GrBufferType intendedType,
GrAccessPattern accessPattern, bool cpuBacked)
: INHERITED(gpu, kCached_LifeCycle),
fMapPtr(nullptr),
fGpuMemorySize(gpuMemorySize), // TODO: Zero for cpu backed buffers?
fAccessPattern(accessPattern),
fCPUBacked(cpuBacked) {
if (!fCPUBacked && SkIsPow2(fGpuMemorySize) && kDynamic_GrAccessPattern == fAccessPattern) {
GrScratchKey key;
ComputeScratchKeyForDynamicBuffer(fGpuMemorySize, intendedType, &key);
this->setScratchKey(key);
}
}
void* fMapPtr;
private:
virtual size_t onGpuMemorySize() const { return fGpuMemorySize; }
virtual void onMap() = 0;
virtual void onUnmap() = 0;
virtual bool onUpdateData(const void* src, size_t srcSizeInBytes) = 0;
size_t fGpuMemorySize;
GrAccessPattern fAccessPattern;
bool fCPUBacked;
typedef GrGpuResource INHERITED;
};
#endif