Only support left/right maximizing at 50% width when the --ash-enable-alternate-caption-button

ash/wm/workspace/snap_sizer.h

 // 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 ASH_WM_WORKSPACE_SNAP_SIZER_H_
 #define ASH_WM_WORKSPACE_SNAP_SIZER_H_
 
 #include <vector>
 
 #include "ash/ash_export.h"
 #include "base/basictypes.h"
 #include "base/time/time.h"
 #include "ui/gfx/rect.h"
 
 namespace aura {
 class Window;
 }
 
 namespace ash {
 namespace internal {
 
-// SnapSizer is responsible for determining the resulting bounds of a window
-// that is being snapped to the left or right side of the screen.
-// The bounds used in this class are in the container's coordinates.
+// SnapSizer is responsible for determining how a window should be snapped to
+// the left or right of the screen. The bounds used in this class are in the
+// container's coordinates.
+// The SnapSizer currently only supports side maximizing the window but we want
+// to use this class for docking as well.
+// TODO(varkha): Add docking functionality to SnapSizer.
 class ASH_EXPORT SnapSizer {
  public:
   enum Edge {
     LEFT_EDGE,
     RIGHT_EDGE
   };
 
-  enum InputType {
-    TOUCH_MAXIMIZE_BUTTON_INPUT,
-    OTHER_INPUT
+  enum StepBehavior {
+    STEP_YES,
+    STEP_NO
   };
 
-  // Set |input_type| to |TOUCH_MAXIMIZE_BUTTON_INPUT| when called by a touch
-  // operation by the maximize button. This will allow the user to snap resize
-  // the window beginning close to the border.
+  // If |step_behavior| is STEP_NO, the SnapSizer will always snap to the
+  // default state and will always return the bounds for the default state.
+  // The value of |start| matters only if SnapSizer::Update() is called.
   SnapSizer(aura::Window* window,
             const gfx::Point& start,
             Edge edge,
-            InputType input_type);
+            StepBehavior step_behavior);
   virtual ~SnapSizer();
 
+  // Returns true if a window can be snapped to |edge|.
+  static bool CanSnapWindow(aura::Window* window);
+
   // Snaps a window left or right.
-  static void SnapWindow(aura::Window* window, Edge edge);
+  // If |step_behavior| is STEP_NO or if |window| is not snapped, the window
+  // is snapped with the default state.
+  // If |step_behavior| is STEP_YES and |window| is already snapped, the window
+  // is snapped to the next state.
+  static void SnapWindow(aura::Window* window,
+                         Edge edge,
+                         StepBehavior step_behavior);
+
+  // Snaps the window to the current state.
+  void Snap();
 
   // Updates the target bounds based on a mouse move.
   void Update(const gfx::Point& location);
 
   // Bounds to position the window at.
   const gfx::Rect& target_bounds() const { return target_bounds_; }
 
-  // Returns the appropriate snap bounds (e.g. if a window is already snapped,
-  // then it returns the next snap-bounds).
-  gfx::Rect GetSnapBounds(const gfx::Rect& bounds);
+ private:
+  enum State {
+    SIDE_MAXIMIZE
+  };
 
-  // Set the snap sizer to the button press default size and prevent resizing.
-  void SelectDefaultSizeAndDisableResize();
+  // Returns a list of valid states ordered from the state with the largest
+  // width to the state with the smallest width.
+  static std::vector<State> BuildValidStatesList(aura::Window* window,
+                                                 StepBehavior step_behavior);
 
-  // Returns the target bounds based on the edge and the provided |size_index|.
-  // For unit test purposes this function is not private.
-  gfx::Rect GetTargetBoundsForSize(size_t size_index) const;
-
- private:
   // Calculates the amount to increment by. This returns one of -1, 0 or 1 and
-  // is intended to by applied to |size_index_|. |x| is the current
+  // is intended to by applied to |state_index_|. |x| is the current
   // x-coordinate, and |reference_x| is used to determine whether to increase
   // or decrease the position. It's one of |last_adjust_x_| or |last_update_x_|.
   int CalculateIncrement(int x, int reference_x) const;
 
-  // Changes the bounds. |x| is the current x-coordinate and |delta| the amount
-  // to increase by. |delta| comes from CalculateIncrement() and is applied
-  // to |size_index_|.
-  void ChangeBounds(int x, int delta);
+  // Increments the current state (aka |state_index_|) by |delta| and updates
+  // |target_bounds_|.
+  void IncrementState(int delta);
 
-  // Returns the target bounds based on the edge and |size_index_|.
+  // Returns the target bounds based on |edge_| and |state_index_|.
   gfx::Rect GetTargetBounds() const;
 
   // Returns true if the specified point is along the edge of the screen.
   bool AlongEdge(int x) const;
 
   // Window being snapped.
   aura::Window* window_;
 
   const Edge edge_;
 
   // Current target bounds for the snap.
   gfx::Rect target_bounds_;
 
   // Time Update() was last invoked.
   base::TimeTicks time_last_update_;
 
-  // Index into |kSizes| that dictates the width of the screen the target
-  // bounds should get.
-  int size_index_;
-
-  // If set, |size_index_| will get ignored and the single button default
-  // setting will be used instead.
-  bool resize_disabled_;
-
-  // Number of times Update() has been invoked since last ChangeBounds().
+  // Number of times Update() has been invoked since last IncrementState().
   int num_moves_since_adjust_;
 
-  // X-coordinate the last time ChangeBounds() was invoked.
+  // X-coordinate the last time IncrementState() was invoked.
   int last_adjust_x_;
 
   // X-coordinate last supplied to Update().
   int last_update_x_;
 
   // Initial x-coordinate.
   const int start_x_;
 
-  // |TOUCH_MAXIMIZE_BUTTON_INPUT| if the snap sizer was created through a
-  // touch & drag operation of the maximizer button. It changes the behavior of
-  // the drag / resize behavior when the dragging starts close to the border.
-  const InputType input_type_;
+  // Index into |states_| that dictates the target bounds.
+  int state_index_;
 
-  // A list of usable window widths for size. This gets created when the
-  // sizer gets created.
-  const std::vector<int> usable_width_;
+  // The states that |window_| can step through, ordered from the state with
+  // the largest width to the state with the smallest width.
+  const std::vector<State> states_;
 
   DISALLOW_COPY_AND_ASSIGN(SnapSizer);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_WORKSPACE_SNAP_SIZER_H_