1 
2 /*
3  * Copyright 2010 Google Inc.
4  *
5  * Use of this source code is governed by a BSD-style license that can be
6  * found in the LICENSE file.
7  */
8 
9 #ifndef GrAtlas_DEFINED
10 #define GrAtlas_DEFINED
11 
12 
13 #include "GrTexture.h"
14 #include "GrDrawTarget.h"
15 #include "SkPoint.h"
16 #include "SkTInternalLList.h"
17 
18 class GrGpu;
19 class GrRectanizer;
20 class GrAtlas;
21 
22 // The backing GrTexture for a set of GrAtlases is broken into a spatial grid of GrPlots. When
23 // a GrAtlas needs space on the texture, it requests a GrPlot. Each GrAtlas can claim one
24 // or more GrPlots. The GrPlots keep track of subimage placement via their GrRectanizer. Once a
25 // GrPlot is "full" (i.e. there is no room for the new subimage according to the GrRectanizer), the
26 // GrAtlas can request a new GrPlot via GrAtlas::addToAtlas().
27 //
28 // If all GrPlots are allocated, the replacement strategy is up to the client. The drawToken is
29 // available to ensure that all draw calls are finished for that particular GrPlot.
30 // GrAtlas::removeUnusedPlots() will free up any finished plots for a given GrAtlas.
31 
32 class GrPlot {
33 public:
34     SK_DECLARE_INTERNAL_LLIST_INTERFACE(GrPlot);
35 
36     // This returns a plot ID unique to each plot in a given GrAtlas. They are
37     // consecutive and start at 0.
id()38     int id() const { return fID; }
39 
texture()40     GrTexture* texture() const { return fTexture; }
41 
42     bool addSubImage(int width, int height, const void*, SkIPoint16*);
43 
drawToken()44     GrDrawTarget::DrawToken drawToken() const { return fDrawToken; }
setDrawToken(GrDrawTarget::DrawToken draw)45     void setDrawToken(GrDrawTarget::DrawToken draw) { fDrawToken = draw; }
46 
47     void uploadToTexture();
48 
49     void resetRects();
50 
51 private:
52     GrPlot();
53     ~GrPlot(); // does not try to delete the fNext field
54     void init(GrAtlas* atlas, int id, int offX, int offY, int width, int height, size_t bpp,
55               bool batchUploads);
56 
57     // for recycling
58     GrDrawTarget::DrawToken fDrawToken;
59 
60     int                     fID;
61     unsigned char*          fPlotData;
62     GrTexture*              fTexture;
63     GrRectanizer*           fRects;
64     GrAtlas*                fAtlas;
65     SkIPoint16              fOffset;        // the offset of the plot in the backing texture
66     size_t                  fBytesPerPixel;
67     SkIRect                 fDirtyRect;
68     bool                    fDirty;
69     bool                    fBatchUploads;
70 
71     friend class GrAtlas;
72 };
73 
74 typedef SkTInternalLList<GrPlot> GrPlotList;
75 
76 class GrAtlas {
77 public:
78     // This class allows each client to independently track the GrPlots in
79     // which its data is stored.
80     class ClientPlotUsage {
81     public:
isEmpty()82         bool isEmpty() const { return 0 == fPlots.count(); }
83 
84 #ifdef SK_DEBUG
contains(const GrPlot * plot)85         bool contains(const GrPlot* plot) const {
86             return fPlots.contains(const_cast<GrPlot*>(plot));
87         }
88 #endif
89 
90     private:
91         SkTDArray<GrPlot*> fPlots;
92 
93         friend class GrAtlas;
94     };
95 
96     GrAtlas(GrGpu*, GrPixelConfig, GrSurfaceFlags flags,
97             const SkISize& backingTextureSize,
98             int numPlotsX, int numPlotsY, bool batchUploads);
99     ~GrAtlas();
100 
101     // Adds a width x height subimage to the atlas. Upon success it returns
102     // the containing GrPlot and absolute location in the backing texture.
103     // NULL is returned if the subimage cannot fit in the atlas.
104     // If provided, the image data will either be immediately uploaded or
105     // written to the CPU-side backing bitmap.
106     GrPlot* addToAtlas(ClientPlotUsage*, int width, int height, const void* image, SkIPoint16* loc);
107 
108     // remove reference to this plot
109     static void RemovePlot(ClientPlotUsage* usage, const GrPlot* plot);
110 
111     // get a plot that's not being used by the current draw
112     // this allows us to overwrite this plot without flushing
113     GrPlot* getUnusedPlot();
114 
getTexture()115     GrTexture* getTexture() const {
116         return fTexture;
117     }
118 
119     void uploadPlotsToTexture();
120 
121     enum IterOrder {
122         kLRUFirst_IterOrder,
123         kMRUFirst_IterOrder
124     };
125 
126     typedef GrPlotList::Iter PlotIter;
iterInit(PlotIter * iter,IterOrder order)127     GrPlot* iterInit(PlotIter* iter, IterOrder order) {
128         return iter->init(fPlotList, kLRUFirst_IterOrder == order
129                                                        ? GrPlotList::Iter::kTail_IterStart
130                                                        : GrPlotList::Iter::kHead_IterStart);
131     }
132 
133 private:
134     void makeMRU(GrPlot* plot);
135 
136     GrGpu*         fGpu;
137     GrPixelConfig  fPixelConfig;
138     GrSurfaceFlags fFlags;
139     GrTexture*     fTexture;
140     SkISize        fBackingTextureSize;
141     int            fNumPlotsX;
142     int            fNumPlotsY;
143     bool           fBatchUploads;
144 
145     // allocated array of GrPlots
146     GrPlot*       fPlotArray;
147     // LRU list of GrPlots (MRU at head - LRU at tail)
148     GrPlotList    fPlotList;
149 };
150 
151 #endif
152