views::Label: Implement context menu, keyboard shortcuts for copy/select all.

ui/views/controls/label.h

Index: ui/views/controls/label.h
diff --git a/ui/views/controls/label.h b/ui/views/controls/label.h
index df1414c3569854a61f5fa115e09055d80f639347..1aa91f2dc24a92ae05177e05bfd7a2dfc6e842bd 100644
--- a/ui/views/controls/label.h
+++ b/ui/views/controls/label.h
@@ -8,16 +8,22 @@
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
+#include "ui/base/models/simple_menu_model.h"
 #include "ui/gfx/render_text.h"
+#include "ui/views/context_menu_controller.h"
 #include "ui/views/selection_controller_delegate.h"
 #include "ui/views/view.h"
 
 namespace views {
 class LabelTest;
+class MenuRunner;
 class SelectionController;
 
 // A view subclass that can display a string.
-class VIEWS_EXPORT Label : public View, public SelectionControllerDelegate {
+class VIEWS_EXPORT Label : public View,
+                           public ContextMenuController,
+                           public SelectionControllerDelegate,
+                           public ui::SimpleMenuModel::Delegate {

[msw, 2016/11/09 18:32:53]

It would be nice to use composition instead of inheritance, and have a shared
context menu model/controller class for Textfield and Label, but I don't know if
that's really feasible.

[karandeepb, 2016/11/15 10:54:32]

It may be feasible, but since we are just implementing Copy/Select All, unlike
the text selection case, there isn't much logic to be shared between the two
classes. Also, again, the controller class would need to have a delegate
interface to interact with, which may lead to unnecessary boilerplate.

[msw, 2016/11/15 20:06:45]

Agreed, it's fine as-is for now.

  public:
   // Internal class name.
   static const char kViewClassName[];
@@ -208,6 +214,9 @@ class VIEWS_EXPORT Label : public View, public SelectionControllerDelegate {
   bool OnMouseDragged(const ui::MouseEvent& event) override;
   void OnMouseReleased(const ui::MouseEvent& event) override;
   void OnMouseCaptureLost() override;
+  bool AcceleratorPressed(const ui::Accelerator& accelerator) override;
+  bool CanHandleAccelerators() const override;
+  bool OnKeyPressed(const ui::KeyEvent& event) override;

[msw, 2016/11/09 18:32:53]

nit: match the order in view.h

[karandeepb, 2016/11/15 10:54:32]

Done. Order for the existing functions wasn't correct, but I guess it's ok for
the new functions.

 
  private:
   FRIEND_TEST_ALL_PREFIXES(LabelTest, ResetRenderTextData);
@@ -218,6 +227,18 @@ class VIEWS_EXPORT Label : public View, public SelectionControllerDelegate {
   FRIEND_TEST_ALL_PREFIXES(LabelTest, MultiLineSizingWithElide);
   friend class LabelTest;
 
+  // ui::SimpleMenuModel::Delegate overrides:

[msw, 2016/11/09 18:32:53]

nit: try to keep the same order as the subclass list.

[karandeepb, 2016/11/15 10:54:32]

Done.

+  bool IsCommandIdChecked(int command_id) const override;
+  bool IsCommandIdEnabled(int command_id) const override;
+  void ExecuteCommand(int command_id, int event_flags) override;
+  bool GetAcceleratorForCommandId(int command_id,
+                                  ui::Accelerator* accelerator) const override;
+
+  // ContextMenuController overrides:
+  void ShowContextMenuForView(View* source,
+                              const gfx::Point& point,
+                              ui::MenuSourceType source_type) override;
+
   // SelectionControllerDelegate overrides:
   gfx::RenderText* GetRenderTextForSelectionController() override;
   bool IsReadOnly() const override;
@@ -263,6 +284,15 @@ class VIEWS_EXPORT Label : public View, public SelectionControllerDelegate {
   // Empties |lines_| and updates |stored_selection_range_|.
   void ClearRenderTextLines() const;
 
+  // Returns the currently selected text.
+  base::string16 GetSelectedText() const;
+
+  // Updates the clipboard with the currently selected text.
+  void CopyToClipboard();
+
+  // Builds |context_menu_contents_|.
+  void BuildContextMenuContents();
+
   // An un-elided and single-line RenderText object used for preferred sizing.
   std::unique_ptr<gfx::RenderText> render_text_;
 
@@ -309,6 +339,10 @@ class VIEWS_EXPORT Label : public View, public SelectionControllerDelegate {
 
   std::unique_ptr<SelectionController> selection_controller_;
 
+  // Context menu related members.
+  std::unique_ptr<ui::SimpleMenuModel> context_menu_contents_;

[msw, 2016/11/09 18:32:53]

nit: avoid unique_ptr, use plain member, if possible.
(but I guess this follows Textfield, so it's okay as-is too)

[karandeepb, 2016/11/15 10:54:32]

Done.

+  std::unique_ptr<views::MenuRunner> context_menu_runner_;
+
   DISALLOW_COPY_AND_ASSIGN(Label);
 };