ui/views/painter.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 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_