Canvas refactoring part 3....

gfx/canvas.h

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef GFX_CANVAS_H_
 #define GFX_CANVAS_H_
 
-#include "gfx/canvas_skia.h"
+#include <string>
+
+#include "gfx/native_widget_types.h"
+// TODO(beng): remove this include when we no longer depend on SkTypes.
+#include "skia/ext/platform_canvas.h"
 
 namespace gfx {
 
-// Temporary compatibility shim, remove once Canvas2->Canvas.
-class Canvas : public CanvasSkia {
+class CanvasSkia;
+class Font;
+class Rect;
+
+// TODO(beng): documentation.
+class Canvas {
  public:
-  Canvas(int width, int height, bool is_opaque)
-      : CanvasSkia(width, height, is_opaque) {
-  }
-  Canvas() : CanvasSkia() {}
+  // Specifies the alignment for text rendered with the DrawStringInt method.
+  enum {
+    TEXT_ALIGN_LEFT = 1,
+    TEXT_ALIGN_CENTER = 2,
+    TEXT_ALIGN_RIGHT = 4,
+    TEXT_VALIGN_TOP = 8,
+    TEXT_VALIGN_MIDDLE = 16,
+    TEXT_VALIGN_BOTTOM = 32,
 
-  // Overridden from Canvas2:
-  Canvas* AsCanvas() {
-    return this;
-  }
+    // Specifies the text consists of multiple lines.
+    MULTI_LINE = 64,
 
- private:
-  DISALLOW_COPY_AND_ASSIGN(Canvas);
+    // By default DrawStringInt does not process the prefix ('&') character
+    // specially. That is, the string "&foo" is rendered as "&foo". When
+    // rendering text from a resource that uses the prefix character for
+    // mnemonics, the prefix should be processed and can be rendered as an
+    // underline (SHOW_PREFIX), or not rendered at all (HIDE_PREFIX).
+    SHOW_PREFIX = 128,
+    HIDE_PREFIX = 256,
+
+    // Prevent ellipsizing
+    NO_ELLIPSIS = 512,
+
+    // Specifies if words can be split by new lines.
+    // This only works with MULTI_LINE.
+    CHARACTER_BREAK = 1024,
+
+    // Instructs DrawStringInt() to render the text using RTL directionality.
+    // In most cases, passing this flag is not necessary because information
+    // about the text directionality is going to be embedded within the string
+    // in the form of special Unicode characters. However, we don't insert
+    // directionality characters into strings if the locale is LTR because some
+    // platforms (for example, an English Windows XP with no RTL fonts
+    // installed) don't support these characters. Thus, this flag should be
+    // used to render text using RTL directionality when the locale is LTR.
+    FORCE_RTL_DIRECTIONALITY = 2048,
+  };
+
+  virtual ~Canvas() {}
+
+  // Creates an empty canvas. Must be initialized before it can be used.
+  static Canvas* CreateCanvas();
+
+  // Creates a canvas with the specified size.
+  static Canvas* CreateCanvas(int width, int height, bool is_opaque);
+
+  // Retrieves the clip rectangle and sets it in the specified rectangle if any.
+  // Returns true if the clip rect is non-empty.
+  virtual bool GetClipRect(gfx::Rect* clip_rect) = 0;
+
+  // Wrapper function that takes integer arguments.
+  // Returns true if the clip is non-empty.
+  // See clipRect for specifics.
+  virtual bool ClipRectInt(int x, int y, int w, int h) = 0;
+
+  // Test whether the provided rectangle intersects the current clip rect.
+  virtual bool IntersectsClipRectInt(int x, int y, int w, int h) = 0;
+
+  // Wrapper function that takes integer arguments.
+  // See translate() for specifics.
+  virtual void TranslateInt(int x, int y) = 0;
+
+  // Wrapper function that takes integer arguments.
+  // See scale() for specifics.
+  virtual void ScaleInt(int x, int y) = 0;
+
+  // Fills the given rectangle with the given paint's parameters.
+  virtual void FillRectInt(int x, int y, int w, int h,
+                           const SkPaint& paint) = 0;
+
+  // Fills the specified region with the specified color using a transfer
+  // mode of SkXfermode::kSrcOver_Mode.
+  virtual void FillRectInt(const SkColor& color, int x, int y, int w,
+                           int h) = 0;
+
+  // Draws a single pixel rect in the specified region with the specified
+  // color, using a transfer mode of SkXfermode::kSrcOver_Mode.
+  //
+  // NOTE: if you need a single pixel line, use DraLineInt.
+  virtual void DrawRectInt(const SkColor& color, int x, int y, int w,
+                           int h) = 0;
+
+  // Draws a single pixel rect in the specified region with the specified
+  // color and transfer mode.
+  //
+  // NOTE: if you need a single pixel line, use DraLineInt.
+  virtual void DrawRectInt(const SkColor& color, int x, int y, int w, int h,
+                           SkXfermode::Mode mode) = 0;
+
+  // Draws a single pixel line with the specified color.
+  virtual void DrawLineInt(const SkColor& color, int x1, int y1, int x2,
+                           int y2) = 0;
+
+  // Draws a bitmap with the origin at the specified location. The upper left
+  // corner of the bitmap is rendered at the specified location.
+  virtual void DrawBitmapInt(const SkBitmap& bitmap, int x, int y) = 0;
+
+  // Draws a bitmap with the origin at the specified location, using the
+  // specified paint. The upper left corner of the bitmap is rendered at the
+  // specified location.
+  virtual void DrawBitmapInt(const SkBitmap& bitmap, int x, int y,
+                             const SkPaint& paint) = 0;
+
+  // Draws a portion of a bitmap in the specified location. The src parameters
+  // correspond to the region of the bitmap to draw in the region defined
+  // by the dest coordinates.
+  //
+  // If the width or height of the source differs from that of the destination,
+  // the bitmap will be scaled. When scaling down, it is highly recommended
+  // that you call buildMipMap(false) on your bitmap to ensure that it has
+  // a mipmap, which will result in much higher-quality output. Set |filter|
+  // to use filtering for bitmaps, otherwise the nearest-neighbor algorithm
+  // is used for resampling.
+  //
+  // An optional custom SkPaint can be provided.
+  virtual void DrawBitmapInt(const SkBitmap& bitmap, int src_x, int src_y,
+                             int src_w, int src_h, int dest_x, int dest_y,
+                             int dest_w, int dest_h, bool filter) = 0;
+  virtual void DrawBitmapInt(const SkBitmap& bitmap, int src_x, int src_y,
+                             int src_w, int src_h, int dest_x, int dest_y,
+                             int dest_w, int dest_h, bool filter,
+                             const SkPaint& paint) = 0;
+
+  // Draws text with the specified color, font and location. The text is
+  // aligned to the left, vertically centered, clipped to the region. If the
+  // text is too big, it is truncated and '...' is added to the end.
+  virtual void DrawStringInt(const std::wstring& text, const gfx::Font& font,
+                             const SkColor& color, int x, int y, int w,
+                             int h) = 0;
+  virtual void DrawStringInt(const std::wstring& text, const gfx::Font& font,
+                             const SkColor& color,
+                             const gfx::Rect& display_rect) = 0;
+
+  // Draws text with the specified color, font and location. The last argument
+  // specifies flags for how the text should be rendered. It can be one of
+  // TEXT_ALIGN_CENTER, TEXT_ALIGN_RIGHT or TEXT_ALIGN_LEFT.
+  virtual void DrawStringInt(const std::wstring& text, const gfx::Font& font,
+                             const SkColor& color, int x, int y, int w, int h,
+                             int flags) = 0;
+
+  // Draws a dotted gray rectangle used for focus purposes.
+  virtual void DrawFocusRect(int x, int y, int width, int height) = 0;
+
+  // Tiles the image in the specified region.
+  virtual void TileImageInt(const SkBitmap& bitmap, int x, int y, int w,
+                            int h) = 0;
+  virtual void TileImageInt(const SkBitmap& bitmap, int src_x, int src_y,
+                            int dest_x, int dest_y, int w, int h) = 0;
+
+  // Extracts a bitmap from the contents of this canvas.
+  virtual SkBitmap ExtractBitmap() const = 0;

[brettw, 2010/06/24 21:30:54]

Probably you want this to be on the software canvas only. I think the way we use
it now you can just move it there and it will work (since we make a CanvasSkia
and then extract the bitmap).

+
+  // TODO(beng): remove this once we don't need to use any skia-specific methods
+  //             through this interface.
+  // A quick and dirty way to obtain the underlying SkCanvas.
+  virtual CanvasSkia* AsCanvasSkia() { return NULL; }
+  virtual const CanvasSkia* AsCanvasSkia() const { return NULL; }
 };
 
-}
+class CanvasPaint {
+ public:
+  virtual ~CanvasPaint() {}
+
+  // Creates a canvas that paints to |view| when it is destroyed. The canvas is
+  // sized to the client area of |view|.
+  static CanvasPaint* CreateCanvasPaint(gfx::NativeView view);
+
+  // Returns true if the canvas has an invalid rect that needs to be repainted.
+  virtual bool IsValid() const = 0;
+
+  // Returns the rectangle that is invalid.
+  virtual gfx::Rect GetInvalidRect() const = 0;
+
+  // Returns the underlying Canvas.
+  virtual Canvas* AsCanvas() = 0;
+};
+
+}  // namespace gfx;
 
 #endif  // GFX_CANVAS_H_