skia2/include/gpu/GrContext.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 GrContext_DEFINED
#define GrContext_DEFINED

#include "GrCaps.h"
#include "GrClip.h"
#include "GrColor.h"
#include "GrPaint.h"
#include "GrRenderTarget.h"
#include "GrTextureProvider.h"
#include "SkMatrix.h"
#include "SkPathEffect.h"
#include "SkTypes.h"
#include "../private/GrAuditTrail.h"
#include "../private/GrSingleOwner.h"

class GrAtlasGlyphCache;
struct GrContextOptions;
class GrContextPriv;
class GrContextThreadSafeProxy;
class GrDrawingManager;
struct GrDrawOpAtlasConfig;
class GrRenderTargetContext;
class GrFragmentProcessor;
class GrGpu;
class GrIndexBuffer;
class GrOvalRenderer;
class GrPath;
class GrPipelineBuilder;
class GrResourceEntry;
class GrResourceCache;
class GrResourceProvider;
class GrTextBlobCache;
class GrTextContext;
class GrSamplerParams;
class GrVertexBuffer;
class GrSwizzle;
class SkTraceMemoryDump;

class SK_API GrContext : public SkRefCnt {
public:
    /**
     * Creates a GrContext for a backend context.
     */
    static GrContext* Create(GrBackend, GrBackendContext, const GrContextOptions& options);
    static GrContext* Create(GrBackend, GrBackendContext);

    /**
     * Only defined in test apps.
     */
    static GrContext* CreateMockContext();

    virtual ~GrContext();

    sk_sp<GrContextThreadSafeProxy> threadSafeProxy();

    /**
     * The GrContext normally assumes that no outsider is setting state
     * within the underlying 3D API's context/device/whatever. This call informs
     * the context that the state was modified and it should resend. Shouldn't
     * be called frequently for good performance.
     * The flag bits, state, is dpendent on which backend is used by the
     * context, either GL or D3D (possible in future).
     */
    void resetContext(uint32_t state = kAll_GrBackendState);

    /**
     * Callback function to allow classes to cleanup on GrContext destruction.
     * The 'info' field is filled in with the 'info' passed to addCleanUp.
     */
    typedef void (*PFCleanUpFunc)(const GrContext* context, void* info);

    /**
     * Add a function to be called from within GrContext's destructor.
     * This gives classes a chance to free resources held on a per context basis.
     * The 'info' parameter will be stored and passed to the callback function.
     */
    void addCleanUp(PFCleanUpFunc cleanUp, void* info) {
        CleanUpData* entry = fCleanUpData.push();

        entry->fFunc = cleanUp;
        entry->fInfo = info;
    }

    /**
     * Abandons all GPU resources and assumes the underlying backend 3D API context is not longer
     * usable. Call this if you have lost the associated GPU context, and thus internal texture,
     * buffer, etc. references/IDs are now invalid. Calling this ensures that the destructors of the
     * GrContext and any of its created resource objects will not make backend 3D API calls. Content
     * rendered but not previously flushed may be lost. After this function is called all subsequent
     * calls on the GrContext will fail or be no-ops.
     *
     * The typical use case for this function is that the underlying 3D context was lost and further
     * API calls may crash.
     */
    void abandonContext();

    /**
     * This is similar to abandonContext() however the underlying 3D context is not yet lost and
     * the GrContext will cleanup all allocated resources before returning. After returning it will
     * assume that the underlying context may no longer be valid.
     *
     * The typical use case for this function is that the client is going to destroy the 3D context
     * but can't guarantee that GrContext will be destroyed first (perhaps because it may be ref'ed
     * elsewhere by either the client or Skia objects).
     */
    void releaseResourcesAndAbandonContext();

    ///////////////////////////////////////////////////////////////////////////
    // Resource Cache

    /**
     *  Return the current GPU resource cache limits.
     *
     *  @param maxResources If non-null, returns maximum number of resources that
     *                      can be held in the cache.
     *  @param maxResourceBytes If non-null, returns maximum number of bytes of
     *                          video memory that can be held in the cache.
     */
    void getResourceCacheLimits(int* maxResources, size_t* maxResourceBytes) const;

    /**
     *  Gets the current GPU resource cache usage.
     *
     *  @param resourceCount If non-null, returns the number of resources that are held in the
     *                       cache.
     *  @param maxResourceBytes If non-null, returns the total number of bytes of video memory held
     *                          in the cache.
     */
    void getResourceCacheUsage(int* resourceCount, size_t* resourceBytes) const;

    /**
     *  Specify the GPU resource cache limits. If the current cache exceeds either
     *  of these, it will be purged (LRU) to keep the cache within these limits.
     *
     *  @param maxResources The maximum number of resources that can be held in
     *                      the cache.
     *  @param maxResourceBytes The maximum number of bytes of video memory
     *                          that can be held in the cache.
     */
    void setResourceCacheLimits(int maxResources, size_t maxResourceBytes);

    GrTextureProvider* textureProvider() { return fTextureProvider; }
    const GrTextureProvider* textureProvider() const { return fTextureProvider; }

    /**
     * Frees GPU created by the context. Can be called to reduce GPU memory
     * pressure.
     */
    void freeGpuResources();

    /**
     * Purge all the unlocked resources from the cache.
     * This entry point is mainly meant for timing texture uploads
     * and is not defined in normal builds of Skia.
     */
    void purgeAllUnlockedResources();

    /** Access the context capabilities */
    const GrCaps* caps() const { return fCaps; }

    /**
     * Returns the recommended sample count for a render target when using this
     * context.
     *
     * @param  config the configuration of the render target.
     * @param  dpi the display density in dots per inch.
     *
     * @return sample count that should be perform well and have good enough
     *         rendering quality for the display. Alternatively returns 0 if
     *         MSAA is not supported or recommended to be used by default.
     */
    int getRecommendedSampleCount(GrPixelConfig config, SkScalar dpi) const;

    /**
     * Create both a GrRenderTarget and a matching GrRenderTargetContext to wrap it.
     * We guarantee that "asTexture" will succeed for renderTargetContexts created
     * via this entry point.
     */
    sk_sp<GrRenderTargetContext> makeRenderTargetContext(
                                                 SkBackingFit fit,
                                                 int width, int height,
                                                 GrPixelConfig config,
                                                 sk_sp<SkColorSpace> colorSpace,
                                                 int sampleCnt = 0,
                                                 GrSurfaceOrigin origin = kBottomLeft_GrSurfaceOrigin,
                                                 const SkSurfaceProps* surfaceProps = nullptr,
                                                 SkBudgeted = SkBudgeted::kYes);

    // Create a new render target context as above but have it backed by a deferred-style
    // GrRenderTargetProxy rather than one that is backed by an actual GrRenderTarget
    sk_sp<GrRenderTargetContext> makeDeferredRenderTargetContext(
                                                 SkBackingFit fit, 
                                                 int width, int height,
                                                 GrPixelConfig config,
                                                 sk_sp<SkColorSpace> colorSpace,
                                                 int sampleCnt = 0,
                                                 GrSurfaceOrigin origin = kBottomLeft_GrSurfaceOrigin,
                                                 const SkSurfaceProps* surfaceProps = nullptr,
                                                 SkBudgeted = SkBudgeted::kYes);
    /*
     * This method will attempt to create a renderTargetContext that has, at least, the number of
     * channels and precision per channel as requested in 'config' (e.g., A8 and 888 can be
     * converted to 8888). It may also swizzle the channels (e.g., BGRA -> RGBA).
     * SRGB-ness will be preserved.
     */
    sk_sp<GrRenderTargetContext> makeRenderTargetContextWithFallback(
                                                 SkBackingFit fit,
                                                 int width, int height,
                                                 GrPixelConfig config,
                                                 sk_sp<SkColorSpace> colorSpace,
                                                 int sampleCnt = 0,
                                                 GrSurfaceOrigin origin = kBottomLeft_GrSurfaceOrigin,
                                                 const SkSurfaceProps* surfaceProps = nullptr,
                                                 SkBudgeted budgeted = SkBudgeted::kYes);

    // Create a new render target context as above but have it backed by a deferred-style
    // GrRenderTargetProxy rather than one that is backed by an actual GrRenderTarget
    sk_sp<GrRenderTargetContext> makeDeferredRenderTargetContextWithFallback(
                                                 SkBackingFit fit,
                                                 int width, int height,
                                                 GrPixelConfig config,
                                                 sk_sp<SkColorSpace> colorSpace,
                                                 int sampleCnt = 0,
                                                 GrSurfaceOrigin origin = kBottomLeft_GrSurfaceOrigin,
                                                 const SkSurfaceProps* surfaceProps = nullptr,
                                                 SkBudgeted budgeted = SkBudgeted::kYes);

    ///////////////////////////////////////////////////////////////////////////
    // Misc.

    /**
     * Call to ensure all drawing to the context has been issued to the
     * underlying 3D API.
     */
    void flush();

   /**
    * These flags can be used with the read/write pixels functions below.
    */
    enum PixelOpsFlags {
        /** The GrContext will not be flushed before the surface read or write. This means that
            the read or write may occur before previous draws have executed. */
        kDontFlush_PixelOpsFlag = 0x1,
        /** Any surface writes should be flushed to the backend 3D API after the surface operation
            is complete */
        kFlushWrites_PixelOp = 0x2,
        /** The src for write or dst read is unpremultiplied. This is only respected if both the
            config src and dst configs are an RGBA/BGRA 8888 format. */
        kUnpremul_PixelOpsFlag  = 0x4,
    };

    /**
     * Reads a rectangle of pixels from a surface.
     * @param surface       the surface to read from.
     * @param srcColorSpace color space of the surface
     * @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 dstColorSpace color space of the destination buffer
     * @param buffer        memory to read the rectangle into.
     * @param rowBytes      number of bytes bewtween consecutive rows. Zero means rows are tightly
     *                      packed.
     * @param pixelOpsFlags see PixelOpsFlags enum above.
     *
     * @return true if the read succeeded, false if not. The read can fail because of an unsupported
     *         pixel configs
     */
    bool readSurfacePixels(GrSurface* surface, SkColorSpace* srcColorSpace,
                           int left, int top, int width, int height,
                           GrPixelConfig config, SkColorSpace* dstColorSpace, void* buffer,
                           size_t rowBytes = 0,
                           uint32_t pixelOpsFlags = 0);

    /**
     * Writes a rectangle of pixels to a surface.
     * @param surface       the surface to write to.
     * @param dstColorSpace color space of the surface
     * @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 srcColorSpace color space 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.
     * @param pixelOpsFlags see PixelOpsFlags enum above.
     * @return true if the write succeeded, false if not. The write can fail because of an
     *         unsupported combination of surface and src configs.
     */
    bool writeSurfacePixels(GrSurface* surface, SkColorSpace* dstColorSpace,
                            int left, int top, int width, int height,
                            GrPixelConfig config, SkColorSpace* srcColorSpace, const void* buffer,
                            size_t rowBytes,
                            uint32_t pixelOpsFlags = 0);

    /**
     * After this returns any pending writes to the surface will have been issued to the backend 3D API.
     */
    void flushSurfaceWrites(GrSurface* surface);

    /**
     * After this returns any pending reads or writes to the surface will have been issued to the
     * backend 3D API.
     */
    void flushSurfaceIO(GrSurface* surface);

    /**
     * Finalizes all pending reads and writes to the surface and also performs an MSAA resolve
     * if necessary.
     *
     * It is not necessary to call this before reading the render target via Skia/GrContext.
     * GrContext will detect when it must perform a resolve before reading pixels back from the
     * surface or using it as a texture.
     */
    void prepareSurfaceForExternalIO(GrSurface*);

    /**
     * As above, but additionally flushes the backend API (eg calls glFlush), and returns a fence
     * that can be used to determine if the surface is safe to use on another context or thread.
     */
    GrFence SK_WARN_UNUSED_RESULT prepareSurfaceForExternalIOAndFlush(GrSurface*);

    /**
     * An ID associated with this context, guaranteed to be unique.
     */
    uint32_t uniqueID() { return fUniqueID; }

    ///////////////////////////////////////////////////////////////////////////
    // Functions intended for internal use only.
    GrGpu* getGpu() { return fGpu; }
    const GrGpu* getGpu() const { return fGpu; }
    GrAtlasGlyphCache* getAtlasGlyphCache() { return fAtlasGlyphCache; }
    GrTextBlobCache* getTextBlobCache() { return fTextBlobCache.get(); }
    bool abandoned() const;
    GrResourceProvider* resourceProvider() { return fResourceProvider; }
    const GrResourceProvider* resourceProvider() const { return fResourceProvider; }
    GrResourceCache* getResourceCache() { return fResourceCache; }

    /** Reset GPU stats */
    void resetGpuStats() const ;

    /** Prints cache stats to the string if GR_CACHE_STATS == 1. */
    void dumpCacheStats(SkString*) const;
    void dumpCacheStatsKeyValuePairs(SkTArray<SkString>* keys, SkTArray<double>* values) const;
    void printCacheStats() const;

    /** Prints GPU stats to the string if GR_GPU_STATS == 1. */
    void dumpGpuStats(SkString*) const;
    void dumpGpuStatsKeyValuePairs(SkTArray<SkString>* keys, SkTArray<double>* values) const;
    void printGpuStats() const;

    /** Specify the TextBlob cache limit. If the current cache exceeds this limit it will purge.
        this is for testing only */
    void setTextBlobCacheLimit_ForTesting(size_t bytes);

    /** Specify the sizes of the GrAtlasTextContext atlases.  The configs pointer below should be
        to an array of 3 entries */
    void setTextContextAtlasSizes_ForTesting(const GrDrawOpAtlasConfig* configs);

    /** Enumerates all cached GPU resources and dumps their memory to traceMemoryDump. */
    void dumpMemoryStatistics(SkTraceMemoryDump* traceMemoryDump) const;

    /** Get pointer to atlas texture for given mask format. Note that this wraps an
        actively mutating texture in an SkImage. This could yield unexpected results
        if it gets cached or used more generally. */
    sk_sp<SkImage> getFontAtlasImage_ForTesting(GrMaskFormat format);

    GrAuditTrail* getAuditTrail() { return &fAuditTrail; }

    /** This is only useful for debug purposes */
    SkDEBUGCODE(GrSingleOwner* debugSingleOwner() const { return &fSingleOwner; } )

    // Provides access to functions that aren't part of the public API.
    GrContextPriv contextPriv();
    const GrContextPriv contextPriv() const;

private:
    GrGpu*                                  fGpu;
    const GrCaps*                           fCaps;
    GrResourceCache*                        fResourceCache;
    // this union exists because the inheritance of GrTextureProvider->GrResourceProvider
    // is in a private header.
    union {
        GrResourceProvider*                 fResourceProvider;
        GrTextureProvider*                  fTextureProvider;
    };

    sk_sp<GrContextThreadSafeProxy>         fThreadSafeProxy;

    GrAtlasGlyphCache*                      fAtlasGlyphCache;
    std::unique_ptr<GrTextBlobCache>        fTextBlobCache;

    bool                                    fDisableGpuYUVConversion;
    bool                                    fDidTestPMConversions;
    int                                     fPMToUPMConversion;
    int                                     fUPMToPMConversion;

    // In debug builds we guard against improper thread handling
    // This guard is passed to the GrDrawingManager and, from there to all the
    // GrRenderTargetContexts.  It is also passed to the GrTextureProvider and SkGpuDevice.
    mutable GrSingleOwner                   fSingleOwner;

    struct CleanUpData {
        PFCleanUpFunc fFunc;
        void*         fInfo;
    };

    SkTDArray<CleanUpData>                  fCleanUpData;

    const uint32_t                          fUniqueID;

    std::unique_ptr<GrDrawingManager>       fDrawingManager;

    GrAuditTrail                            fAuditTrail;

    // TODO: have the GrClipStackClip use renderTargetContexts and rm this friending
    friend class GrContextPriv;

    GrContext(); // init must be called after the constructor.
    bool init(GrBackend, GrBackendContext, const GrContextOptions& options);

    void initMockContext();
    void initCommon(const GrContextOptions&);

    /**
     * These functions create premul <-> unpremul effects if it is possible to generate a pair
     * of effects that make a readToUPM->writeToPM->readToUPM cycle invariant. Otherwise, they
     * return NULL. They also can perform a swizzle as part of the draw.
     */
    sk_sp<GrFragmentProcessor> createPMToUPMEffect(GrTexture*, const GrSwizzle&, const SkMatrix&);
    sk_sp<GrFragmentProcessor> createPMToUPMEffect(sk_sp<GrTextureProxy>, const GrSwizzle&,
                                                   const SkMatrix&);
    sk_sp<GrFragmentProcessor> createUPMToPMEffect(sk_sp<GrTextureProxy>, const GrSwizzle&,
                                                   const SkMatrix&);
    /** Called before either of the above two functions to determine the appropriate fragment
        processors for conversions. */
    void testPMConversionsIfNecessary(uint32_t flags);
    /** Returns true if we've already determined that createPMtoUPMEffect and createUPMToPMEffect
        will fail. In such cases fall back to SW conversion. */
    bool didFailPMUPMConversionTest() const;

    /**
     * A callback similar to the above for use by the TextBlobCache
     * TODO move textblob draw calls below context so we can use the call above.
     */
    static void TextBlobCacheOverBudgetCB(void* data);

    typedef SkRefCnt INHERITED;
};

/**
 * Can be used to perform actions related to the generating GrContext in a thread safe manner. The
 * proxy does not access the 3D API (e.g. OpenGL) that backs the generating GrContext.
 */
class GrContextThreadSafeProxy : public SkRefCnt {
private:
    GrContextThreadSafeProxy(sk_sp<const GrCaps> caps, uint32_t uniqueID)
        : fCaps(std::move(caps))
        , fContextUniqueID(uniqueID) {}

    sk_sp<const GrCaps> fCaps;
    uint32_t            fContextUniqueID;

    friend class GrContext;
    friend class SkImage;

    typedef SkRefCnt INHERITED;
};

#endif