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 "SkMatrix.h"
#include "SkPathEffect.h"
#include "SkTypes.h"
#include "../private/GrRecordingContext.h"
#include "GrContextOptions.h"

// We shouldn't need this but currently Android is relying on this being include transitively.
#include "SkUnPreMultiply.h"

class GrAtlasManager;
class GrBackendFormat;
class GrBackendSemaphore;
class GrCaps;
class GrContextPriv;
class GrContextThreadSafeProxy;
class GrFragmentProcessor;
struct GrGLInterface;
class GrGpu;
struct GrMockOptions;
class GrPath;
class GrRenderTargetContext;
class GrResourceCache;
class GrResourceProvider;
class GrSamplerState;
class GrSkSLFPFactoryCache;
class GrSurfaceProxy;
class GrSwizzle;
class GrTextContext;
class GrTextureProxy;
struct GrVkBackendContext;

class SkImage;
class SkSurfaceProps;
class SkTaskGroup;
class SkTraceMemoryDump;

class SK_API GrContext : public GrRecordingContext {
public:
    /**
     * Creates a GrContext for a backend context. If no GrGLInterface is provided then the result of
     * GrGLMakeNativeInterface() is used if it succeeds.
     */
    static sk_sp<GrContext> MakeGL(sk_sp<const GrGLInterface>, const GrContextOptions&);
    static sk_sp<GrContext> MakeGL(sk_sp<const GrGLInterface>);
    static sk_sp<GrContext> MakeGL(const GrContextOptions&);
    static sk_sp<GrContext> MakeGL();

    static sk_sp<GrContext> MakeVulkan(const GrVkBackendContext&, const GrContextOptions&);
    static sk_sp<GrContext> MakeVulkan(const GrVkBackendContext&);

#ifdef SK_METAL
    /**
     * Makes a GrContext which uses Metal as the backend. The device parameter is an MTLDevice
     * and queue is an MTLCommandQueue which should be used by the backend. These objects must
     * have a ref on them which can be transferred to Ganesh which will release the ref when the
     * GrContext is destroyed.
     */
    static sk_sp<GrContext> MakeMetal(void* device, void* queue, const GrContextOptions& options);
    static sk_sp<GrContext> MakeMetal(void* device, void* queue);
#endif

    static sk_sp<GrContext> MakeMock(const GrMockOptions*, const GrContextOptions&);
    static sk_sp<GrContext> MakeMock(const GrMockOptions*);

    ~GrContext() override;

    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);

    /**
     * If the backend is GrBackendApi::kOpenGL, then all texture unit/target combinations for which
     * the GrContext has modified the bound texture will have texture id 0 bound. This does not
     * flush the GrContext. Calling resetContext() does not change the set that will be bound
     * to texture id 0 on the next call to resetGLTextureBindings(). After this is called
     * all unit/target combinations are considered to have unmodified bindings until the GrContext
     * subsequently modifies them (meaning if this is called twice in a row with no intervening
     * GrContext usage then the second call is a no-op.)
     */
    void resetGLTextureBindings();

    /**
     * Abandons all GPU resources and assumes the underlying backend 3D API context is no 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() override;

    /**
     * Returns true if the context was abandoned.
     */
    using GrImageContext::abandoned;

    /**
     * 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).
     */
    virtual 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;

    /**
     *  Gets the number of bytes in the cache consumed by purgeable (e.g. unlocked) resources.
     */
    size_t getResourceCachePurgeableBytes() 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);

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

    /**
     * Purge GPU resources that haven't been used in the past 'msNotUsed' milliseconds or are
     * otherwise marked for deletion, regardless of whether the context is under budget.
     */
    void performDeferredCleanup(std::chrono::milliseconds msNotUsed);

    // Temporary compatibility API for Android.
    void purgeResourcesNotUsedInMs(std::chrono::milliseconds msNotUsed) {
        this->performDeferredCleanup(msNotUsed);
    }

    /**
     * Purge unlocked resources from the cache until the the provided byte count has been reached
     * or we have purged all unlocked resources. The default policy is to purge in LRU order, but
     * can be overridden to prefer purging scratch resources (in LRU order) prior to purging other
     * resource types.
     *
     * @param maxBytesToPurge the desired number of bytes to be purged.
     * @param preferScratchResources If true scratch resources will be purged prior to other
     *                               resource types.
     */
    void purgeUnlockedResources(size_t bytesToPurge, bool preferScratchResources);

    /**
     * This entry point is intended for instances where an app has been backgrounded or
     * suspended.
     * If 'scratchResourcesOnly' is true all unlocked scratch resources will be purged but the
     * unlocked resources with persistent data will remain. If 'scratchResourcesOnly' is false
     * then all unlocked resources will be purged.
     * In either case, after the unlocked resources are purged a separate pass will be made to
     * ensure that resource usage is under budget (i.e., even if 'scratchResourcesOnly' is true
     * some resources with persistent data may be purged to be under budget).
     *
     * @param scratchResourcesOnly   If true only unlocked scratch resources will be purged prior
     *                               enforcing the budget requirements.
     */
    void purgeUnlockedResources(bool scratchResourcesOnly);

    /**
     * Gets the maximum supported texture size.
     */
    int maxTextureSize() const;

    /**
     * Gets the maximum supported render target size.
     */
    int maxRenderTargetSize() const;

    /**
     * Can a SkImage be created with the given color type.
     */
    bool colorTypeSupportedAsImage(SkColorType) const;

    /**
     * Can a SkSurface be created with the given color type. To check whether MSAA is supported
     * use maxSurfaceSampleCountForColorType().
     */
    bool colorTypeSupportedAsSurface(SkColorType colorType) const {
        return this->maxSurfaceSampleCountForColorType(colorType) > 0;
    }

    /**
     * Gets the maximum supported sample count for a color type. 1 is returned if only non-MSAA
     * rendering is supported for the color type. 0 is returned if rendering to this color type
     * is not supported at all.
     */
    int maxSurfaceSampleCountForColorType(SkColorType) const;

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

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

    /**
     * Call to ensure all drawing to the context has been issued to the underlying 3D API. After
     * issuing all commands, numSemaphore semaphores will be signaled by the gpu. The client passes
     * in an array of numSemaphores GrBackendSemaphores. In general these GrBackendSemaphore's can
     * be either initialized or not. If they are initialized, the backend uses the passed in
     * semaphore. If it is not initialized, a new semaphore is created and the GrBackendSemaphore
     * object is initialized with that semaphore.
     *
     * The client will own and be responsible for deleting the underlying semaphores that are stored
     * and returned in initialized GrBackendSemaphore objects. The GrBackendSemaphore objects
     * themselves can be deleted as soon as this function returns.
     *
     * If the backend API is OpenGL only uninitialized GrBackendSemaphores are supported.
     * If the backend API is Vulkan either initialized or unitialized semaphores are supported.
     * If unitialized, the semaphores which are created will be valid for use only with the VkDevice
     * with which they were created.
     *
     * If this call returns GrSemaphoresSubmited::kNo, the GPU backend will not have created or
     * added any semaphores to signal on the GPU. Thus the client should not have the GPU wait on
     * any of the semaphores. However, any pending commands to the context will still be flushed.
     */
    GrSemaphoresSubmitted flushAndSignalSemaphores(int numSemaphores,
                                                   GrBackendSemaphore signalSemaphores[]);

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

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

    bool supportsDistanceFieldText() const;

    void storeVkPipelineCacheData();

    static size_t ComputeTextureSize(SkColorType type, int width, int height, GrMipMapped,
                                     bool useNextPow2 = false);

protected:
    GrContext(GrBackendApi, const GrContextOptions&, int32_t contextID = SK_InvalidGenID);

    bool init(sk_sp<const GrCaps>, sk_sp<GrSkSLFPFactoryCache>) override;

    GrContext* asDirectContext() override { return this; }

    virtual GrAtlasManager* onGetAtlasManager() = 0;

    sk_sp<GrContextThreadSafeProxy>         fThreadSafeProxy;

private:
    // fTaskGroup must appear before anything that uses it (e.g. fGpu), so that it is destroyed
    // after all of its users. Clients of fTaskGroup will generally want to ensure that they call
    // wait() on it as they are being destroyed, to avoid the possibility of pending tasks being
    // invoked after objects they depend upon have already been destroyed.
    std::unique_ptr<SkTaskGroup>            fTaskGroup;
    sk_sp<GrGpu>                            fGpu;
    GrResourceCache*                        fResourceCache;
    GrResourceProvider*                     fResourceProvider;

    bool                                    fDidTestPMConversions;
    // true if the PM/UPM conversion succeeded; false otherwise
    bool                                    fPMUPMConversionsRoundTrip;

    GrContextOptions::PersistentCache*      fPersistentCache;

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

    /**
     * These functions create premul <-> unpremul effects, using the specialized round-trip effects
     * from GrConfigConversionEffect.
     */
    std::unique_ptr<GrFragmentProcessor> createPMToUPMEffect(std::unique_ptr<GrFragmentProcessor>);
    std::unique_ptr<GrFragmentProcessor> createUPMToPMEffect(std::unique_ptr<GrFragmentProcessor>);

    /**
     * Returns true if createPMToUPMEffect and createUPMToPMEffect will succeed. In other words,
     * did we find a pair of round-trip preserving conversion effects?
     */
    bool validPMUPMConversionExists();

    typedef GrRecordingContext INHERITED;
};

#endif