1 /*
2 * Copyright 2012 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #ifndef SkSurface_Base_DEFINED
9 #define SkSurface_Base_DEFINED
10
11 #include "SkCanvas.h"
12 #include "SkImagePriv.h"
13 #include "SkSurface.h"
14 #include "SkSurfacePriv.h"
15
16 class SkSurface_Base : public SkSurface {
17 public:
18 SkSurface_Base(int width, int height, const SkSurfaceProps*);
19 SkSurface_Base(const SkImageInfo&, const SkSurfaceProps*);
20 virtual ~SkSurface_Base();
21
22 virtual GrBackendTexture onGetBackendTexture(BackendHandleAccess);
23 virtual GrBackendRenderTarget onGetBackendRenderTarget(BackendHandleAccess);
24
25 /**
26 * Allocate a canvas that will draw into this surface. We will cache this
27 * canvas, to return the same object to the caller multiple times. We
28 * take ownership, and will call unref() on the canvas when we go out of
29 * scope.
30 */
31 virtual SkCanvas* onNewCanvas() = 0;
32
33 virtual sk_sp<SkSurface> onNewSurface(const SkImageInfo&) = 0;
34
35 /**
36 * Allocate an SkImage that represents the current contents of the surface.
37 * This needs to be able to outlive the surface itself (if need be), and
38 * must faithfully represent the current contents, even if the surface
39 * is changed after this called (e.g. it is drawn to via its canvas).
40 *
41 * If a subset is specified, the the impl must make a copy, rather than try to wait
42 * on copy-on-write.
43 */
44 virtual sk_sp<SkImage> onNewImageSnapshot(const SkIRect* subset = nullptr) { return nullptr; }
45
46 virtual void onWritePixels(const SkPixmap&, int x, int y) = 0;
47
48 /**
49 * Default implementation:
50 *
51 * image = this->newImageSnapshot();
52 * if (image) {
53 * image->draw(canvas, ...);
54 * image->unref();
55 * }
56 */
57 virtual void onDraw(SkCanvas*, SkScalar x, SkScalar y, const SkPaint*);
58
59 /**
60 * Called as a performance hint when the Surface is allowed to make it's contents
61 * undefined.
62 */
onDiscard()63 virtual void onDiscard() {}
64
65 /**
66 * If the surface is about to change, we call this so that our subclass
67 * can optionally fork their backend (copy-on-write) in case it was
68 * being shared with the cachedImage.
69 */
70 virtual void onCopyOnWrite(ContentChangeMode) = 0;
71
72 /**
73 * Signal the surface to remind its backing store that it's mutable again.
74 * Called only when we _didn't_ copy-on-write; we assume the copies start mutable.
75 */
onRestoreBackingMutability()76 virtual void onRestoreBackingMutability() {}
77
78 /**
79 * Issue any pending surface IO to the current backend 3D API and resolve any surface MSAA.
80 * Inserts the requested number of semaphores for the gpu to signal when work is complete on the
81 * gpu and inits the array of GrBackendSemaphores with the signaled semaphores.
82 */
onFlush(int numSemaphores,GrBackendSemaphore signalSemaphores[])83 virtual GrSemaphoresSubmitted onFlush(int numSemaphores,
84 GrBackendSemaphore signalSemaphores[]) {
85 return GrSemaphoresSubmitted::kNo;
86 }
87
88 /**
89 * Caused the current backend 3D API to wait on the passed in semaphores before executing new
90 * commands on the gpu. Any previously submitting commands will not be blocked by these
91 * semaphores.
92 */
onWait(int numSemaphores,const GrBackendSemaphore * waitSemaphores)93 virtual bool onWait(int numSemaphores, const GrBackendSemaphore* waitSemaphores) {
94 return false;
95 }
96
onCharacterize(SkSurfaceCharacterization *)97 virtual bool onCharacterize(SkSurfaceCharacterization*) const { return false; }
onDraw(const SkDeferredDisplayList *)98 virtual bool onDraw(const SkDeferredDisplayList*) { return false; }
99
100 inline SkCanvas* getCachedCanvas();
101 inline sk_sp<SkImage> refCachedImage();
102
hasCachedImage()103 bool hasCachedImage() const { return fCachedImage != nullptr; }
104
105 // called by SkSurface to compute a new genID
106 uint32_t newGenerationID();
107
108 private:
109 std::unique_ptr<SkCanvas> fCachedCanvas;
110 sk_sp<SkImage> fCachedImage;
111
112 void aboutToDraw(ContentChangeMode mode);
113
114 // Returns true if there is an outstanding image-snapshot, indicating that a call to aboutToDraw
115 // would trigger a copy-on-write.
116 bool outstandingImageSnapshot() const;
117
118 friend class SkCanvas;
119 friend class SkSurface;
120
121 typedef SkSurface INHERITED;
122 };
123
getCachedCanvas()124 SkCanvas* SkSurface_Base::getCachedCanvas() {
125 if (nullptr == fCachedCanvas) {
126 fCachedCanvas = std::unique_ptr<SkCanvas>(this->onNewCanvas());
127 if (fCachedCanvas) {
128 fCachedCanvas->setSurfaceBase(this);
129 }
130 }
131 return fCachedCanvas.get();
132 }
133
refCachedImage()134 sk_sp<SkImage> SkSurface_Base::refCachedImage() {
135 if (fCachedImage) {
136 return fCachedImage;
137 }
138
139 fCachedImage = this->onNewImageSnapshot();
140
141 SkASSERT(!fCachedCanvas || fCachedCanvas->getSurfaceBase() == this);
142 return fCachedImage;
143 }
144
145 #endif
146