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
onGetTextureHandle(BackendHandleAccess)22 virtual GrBackendObject onGetTextureHandle(BackendHandleAccess) {
23 return 0;
24 }
25
onGetRenderTargetHandle(GrBackendObject *,BackendHandleAccess)26 virtual bool onGetRenderTargetHandle(GrBackendObject*, BackendHandleAccess) {
27 return false;
28 }
29
30 /**
31 * Allocate a canvas that will draw into this surface. We will cache this
32 * canvas, to return the same object to the caller multiple times. We
33 * take ownership, and will call unref() on the canvas when we go out of
34 * scope.
35 */
36 virtual SkCanvas* onNewCanvas() = 0;
37
38 virtual sk_sp<SkSurface> onNewSurface(const SkImageInfo&) = 0;
39
40 /**
41 * Allocate an SkImage that represents the current contents of the surface.
42 * This needs to be able to outlive the surface itself (if need be), and
43 * must faithfully represent the current contents, even if the surface
44 * is changed after this called (e.g. it is drawn to via its canvas).
45 */
46 virtual sk_sp<SkImage> onNewImageSnapshot() = 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 bool onFlush(int numSemaphores, GrBackendSemaphore* signalSemaphores) {
84 return false;
85 }
86
87 /**
88 * Caused the current backend 3D API to wait on the passed in semaphores before executing new
89 * commands on the gpu. Any previously submitting commands will not be blocked by these
90 * semaphores.
91 */
onWait(int numSemaphores,const GrBackendSemaphore * waitSemaphores)92 virtual bool onWait(int numSemaphores, const GrBackendSemaphore* waitSemaphores) {
93 return false;
94 }
95
96 inline SkCanvas* getCachedCanvas();
97 inline sk_sp<SkImage> refCachedImage();
98
hasCachedImage()99 bool hasCachedImage() const { return fCachedImage != nullptr; }
100
101 // called by SkSurface to compute a new genID
102 uint32_t newGenerationID();
103
104 private:
105 std::unique_ptr<SkCanvas> fCachedCanvas;
106 sk_sp<SkImage> fCachedImage;
107
108 void aboutToDraw(ContentChangeMode mode);
109
110 // Returns true if there is an outstanding image-snapshot, indicating that a call to aboutToDraw
111 // would trigger a copy-on-write.
112 bool outstandingImageSnapshot() const;
113
114 friend class SkCanvas;
115 friend class SkSurface;
116
117 typedef SkSurface INHERITED;
118 };
119
getCachedCanvas()120 SkCanvas* SkSurface_Base::getCachedCanvas() {
121 if (nullptr == fCachedCanvas) {
122 fCachedCanvas = std::unique_ptr<SkCanvas>(this->onNewCanvas());
123 if (fCachedCanvas) {
124 fCachedCanvas->setSurfaceBase(this);
125 }
126 }
127 return fCachedCanvas.get();
128 }
129
refCachedImage()130 sk_sp<SkImage> SkSurface_Base::refCachedImage() {
131 if (fCachedImage) {
132 return fCachedImage;
133 }
134
135 fCachedImage = this->onNewImageSnapshot();
136
137 SkASSERT(!fCachedCanvas || fCachedCanvas->getSurfaceBase() == this);
138 return fCachedImage;
139 }
140
141 #endif
142