1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #ifndef SKIA_EXT_PLATFORM_CANVAS_H_
6 #define SKIA_EXT_PLATFORM_CANVAS_H_
7
8 // The platform-specific device will include the necessary platform headers
9 // to get the surface type.
10 #include "base/basictypes.h"
11 #include "skia/ext/platform_device.h"
12 #include "skia/ext/refptr.h"
13 #include "third_party/skia/include/core/SkBitmap.h"
14 #include "third_party/skia/include/core/SkCanvas.h"
15 #include "third_party/skia/include/core/SkPixelRef.h"
16
17 namespace skia {
18
19 typedef SkCanvas PlatformCanvas;
20
21 //
22 // Note about error handling.
23 //
24 // Creating a canvas can fail at times, most often because we fail to allocate
25 // the backing-store (pixels). This can be from out-of-memory, or something
26 // more opaque, like GDI or cairo reported a failure.
27 //
28 // To allow the caller to handle the failure, every Create... factory takes an
29 // enum as its last parameter. The default value is kCrashOnFailure. If the
30 // caller passes kReturnNullOnFailure, then the caller is responsible to check
31 // the return result.
32 //
33 enum OnFailureType {
34 CRASH_ON_FAILURE,
35 RETURN_NULL_ON_FAILURE
36 };
37
38 #if defined(WIN32)
39 // The shared_section parameter is passed to gfx::PlatformDevice::create.
40 // See it for details.
41 SK_API SkCanvas* CreatePlatformCanvas(int width,
42 int height,
43 bool is_opaque,
44 HANDLE shared_section,
45 OnFailureType failure_type);
46 #elif defined(__APPLE__)
47 SK_API SkCanvas* CreatePlatformCanvas(CGContextRef context,
48 int width,
49 int height,
50 bool is_opaque,
51 OnFailureType failure_type);
52
53 SK_API SkCanvas* CreatePlatformCanvas(int width,
54 int height,
55 bool is_opaque,
56 uint8_t* context,
57 OnFailureType failure_type);
58 #elif defined(__linux__) || defined(__FreeBSD__) || defined(__OpenBSD__) || \
59 defined(__sun) || defined(ANDROID)
60 // Linux ---------------------------------------------------------------------
61
62 // Construct a canvas from the given memory region. The memory is not cleared
63 // first. @data must be, at least, @height * StrideForWidth(@width) bytes.
64 SK_API SkCanvas* CreatePlatformCanvas(int width,
65 int height,
66 bool is_opaque,
67 uint8_t* data,
68 OnFailureType failure_type);
69 #endif
70
CreatePlatformCanvas(int width,int height,bool is_opaque)71 static inline SkCanvas* CreatePlatformCanvas(int width,
72 int height,
73 bool is_opaque) {
74 return CreatePlatformCanvas(width, height, is_opaque, 0, CRASH_ON_FAILURE);
75 }
76
77 SK_API SkCanvas* CreateCanvas(const skia::RefPtr<SkBaseDevice>& device,
78 OnFailureType failure_type);
79
CreateBitmapCanvas(int width,int height,bool is_opaque)80 static inline SkCanvas* CreateBitmapCanvas(int width,
81 int height,
82 bool is_opaque) {
83 return CreatePlatformCanvas(width, height, is_opaque, 0, CRASH_ON_FAILURE);
84 }
85
TryCreateBitmapCanvas(int width,int height,bool is_opaque)86 static inline SkCanvas* TryCreateBitmapCanvas(int width,
87 int height,
88 bool is_opaque) {
89 return CreatePlatformCanvas(width, height, is_opaque, 0,
90 RETURN_NULL_ON_FAILURE);
91 }
92
93 // Return the stride (length of a line in bytes) for the given width. Because
94 // we use 32-bits per pixel, this will be roughly 4*width. However, for
95 // alignment reasons we may wish to increase that.
96 SK_API size_t PlatformCanvasStrideForWidth(unsigned width);
97
98 // Returns the SkBaseDevice pointer of the topmost rect with a non-empty
99 // clip. In practice, this is usually either the top layer or nothing, since
100 // we usually set the clip to new layers when we make them.
101 //
102 // This may return NULL, so callers need to check.
103 //
104 // This is different than SkCanvas' getDevice, because that returns the
105 // bottommost device.
106 //
107 // Danger: the resulting device should not be saved. It will be invalidated
108 // by the next call to save() or restore().
109 SK_API SkBaseDevice* GetTopDevice(const SkCanvas& canvas);
110
111 // Returns true if native platform routines can be used to draw on the
112 // given canvas. If this function returns false, BeginPlatformPaint will
113 // return NULL PlatformSurface.
114 SK_API bool SupportsPlatformPaint(const SkCanvas* canvas);
115
116 // Draws into the a native platform surface, |context|. Forwards to
117 // DrawToNativeContext on a PlatformDevice instance bound to the top device.
118 // If no PlatformDevice instance is bound, is a no-operation.
119 SK_API void DrawToNativeContext(SkCanvas* canvas,
120 PlatformSurface context,
121 int x,
122 int y,
123 const PlatformRect* src_rect);
124
125 // Sets the opacity of each pixel in the specified region to be opaque.
126 SK_API void MakeOpaque(SkCanvas* canvas, int x, int y, int width, int height);
127
128 // These calls should surround calls to platform drawing routines, the
129 // surface returned here can be used with the native platform routines.
130 //
131 // Call EndPlatformPaint when you are done and want to use skia operations
132 // after calling the platform-specific BeginPlatformPaint; this will
133 // synchronize the bitmap to OS if necessary.
134 SK_API PlatformSurface BeginPlatformPaint(SkCanvas* canvas);
135 SK_API void EndPlatformPaint(SkCanvas* canvas);
136
137 // Helper class for pairing calls to BeginPlatformPaint and EndPlatformPaint.
138 // Upon construction invokes BeginPlatformPaint, and upon destruction invokes
139 // EndPlatformPaint.
140 class SK_API ScopedPlatformPaint {
141 public:
ScopedPlatformPaint(SkCanvas * canvas)142 explicit ScopedPlatformPaint(SkCanvas* canvas) : canvas_(canvas) {
143 platform_surface_ = BeginPlatformPaint(canvas);
144 }
~ScopedPlatformPaint()145 ~ScopedPlatformPaint() { EndPlatformPaint(canvas_); }
146
147 // Returns the PlatformSurface to use for native platform drawing calls.
GetPlatformSurface()148 PlatformSurface GetPlatformSurface() { return platform_surface_; }
149 private:
150 SkCanvas* canvas_;
151 PlatformSurface platform_surface_;
152
153 // Disallow copy and assign
154 ScopedPlatformPaint(const ScopedPlatformPaint&);
155 ScopedPlatformPaint& operator=(const ScopedPlatformPaint&);
156 };
157
158 // PlatformBitmap holds a PlatformSurface that can also be used as an SkBitmap.
159 class SK_API PlatformBitmap {
160 public:
161 PlatformBitmap();
162 ~PlatformBitmap();
163
164 // Returns true if the bitmap was able to allocate its surface.
165 bool Allocate(int width, int height, bool is_opaque);
166
167 // Returns the platform surface, or 0 if Allocate() did not return true.
GetSurface()168 PlatformSurface GetSurface() { return surface_; }
169
170 // Return the skia bitmap, which will be empty if Allocate() did not
171 // return true.
172 //
173 // The resulting SkBitmap holds a refcount on the underlying platform surface,
174 // so the surface will remain allocated so long as the SkBitmap or its copies
175 // stay around.
GetBitmap()176 const SkBitmap& GetBitmap() { return bitmap_; }
177
178 private:
179 SkBitmap bitmap_;
180 PlatformSurface surface_; // initialized to 0
181 intptr_t platform_extra_; // platform specific, initialized to 0
182
183 DISALLOW_COPY_AND_ASSIGN(PlatformBitmap);
184 };
185
186 } // namespace skia
187
188 #endif // SKIA_EXT_PLATFORM_CANVAS_H_
189