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* Copyright 2011 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef GrGpu_DEFINED
#define GrGpu_DEFINED
#include "GrDrawTarget.h"
#include "GrRefCnt.h"
#include "GrClipMaskManager.h"
#include "SkPath.h"
class GrContext;
class GrIndexBufferAllocPool;
class GrPath;
class GrPathRenderer;
class GrPathRendererChain;
class GrResource;
class GrStencilBuffer;
class GrVertexBufferAllocPool;
class GrGpu : public GrDrawTarget {
* Additional blend coefficients for dual source blending, not exposed
* through GrPaint/GrContext.
enum ExtendedBlendCoeffs {
// source 2 refers to second output color when
// using dual source blending.
kS2C_GrBlendCoeff = kPublicGrBlendCoeffCount,
* Create an instance of GrGpu that matches the specified backend. If the requested backend is
* not supported (at compile-time or run-time) this returns NULL. The context will not be
* fully constructed and should not be used by GrGpu until after this function returns.
static GrGpu* Create(GrBackend, GrBackendContext, GrContext* context);
GrGpu(GrContext* context);
virtual ~GrGpu();
GrContext* getContext() { return this->INHERITED::getContext(); }
const GrContext* getContext() const { return this->INHERITED::getContext(); }
* The GrGpu object normally assumes that no outsider is setting state
* within the underlying 3D API's context/device/whatever. This call informs
* the GrGpu that the state was modified and it shouldn't make assumptions
* about the state.
void markContextDirty(uint32_t state = kAll_GrBackendState) {
fResetBits |= state;
void unimpl(const char[]);
* Creates a texture object. If desc width or height is not a power of
* two but underlying API requires a power of two texture then srcData
* will be embedded in a power of two texture. The extra width and height
* is filled as though srcData were rendered clamped into the texture.
* If kRenderTarget_TextureFlag is specified the GrRenderTarget is
* accessible via GrTexture::asRenderTarget(). The texture will hold a ref
* on the render target until the texture is destroyed.
* @param desc describes the texture to be created.
* @param srcData texel data to load texture. Begins with full-size
* palette data for paletted textures. Contains width*
* height texels. If NULL texture data is uninitialized.
* @return The texture object if successful, otherwise NULL.
GrTexture* createTexture(const GrTextureDesc& desc,
const void* srcData, size_t rowBytes);
* Implements GrContext::wrapBackendTexture
GrTexture* wrapBackendTexture(const GrBackendTextureDesc&);
* Implements GrContext::wrapBackendTexture
GrRenderTarget* wrapBackendRenderTarget(const GrBackendRenderTargetDesc&);
* Creates a vertex buffer.
* @param size size in bytes of the vertex buffer
* @param dynamic hints whether the data will be frequently changed
* by either GrVertexBuffer::lock or
* GrVertexBuffer::updateData.
* @return The vertex buffer if successful, otherwise NULL.
GrVertexBuffer* createVertexBuffer(uint32_t size, bool dynamic);
* Creates an index buffer.
* @param size size in bytes of the index buffer
* @param dynamic hints whether the data will be frequently changed
* by either GrIndexBuffer::lock or
* GrIndexBuffer::updateData.
* @return The index buffer if successful, otherwise NULL.
GrIndexBuffer* createIndexBuffer(uint32_t size, bool dynamic);
* Creates a path object that can be stenciled using stencilPath(). It is
* only legal to call this if the caps report support for path stenciling.
GrPath* createPath(const SkPath& path);
* Returns an index buffer that can be used to render quads.
* Six indices per quad: 0, 1, 2, 0, 2, 3, etc.
* The max number of quads can be queried using GrIndexBuffer::maxQuads().
* Draw with kTriangles_GrPrimitiveType
* @ return the quad index buffer
const GrIndexBuffer* getQuadIndexBuffer() const;
* Resolves MSAA.
void resolveRenderTarget(GrRenderTarget* target);
* Ensures that the current render target is actually set in the
* underlying 3D API. Used when client wants to use 3D API to directly
* render to the RT.
void forceRenderTargetFlush();
* Gets a preferred 8888 config to use for writing/reading pixel data to/from a surface with
* config surfaceConfig. The returned config must have at least as many bits per channel as the
* readConfig or writeConfig param.
virtual GrPixelConfig preferredReadPixelsConfig(GrPixelConfig readConfig,
GrPixelConfig surfaceConfig) const {
return readConfig;
virtual GrPixelConfig preferredWritePixelsConfig(GrPixelConfig writeConfig,
GrPixelConfig surfaceConfig) const {
return writeConfig;
* Called before uploading writing pixels to a GrTexture when the src pixel config doesn't
* match the texture's config.
virtual bool canWriteTexturePixels(const GrTexture*, GrPixelConfig srcConfig) const = 0;
* OpenGL's readPixels returns the result bottom-to-top while the skia
* API is top-to-bottom. Thus we have to do a y-axis flip. The obvious
* solution is to have the subclass do the flip using either the CPU or GPU.
* However, the caller (GrContext) may have transformations to apply and can
* simply fold in the y-flip for free. On the other hand, the subclass may
* be able to do it for free itself. For example, the subclass may have to
* do memcpys to handle rowBytes that aren't tight. It could do the y-flip
* concurrently.
* This function returns true if a y-flip is required to put the pixels in
* top-to-bottom order and the subclass cannot do it for free.
* See read pixels for the params
* @return true if calling readPixels with the same set of params will
* produce bottom-to-top data
virtual bool readPixelsWillPayForYFlip(GrRenderTarget* renderTarget,
int left, int top,
int width, int height,
GrPixelConfig config,
size_t rowBytes) const = 0;
* This should return true if reading a NxM rectangle of pixels from a
* render target is faster if the target has dimensons N and M and the read
* rectangle has its top-left at 0,0.
virtual bool fullReadPixelsIsFasterThanPartial() const { return false; };
* Reads a rectangle of pixels from a render target.
* @param renderTarget the render target to read from. NULL means the
* current render target.
* @param left left edge of the rectangle to read (inclusive)
* @param top top edge of the rectangle to read (inclusive)
* @param width width of rectangle to read in pixels.
* @param height height of rectangle to read in pixels.
* @param config the pixel config of the destination buffer
* @param buffer memory to read the rectangle into.
* @param rowBytes the number of bytes between consecutive rows. Zero
* means rows are tightly packed.
* @param invertY buffer should be populated bottom-to-top as opposed
* to top-to-bottom (skia's usual order)
* @return true if the read succeeded, false if not. The read can fail
* because of a unsupported pixel config or because no render
* target is currently set.
bool readPixels(GrRenderTarget* renderTarget,
int left, int top, int width, int height,
GrPixelConfig config, void* buffer, size_t rowBytes);
* Updates the pixels in a rectangle of a texture.
* @param left left edge of the rectangle to write (inclusive)
* @param top top edge of the rectangle to write (inclusive)
* @param width width of rectangle to write in pixels.
* @param height height of rectangle to write in pixels.
* @param config the pixel config of the source buffer
* @param buffer memory to read pixels from
* @param rowBytes number of bytes between consecutive rows. Zero
* means rows are tightly packed.
bool writeTexturePixels(GrTexture* texture,
int left, int top, int width, int height,
GrPixelConfig config, const void* buffer,
size_t rowBytes);
* Called to tell Gpu object that all GrResources have been lost and should
* be abandoned. Overrides must call INHERITED::abandonResources().
virtual void abandonResources();
* Called to tell Gpu object to release all GrResources. Overrides must call
* INHERITED::releaseResources().
void releaseResources();
* Add resource to list of resources. Should only be called by GrResource.
* @param resource the resource to add.
void insertResource(GrResource* resource);
* Remove resource from list of resources. Should only be called by
* GrResource.
* @param resource the resource to remove.
void removeResource(GrResource* resource);
// GrDrawTarget overrides
virtual void clear(const SkIRect* rect,
GrColor color,
GrRenderTarget* renderTarget = NULL) SK_OVERRIDE;
virtual void purgeResources() SK_OVERRIDE {
// The clip mask manager can rebuild all its clip masks so just
// get rid of them all.
// After the client interacts directly with the 3D context state the GrGpu
// must resync its internal state and assumptions about 3D context state.
// Each time this occurs the GrGpu bumps a timestamp.
// state of the 3D context
// At 10 resets / frame and 60fps a 64bit timestamp will overflow in about
// a billion years.
typedef uint64_t ResetTimestamp;
// This timestamp is always older than the current timestamp
static const ResetTimestamp kExpiredTimestamp = 0;
// Returns a timestamp based on the number of times the context was reset.
// This timestamp can be used to lazily detect when cached 3D context state
// is dirty.
ResetTimestamp getResetTimestamp() const {
return fResetTimestamp;
* Can the provided configuration act as a color render target?
bool isConfigRenderable(GrPixelConfig config) const {
SkASSERT(kGrPixelConfigCnt > config);
return fConfigRenderSupport[config];
* These methods are called by the clip manager's setupClipping function
* which (called as part of GrGpu's implementation of onDraw and
* onStencilPath member functions.) The GrGpu subclass should flush the
* stencil state to the 3D API in its implementation of flushGraphicsState.
void enableScissor(const SkIRect& rect) {
fScissorState.fEnabled = true;
fScissorState.fRect = rect;
void disableScissor() { fScissorState.fEnabled = false; }
* Like the scissor methods above this is called by setupClipping and
* should be flushed by the GrGpu subclass in flushGraphicsState. These
* stencil settings should be used in place of those on the GrDrawState.
* They have been adjusted to account for any interactions between the
* GrDrawState's stencil settings and stencil clipping.
void setStencilSettings(const GrStencilSettings& settings) {
fStencilSettings = settings;
void disableStencil() { fStencilSettings.setDisabled(); }
// GrGpu subclass sets clip bit in the stencil buffer. The subclass is
// free to clear the remaining bits to zero if masked clears are more
// expensive than clearing all bits.
virtual void clearStencilClip(const SkIRect& rect, bool insideClip) = 0;
enum PrivateDrawStateStateBits {
kFirstBit = (GrDrawState::kLastPublicStateBit << 1),
kModifyStencilClip_StateBit = kFirstBit, // allows draws to modify
// stencil bits used for
// clipping.
enum DrawType {
DrawType PrimTypeToDrawType(GrPrimitiveType type) {
switch (type) {
case kTriangles_GrPrimitiveType:
case kTriangleStrip_GrPrimitiveType:
case kTriangleFan_GrPrimitiveType:
return kDrawTriangles_DrawType;
case kPoints_GrPrimitiveType:
return kDrawPoints_DrawType;
case kLines_GrPrimitiveType:
case kLineStrip_GrPrimitiveType:
return kDrawLines_DrawType;
GrCrash("Unexpected primitive type");
return kDrawTriangles_DrawType;
// prepares clip flushes gpu state before a draw
bool setupClipAndFlushState(DrawType,
const GrDeviceCoordTexture* dstCopy,
GrDrawState::AutoRestoreEffects* are);
// Functions used to map clip-respecting stencil tests into normal
// stencil funcs supported by GPUs.
static GrStencilFunc ConvertStencilFunc(bool stencilInClip,
GrStencilFunc func);
static void ConvertStencilFuncAndMask(GrStencilFunc func,
bool clipInStencil,
unsigned int clipBit,
unsigned int userBits,
unsigned int* ref,
unsigned int* mask);
GrClipMaskManager fClipMaskManager;
struct GeometryPoolState {
const GrVertexBuffer* fPoolVertexBuffer;
int fPoolStartVertex;
const GrIndexBuffer* fPoolIndexBuffer;
int fPoolStartIndex;
const GeometryPoolState& getGeomPoolState() {
return fGeomPoolStateStack.back();
// The state of the scissor is controlled by the clip manager
struct ScissorState {
bool fEnabled;
SkIRect fRect;
} fScissorState;
// The final stencil settings to use as determined by the clip manager.
GrStencilSettings fStencilSettings;
// Derived classes need access to this so they can fill it out in their
// constructors
bool fConfigRenderSupport[kGrPixelConfigCnt];
// Helpers for setting up geometry state
void finalizeReservedVertices();
void finalizeReservedIndices();
// GrDrawTarget overrides
virtual bool onReserveVertexSpace(size_t vertexSize, int vertexCount, void** vertices) SK_OVERRIDE;
virtual bool onReserveIndexSpace(int indexCount, void** indices) SK_OVERRIDE;
virtual void releaseReservedVertexSpace() SK_OVERRIDE;
virtual void releaseReservedIndexSpace() SK_OVERRIDE;
virtual void onSetVertexSourceToArray(const void* vertexArray, int vertexCount) SK_OVERRIDE;
virtual void onSetIndexSourceToArray(const void* indexArray, int indexCount) SK_OVERRIDE;
virtual void releaseVertexArray() SK_OVERRIDE;
virtual void releaseIndexArray() SK_OVERRIDE;
virtual void geometrySourceWillPush() SK_OVERRIDE;
virtual void geometrySourceWillPop(const GeometrySrcState& restoredState) SK_OVERRIDE;
// called when the 3D context state is unknown. Subclass should emit any
// assumed 3D context state and dirty any state cache.
virtual void onResetContext(uint32_t resetBits) = 0;
// overridden by backend-specific derived class to create objects.
virtual GrTexture* onCreateTexture(const GrTextureDesc& desc,
const void* srcData,
size_t rowBytes) = 0;
virtual GrTexture* onWrapBackendTexture(const GrBackendTextureDesc&) = 0;
virtual GrRenderTarget* onWrapBackendRenderTarget(const GrBackendRenderTargetDesc&) = 0;
virtual GrVertexBuffer* onCreateVertexBuffer(uint32_t size, bool dynamic) = 0;
virtual GrIndexBuffer* onCreateIndexBuffer(uint32_t size, bool dynamic) = 0;
virtual GrPath* onCreatePath(const SkPath& path) = 0;
// overridden by backend-specific derived class to perform the clear and
// clearRect. NULL rect means clear whole target.
virtual void onClear(const SkIRect* rect, GrColor color) = 0;
// overridden by backend-specific derived class to perform the draw call.
virtual void onGpuDraw(const DrawInfo&) = 0;
// when GrDrawTarget::stencilPath is called the draw state's current stencil
// settings are ignored. Instead the GrGpu decides the stencil rules
// necessary to stencil the path. These are still subject to filtering by
// the clip mask manager.
virtual void setStencilPathSettings(const GrPath&,
GrStencilSettings* settings) = 0;
// overridden by backend-specific derived class to perform the path stenciling.
virtual void onGpuStencilPath(const GrPath*, SkPath::FillType) = 0;
// overridden by backend-specific derived class to perform flush
virtual void onForceRenderTargetFlush() = 0;
// overridden by backend-specific derived class to perform the read pixels.
virtual bool onReadPixels(GrRenderTarget* target,
int left, int top, int width, int height,
void* buffer,
size_t rowBytes) = 0;
// overridden by backend-specific derived class to perform the texture update
virtual bool onWriteTexturePixels(GrTexture* texture,
int left, int top, int width, int height,
GrPixelConfig config, const void* buffer,
size_t rowBytes) = 0;
// overridden by backend-specific derived class to perform the resolve
virtual void onResolveRenderTarget(GrRenderTarget* target) = 0;
// width and height may be larger than rt (if underlying API allows it).
// Should attach the SB to the RT. Returns false if compatible sb could
// not be created.
virtual bool createStencilBufferForRenderTarget(GrRenderTarget*, int width, int height) = 0;
// attaches an existing SB to an existing RT.
virtual bool attachStencilBufferToRenderTarget(GrStencilBuffer*, GrRenderTarget*) = 0;
// The GrGpu typically records the clients requested state and then flushes
// deltas from previous state at draw time. This function does the
// backend-specific flush of the state.
// returns false if current state is unsupported.
virtual bool flushGraphicsState(DrawType, const GrDeviceCoordTexture* dstCopy) = 0;
// clears the entire stencil buffer to 0
virtual void clearStencil() = 0;
// Given a rt, find or create a stencil buffer and attach it
bool attachStencilBufferToRenderTarget(GrRenderTarget* target);
// GrDrawTarget overrides
virtual void onDraw(const DrawInfo&) SK_OVERRIDE;
virtual void onStencilPath(const GrPath* path, const SkStrokeRec& stroke,
SkPath::FillType) SK_OVERRIDE;
// readies the pools to provide vertex/index data.
void prepareVertexPool();
void prepareIndexPool();
void resetContext() {
// We call this because the client may have messed with the
// stencil buffer. Perhaps we should detect whether it is a
// internally created stencil buffer and if so skip the invalidate.
fResetBits = 0;
void handleDirtyContext() {
if (fResetBits) {
enum {
kPreallocGeomPoolStateStackCnt = 4,
typedef SkTInternalLList<GrResource> ResourceList;
SkSTArray<kPreallocGeomPoolStateStackCnt, GeometryPoolState, true> fGeomPoolStateStack;
ResetTimestamp fResetTimestamp;
uint32_t fResetBits;
GrVertexBufferAllocPool* fVertexPool;
GrIndexBufferAllocPool* fIndexPool;
// counts number of uses of vertex/index pool in the geometry stack
int fVertexPoolUseCnt;
int fIndexPoolUseCnt;
// these are mutable so they can be created on-demand
mutable GrIndexBuffer* fQuadIndexBuffer;
// Used to abandon/release all resources created by this GrGpu. TODO: Move this
// functionality to GrResourceCache.
ResourceList fResourceList;
typedef GrDrawTarget INHERITED;