path: root/app/gfx/canvas.h

// Copyright (c) 2006-2008 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 APP_GFX_CANVAS_H_
#define APP_GFX_CANVAS_H_

#if defined(OS_WIN)
#include <windows.h>
#endif

#include <string>

#include "base/basictypes.h"
#include "skia/ext/platform_canvas.h"

#if defined(OS_LINUX)
typedef struct _cairo cairo_t;
typedef struct _GdkPixbuf GdkPixbuf;
#endif

namespace gfx {

class Font;
class Rect;

// Canvas is a SkCanvas subclass that provides a number of methods for common
// operations used throughout an application built using base/gfx and app/gfx.
//
// All methods that take integer arguments (as is used throughout views)
// end with Int. If you need to use methods provided by the superclass
// you'll need to do a conversion. In particular you'll need to use
// macro SkIntToScalar(xxx), or if converting from a scalar to an integer
// SkScalarRound.
//
// A handful of methods in this class are overloaded providing an additional
// argument of type SkXfermode::Mode. SkXfermode::Mode specifies how the
// source and destination colors are combined. Unless otherwise specified,
// the variant that does not take a SkXfermode::Mode uses a transfer mode
// of kSrcOver_Mode.
class Canvas : public skia::PlatformCanvas {
 public:
  // 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,

    // Specifies the text consists of multiple lines.
    MULTI_LINE = 64,

    // 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,
  };

  // Creates an empty Canvas. Callers must use initialize before using the
  // canvas.
  Canvas();

  Canvas(int width, int height, bool is_opaque);

  virtual ~Canvas();

  // Retrieves the clip rectangle and sets it in the specified rectangle if any.
  // Returns true if the clip rect is non-empty.
  bool GetClipRect(gfx::Rect* clip_rect);

  // Wrapper function that takes integer arguments.
  // Returns true if the clip is non-empty.
  // See clipRect for specifics.
  bool ClipRectInt(int x, int y, int w, int h);

  // Test whether the provided rectangle intersects the current clip rect.
  bool IntersectsClipRectInt(int x, int y, int w, int h);

  // Wrapper function that takes integer arguments.
  // See translate() for specifics.
  void TranslateInt(int x, int y);

  // Wrapper function that takes integer arguments.
  // See scale() for specifics.
  void ScaleInt(int x, int y);

  // Fills the given rectangle with the given paint's parameters.
  void FillRectInt(int x, int y, int w, int h, const SkPaint& paint);

  // Fills the specified region with the specified color using a transfer
  // mode of SkXfermode::kSrcOver_Mode.
  void FillRectInt(const SkColor& color, int x, int y, int w, int h);

  // 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.
  void DrawRectInt(const SkColor& color, int x, int y, int w, int h);

  // 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.
  void DrawRectInt(const SkColor& color, int x, int y, int w, int h,
                   SkXfermode::Mode mode);

  // Draws a single pixel line with the specified color.
  void DrawLineInt(const SkColor& color, int x1, int y1, int x2, int y2);

  // Draws a bitmap with the origin at the specified location. The upper left
  // corner of the bitmap is rendered at the specified location.
  void DrawBitmapInt(const SkBitmap& bitmap, int x, int y);

  // 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.
  void DrawBitmapInt(const SkBitmap& bitmap, int x, int y,
                     const SkPaint& paint);

  // 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.
  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);
  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);

  // 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.
  void DrawStringInt(const std::wstring& text, const gfx::Font& font,
                     const SkColor& color, int x, int y, int w, int h);

  // 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.
  void DrawStringInt(const std::wstring& text, const gfx::Font& font,
                     const SkColor& color, int x, int y, int w, int h,
                     int flags);

#ifdef OS_WIN  // Only implemented on Windows for now.
  // Draws text with a 1-pixel halo around it of the given color. It allows
  // ClearType to be drawn to an otherwise transparenct bitmap for drag images.
  // Drag images have only 1-bit of transparency, so we don't do any fancy
  // blurring.
  void DrawStringWithHalo(const std::wstring& text, const gfx::Font& font,
                          const SkColor& text_color, const SkColor& halo_color,
                          int x, int y, int w, int h, int flags);
#endif

  // Draws a dotted gray rectangle used for focus purposes.
  void DrawFocusRect(int x, int y, int width, int height);

  // Tiles the image in the specified region.
  void TileImageInt(const SkBitmap& bitmap, int x, int y, int w, int h);
  void TileImageInt(const SkBitmap& bitmap, int src_x, int src_y,
                    int dest_x, int dest_y, int w, int h);

  // Extracts a bitmap from the contents of this canvas.
  SkBitmap ExtractBitmap() const;

#if defined(OS_LINUX)
  // Applies current matrix on the canvas to the cairo context. This should be
  // invoked anytime you plan on drawing directly to the cairo context. Be
  // sure and set the matrix back to the identity when done.
  void ApplySkiaMatrixToCairoContext(cairo_t* cr);

  // Draw the pixbuf in its natural size at (x, y).
  void DrawGdkPixbuf(GdkPixbuf* pixbuf, int x, int y);
#endif

  // Compute the size required to draw some text with the provided font.
  // Attempts to fit the text with the provided width and height. Increases
  // height and then width as needed to make the text fit. This method
  // supports multiple lines.
  static void SizeStringInt(const std::wstring& test, const gfx::Font& font,
                            int *width, int* height, int flags);

 private:
#if defined(OS_WIN)
  // 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.
  void DrawStringInt(const std::wstring& text, HFONT font,
                     const SkColor& color, int x, int y, int w, int h,
                     int flags);
#endif

  DISALLOW_COPY_AND_ASSIGN(Canvas);
};

}  // namespace gfx;

#endif  // APP_GFX_CANVAS_H_