Make Textfield scroll continuously when dragging beyond edges.

ui/views/controls/textfield/textfield.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 UI_VIEWS_CONTROLS_TEXTFIELD_TEXTFIELD_H_
 #define UI_VIEWS_CONTROLS_TEXTFIELD_TEXTFIELD_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 305 matching lines @@
   void UpdateCursor();
 
   // Repaint the cursor.
   void RepaintCursor();
 
   void PaintTextAndCursor(gfx::Canvas* canvas);
 
   // Helper function to call MoveCursorTo on the TextfieldModel.
   void MoveCursorTo(const gfx::Point& point, bool select);
 
+  // Helper function to update the selection on a mouse drag.
+  void SelectThroughLastDragLocation();
+
   // Convenience method to notify the InputMethod and TouchSelectionController.
   void OnCaretBoundsChanged();
 
   // Convenience method to call TextfieldController::OnBeforeUserAction();
   void OnBeforeUserAction();
 
   // Convenience method to call TextfieldController::OnAfterUserAction();
   void OnAfterUserAction();
 
   // Calls |model_->Cut()| and notifies TextfieldController on success.
@@ skipping 35 matching lines @@
 
   // True if this Textfield cannot accept input and is read-only.
   bool read_only_;
 
   // The default number of average characters for the width of this text field.
   // This will be reported as the "desired size". Defaults to 0.
   int default_width_in_chars_;
 
   scoped_ptr<Painter> focus_painter_;
 
-  // Text color.  Only used if |use_default_text_color_| is false.
+  // Flags indicating whether text and background system colors should be used,
+  // and the actual color values used if the corresponding flags are set false.
   SkColor text_color_;
-
-  // Should we use the system text color instead of |text_color_|?
   bool use_default_text_color_;
-
-  // Background color.  Only used if |use_default_background_color_| is false.
   SkColor background_color_;
-
-  // Should we use the system background color instead of |background_color_|?
   bool use_default_background_color_;
 
   // Text to display when empty.
   base::string16 placeholder_text_;
 
   // Placeholder text color.
   SkColor placeholder_text_color_;
 
   // The accessible name of the text field.
   base::string16 accessible_name_;
 
   // The input type of this text field.
   ui::TextInputType text_input_type_;
 
   // The duration and timer to reveal the last typed password character.
   base::TimeDelta password_reveal_duration_;
   base::OneShotTimer<Textfield> password_reveal_timer_;
 
-  // Keeps track of whether currently performing a user action (i.e. when
-  // OnBeforeUserAction() has been called, but OnAfterUserAction() is yet to be
-  // called).
+  // Tracks whether a user action is being performed; i.e. OnBeforeUserAction()
+  // has been called, but OnAfterUserAction() has not yet been called.
   bool performing_user_action_;
 
   // True if InputMethod::CancelComposition() should not be called.
   bool skip_input_method_cancel_composition_;
 
   // The text editing cursor repaint timer and visibility.
   base::RepeatingTimer<Textfield> cursor_repaint_timer_;
   bool cursor_visible_;
 
   // The drop cursor is a visual cue for where dragged text will be dropped.
   bool drop_cursor_visible_;
   gfx::SelectionModel drop_cursor_position_;
 
   // Is the user potentially dragging and dropping from this view?
   bool initiating_drag_;
 
+  // A timer and point used to modify the selection when dragging.
+  base::RepeatingTimer<Textfield> drag_selection_timer_;
+  gfx::Point last_drag_location_;
+
   // State variables used to track double and triple clicks.
   size_t aggregated_clicks_;
   base::TimeDelta last_click_time_;
   gfx::Point last_click_location_;
   gfx::Range double_click_word_;
 
   scoped_ptr<ui::TouchSelectionController> touch_selection_controller_;
 
   // Context menu related members.
   scoped_ptr<ui::SimpleMenuModel> context_menu_contents_;
   scoped_ptr<views::MenuRunner> context_menu_runner_;
 
   // Used to bind callback functions to this object.
   base::WeakPtrFactory<Textfield> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Textfield);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_TEXTFIELD_TEXTFIELD_H_