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      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 UI_VIEWS_PAINTER_H_
      6 #define UI_VIEWS_PAINTER_H_
      7 
      8 #include "base/basictypes.h"
      9 #include "base/compiler_specific.h"
     10 #include "third_party/skia/include/core/SkColor.h"
     11 #include "ui/views/views_export.h"
     12 
     13 namespace gfx {
     14 class Canvas;
     15 class ImageSkia;
     16 class Insets;
     17 class Rect;
     18 class Size;
     19 }
     20 
     21 // A macro to define arrays of IDR constants used with CreateImageGridPainter.
     22 #define IMAGE_GRID(x) { x ## _TOP_LEFT,    x ## _TOP,    x ## _TOP_RIGHT, \
     23                         x ## _LEFT,        x ## _CENTER, x ## _RIGHT, \
     24                         x ## _BOTTOM_LEFT, x ## _BOTTOM, x ## _BOTTOM_RIGHT, }
     25 
     26 namespace views {
     27 
     28 // Painter, as the name implies, is responsible for painting in a particular
     29 // region. Think of Painter as a Border or Background that can be painted
     30 // in any region of a View.
     31 class VIEWS_EXPORT Painter {
     32  public:
     33   Painter();
     34   virtual ~Painter();
     35 
     36   // A convenience method for painting a Painter in a particular region.
     37   // This translates the canvas to x/y and paints the painter.
     38   static void PaintPainterAt(gfx::Canvas* canvas,
     39                              Painter* painter,
     40                              const gfx::Rect& rect);
     41 
     42   // Creates a painter that draws a gradient between the two colors.
     43   static Painter* CreateHorizontalGradient(SkColor c1, SkColor c2);
     44   static Painter* CreateVerticalGradient(SkColor c1, SkColor c2);
     45 
     46   // Creates a painter that draws a multi-color gradient. |colors| contains the
     47   // gradient colors and |pos| the relative positions of the colors. The first
     48   // element in |pos| must be 0.0 and the last element 1.0. |count| contains
     49   // the number of elements in |colors| and |pos|.
     50   static Painter* CreateVerticalMultiColorGradient(SkColor* colors,
     51                                                    SkScalar* pos,
     52                                                    size_t count);
     53 
     54   // Creates a painter that divides |image| into nine regions. The four corners
     55   // are rendered at the size specified in insets (eg. the upper-left corner is
     56   // rendered at 0 x 0 with a size of insets.left() x insets.top()). The center
     57   // and edge images are stretched to fill the painted area.
     58   static Painter* CreateImagePainter(const gfx::ImageSkia& image,
     59                                      const gfx::Insets& insets);
     60 
     61   // Creates a painter that paints images in a scalable grid. The images must
     62   // share widths by column and heights by row. The corners are painted at full
     63   // size, while center and edge images are stretched to fill the painted area.
     64   // The center image may be zero (to be skipped). This ordering must be used:
     65   // Top-Left/Top/Top-Right/Left/[Center]/Right/Bottom-Left/Bottom/Bottom-Right.
     66   static Painter* CreateImageGridPainter(const int image_ids[]);
     67 
     68   // Returns the minimum size this painter can paint without obvious graphical
     69   // problems (e.g. overlapping images).
     70   virtual gfx::Size GetMinimumSize() const = 0;
     71 
     72   // Paints the painter in the specified region.
     73   virtual void Paint(gfx::Canvas* canvas, const gfx::Size& size) = 0;
     74 
     75  private:
     76   DISALLOW_COPY_AND_ASSIGN(Painter);
     77 };
     78 
     79 // HorizontalPainter paints 3 images into a box: left, center and right. The
     80 // left and right images are drawn to size at the left/right edges of the
     81 // region. The center is tiled in the remaining space. All images must have the
     82 // same height.
     83 class VIEWS_EXPORT HorizontalPainter : public Painter {
     84  public:
     85   // Constructs a new HorizontalPainter loading the specified image names.
     86   // The images must be in the order left, right and center.
     87   explicit HorizontalPainter(const int image_resource_names[]);
     88   virtual ~HorizontalPainter();
     89 
     90   // Painter:
     91   virtual gfx::Size GetMinimumSize() const OVERRIDE;
     92   virtual void Paint(gfx::Canvas* canvas, const gfx::Size& size) OVERRIDE;
     93 
     94  private:
     95   // The image chunks.
     96   enum BorderElements {
     97     LEFT,
     98     CENTER,
     99     RIGHT
    100   };
    101 
    102   // NOTE: the images are owned by ResourceBundle. Don't free them.
    103   const gfx::ImageSkia* images_[3];
    104 
    105   DISALLOW_COPY_AND_ASSIGN(HorizontalPainter);
    106 };
    107 
    108 }  // namespace views
    109 
    110 #endif  // UI_VIEWS_PAINTER_H_
    111