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(SkBudgeted, SkCopyPixelsMode) = 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 */
onPrepareForExternalIO()81 virtual void onPrepareForExternalIO() {}
82
83 inline SkCanvas* getCachedCanvas();
84 inline sk_sp<SkImage> refCachedImage(SkBudgeted, ForceUnique);
85
hasCachedImage()86 bool hasCachedImage() const { return fCachedImage != nullptr; }
87
88 // called by SkSurface to compute a new genID
89 uint32_t newGenerationID();
90
91 private:
92 SkCanvas* fCachedCanvas;
93 SkImage* fCachedImage;
94
95 void aboutToDraw(ContentChangeMode mode);
96
97 // Returns true if there is an outstanding image-snapshot, indicating that a call to aboutToDraw
98 // would trigger a copy-on-write.
99 bool outstandingImageSnapshot() const;
100
101 friend class SkCanvas;
102 friend class SkSurface;
103
104 typedef SkSurface INHERITED;
105 };
106
getCachedCanvas()107 SkCanvas* SkSurface_Base::getCachedCanvas() {
108 if (nullptr == fCachedCanvas) {
109 fCachedCanvas = this->onNewCanvas();
110 if (fCachedCanvas) {
111 fCachedCanvas->setSurfaceBase(this);
112 }
113 }
114 return fCachedCanvas;
115 }
116
refCachedImage(SkBudgeted budgeted,ForceUnique unique)117 sk_sp<SkImage> SkSurface_Base::refCachedImage(SkBudgeted budgeted, ForceUnique unique) {
118 SkImage* snap = fCachedImage;
119 if (kYes_ForceUnique == unique && snap && !snap->unique()) {
120 snap = nullptr;
121 }
122 if (snap) {
123 return sk_ref_sp(snap);
124 }
125 SkCopyPixelsMode cpm = (kYes_ForceUnique == unique) ? kAlways_SkCopyPixelsMode :
126 kIfMutable_SkCopyPixelsMode;
127 snap = this->onNewImageSnapshot(budgeted, cpm).release();
128 if (kNo_ForceUnique == unique) {
129 SkASSERT(!fCachedImage);
130 fCachedImage = SkSafeRef(snap);
131 }
132 SkASSERT(!fCachedCanvas || fCachedCanvas->getSurfaceBase() == this);
133 return sk_sp<SkImage>(snap);
134 }
135
136 #endif
137