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 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 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 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: 142 explicit ScopedPlatformPaint(SkCanvas* canvas) : canvas_(canvas) { 143 platform_surface_ = BeginPlatformPaint(canvas); 144 } 145 ~ScopedPlatformPaint() { EndPlatformPaint(canvas_); } 146 147 // Returns the PlatformSurface to use for native platform drawing calls. 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. 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. 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
