Views: Extract text selection code from Textfield.

ui/views/selection_controller_delegate.h

+// Copyright 2016 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_SELECTION_CONTROLLER_DELEGATE_H_
+#define UI_VIEWS_SELECTION_CONTROLLER_DELEGATE_H_
+
+#include "ui/views/views_export.h"
+
+namespace ui {
+class MouseEvent;
+}
+
+namespace views {
+
+// An interface implemented/managed by a view which uses the
+// SelectionController.
+class VIEWS_EXPORT SelectionControllerDelegate {
+ public:
+  // Returns the associated RenderText instance to be used for selection.
+  virtual gfx::RenderText* GetRenderTextForSelectionController() = 0;
+
+  // Methods related to properties of the associated view.
+
+  // Returns true if the associated text view is read only.
+  virtual bool IsReadOnly() const = 0;
+  // Returns whether there is a drag operation originating from the associated
+  // view.
+  virtual bool HasTextBeingDragged() const = 0;
+  // Sets whether text is being dragged from the associated view.
+  virtual void SetTextBeingDragged(bool value) = 0;
+  // Returns the height of the associated view.
+  virtual int GetViewHeight() const = 0;
+  // Returns the width of the associated view.
+  virtual int GetViewWidth() const = 0;
+  // Returns the drag selection timer delay. This is the duration after which a
+  // drag selection is updated when the event location is outside the text
+  // bounds.
+  virtual int GetDragSelectionDelay() const = 0;
+
+  // Called before a mouse action which may change the associated view's
+  // selection and/or text. Should not be called in succession and must always
+  // be followed by an OnAfterMouseAction call.
+  virtual void OnBeforeMouseAction() = 0;

[sky, 2016/10/21 15:03:40]

You are going to need to handle touch/gesture at some point. I'm ok postponing
that for now, but I think you should at least get the api right. Don't use Mouse
here as it's going to be used for touch/gesture in the future. We've used
Pointer to mean touch or mouse. So, I recommend using Pointer here too, e.g.
OnBeforePointerAction.

[karandeepb, 2016/10/25 05:30:42]

Done.

+  // Called after a mouse action. |text_changed| and |selection_changed| can be
+  // used by subclasses to make any necessary updates like redraw the text. Must
+  // always be preceeded by an OnBeforeMouseAction call.
+  virtual void OnAfterMouseAction(bool text_changed,
+                                  bool selection_changed) = 0;
+
+  // Pastes the text from the selection clipboard at the current cursor
+  // position. Always called within a mouse action for a non-readonly view.
+  // Returns true if some text was pasted.
+  virtual bool PasteSelectionClipboard() = 0;
+  // Updates the selection clipboard with the currently selected text. Should
+  // empty the selection clipboard if no text is currently selected.
+  // NO-OP if the associated text view is obscured. Since this does not modify
+  // the render text instance, it may be called outside of a mouse action.
+  virtual void UpdateSelectionClipboard() = 0;
+
+ protected:
+  virtual ~SelectionControllerDelegate() {}
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_SELECTION_CONTROLLER_DELEGATE_H_