// Copyright (c) 2012 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 UI_GFX_CANVAS_H_
#define UI_GFX_CANVAS_H_
#include <vector>
#include "base/basictypes.h"
#include "base/memory/scoped_ptr.h"
#include "base/strings/string16.h"
#include "skia/ext/platform_canvas.h"
#include "skia/ext/refptr.h"
#include "ui/gfx/image/image_skia.h"
#include "ui/gfx/native_widget_types.h"
#include "ui/gfx/shadow_value.h"
namespace gfx {
class Rect;
class FontList;
class Point;
class Size;
class Transform;
// Canvas is a SkCanvas wrapper that provides a number of methods for
// common operations used throughout an application built using ui/gfx.
//
// All methods that take integer arguments (as is used throughout views)
// end with Int. If you need to use methods provided by SkCanvas, you'll
// need to do a conversion. In particular you'll need to use |SkIntToScalar()|,
// 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 GFX_EXPORT Canvas {
public:
enum TruncateFadeMode {
TruncateFadeTail,
TruncateFadeHead,
};
// Specifies the alignment for text rendered with the DrawStringRect method.
enum {
TEXT_ALIGN_LEFT = 1 << 0,
TEXT_ALIGN_CENTER = 1 << 1,
TEXT_ALIGN_RIGHT = 1 << 2,
// Specifies the text consists of multiple lines.
MULTI_LINE = 1 << 3,
// By default DrawStringRect 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 = 1 << 4,
HIDE_PREFIX = 1 << 5,
// Prevent ellipsizing
NO_ELLIPSIS = 1 << 6,
// Specifies if words can be split by new lines.
// This only works with MULTI_LINE.
CHARACTER_BREAK = 1 << 7,
// Instructs DrawStringRect() 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 = 1 << 8,
// Similar to FORCE_RTL_DIRECTIONALITY, but left-to-right.
// See FORCE_RTL_DIRECTIONALITY for details.
FORCE_LTR_DIRECTIONALITY = 1 << 9,
// Instructs DrawStringRect() to not use subpixel rendering. This is useful
// when rendering text onto a fully- or partially-transparent background
// that will later be blended with another image.
NO_SUBPIXEL_RENDERING = 1 << 10,
};
// Creates an empty canvas with image_scale of 1x.
Canvas();
// Creates canvas with provided DIP |size| and |image_scale|.
// If this canvas is not opaque, it's explicitly cleared to transparent before
// being returned.
Canvas(const Size& size, float image_scale, bool is_opaque);
// Constructs a canvas with the size and the image_scale of the provided
// |image_rep|, and draws the |image_rep| into it.
Canvas(const ImageSkiaRep& image_rep, bool is_opaque);
virtual ~Canvas();
// Creates a Canvas backed by an |sk_canvas| with |image_scale_|.
// |sk_canvas| is assumed to be already scaled based on |image_scale|
// so no additional scaling is applied.
static Canvas* CreateCanvasWithoutScaling(SkCanvas* sk_canvas,
float image_scale);
// Recreates the backing platform canvas with DIP |size| and |image_scale_|.
// If the canvas is not opaque, it is explicitly cleared.
// This method is public so that canvas_skia_paint can recreate the platform
// canvas after having initialized the canvas.
// TODO(pkotwicz): Push the image_scale into skia::PlatformCanvas such that
// this method can be private.
void RecreateBackingCanvas(const Size& size,
float image_scale,
bool is_opaque);
// Compute the size required to draw some text with the provided fonts.
// 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. On Skia only a line_height can be specified and
// specifying a 0 value for it will cause the default height to be used.
static void SizeStringInt(const base::string16& text,
const FontList& font_list,
int* width,
int* height,
int line_height,
int flags);
// This is same as SizeStringInt except that fractional size is returned.
// See comment in GetStringWidthF for its usage.
static void SizeStringFloat(const base::string16& text,
const FontList& font_list,
float* width,
float* height,
int line_height,
int flags);
// Returns the number of horizontal pixels needed to display the specified
// |text| with |font_list|.
static int GetStringWidth(const base::string16& text,
const FontList& font_list);
// This is same as GetStringWidth except that fractional width is returned.
// Use this method for the scenario that multiple string widths need to be
// summed up. This is because GetStringWidth returns the ceiled width and
// adding multiple ceiled widths could cause more precision loss for certain
// platform like Mac where the fractioal width is used.
static float GetStringWidthF(const base::string16& text,
const FontList& font_list);
// Returns the default text alignment to be used when drawing text on a
// Canvas based on the directionality of the system locale language.
// This function is used by Canvas::DrawStringRect when the text alignment
// is not specified.
//
// This function returns either Canvas::TEXT_ALIGN_LEFT or
// Canvas::TEXT_ALIGN_RIGHT.
static int DefaultCanvasTextAlignment();
// Draws text with a 1-pixel halo around it of the given color.
// On Windows, it allows ClearType to be drawn to an otherwise transparent
// bitmap for drag images. Drag images have only 1-bit of transparency, so
// we don't do any fancy blurring.
// On Linux, text with halo is created by stroking it with 2px |halo_color|
// then filling it with |text_color|.
// On Mac, NOTIMPLEMENTED.
// TODO(dhollowa): Skia-native implementation is underway. Cut over to
// that when ready. http::/crbug.com/109946
void DrawStringRectWithHalo(const base::string16& text,
const FontList& font_list,
SkColor text_color,
SkColor halo_color,
const Rect& display_rect,
int flags);
// Extracts an ImageSkiaRep from the contents of this canvas.
ImageSkiaRep ExtractImageRep() const;
// Draws a dashed rectangle of the specified color.
void DrawDashedRect(const Rect& rect, SkColor color);
// Saves a copy of the drawing state onto a stack, operating on this copy
// until a balanced call to Restore() is made.
void Save();
// As with Save(), except draws to a layer that is blended with the canvas
// at the specified alpha once Restore() is called.
// |layer_bounds| are the bounds of the layer relative to the current
// transform.
void SaveLayerAlpha(uint8 alpha);
void SaveLayerAlpha(uint8 alpha, const Rect& layer_bounds);
// Restores the drawing state after a call to Save*(). It is an error to
// call Restore() more times than Save*().
void Restore();
// Adds |rect| to the current clip.
void ClipRect(const Rect& rect);
// Adds |path| to the current clip.
void ClipPath(const SkPath& path);
// Returns true if the current clip is empty.
bool IsClipEmpty() const;
// Returns the bounds of the current clip (in local coordinates) in the
// |bounds| parameter, and returns true if it is non empty.
bool GetClipBounds(Rect* bounds);
void Translate(const Vector2d& offset);
void Scale(int x_scale, int y_scale);
// Fills the entire canvas' bitmap (restricted to current clip) with
// specified |color| using a transfer mode of SkXfermode::kSrcOver_Mode.
void DrawColor(SkColor color);
// Fills the entire canvas' bitmap (restricted to current clip) with
// specified |color| and |mode|.
void DrawColor(SkColor color, SkXfermode::Mode mode);
// Fills |rect| with |color| using a transfer mode of
// SkXfermode::kSrcOver_Mode.
void FillRect(const Rect& rect, SkColor color);
// Fills |rect| with the specified |color| and |mode|.
void FillRect(const Rect& rect, SkColor color, SkXfermode::Mode mode);
// 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 DrawLine.
void DrawRect(const Rect& rect, SkColor color);
// 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 DrawLine.
void DrawRect(const Rect& rect, SkColor color, SkXfermode::Mode mode);
// Draws the given rectangle with the given |paint| parameters.
void DrawRect(const Rect& rect, const SkPaint& paint);
// Draw the given point with the given |paint| parameters.
void DrawPoint(const Point& p, const SkPaint& paint);
// Draws a single pixel line with the specified color.
void DrawLine(const Point& p1, const Point& p2, SkColor color);
// Draws a line with the given |paint| parameters.
void DrawLine(const Point& p1, const Point& p2, const SkPaint& paint);
// Draws a circle with the given |paint| parameters.
void DrawCircle(const Point& center_point,
int radius,
const SkPaint& paint);
// Draws the given rectangle with rounded corners of |radius| using the
// given |paint| parameters.
void DrawRoundRect(const Rect& rect, int radius, const SkPaint& paint);
// Draws the given path using the given |paint| parameters.
void DrawPath(const SkPath& path, const SkPaint& paint);
// Draws an image with the origin at the specified location. The upper left
// corner of the bitmap is rendered at the specified location.
// Parameters are specified relative to current canvas scale not in pixels.
// Thus, x is 2 pixels if canvas scale = 2 & |x| = 1.
void DrawImageInt(const ImageSkia&, int x, int y);
// Helper for DrawImageInt(..., paint) that constructs a temporary paint and
// calls paint.setAlpha(alpha).
void DrawImageInt(const ImageSkia&, int x, int y, uint8 alpha);
// Draws an image with the origin at the specified location, using the
// specified paint. The upper left corner of the bitmap is rendered at the
// specified location.
// Parameters are specified relative to current canvas scale not in pixels.
// Thus, |x| is 2 pixels if canvas scale = 2 & |x| = 1.
void DrawImageInt(const ImageSkia& image,
int x,
int y,
const SkPaint& paint);
// Draws a portion of an image 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 image will be scaled. When scaling down, a mipmap will be generated.
// Set |filter| to use filtering for images, otherwise the nearest-neighbor
// algorithm is used for resampling.
//
// An optional custom SkPaint can be provided.
// Parameters are specified relative to current canvas scale not in pixels.
// Thus, |x| is 2 pixels if canvas scale = 2 & |x| = 1.
void DrawImageInt(const ImageSkia& image,
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 DrawImageInt(const ImageSkia& image,
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 an |image| with the top left corner at |x| and |y|, clipped to
// |path|.
// Parameters are specified relative to current canvas scale not in pixels.
// Thus, x is 2 pixels if canvas scale = 2 & |x| = 1.
void DrawImageInPath(const ImageSkia& image,
int x,
int y,
const SkPath& path,
const SkPaint& paint);
// Draws text with the specified color, fonts 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 DrawStringRect(const base::string16& text,
const FontList& font_list,
SkColor color,
const Rect& display_rect);
// Draws text with the specified color, fonts 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 DrawStringRectWithFlags(const base::string16& text,
const FontList& font_list,
SkColor color,
const Rect& display_rect,
int flags);
// Similar to above DrawStringRect method but with text shadows support.
// Currently it's only implemented for canvas skia. Specifying a 0 line_height
// will cause the default height to be used.
void DrawStringRectWithShadows(const base::string16& text,
const FontList& font_list,
SkColor color,
const Rect& text_bounds,
int line_height,
int flags,
const ShadowValues& shadows);
// Draws a dotted gray rectangle used for focus purposes.
void DrawFocusRect(const Rect& rect);
// Draws a |rect| in the specified region with the specified |color| with a
// with of one logical pixel which might be more device pixels.
void DrawSolidFocusRect(const Rect& rect, SkColor color);
// Tiles the image in the specified region.
// Parameters are specified relative to current canvas scale not in pixels.
// Thus, |x| is 2 pixels if canvas scale = 2 & |x| = 1.
void TileImageInt(const ImageSkia& image,
int x,
int y,
int w,
int h);
void TileImageInt(const ImageSkia& image,
int src_x,
int src_y,
int dest_x,
int dest_y,
int w,
int h);
void TileImageInt(const ImageSkia& image,
int src_x,
int src_y,
float tile_scale_x,
float tile_scale_y,
int dest_x,
int dest_y,
int w,
int h);
// Returns a native drawing context for platform specific drawing routines to
// use. Must be balanced by a call to EndPlatformPaint().
NativeDrawingContext BeginPlatformPaint();
// Signifies the end of platform drawing using the native drawing context
// returned by BeginPlatformPaint().
void EndPlatformPaint();
// Apply transformation on the canvas.
void Transform(const Transform& transform);
// Draws the given string with the beginning or the end using a fade gradient.
void DrawFadeTruncatingStringRect(
const base::string16& text,
TruncateFadeMode truncate_mode,
const FontList& font_list,
SkColor color,
const Rect& display_rect);
void DrawFadeTruncatingStringRectWithFlags(
const base::string16& text,
TruncateFadeMode truncate_mode,
const FontList& font_list,
SkColor color,
const Rect& display_rect,
int flags);
skia::PlatformCanvas* platform_canvas() const { return owned_canvas_.get(); }
SkCanvas* sk_canvas() const { return canvas_; }
float image_scale() const { return image_scale_; }
private:
Canvas(SkCanvas* canvas, float image_scale);
// Test whether the provided rectangle intersects the current clip rect.
bool IntersectsClipRectInt(int x, int y, int w, int h);
bool IntersectsClipRect(const Rect& rect);
// Returns the image rep which best matches the canvas |image_scale_|.
// Returns a null image rep if |image| contains no image reps.
// Builds mip map for returned image rep if necessary.
//
// An optional additional user defined scale can be provided.
const ImageSkiaRep& GetImageRepToPaint(const ImageSkia& image) const;
const ImageSkiaRep& GetImageRepToPaint(
const ImageSkia& image,
float user_defined_scale_factor_x,
float user_defined_scale_factor_y) const;
// The device scale factor at which drawing on this canvas occurs.
// An additional scale can be applied via Canvas::Scale(). However,
// Canvas::Scale() does not affect |image_scale_|.
float image_scale_;
skia::RefPtr<skia::PlatformCanvas> owned_canvas_;
SkCanvas* canvas_;
DISALLOW_COPY_AND_ASSIGN(Canvas);
};
} // namespace gfx
#endif // UI_GFX_CANVAS_H_