skia/ext/platform_device.h

   1 // Copyright (c) 2012 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_DEVICE_H_
   6 #define SKIA_EXT_PLATFORM_DEVICE_H_
   7
   8 #include "build/build_config.h"
   9
  10 #if defined(OS_WIN)
  11 #include <windows.h>
  12 #include <vector>
  13 #endif
  14
  15 #include "third_party/skia/include/core/SkColor.h"
  16 #include "third_party/skia/include/core/SkBitmapDevice.h"
  17 #include "third_party/skia/include/core/SkTypes.h"
  18
  19 class SkMatrix;
  20 class SkMetaData;
  21 class SkPath;
  22 class SkRegion;
  23
  24 #if defined(USE_CAIRO)
  25 typedef struct _cairo cairo_t;
  26 typedef struct _cairo_rectangle cairo_rectangle_t;
  27 #elif defined(OS_MACOSX)
  28 typedef struct CGContext* CGContextRef;
  29 typedef struct CGRect CGRect;
  30 #endif
  31
  32 namespace skia {
  33
  34 class PlatformDevice;
  35
  36 #if defined(OS_WIN)
  37 typedef HDC PlatformSurface;
  38 typedef RECT PlatformRect;
  39 #elif defined(USE_CAIRO)
  40 typedef cairo_t* PlatformSurface;
  41 typedef cairo_rectangle_t PlatformRect;
  42 #elif defined(OS_MACOSX)
  43 typedef CGContextRef PlatformSurface;
  44 typedef CGRect PlatformRect;
  45 #else
  46 typedef void* PlatformSurface;
  47 typedef SkIRect* PlatformRect;
  48 #endif
  49
  50 // The following routines provide accessor points for the functionality
  51 // exported by the various PlatformDevice ports.
  52 // All calls to PlatformDevice::* should be routed through these
  53 // helper functions.
  54
  55 // Bind a PlatformDevice instance, |platform_device| to |device|.  Subsequent
  56 // calls to the functions exported below will forward the request to the
  57 // corresponding method on the bound PlatformDevice instance.    If no
  58 // PlatformDevice has been bound to the SkBaseDevice passed, then the
  59 // routines are NOPS.
  60 SK_API void SetPlatformDevice(SkBaseDevice* device,
  61                               PlatformDevice* platform_device);
  62 SK_API PlatformDevice* GetPlatformDevice(SkBaseDevice* device);
  63
  64
  65 #if defined(OS_WIN)
  66 // Initializes the default settings and colors in a device context.
  67 SK_API void InitializeDC(HDC context);
  68 #elif defined(OS_MACOSX)
  69 // Returns the CGContext that backing the SkBaseDevice.  Forwards to the bound
  70 // PlatformDevice.  Returns NULL if no PlatformDevice is bound.
  71 SK_API CGContextRef GetBitmapContext(SkBaseDevice* device);
  72 #endif
  73
  74 // Following routines are used in print preview workflow to mark the draft mode
  75 // metafile and preview metafile.
  76 SK_API SkMetaData& getMetaData(const SkCanvas& canvas);
  77 SK_API void SetIsDraftMode(const SkCanvas& canvas, bool draft_mode);
  78 SK_API bool IsDraftMode(const SkCanvas& canvas);
  79
  80 #if defined(OS_MACOSX) || defined(OS_WIN)
  81 SK_API void SetIsPreviewMetafile(const SkCanvas& canvas, bool is_preview);
  82 SK_API bool IsPreviewMetafile(const SkCanvas& canvas);
  83 #endif
  84
  85 // A SkBitmapDevice is basically a wrapper around SkBitmap that provides a
  86 // surface for SkCanvas to draw into. PlatformDevice provides a surface
  87 // Windows can also write to. It also provides functionality to play well
  88 // with GDI drawing functions. This class is abstract and must be subclassed.
  89 // It provides the basic interface to implement it either with or without
  90 // a bitmap backend.
  91 //
  92 // PlatformDevice provides an interface which sub-classes of SkBaseDevice can
  93 // also provide to allow for drawing by the native platform into the device.
  94 // TODO(robertphillips): Once the bitmap-specific entry points are removed
  95 // from SkBaseDevice it might make sense for PlatformDevice to be derived
  96 // from it.
  97 class SK_API PlatformDevice {
  98  public:
  99   virtual ~PlatformDevice() {}
 100
 101 #if defined(OS_MACOSX)
 102   // The CGContext that corresponds to the bitmap, used for CoreGraphics
 103   // operations drawing into the bitmap. This is possibly heavyweight, so it
 104   // should exist only during one pass of rendering.
 105   virtual CGContextRef GetBitmapContext() = 0;
 106 #endif
 107
 108   // The DC that corresponds to the bitmap, used for GDI operations drawing
 109   // into the bitmap. This is possibly heavyweight, so it should be existant
 110   // only during one pass of rendering.
 111   virtual PlatformSurface BeginPlatformPaint();
 112
 113   // Finish a previous call to beginPlatformPaint.
 114   virtual void EndPlatformPaint();
 115
 116   // Returns true if GDI operations can be used for drawing into the bitmap.
 117   virtual bool SupportsPlatformPaint();
 118
 119 #if defined(OS_WIN)
 120   // Loads a SkPath into the GDI context. The path can there after be used for
 121   // clipping or as a stroke. Returns false if the path failed to be loaded.
 122   static bool LoadPathToDC(HDC context, const SkPath& path);
 123
 124   // Loads a SkRegion into the GDI context.
 125   static void LoadClippingRegionToDC(HDC context, const SkRegion& region,
 126                                      const SkMatrix& transformation);
 127
 128   // Draws to the given screen DC, if the bitmap DC doesn't exist, this will
 129   // temporarily create it. However, if you have created the bitmap DC, it will
 130   // be more efficient if you don't free it until after this call so it doesn't
 131   // have to be created twice.  If src_rect is null, then the entirety of the
 132   // source device will be copied.
 133   virtual void DrawToHDC(HDC, int x, int y, const RECT* src_rect);
 134 #endif
 135
 136  protected:
 137 #if defined(OS_WIN)
 138   // Arrays must be inside structures.
 139   struct CubicPoints {
 140     SkPoint p[4];
 141   };
 142   typedef std::vector<CubicPoints> CubicPath;
 143   typedef std::vector<CubicPath> CubicPaths;
 144
 145   // Loads the specified Skia transform into the device context, excluding
 146   // perspective (which GDI doesn't support).
 147   static void LoadTransformToDC(HDC dc, const SkMatrix& matrix);
 148
 149   // Transforms SkPath's paths into a series of cubic path.
 150   static bool SkPathToCubicPaths(CubicPaths* paths, const SkPath& skpath);
 151 #endif
 152 };
 153
 154 }  // namespace skia
 155
 156 #endif  // SKIA_EXT_PLATFORM_DEVICE_H_