Label selection experiment

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 9421d1dc68fcad05c2434e122a395c3df2cb994f..1ef8e09ed1ee1fc811249012b69bd467786852ae 100644
--- a/ui/views/controls/label.h
+++ b/ui/views/controls/label.h
@@ -8,13 +8,15 @@
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
+#include "base/optional.h"
 #include "ui/gfx/render_text.h"
+#include "ui/views/selection_controller.h"
 #include "ui/views/view.h"
 
 namespace views {
 
 // A view subclass that can display a string.
-class VIEWS_EXPORT Label : public View {
+class VIEWS_EXPORT Label : public View, SelectionController::Delegate {
  public:
   // Internal class name.
   static const char kViewClassName[];
@@ -51,11 +53,23 @@ class VIEWS_EXPORT Label : public View {
 
   SkColor enabled_color() const { return actual_enabled_color_; }
 
-  // Sets the background color.  This won't be explicitly drawn, but the label
+  // Sets the background color. This won't be explicitly drawn, but the label
   // will force the text color to be readable over it.
   void SetBackgroundColor(SkColor color);
   SkColor background_color() const { return background_color_; }
 
+  // Sets the selection text color. This will automatically force the color to
+  // be readable over the selection background color, if auto color readability
+  // is enabled. Initialized with system default.
+  void SetSelectionTextColor(SkColor color);
+  SkColor selection_text_color() const { return actual_selection_text_color_; }
+
+  // Sets the selection background color. Initialized with system default.
+  void SetSelectionBackgroundColor(SkColor color);
+  SkColor selection_background_color() const {
+    return selection_background_color_;
+  }
+
   // Set drop shadows underneath the text.
   void SetShadows(const gfx::ShadowValues& shadows);
   const gfx::ShadowValues& shadows() const { return render_text_->shadows(); }
@@ -126,6 +140,31 @@ class VIEWS_EXPORT Label : public View {
   // Get the text as displayed to the user, respecting the obscured flag.
   base::string16 GetDisplayTextForTesting();
 
+  // Returns true if the label can be made selectable. For example, multiline
+  // labels do not currently support text selection.
+  virtual bool IsSelectionSupported() const;
+
+  // Returns true if the label is selectable. Default is false.
+  bool selectable() const { return selection_controller_.get() != nullptr; }
+
+  // Sets whether the label is selectable. False is returned if the call fails,
+  // i.e. when selection is not supported but |selectable| is true.
+  bool SetSelectable(bool selectable);
+
+  // Returns true if the label has a selection.
+  // Todo(karandeepb): Make the method const.
+  bool HasSelection();
+
+  // Selects the entire text. NO-OP if the label is not selectable.
+  void SelectAll();
+
+  // Clears any active selection.
+  void ClearSelection();
+
+  // Selects the given text range. NO-OP if the label is not selectable or the
+  // |range| endpoints don't lie on the grapheme boundaries.
+  void SelectRange(const gfx::Range& range);
+
   // View:
   gfx::Insets GetInsets() const override;
   int GetBaseline() const override;
@@ -159,6 +198,12 @@ class VIEWS_EXPORT Label : public View {
   void OnPaint(gfx::Canvas* canvas) override;
   void OnDeviceScaleFactorChanged(float device_scale_factor) override;
   void OnNativeThemeChanged(const ui::NativeTheme* theme) override;
+  gfx::NativeCursor GetCursor(const ui::MouseEvent& event) override;
+  void OnFocus() override;
+  void OnBlur() override;
+  bool OnMousePressed(const ui::MouseEvent& event) override;
+  bool OnMouseDragged(const ui::MouseEvent& event) override;
+  void OnMouseReleased(const ui::MouseEvent& event) override;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(LabelTest, ResetRenderTextData);
@@ -167,6 +212,22 @@ class VIEWS_EXPORT Label : public View {
   FRIEND_TEST_ALL_PREFIXES(LabelFocusTest, FocusBounds);
   FRIEND_TEST_ALL_PREFIXES(LabelFocusTest, EmptyLabel);
 
+  // SelectionController::Delegate overrides:
+  gfx::RenderText* GetRenderTextForSelection() override;
+  bool IsReadOnly() const override;
+  bool SupportsDrag() const override;
+  bool HasTextBeingDragged() const override;
+  void SetTextBeingDragged(bool value) override;
+  int GetViewHeight() const override;
+  int GetViewWidth() const override;
+  int GetDragSelectionDelay() const override;
+  void OnBeforeMouseAction() override;
+  void OnAfterMouseAction(bool text_changed, bool selection_changed) override;
+  void OnBeforeSelectionUpdated() override;
+  void OnAfterSelectionUpdated() override;
+  void PasteSelectionClipboard(const ui::MouseEvent& event) override;
+  void UpdateSelectionClipboard() override;
+
   void Init(const base::string16& text, const gfx::FontList& font_list);
 
   void ResetLayout();
@@ -193,22 +254,38 @@ class VIEWS_EXPORT Label : public View {
 
   bool ShouldShowDefaultTooltip() const;
 
+  // Called when the text selection is updated. NO-OP if a mouse action is in
+  // progress.
+  void OnSelectionUpdated();
+
+  // Empties |lines_| and updates |last_selection_range_|.
+  void ClearLines();
+
   // An un-elided and single-line RenderText object used for preferred sizing.
   std::unique_ptr<gfx::RenderText> render_text_;
 
   // The RenderText instances used to display elided and multi-line text.
   std::vector<std::unique_ptr<gfx::RenderText>> lines_;
 
+  // Persists the current selection range between the calls to ClearLines() and
+  // MaybeBuildRenderTextLines().
+  base::Optional<gfx::Range> last_selection_range_;
+
   SkColor requested_enabled_color_;
   SkColor actual_enabled_color_;
   SkColor requested_disabled_color_;
   SkColor actual_disabled_color_;
   SkColor background_color_;
+  SkColor requested_selection_text_color_;
+  SkColor actual_selection_text_color_;
+  SkColor selection_background_color_;
 
   // Set to true once the corresponding setter is invoked.
   bool enabled_color_set_;
   bool disabled_color_set_;
   bool background_color_set_;
+  bool selection_text_color_set_;
+  bool selection_background_color_set_;
 
   gfx::ElideBehavior elide_behavior_;
 
@@ -227,6 +304,12 @@ class VIEWS_EXPORT Label : public View {
   // closed.
   bool is_first_paint_text_;
 
+  // Tracks whether a mouse action is being performed i.e. OnBeforeMouseAction()
+  // has been called, but OnAfterMouseAction() has not yet been called.
+  bool performing_mouse_action_;
+
+  std::unique_ptr<SelectionController> selection_controller_;
+
   DISALLOW_COPY_AND_ASSIGN(Label);
 };