src/gpu/GrPipeline.h

/*
 * Copyright 2015 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef GrPipeline_DEFINED
#define GrPipeline_DEFINED

#include "GrColor.h"
#include "GrFragmentProcessor.h"
#include "GrNonAtomicRef.h"
#include "GrPendingIOResource.h"
#include "GrProcessorSet.h"
#include "GrProgramDesc.h"
#include "GrRect.h"
#include "GrScissorState.h"
#include "GrUserStencilSettings.h"
#include "GrWindowRectsState.h"
#include "SkMatrix.h"
#include "SkRefCnt.h"
#include "effects/GrCoverageSetOpXP.h"
#include "effects/GrDisableColorXP.h"
#include "effects/GrPorterDuffXferProcessor.h"
#include "effects/GrSimpleTextureEffect.h"

class GrAppliedClip;
class GrOp;
class GrRenderTargetContext;

/**
 * This immutable object contains information needed to set build a shader program and set API
 * state for a draw. It is used along with a GrPrimitiveProcessor and a source of geometric
 * data (GrMesh or GrPath) to draw.
 */
class GrPipeline {
public:
    ///////////////////////////////////////////////////////////////////////////
    /// @name Creation

    enum Flags {
        /**
         * Perform HW anti-aliasing. This means either HW FSAA, if supported by the render target,
         * or smooth-line rendering if a line primitive is drawn and line smoothing is supported by
         * the 3D API.
         */
        kHWAntialias_Flag = 0x1,
        /**
         * Modifies the vertex shader so that vertices will be positioned at pixel centers.
         */
        kSnapVerticesToPixelCenters_Flag = 0x2,
    };

    struct InitArgs {
        uint32_t fFlags = 0;
        const GrUserStencilSettings* fUserStencil = &GrUserStencilSettings::kUnused;
        const GrCaps* fCaps = nullptr;
        GrResourceProvider* fResourceProvider = nullptr;
        GrXferProcessor::DstProxy fDstProxy;
    };

    /**
     * Some state can be changed between GrMeshes without changing GrPipelines. This is generally
     * less expensive then using multiple pipelines. Such state is called "dynamic state". It can
     * be specified in two ways:
     * 1) FixedDynamicState - use this to specify state that does not vary between GrMeshes.
     * 2) DynamicStateArrays - use this to specify per mesh values for dynamic state.
     **/
    struct FixedDynamicState {
        explicit FixedDynamicState(const SkIRect& scissorRect) : fScissorRect(scissorRect) {}
        FixedDynamicState() = default;
        SkIRect fScissorRect = SkIRect::EmptyIRect();
        // Must have GrPrimitiveProcessor::numTextureSamplers() entries. Can be null if no samplers
        // or textures are passed using DynamicStateArrays.
        GrTextureProxy** fPrimitiveProcessorTextures = nullptr;
    };

    /**
     * Any non-null array overrides the FixedDynamicState on a mesh-by-mesh basis. Arrays must
     * have one entry for each GrMesh.
     */
    struct DynamicStateArrays {
        const SkIRect* fScissorRects = nullptr;
        // Must have GrPrimitiveProcessor::numTextureSamplers() * num_meshes entries.
        // Can be null if no samplers or to use the same textures for all meshes via'
        // FixedDynamicState.
        GrTextureProxy** fPrimitiveProcessorTextures = nullptr;
    };

    /**
     * Creates a simple pipeline with default settings and no processors. The provided blend mode
     * must be "Porter Duff" (<= kLastCoeffMode). If using GrScissorTest::kEnabled, the caller must
     * specify a scissor rectangle through the DynamicState struct.
     **/
    GrPipeline(GrScissorTest, SkBlendMode);

    GrPipeline(const InitArgs&, GrProcessorSet&&, GrAppliedClip&&);

    GrPipeline(const GrPipeline&) = delete;
    GrPipeline& operator=(const GrPipeline&) = delete;

    /// @}

    ///////////////////////////////////////////////////////////////////////////
    /// @name GrFragmentProcessors

    // Make the renderTargetContext's GrOpList be dependent on any GrOpLists in this pipeline
    void addDependenciesTo(GrOpList* recipient, const GrCaps&) const;

    int numColorFragmentProcessors() const { return fNumColorProcessors; }
    int numCoverageFragmentProcessors() const {
        return fFragmentProcessors.count() - fNumColorProcessors;
    }
    int numFragmentProcessors() const { return fFragmentProcessors.count(); }

    const GrXferProcessor& getXferProcessor() const {
        if (fXferProcessor) {
            return *fXferProcessor.get();
        } else {
            // A null xp member means the common src-over case. GrXferProcessor's ref'ing
            // mechanism is not thread safe so we do not hold a ref on this global.
            return GrPorterDuffXPFactory::SimpleSrcOverXP();
        }
    }

    /**
     * If the GrXferProcessor uses a texture to access the dst color, then this returns that
     * texture and the offset to the dst contents within that texture.
     */
    GrTextureProxy* dstTextureProxy(SkIPoint* offset = nullptr) const {
        if (offset) {
            *offset = fDstTextureOffset;
        }
        return fDstTextureProxy.get();
    }

    GrTexture* peekDstTexture(SkIPoint* offset = nullptr) const {
        if (GrTextureProxy* dstProxy = this->dstTextureProxy(offset)) {
            return dstProxy->peekTexture();
        }

        return nullptr;
    }

    const GrFragmentProcessor& getColorFragmentProcessor(int idx) const {
        SkASSERT(idx < this->numColorFragmentProcessors());
        return *fFragmentProcessors[idx].get();
    }

    const GrFragmentProcessor& getCoverageFragmentProcessor(int idx) const {
        SkASSERT(idx < this->numCoverageFragmentProcessors());
        return *fFragmentProcessors[fNumColorProcessors + idx].get();
    }

    const GrFragmentProcessor& getFragmentProcessor(int idx) const {
        return *fFragmentProcessors[idx].get();
    }

    /// @}

    const GrUserStencilSettings* getUserStencil() const { return fUserStencilSettings; }

    bool isScissorEnabled() const {
        return SkToBool(fFlags & kScissorEnabled_Flag);
    }

    const GrWindowRectsState& getWindowRectsState() const { return fWindowRectsState; }

    bool isHWAntialiasState() const { return SkToBool(fFlags & kHWAntialias_Flag); }
    bool snapVerticesToPixelCenters() const {
        return SkToBool(fFlags & kSnapVerticesToPixelCenters_Flag);
    }
    bool hasStencilClip() const {
        return SkToBool(fFlags & kHasStencilClip_Flag);
    }
    bool isStencilEnabled() const {
        return SkToBool(fFlags & kStencilEnabled_Flag);
    }
    bool isBad() const { return SkToBool(fFlags & kIsBad_Flag); }

    GrXferBarrierType xferBarrierType(GrTexture*, const GrCaps&) const;

    static SkString DumpFlags(uint32_t flags) {
        if (flags) {
            SkString result;
            if (flags & GrPipeline::kSnapVerticesToPixelCenters_Flag) {
                result.append("Snap vertices to pixel center.\n");
            }
            if (flags & GrPipeline::kHWAntialias_Flag) {
                result.append("HW Antialiasing enabled.\n");
            }
            return result;
        }
        return SkString("No pipeline flags\n");
    }

private:
    void markAsBad() { fFlags |= kIsBad_Flag; }

    /** This is a continuation of the public "Flags" enum. */
    enum PrivateFlags {
        kHasStencilClip_Flag = 0x10,
        kStencilEnabled_Flag = 0x20,
        kScissorEnabled_Flag = 0x40,
        kIsBad_Flag = 0x80,
    };

    using DstTextureProxy = GrPendingIOResource<GrTextureProxy, kRead_GrIOType>;
    using FragmentProcessorArray = SkAutoSTArray<8, std::unique_ptr<const GrFragmentProcessor>>;

    DstTextureProxy fDstTextureProxy;
    SkIPoint fDstTextureOffset;
    GrWindowRectsState fWindowRectsState;
    const GrUserStencilSettings* fUserStencilSettings;
    uint16_t fFlags;
    sk_sp<const GrXferProcessor> fXferProcessor;
    FragmentProcessorArray fFragmentProcessors;

    // This value is also the index in fFragmentProcessors where coverage processors begin.
    int fNumColorProcessors;
};

#endif