src/gpu/GrAtlas.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 GrAtlas_DEFINED
#define GrAtlas_DEFINED


#include "SkPoint.h"
#include "GrTexture.h"
#include "GrDrawTarget.h"

class GrGpu;
class GrRectanizer;
class GrAtlasMgr;
class GrAtlas;

// The backing GrTexture for a set of GrAtlases is broken into a spatial grid of GrPlots. When
// a GrAtlas needs space on the texture, it requests a GrPlot. Each GrAtlas can claim one
// or more GrPlots. The GrPlots keep track of subimage placement via their GrRectanizer. Once a
// GrPlot is "full" (i.e. there is no room for the new subimage according to the GrRectanizer), the
// GrAtlas can request a new GrPlot via GrAtlasMgr::addToAtlas().
//
// If all GrPlots are allocated, the replacement strategy is up to the client. The drawToken is
// available to ensure that all draw calls are finished for that particular GrPlot.
// GrAtlasMgr::removeUnusedPlots() will free up any finished plots for a given GrAtlas.

class GrPlot {
public:
    SK_DECLARE_INTERNAL_LLIST_INTERFACE(GrPlot);

    GrTexture* texture() const { return fTexture; }

    bool addSubImage(int width, int height, const void*, SkIPoint16*);

    GrDrawTarget::DrawToken drawToken() const { return fDrawToken; }
    void setDrawToken(GrDrawTarget::DrawToken draw) { fDrawToken = draw; }

    void uploadToTexture();

    void resetRects();

private:
    GrPlot();
    ~GrPlot(); // does not try to delete the fNext field
    void init(GrAtlasMgr* mgr, int offX, int offY, int width, int height, size_t bpp,
              bool batchUploads);

    // for recycling
    GrDrawTarget::DrawToken fDrawToken;

    unsigned char*          fPlotData;
    GrTexture*              fTexture;
    GrRectanizer*           fRects;
    GrAtlasMgr*             fAtlasMgr;
    SkIPoint16              fOffset;        // the offset of the plot in the backing texture
    size_t                  fBytesPerPixel;
    SkIRect                 fDirtyRect;
    bool                    fDirty;
    bool                    fBatchUploads;

    friend class GrAtlasMgr;
};

typedef SkTInternalLList<GrPlot> GrPlotList;

class GrAtlasMgr {
public:
    GrAtlasMgr(GrGpu*, GrPixelConfig, const SkISize& backingTextureSize,
               int numPlotsX, int numPlotsY, bool batchUploads);
    ~GrAtlasMgr();

    // add subimage of width, height dimensions to atlas
    // returns the containing GrPlot and location relative to the backing texture
    GrPlot* addToAtlas(GrAtlas*, int width, int height, const void*, SkIPoint16*);

    // remove reference to this plot
    bool removePlot(GrAtlas* atlas, const GrPlot* plot);

    // get a plot that's not being used by the current draw
    // this allows us to overwrite this plot without flushing
    GrPlot* getUnusedPlot();

    GrTexture* getTexture() const {
        return fTexture;
    }

    void uploadPlotsToTexture();

private:
    void moveToHead(GrPlot* plot);

    GrGpu*        fGpu;
    GrPixelConfig fPixelConfig;
    GrTexture*    fTexture;
    SkISize       fBackingTextureSize;
    int           fNumPlotsX;
    int           fNumPlotsY;
    bool          fBatchUploads;

    // allocated array of GrPlots
    GrPlot*       fPlotArray;
    // LRU list of GrPlots
    GrPlotList    fPlotList;
};

class GrAtlas {
public:
    GrAtlas() { }
    ~GrAtlas() { }

    bool isEmpty() { return 0 == fPlots.count(); }

private:
    SkTDArray<GrPlot*> fPlots;

    friend class GrAtlasMgr;
};

#endif