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   // A convenience method for painting a Painter in a particular region.
  34   // This translates the canvas to x/y and paints the painter.
  35   static void PaintPainterAt(gfx::Canvas* canvas,
  36                              Painter* painter,
  37                              const gfx::Rect& rect);
  38
  39   // Creates a painter that draws a gradient between the two colors.
  40   static Painter* CreateHorizontalGradient(SkColor c1, SkColor c2);
  41   static Painter* CreateVerticalGradient(SkColor c1, SkColor c2);
  42
  43   // Creates a painter that draws a multi-color gradient. |colors| contains the
  44   // gradient colors and |pos| the relative positions of the colors. The first
  45   // element in |pos| must be 0.0 and the last element 1.0. |count| contains
  46   // the number of elements in |colors| and |pos|.
  47   static Painter* CreateVerticalMultiColorGradient(SkColor* colors,
  48                                                    SkScalar* pos,
  49                                                    size_t count);
  50
  51   // Creates a painter that divides |image| into nine regions. The four corners
  52   // are rendered at the size specified in insets (eg. the upper-left corner is
  53   // rendered at 0 x 0 with a size of insets.left() x insets.top()). The four
  54   // edges are tiled and the center is stretched to fill the destination size.
  55   static Painter* CreateImagePainter(const gfx::ImageSkia& image,
  56                                      const gfx::Insets& insets);
  57
  58   // Creates a painter that paints nine images as a scalable grid. The four
  59   // corners are rendered in their full sizes (they are assumed to share widths
  60   // by column and heights by row). The four edges are tiled and the center is
  61   // stretched to fill the destination size.
  62   // |image_ids| must contain nine image IDs specified in this order: Top-Left,
  63   // Top, Top-Right, Left, Center, Right, Bottom-Left, Bottom, Bottom-Right.
  64   static Painter* CreateImageGridPainter(const int image_ids[]);
  65
  66   virtual ~Painter() {}
  67
  68   // Paints the painter in the specified region.
  69   virtual void Paint(gfx::Canvas* canvas, const gfx::Size& size) = 0;
  70 };
  71
  72 // HorizontalPainter paints 3 images into a box: left, center and right. The
  73 // left and right images are drawn to size at the left/right edges of the
  74 // region. The center is tiled in the remaining space. All images must have the
  75 // same height.
  76 class VIEWS_EXPORT HorizontalPainter : public Painter {
  77  public:
  78   // Constructs a new HorizontalPainter loading the specified image names.
  79   // The images must be in the order left, right and center.
  80   explicit HorizontalPainter(const int image_resource_names[]);
  81
  82   virtual ~HorizontalPainter() {}
  83
  84   // Paints the images.
  85   virtual void Paint(gfx::Canvas* canvas, const gfx::Size& size) OVERRIDE;
  86
  87   // Height of the images.
  88   int height() const { return height_; }
  89
  90  private:
  91   // The image chunks.
  92   enum BorderElements {
  93     LEFT,
  94     CENTER,
  95     RIGHT
  96   };
  97
  98   // The height.
  99   int height_;
 100   // NOTE: the images are owned by ResourceBundle. Don't free them.
 101   const gfx::ImageSkia* images_[3];
 102
 103   DISALLOW_COPY_AND_ASSIGN(HorizontalPainter);
 104 };
 105
 106 }  // namespace views
 107
 108 #endif  // UI_VIEWS_PAINTER_H_