chrome/browser/ui/app_list/app_list_positioner.h

   1 // Copyright 2013 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 CHROME_BROWSER_UI_APP_LIST_APP_LIST_POSITIONER_H_
   6 #define CHROME_BROWSER_UI_APP_LIST_APP_LIST_POSITIONER_H_
   7
   8 #include "ui/gfx/display.h"
   9 #include "ui/gfx/geometry/size.h"
  10
  11 namespace gfx {
  12 class Point;
  13 class Rect;
  14 }
  15
  16 // Helps anchor the App List, onto the shelf (taskbar, dock or similar) or to
  17 // the corner of a display. This class does not impose any particular policy for
  18 // when and how to anchor the window. The platform-specific code that uses this
  19 // class is free to decide, for example, when the window should be anchored to
  20 // the cursor versus the corner of the shelf. This class just performs the
  21 // calculations necessary to position the App List correctly.
  22 class AppListPositioner {
  23  public:
  24   // Represents one of the four edges of the screen.
  25   enum ScreenEdge {
  26     SCREEN_EDGE_UNKNOWN,
  27     SCREEN_EDGE_LEFT,
  28     SCREEN_EDGE_RIGHT,
  29     SCREEN_EDGE_TOP,
  30     SCREEN_EDGE_BOTTOM
  31   };
  32
  33   // Represents one of the four corners of the screen.
  34   enum ScreenCorner {
  35     SCREEN_CORNER_TOP_LEFT,
  36     SCREEN_CORNER_TOP_RIGHT,
  37     SCREEN_CORNER_BOTTOM_LEFT,
  38     SCREEN_CORNER_BOTTOM_RIGHT
  39   };
  40
  41   // The |display| pointer is borrowed, and must outlive this object's lifetime.
  42   // |window_size| is the size of the App List.
  43   // |min_distance_from_edge| is the minimum distance, in pixels, to position
  44   // the app list from the shelf or edge of screen.
  45   AppListPositioner(const gfx::Display& display,
  46                     const gfx::Size& window_size,
  47                     int min_distance_from_edge);
  48
  49   // Subtracts a rectangle from the display's work area. This can be used to
  50   // ensure that the app list does not overlap the shelf, even in situations
  51   // where the shelf is considered part of the work area.
  52   void WorkAreaSubtract(const gfx::Rect& rect);
  53
  54   // Shrinks the display's work area by the given amount on each side.
  55   void WorkAreaInset(int left, int top, int right, int bottom);
  56
  57   // Finds the position for a window to anchor it to a corner of the screen.
  58   // |corner| specifies which corner to anchor the window to. Returns the
  59   // intended coordinates for the center of the window. This should only be used
  60   // when there is no shelf on the display, because if there is, the returned
  61   // anchor point will potentially position the window under it.
  62   gfx::Point GetAnchorPointForScreenCorner(ScreenCorner corner) const;
  63
  64   // Finds the position for a window to anchor it to the center of the screen.
  65   // Returns the intended coordinates for the center of the window.
  66   gfx::Point GetAnchorPointForScreenCenter() const;
  67
  68   // Finds the position for a window to anchor it to the corner of the shelf.
  69   // The window will be aligned to the left of the work area for horizontal
  70   // shelves, or to the top for vertical shelves. |shelf_edge| specifies the
  71   // location of the shelf. |shelf_edge| must not be SCREEN_EDGE_UNKNOWN.
  72   // Returns the intended coordinates for the center of the window.
  73   gfx::Point GetAnchorPointForShelfCorner(ScreenEdge shelf_edge) const;
  74
  75   // Finds the position for a window to anchor it to the center of the shelf.
  76   // |shelf_edge| specifies the location of the shelf. It must not be
  77   // SCREEN_EDGE_UNKNOWN. Returns the intended coordinates for the center of the
  78   // window.
  79   gfx::Point GetAnchorPointForShelfCenter(ScreenEdge shelf_edge) const;
  80
  81   // Finds the position for a window to anchor it to the shelf at a point
  82   // closest to the user's mouse cursor. |shelf_edge| specifies the location of
  83   // the shelf; |cursor| specifies the location of the user's mouse cursor.
  84   // |shelf_edge| must not be SCREEN_EDGE_UNKNOWN. Returns the intended
  85   // coordinates for the center of the window.
  86   gfx::Point GetAnchorPointForShelfCursor(ScreenEdge shelf_edge,
  87                                           const gfx::Point& cursor) const;
  88
  89   // Determines which edge of the screen the shelf is attached to. Returns
  90   // SCREEN_EDGE_UNKNOWN if the shelf is unavailable, hidden, or not on the
  91   // current screen.
  92   ScreenEdge GetShelfEdge(const gfx::Rect& shelf_rect) const;
  93
  94   // Gets the lateral distance of the mouse cursor from the edge of the shelf.
  95   // For horizontal shelves, this is the vertical distance; for vertical
  96   // shelves, this is the horizontal distance. If the cursor is inside the
  97   // shelf, returns 0.
  98   int GetCursorDistanceFromShelf(ScreenEdge shelf_edge,
  99                                  const gfx::Point& cursor) const;
 100
 101  private:
 102   // Ensures that an anchor point will result in a window that is fully within
 103   // the work area. Returns the updated anchor point.
 104   gfx::Point ClampAnchorPoint(gfx::Point anchor) const;
 105
 106   gfx::Display display_;
 107
 108   // Size of the App List.
 109   gfx::Size window_size_;
 110
 111   // The minimum distance, in pixels, to position the app list from the shelf
 112   // or edge of screen.
 113   int min_distance_from_edge_;
 114 };
 115
 116 #endif  // CHROME_BROWSER_UI_APP_LIST_APP_LIST_POSITIONER_H_