src/gpu/GrSurfaceContext.h

/*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef GrSurfaceContext_DEFINED
#define GrSurfaceContext_DEFINED

#include "include/core/SkFilterQuality.h"
#include "include/core/SkImageInfo.h"
#include "include/core/SkRect.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkSurface.h"
#include "src/gpu/GrColorInfo.h"
#include "src/gpu/GrDataUtils.h"
#include "src/gpu/GrSurfaceProxy.h"
#include "src/gpu/GrSurfaceProxyView.h"

class GrAuditTrail;
class GrDrawingManager;
class GrRecordingContext;
class GrRenderTargetContext;
class GrRenderTargetProxy;
class GrSingleOwner;
class GrSurface;
class GrSurfaceContextPriv;
class GrSurfaceProxy;
class GrTextureProxy;
struct SkIPoint;
struct SkIRect;

/**
 * A helper object to orchestrate commands for a particular surface
 */
class GrSurfaceContext {
public:
    virtual ~GrSurfaceContext() = default;

    const GrColorInfo& colorInfo() const { return fColorInfo; }
    GrSurfaceOrigin origin() const { return fOrigin; }
    GrSurfaceProxyView textureSurfaceView() {
        return { this->asSurfaceProxyRef(), fOrigin, fTextureSwizzle };
    }

    // TODO: these two calls would be way cooler if this object had a GrSurfaceProxy pointer
    int width() const { return this->asSurfaceProxy()->width(); }
    int height() const { return this->asSurfaceProxy()->height(); }

    const GrCaps* caps() const;

    /**
     * Reads a rectangle of pixels from the render target context.
     * @param dstInfo       image info for the destination
     * @param dst           destination pixels for the read
     * @param rowBytes      bytes in a row of 'dst'
     * @param srcPt         offset w/in the surface context from which to read
     * @param direct        The direct context to use. If null will use our GrRecordingContext if it
     *                      is a GrDirectContext and fail otherwise.
     */
    bool readPixels(const GrImageInfo& dstInfo, void* dst, size_t rowBytes, SkIPoint srcPt,
                    GrContext* direct = nullptr);

    /**
     * Writes a rectangle of pixels [srcInfo, srcBuffer, srcRowbytes] into the
     * renderTargetContext at the specified position.
     * @param srcInfo       image info for the source pixels
     * @param src           source for the write
     * @param rowBytes      bytes in a row of 'src'
     * @param dstPt         offset w/in the surface context at which to write
     * @param direct        The direct context to use. If null will use our GrRecordingContext if it
     *                      is a GrDirectContext and fail otherwise.
     */
    bool writePixels(const GrImageInfo& srcInfo, const void* src, size_t rowBytes, SkIPoint dstPt,
                     GrContext* direct = nullptr);

    // TODO: this is virtual b.c. this object doesn't have a pointer to the wrapped GrSurfaceProxy?
    virtual GrSurfaceProxy* asSurfaceProxy() = 0;
    virtual const GrSurfaceProxy* asSurfaceProxy() const = 0;
    virtual sk_sp<GrSurfaceProxy> asSurfaceProxyRef() = 0;

    virtual GrTextureProxy* asTextureProxy() = 0;
    virtual const GrTextureProxy* asTextureProxy() const = 0;
    virtual sk_sp<GrTextureProxy> asTextureProxyRef() = 0;

    virtual GrRenderTargetProxy* asRenderTargetProxy() = 0;
    virtual sk_sp<GrRenderTargetProxy> asRenderTargetProxyRef() = 0;

    virtual GrRenderTargetContext* asRenderTargetContext() { return nullptr; }

    GrAuditTrail* auditTrail();

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

#if GR_TEST_UTILS
    bool testCopy(GrSurfaceProxy* src, const SkIRect& srcRect, const SkIPoint& dstPoint) {
        return this->copy(src, srcRect, dstPoint);
    }

    bool testCopy(GrSurfaceProxy* src) {
        return this->copy(src);
    }
#endif


protected:
    friend class GrSurfaceContextPriv;

    GrSurfaceContext(GrRecordingContext*, GrColorType, SkAlphaType, sk_sp<SkColorSpace>,
                     GrSurfaceOrigin, GrSwizzle texSwizzle);

    GrDrawingManager* drawingManager();
    const GrDrawingManager* drawingManager() const;

    SkDEBUGCODE(virtual void validate() const = 0;)

    SkDEBUGCODE(GrSingleOwner* singleOwner();)

    GrRecordingContext* fContext;

    GrSurfaceOrigin fOrigin;

    // The rescaling step of asyncRescaleAndReadPixels[YUV420]().
    std::unique_ptr<GrRenderTargetContext> rescale(const SkImageInfo& info, const SkIRect& srcRect,
                                                   SkSurface::RescaleGamma rescaleGamma,
                                                   SkFilterQuality rescaleQuality);

    // Inserts a transfer, part of the implementation of asyncReadPixels and
    // asyncRescaleAndReadPixelsYUV420().
    struct PixelTransferResult {
        using ConversionFn = void(void* dst, const void* mappedBuffer);
        // If null then the transfer could not be performed. Otherwise this buffer will contain
        // the pixel data when the transfer is complete.
        sk_sp<GrGpuBuffer> fTransferBuffer;
        // If this is null then the transfer buffer will contain the data in the requested
        // color type. Otherwise, when the transfer is done this must be called to convert
        // from the transfer buffer's color type to the requested color type.
        std::function<ConversionFn> fPixelConverter;
    };
    PixelTransferResult transferPixels(GrColorType colorType, const SkIRect& rect);

private:
    friend class GrSurfaceProxy; // for copy

    /**
     * Copy 'src' into the proxy backing this context. This call will not do any draw fallback.
     * Currently only writePixels and replaceRenderTarget call this directly. All other copies
     * should go through GrSurfaceProxy::Copy.
     * @param src       src of pixels
     * @param srcRect   the subset of 'src' to copy
     * @param dstPoint  the origin of the 'srcRect' in the destination coordinate space
     * @return          true if the copy succeeded; false otherwise
     *
     * Note: Notionally, 'srcRect' is clipped to 'src's extent with 'dstPoint' being adjusted.
     *       Then the 'srcRect' offset by 'dstPoint' is clipped against the dst's extent.
     *       The end result is only valid src pixels and dst pixels will be touched but the copied
     *       regions will not be shifted. The 'src' must have the same origin as the backing proxy
     *       of fSurfaceContext.
     */
    bool copy(GrSurfaceProxy* src, const SkIRect& srcRect, const SkIPoint& dstPoint);

    bool copy(GrSurfaceProxy* src) {
        return this->copy(src, SkIRect::MakeWH(src->width(), src->height()), SkIPoint::Make(0, 0));
    }

    GrColorInfo fColorInfo;
    GrSwizzle fTextureSwizzle;

    typedef SkRefCnt INHERITED;
};

#endif