src/gpu/GrDrawTarget.h

/*
 * Copyright 2010 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef GrDrawTarget_DEFINED
#define GrDrawTarget_DEFINED

#include "GrClip.h"
#include "GrClipMaskManager.h"
#include "GrContext.h"
#include "GrPathProcessor.h"
#include "GrPrimitiveProcessor.h"
#include "GrIndexBuffer.h"
#include "GrPathRendering.h"
#include "GrPipelineBuilder.h"
#include "GrTraceMarker.h"
#include "GrVertexBuffer.h"

#include "SkClipStack.h"
#include "SkMatrix.h"
#include "SkPath.h"
#include "SkStrokeRec.h"
#include "SkTArray.h"
#include "SkTLazy.h"
#include "SkTypes.h"
#include "SkXfermode.h"

class GrBatch;
class GrClip;
class GrDrawTargetCaps;
class GrIndexBufferAllocPool;
class GrPath;
class GrPathRange;
class GrPipeline;
class GrVertexBufferAllocPool;

class GrDrawTarget : public SkRefCnt {
public:
    SK_DECLARE_INST_COUNT(GrDrawTarget)

    typedef GrPathRange::PathIndexType PathIndexType;
    typedef GrPathRendering::PathTransformType PathTransformType;

    ///////////////////////////////////////////////////////////////////////////

    // The context may not be fully constructed and should not be used during GrDrawTarget
    // construction.
    GrDrawTarget(GrContext* context, GrVertexBufferAllocPool*, GrIndexBufferAllocPool*);

    virtual ~GrDrawTarget() {}

    /**
     * Empties the draw buffer of any queued up draws.
     */
    void reset();

    /**
     * This plays any queued up draws to its GrGpu target. It also resets this object (i.e. flushing
     * is destructive).
     */
    void flush();

    /**
     * Gets the capabilities of the draw target.
     */
    const GrDrawTargetCaps* caps() const { return fCaps.get(); }

    void drawBatch(GrPipelineBuilder*, GrBatch*);

    /**
     * Draws path into the stencil buffer. The fill must be either even/odd or
     * winding (not inverse or hairline). It will respect the HW antialias flag
     * on the GrPipelineBuilder (if possible in the 3D API).  Note, we will never have an inverse
     * fill with stencil path
     */
    void stencilPath(GrPipelineBuilder*, const GrPathProcessor*, const GrPath*,
                     GrPathRendering::FillType);

    /**
     * Draws a path. Fill must not be a hairline. It will respect the HW
     * antialias flag on the GrPipelineBuilder (if possible in the 3D API).
     */
    void drawPath(GrPipelineBuilder*, const GrPathProcessor*, const GrPath*,
                  GrPathRendering::FillType);

    /**
     * Draws the aggregate path from combining multiple. Note that this will not
     * always be equivalent to back-to-back calls to drawPath(). It will respect
     * the HW antialias flag on the GrPipelineBuilder (if possible in the 3D API).
     *
     * @param pathRange       Source paths to draw from
     * @param indices         Array of path indices to draw
     * @param indexType       Data type of the array elements in indexBuffer
     * @param transformValues Array of transforms for the individual paths
     * @param transformType   Type of transforms in transformBuffer
     * @param count           Number of paths to draw
     * @param fill            Fill type for drawing all the paths
     */
    void drawPaths(GrPipelineBuilder*,
                   const GrPathProcessor*,
                   const GrPathRange* pathRange,
                   const void* indices,
                   PathIndexType indexType,
                   const float transformValues[],
                   PathTransformType transformType,
                   int count,
                   GrPathRendering::FillType fill);

    /**
     * Helper function for drawing rects.
     *
     * @param rect        the rect to draw
     * @param localRect   optional rect that specifies local coords to map onto
     *                    rect. If NULL then rect serves as the local coords.
     * @param localMatrix Optional local matrix. The local coordinates are specified by localRect,
     *                    or if it is NULL by rect. This matrix applies to the coordinate implied by
     *                    that rectangle before it is input to GrCoordTransforms that read local
     *                    coordinates
     */
    void drawRect(GrPipelineBuilder* pipelineBuilder,
                  GrColor color,
                  const SkMatrix& viewMatrix,
                  const SkRect& rect,
                  const SkRect* localRect,
                  const SkMatrix* localMatrix) {
        this->onDrawRect(pipelineBuilder, color, viewMatrix, rect, localRect, localMatrix);
    }

    /**
     * Helper for drawRect when the caller doesn't need separate local rects or matrices.
     */
    void drawSimpleRect(GrPipelineBuilder* ds, GrColor color, const SkMatrix& viewM,
                        const SkRect& rect) {
        this->drawRect(ds, color, viewM, rect, NULL, NULL);
    }
    void drawSimpleRect(GrPipelineBuilder* ds, GrColor color, const SkMatrix& viewM,
                        const SkIRect& irect) {
        SkRect rect = SkRect::Make(irect);
        this->drawRect(ds, color, viewM, rect, NULL, NULL);
    }


    /**
     * Clear the passed in render target. Ignores the GrPipelineBuilder and clip. Clears the whole
     * thing if rect is NULL, otherwise just the rect. If canIgnoreRect is set then the entire
     * render target can be optionally cleared.
     */
    void clear(const SkIRect* rect,
               GrColor color,
               bool canIgnoreRect,
               GrRenderTarget* renderTarget);

    /**
     * Discards the contents render target.
     **/
    virtual void discard(GrRenderTarget*) = 0;

    /**
     * Called at start and end of gpu trace marking
     * GR_CREATE_GPU_TRACE_MARKER(marker_str, target) will automatically call these at the start
     * and end of a code block respectively
     */
    void addGpuTraceMarker(const GrGpuTraceMarker* marker);
    void removeGpuTraceMarker(const GrGpuTraceMarker* marker);

    /**
     * Takes the current active set of markers and stores them for later use. Any current marker
     * in the active set is removed from the active set and the targets remove function is called.
     * These functions do not work as a stack so you cannot call save a second time before calling
     * restore. Also, it is assumed that when restore is called the current active set of markers
     * is empty. When the stored markers are added back into the active set, the targets add marker
     * is called.
     */
    void saveActiveTraceMarkers();
    void restoreActiveTraceMarkers();

    /**
     * Copies a pixel rectangle from one surface to another. This call may finalize
     * reserved vertex/index data (as though a draw call was made). The src pixels
     * copied are specified by srcRect. They are copied to a rect of the same
     * size in dst with top left at dstPoint. If the src rect is clipped by the
     * src bounds then  pixel values in the dst rect corresponding to area clipped
     * by the src rect are not overwritten. This method can fail and return false
     * depending on the type of surface, configs, etc, and the backend-specific
     * limitations. If rect is clipped out entirely by the src or dst bounds then
     * true is returned since there is no actual copy necessary to succeed.
     */
    bool copySurface(GrSurface* dst,
                     GrSurface* src,
                     const SkIRect& srcRect,
                     const SkIPoint& dstPoint);
    /**
     * Function that determines whether a copySurface call would succeed without actually
     * performing the copy.
     */
    bool canCopySurface(const GrSurface* dst,
                        const GrSurface* src,
                        const SkIRect& srcRect,
                        const SkIPoint& dstPoint);

    /**
     * Release any resources that are cached but not currently in use. This
     * is intended to give an application some recourse when resources are low.
     */
    virtual void purgeResources() {};

    ///////////////////////////////////////////////////////////////////////////
    // Draw execution tracking (for font atlases and other resources)
    class DrawToken {
    public:
        DrawToken(GrDrawTarget* drawTarget, uint32_t drawID) :
                  fDrawTarget(drawTarget), fDrawID(drawID) {}

        bool isIssued() { return fDrawTarget && fDrawTarget->isIssued(fDrawID); }

    private:
        GrDrawTarget*  fDrawTarget;
        uint32_t       fDrawID;   // this may wrap, but we're doing direct comparison
                                  // so that should be okay
    };

    virtual DrawToken getCurrentDrawToken() { return DrawToken(this, 0); }

    /**
     * Used to communicate draw index vertex offsets and counts toto GPUs / subclasses
     */
    class DrawInfo {
    public:
        DrawInfo() {}
        DrawInfo(const DrawInfo& di) { (*this) = di; }
        DrawInfo& operator =(const DrawInfo& di);

        void init(GrPrimitiveType primType, const GrVertexBuffer* vertexBuffer, int startVertex,
                  int vertexCount) {
            SkASSERT(vertexBuffer);
            SkASSERT(vertexCount);
            SkASSERT(startVertex >= 0);
            fPrimitiveType = primType;
            fVertexBuffer.reset(SkRef(vertexBuffer));
            fIndexBuffer.reset(NULL);
            fStartVertex = startVertex;
            fStartIndex = 0;
            fVertexCount = vertexCount;
            fIndexCount = 0;
            fInstanceCount = 0;
            fVerticesPerInstance = 0;
            fIndicesPerInstance = 0;
        }

        void initIndexed(GrPrimitiveType primType,
                         const GrVertexBuffer* vertexBuffer,
                         const GrIndexBuffer* indexBuffer,
                         int startVertex,
                         int startIndex,
                         int vertexCount,
                         int indexCount) {
            SkASSERT(indexBuffer);
            SkASSERT(vertexBuffer);
            SkASSERT(indexCount);
            SkASSERT(vertexCount);
            SkASSERT(startIndex >= 0);
            SkASSERT(startVertex >= 0);
            fPrimitiveType = primType;
            fVertexBuffer.reset(SkRef(vertexBuffer));
            fIndexBuffer.reset(SkRef(indexBuffer));
            fStartVertex = startVertex;
            fStartIndex = startIndex;
            fVertexCount = vertexCount;
            fIndexCount = indexCount;
            fInstanceCount = 0;
            fVerticesPerInstance = 0;
            fIndicesPerInstance = 0;
        }

        void initInstanced(GrPrimitiveType primType,
                           const GrVertexBuffer* vertexBuffer,
                           const GrIndexBuffer* indexBuffer,
                           int startVertex,
                           int verticesPerInstance,
                           int indicesPerInstance,
                           int instanceCount) {
            SkASSERT(vertexBuffer);
            SkASSERT(indexBuffer);
            SkASSERT(instanceCount);
            SkASSERT(verticesPerInstance);
            SkASSERT(indicesPerInstance);
            SkASSERT(startVertex >= 0);
            fPrimitiveType = primType;
            fVertexBuffer.reset(SkRef(vertexBuffer));
            fIndexBuffer.reset(SkRef(indexBuffer));
            fStartVertex = startVertex;
            fStartIndex = 0;
            fVerticesPerInstance = verticesPerInstance;
            fIndicesPerInstance = indicesPerInstance;
            fInstanceCount = instanceCount;
            fVertexCount = instanceCount * fVerticesPerInstance;
            fIndexCount = instanceCount * fIndicesPerInstance;
        }

        /** Variation of the above that may be used when the total number of instances may exceed
            the number of instances supported by the index buffer. To be used with
            nextInstances() to draw in max-sized batches.*/
        void initInstanced(GrPrimitiveType primType,
                           const GrVertexBuffer* vertexBuffer,
                           const GrIndexBuffer* indexBuffer,
                           int startVertex,
                           int verticesPerInstance,
                           int indicesPerInstance,
                           int* instancesRemaining,
                           int maxInstancesPerDraw) {
            int instanceCount = SkTMin(*instancesRemaining, maxInstancesPerDraw);
            *instancesRemaining -= instanceCount;
            this->initInstanced(primType, vertexBuffer, indexBuffer, startVertex,
                                verticesPerInstance, indicesPerInstance, instanceCount);
        }

        GrPrimitiveType primitiveType() const { return fPrimitiveType; }
        int startVertex() const { return fStartVertex; }
        int startIndex() const { return fStartIndex; }
        int vertexCount() const { return fVertexCount; }
        int indexCount() const { return fIndexCount; }

        /** These return 0 if initInstanced was not used to initialize the DrawInfo. */
        int verticesPerInstance() const { return fVerticesPerInstance; }
        int indicesPerInstance() const { return fIndicesPerInstance; }
        int instanceCount() const { return fInstanceCount; }

        bool isIndexed() const { return fIndexCount > 0; }
        bool isInstanced() const { return fInstanceCount > 0; }

        /** Called after using this draw info to draw the next set of instances.
            The vertex offset is advanced while the index buffer is reused at the same
            position. instancesRemaining is number of instances that remain, maxInstances is
            the most number of instances that can be used with the index buffer. If there
            are no instances remaining, the DrawInfo is unmodified and false is returned.*/
        bool nextInstances(int* instancesRemaining, int maxInstances) {
            SkASSERT(this->isInstanced());
            if (!*instancesRemaining) {
                return false;
            }
            fStartVertex += fVertexCount;
            fInstanceCount = SkTMin(*instancesRemaining, maxInstances);
            fVertexCount = fInstanceCount * fVerticesPerInstance;
            fIndexCount = fInstanceCount * fIndicesPerInstance;
            *instancesRemaining -= fInstanceCount;
            return true;
        }

        const GrVertexBuffer* vertexBuffer() const { return fVertexBuffer.get(); }
        const GrIndexBuffer* indexBuffer() const { return fIndexBuffer.get(); }

    private:
        friend class GrDrawTarget;

        GrPrimitiveType         fPrimitiveType;

        int                     fStartVertex;
        int                     fStartIndex;
        int                     fVertexCount;
        int                     fIndexCount;

        int                     fInstanceCount;
        int                     fVerticesPerInstance;
        int                     fIndicesPerInstance;

        GrPendingIOResource<const GrVertexBuffer, kRead_GrIOType> fVertexBuffer;
        GrPendingIOResource<const GrIndexBuffer, kRead_GrIOType>  fIndexBuffer;
    };

    bool programUnitTest(int maxStages);

protected:
    friend class GrCommandBuilder; // for PipelineInfo
    friend class GrTargetCommands; // for PipelineInfo

    GrContext* getContext() { return fContext; }
    const GrContext* getContext() const { return fContext; }

    GrGpu* getGpu() {
        SkASSERT(fContext && fContext->getGpu());
        return fContext->getGpu();
    }
    const GrGpu* getGpu() const {
        SkASSERT(fContext && fContext->getGpu());
        return fContext->getGpu();
    }

    GrVertexBufferAllocPool* getVertexAllocPool() { return fVertexPool; }
    GrIndexBufferAllocPool* getIndexAllocPool() { return fIndexPool; }

    const GrTraceMarkerSet& getActiveTraceMarkers() { return fActiveTraceMarkers; }

    // Makes a copy of the dst if it is necessary for the draw. Returns false if a copy is required
    // but couldn't be made. Otherwise, returns true.  This method needs to be protected because it
    // needs to be accessed by GLPrograms to setup a correct drawstate
    bool setupDstReadIfNecessary(const GrPipelineBuilder&,
                                 const GrProcOptInfo& colorPOI,
                                 const GrProcOptInfo& coveragePOI,
                                 GrDeviceCoordTexture* dstCopy,
                                 const SkRect* drawBounds);

    struct PipelineInfo {
        PipelineInfo(GrPipelineBuilder* pipelineBuilder, GrScissorState* scissor,
                     const GrPrimitiveProcessor* primProc,
                     const SkRect* devBounds, GrDrawTarget* target);

        PipelineInfo(GrPipelineBuilder* pipelineBuilder, GrScissorState* scissor,
                     const GrBatch* batch, const SkRect* devBounds,
                     GrDrawTarget* target);

        bool willBlendWithDst(const GrPrimitiveProcessor* primProc) const {
            return fPipelineBuilder->willBlendWithDst(primProc);
        }
    private:
        friend class GrDrawTarget;

        bool mustSkipDraw() const { return (NULL == fPipelineBuilder); }

        GrPipelineBuilder*      fPipelineBuilder;
        GrScissorState*         fScissor;
        GrProcOptInfo           fColorPOI; 
        GrProcOptInfo           fCoveragePOI; 
        GrDeviceCoordTexture    fDstCopy;
    };

    void setupPipeline(const PipelineInfo& pipelineInfo, GrPipeline* pipeline);

private:
    virtual void onReset() = 0;

    virtual void onFlush() = 0;

    virtual void onDrawBatch(GrBatch*, const PipelineInfo&) = 0;
    // TODO copy in order drawbuffer onDrawRect to here
    virtual void onDrawRect(GrPipelineBuilder*,
                            GrColor color,
                            const SkMatrix& viewMatrix,
                            const SkRect& rect,
                            const SkRect* localRect,
                            const SkMatrix* localMatrix) = 0;

    virtual void onStencilPath(const GrPipelineBuilder&,
                               const GrPathProcessor*,
                               const GrPath*,
                               const GrScissorState&,
                               const GrStencilSettings&) = 0;
    virtual void onDrawPath(const GrPathProcessor*,
                            const GrPath*,
                            const GrStencilSettings&,
                            const PipelineInfo&) = 0;
    virtual void onDrawPaths(const GrPathProcessor*,
                             const GrPathRange*,
                             const void* indices,
                             PathIndexType,
                             const float transformValues[],
                             PathTransformType,
                             int count,
                             const GrStencilSettings&,
                             const PipelineInfo&) = 0;

    virtual void onClear(const SkIRect* rect, GrColor color, bool canIgnoreRect,
                         GrRenderTarget* renderTarget) = 0;

    /** The subclass's copy surface implementation. It should assume that any clipping has already
        been performed on the rect and point and that the GrGpu supports the copy. */
    virtual void onCopySurface(GrSurface* dst,
                               GrSurface* src,
                               const SkIRect& srcRect,
                               const SkIPoint& dstPoint) = 0;

    // Check to see if this set of draw commands has been sent out
    virtual bool       isIssued(uint32_t drawID) { return true; }
    void getPathStencilSettingsForFilltype(GrPathRendering::FillType,
                                           const GrStencilAttachment*,
                                           GrStencilSettings*);
    virtual GrClipMaskManager* clipMaskManager() = 0;
    virtual bool setupClip(GrPipelineBuilder*,
                           GrPipelineBuilder::AutoRestoreFragmentProcessors*,
                           GrPipelineBuilder::AutoRestoreStencil*,
                           GrScissorState*,
                           const SkRect* devBounds) = 0;

    // The context owns us, not vice-versa, so this ptr is not ref'ed by DrawTarget.
    GrContext*                                                      fContext;
    SkAutoTUnref<const GrDrawTargetCaps>                            fCaps;
    // To keep track that we always have at least as many debug marker adds as removes
    int                                                             fGpuTraceMarkerCount;
    GrTraceMarkerSet                                                fActiveTraceMarkers;
    GrTraceMarkerSet                                                fStoredTraceMarkers;
    GrVertexBufferAllocPool*                                        fVertexPool;
    GrIndexBufferAllocPool*                                         fIndexPool;
    bool                                                            fFlushing;

    typedef SkRefCnt INHERITED;
};

/*
 * This class is JUST for clip mask manager.  Everyone else should just use draw target above.
 */
class GrClipTarget : public GrDrawTarget {
public:
    GrClipTarget(GrContext* context,
                 GrVertexBufferAllocPool* vpool,
                 GrIndexBufferAllocPool* ipool)
        : INHERITED(context, vpool, ipool) {
        fClipMaskManager.setClipTarget(this);
    }

    /* Clip mask manager needs access to the context.
     * TODO we only need a very small subset of context in the CMM.
     */
    GrContext* getContext() { return INHERITED::getContext(); }
    const GrContext* getContext() const { return INHERITED::getContext(); }

    /**
     * Clip Mask Manager(and no one else) needs to clear private stencil bits.
     * ClipTarget 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, GrRenderTarget* = NULL) = 0;

    /**
     * Release any resources that are cached but not currently in use. This
     * is intended to give an application some recourse when resources are low.
     */
    void purgeResources() override {
        // The clip mask manager can rebuild all its clip masks so just
        // get rid of them all.
        fClipMaskManager.purgeResources();
    };

protected:
    GrClipMaskManager           fClipMaskManager;

private:
    GrClipMaskManager* clipMaskManager() override { return &fClipMaskManager; }

    virtual bool setupClip(GrPipelineBuilder*,
                           GrPipelineBuilder::AutoRestoreFragmentProcessors*,
                           GrPipelineBuilder::AutoRestoreStencil*,
                           GrScissorState* scissorState,
                           const SkRect* devBounds) override;

    typedef GrDrawTarget INHERITED;
};

#endif