Views:: Make Labels support text selection.

ui/views/controls/label.cc

Index: ui/views/controls/label.cc
diff --git a/ui/views/controls/label.cc b/ui/views/controls/label.cc
index 0c4667dad17cab28ccb7493022d918842fb7fa85..b21fdd6938242c97668ce690a72b33130b0d2190 100644
--- a/ui/views/controls/label.cc
+++ b/ui/views/controls/label.cc
@@ -18,6 +18,8 @@
 #include "base/strings/string_split.h"
 #include "base/strings/utf_string_conversions.h"
 #include "ui/accessibility/ax_view_state.h"
+#include "ui/base/clipboard/scoped_clipboard_writer.h"
+#include "ui/base/cursor/cursor.h"
 #include "ui/base/default_style.h"
 #include "ui/base/material_design/material_design_controller.h"
 #include "ui/base/resource/resource_bundle.h"
@@ -26,6 +28,8 @@
 #include "ui/gfx/geometry/insets.h"
 #include "ui/gfx/text_elider.h"
 #include "ui/native_theme/native_theme.h"
+#include "ui/views/focus/focus_manager.h"
+#include "ui/views/native_cursor.h"
 
 namespace views {
 // static
@@ -100,6 +104,24 @@ void Label::SetBackgroundColor(SkColor color) {
   RecalculateColors();
 }
 
+void Label::SetSelectionTextColor(SkColor color) {
+  if (selection_text_color_set_ && requested_selection_text_color_ == color)
+    return;
+  is_first_paint_text_ = true;
+  requested_selection_text_color_ = color;
+  selection_text_color_set_ = true;
+  RecalculateColors();
+}
+
+void Label::SetSelectionBackgroundColor(SkColor color) {
+  if (selection_background_color_set_ && selection_background_color_ == color)
+    return;
+  is_first_paint_text_ = true;
+  selection_background_color_ = color;
+  selection_background_color_set_ = true;
+  RecalculateColors();
+}
+
 void Label::SetShadows(const gfx::ShadowValues& shadows) {
   // TODO(mukai): early exit if the specified shadows are same.
   is_first_paint_text_ = true;
@@ -147,6 +169,8 @@ void Label::SetMultiLine(bool multi_line) {
   if (render_text_->MultilineSupported())
     render_text_->SetMultiline(multi_line);
   render_text_->SetReplaceNewlineCharsWithSymbols(!multi_line);
+  if (multi_line)
+    SetSelectable(false);
   ResetLayout();
 }
 
@@ -204,7 +228,7 @@ void Label::SetMaximumWidth(int max_width) {
 }
 
 base::string16 Label::GetDisplayTextForTesting() {
-  lines_.clear();
+  ClearLines();
   MaybeBuildRenderTextLines();
   base::string16 result;
   if (lines_.empty())
@@ -217,6 +241,48 @@ base::string16 Label::GetDisplayTextForTesting() {
   return result;
 }
 
+bool Label::IsSelectionSupported() const {
+  return !multi_line() && render_text_->IsSelectionSupported();
+}
+
+bool Label::SetSelectable(bool value) {
+  if (value == selectable())
+    return true;
+
+  if (value && !IsSelectionSupported())
+    return false;
+
+  ClearSelection();
+  selection_controller_.reset(value ? new SelectionController(this) : nullptr);
+  return true;
+}
+
+bool Label::HasSelection() {
+  gfx::RenderText* render_text = GetRenderTextForSelection();
+  return render_text ? !render_text->selection().is_empty() : false;
+}
+
+void Label::SelectAll() {
+  if (!GetRenderTextForSelection())
+    return;
+  GetRenderTextForSelection()->SelectAll(false);
+  OnSelectionUpdated();
+}
+
+void Label::ClearSelection() {
+  if (!GetRenderTextForSelection())
+    return;
+  GetRenderTextForSelection()->ClearSelection();
+  OnSelectionUpdated();
+}
+
+void Label::SelectRange(const gfx::Range& range) {
+  if (!GetRenderTextForSelection())
+    return;
+  if (GetRenderTextForSelection()->SelectRange(range))
+    OnSelectionUpdated();
+}
+
 gfx::Insets Label::GetInsets() const {
   gfx::Insets insets = View::GetInsets();
   if (focus_behavior() != FocusBehavior::NEVER) {
@@ -296,7 +362,7 @@ int Label::GetHeightForWidth(int w) const {
 }
 
 void Label::Layout() {
-  lines_.clear();
+  ClearLines();
 }
 
 const char* Label::GetClassName() const {
@@ -312,8 +378,7 @@ View* Label::GetTooltipHandlerForPoint(const gfx::Point& point) {
 }
 
 bool Label::CanProcessEventsWithinSubtree() const {
-  // Send events to the parent view for handling.
-  return false;
+  return selectable();
 }
 
 void Label::GetAccessibleState(ui::AXViewState* state) {
@@ -389,14 +454,68 @@ void Label::OnPaint(gfx::Canvas* canvas) {
   } else {
     PaintText(canvas);
   }
-  if (HasFocus() && !ui::MaterialDesignController::IsSecondaryUiMaterial())
+
+  // Check for IsAccessibilityFocusable() to prevent drawing a focus rect for
+  // non-focusable labels with selection, which are given focus explicitly in
+  // OnMousePressed.
+  if (HasFocus() && !ui::MaterialDesignController::IsSecondaryUiMaterial() &&
+      IsAccessibilityFocusable()) {
     canvas->DrawFocusRect(GetFocusBounds());
+  }
 }
 
 void Label::OnNativeThemeChanged(const ui::NativeTheme* theme) {
   UpdateColorsFromTheme(theme);
 }
 
+gfx::NativeCursor Label::GetCursor(const ui::MouseEvent& event) {
+  return GetRenderTextForSelection() ? GetNativeIBeamCursor()
+                                     : gfx::kNullCursor;
+}
+
+void Label::OnFocus() {
+  if (GetRenderTextForSelection()) {
+    GetRenderTextForSelection()->set_focused(true);
+    SchedulePaint();
+  }
+  View::OnFocus();
+}
+
+void Label::OnBlur() {
+  if (GetRenderTextForSelection()) {
+    GetRenderTextForSelection()->set_focused(false);
+    SchedulePaint();
+  }
+  View::OnBlur();
+}
+
+bool Label::OnMousePressed(const ui::MouseEvent& event) {
+  DCHECK(selectable());
+  if (!GetRenderTextForSelection())
+    return false;
+
+  // RequestFocus() won't work when the label has FocusBehavior::NEVER. Hence
+  // explicitly set the focused view.
+  // Todo(karandeepb): If a widget with a label having FocusBehavior::NEVER as
+  // the currently focused view (due to selection) was to lose focus, focus

[karandeepb, 2016/10/14 09:31:33]

See the linked doc for some possible approaches to solve this.

+  // won't be restored to the label (and hence a text selection won't be drawn)
+  // when the widget gets focus again. Fix this.
+  // Todo is giving focus to a view with FocusBehavior::NEVER ok?
+  if (GetFocusManager())
+    GetFocusManager()->SetFocusedView(this);
+  return selection_controller_->OnMousePressed(event, false);
+}
+
+bool Label::OnMouseDragged(const ui::MouseEvent& event) {
+  DCHECK(GetRenderTextForSelection());
+  return selection_controller_->OnMouseDragged(event);
+}
+
+void Label::OnMouseReleased(const ui::MouseEvent& event) {
+  DCHECK(GetRenderTextForSelection());
+  selection_controller_->OnMouseReleased(event);
+}
+
 void Label::OnDeviceScaleFactorChanged(float device_scale_factor) {
   View::OnDeviceScaleFactorChanged(device_scale_factor);
   // When the device scale factor is changed, some font rendering parameters is
@@ -407,7 +526,86 @@ void Label::OnDeviceScaleFactorChanged(float device_scale_factor) {
 
 void Label::VisibilityChanged(View* starting_from, bool is_visible) {
   if (!is_visible)
-    lines_.clear();
+    ClearLines();
+}
+
+gfx::RenderText* Label::GetRenderTextForSelection() {
+  if (!selectable())
+    return nullptr;
+  DCHECK(IsSelectionSupported());
+  MaybeBuildRenderTextLines();
+  if (lines_.empty())
+    return nullptr;
+  DCHECK_EQ(1u, lines_.size());
+  return lines_[0].get();
+}
+
+bool Label::IsReadOnly() const {
+  return true;
+}
+
+bool Label::SupportsDrag() const {
+  return false;
+}
+
+bool Label::HasTextBeingDragged() const {
+  return false;
+}
+
+void Label::SetTextBeingDragged(bool value) {}
+
+int Label::GetViewHeight() const {
+  return height();
+}
+
+int Label::GetViewWidth() const {
+  return width();
+}
+
+int Label::GetDragSelectionDelay() const {
+  // Labels don't need to use a repeating timer to update drag selection. Since
+  // the cursor is disabled for labels, a selection outside the display area
+  // won't change the text in the display area. It is expected that all the text
+  // will fit in the display area for labels anyway.
+  return 0;
+}
+
+void Label::OnBeforeMouseAction() {
+  DCHECK(!performing_mouse_action_);
+  DCHECK(GetRenderTextForSelection());
+  performing_mouse_action_ = true;
+}
+
+void Label::OnAfterMouseAction(bool text_changed, bool selection_changed) {
+  DCHECK(!text_changed);
+  DCHECK(performing_mouse_action_);
+  DCHECK(GetRenderTextForSelection());
+  performing_mouse_action_ = false;
+  if (selection_changed)
+    OnSelectionUpdated();
+}
+
+void Label::OnBeforeSelectionUpdated() {
+  DCHECK(performing_mouse_action_);
+}
+
+void Label::OnAfterSelectionUpdated() {
+  DCHECK(performing_mouse_action_);
+  OnSelectionUpdated();
+}
+
+void Label::PasteSelectionClipboard(const ui::MouseEvent& event) {}
+
+void Label::UpdateSelectionClipboard() {
+#if defined(OS_LINUX) && !defined(OS_CHROMEOS)
+  gfx::RenderText* render_text = GetRenderTextForSelection();
+  if (performing_mouse_action_ && !obscured() && render_text) {
+    base::string16 selected_text =
+        render_text->GetTextFromRange(render_text->selection());
+    ui::ScopedClipboardWriter(ui::CLIPBOARD_TYPE_SELECTION)
+        .WriteText(selected_text);
+  }
+#endif
 }
 
 void Label::Init(const base::string16& text, const gfx::FontList& font_list) {
@@ -423,6 +621,7 @@ void Label::Init(const base::string16& text, const gfx::FontList& font_list) {
 
   elide_behavior_ = gfx::ELIDE_TAIL;
   enabled_color_set_ = disabled_color_set_ = background_color_set_ = false;
+  selection_text_color_set_ = selection_background_color_set_ = false;
   subpixel_rendering_enabled_ = true;
   auto_color_readability_ = true;
   multi_line_ = false;
@@ -432,6 +631,7 @@ void Label::Init(const base::string16& text, const gfx::FontList& font_list) {
   fixed_width_ = 0;
   max_width_ = 0;
   is_first_paint_text_ = true;
+  performing_mouse_action_ = false;
   SetText(text);
 }
 
@@ -439,7 +639,7 @@ void Label::ResetLayout() {
   InvalidateLayout();
   PreferredSizeChanged();
   SchedulePaint();
-  lines_.clear();
+  ClearLines();
 }
 
 void Label::MaybeBuildRenderTextLines() {
@@ -493,6 +693,15 @@ void Label::MaybeBuildRenderTextLines() {
     for (size_t i = lines_.size(); i < lines.size(); ++i)
       lines_.back()->SetText(lines_.back()->text() + lines[i]);
   }
+
+  if (GetRenderTextForSelection())
+    GetRenderTextForSelection()->set_focused(HasFocus());
+
+  if (last_selection_range_) {
+    SelectRange(last_selection_range_.value());
+    last_selection_range_.reset();
+  }
+
   ApplyTextColors();
 }
 
@@ -571,6 +780,11 @@ void Label::RecalculateColors() {
       color_utils::GetReadableColor(requested_disabled_color_,
                                     background_color_) :
       requested_disabled_color_;
+  actual_selection_text_color_ =
+      auto_color_readability_
+          ? color_utils::GetReadableColor(requested_selection_text_color_,
+                                          selection_background_color_)
+          : requested_selection_text_color_;
 
   ApplyTextColors();
   SchedulePaint();
@@ -582,6 +796,9 @@ void Label::ApplyTextColors() {
       SkColorGetA(background_color_) != 0xFF || !subpixel_rendering_enabled_;
   for (size_t i = 0; i < lines_.size(); ++i) {
     lines_[i]->SetColor(color);
+    lines_[i]->set_selection_color(actual_selection_text_color_);
+    lines_[i]->set_selection_background_focused_color(
+        selection_background_color_);
     lines_[i]->set_subpixel_rendering_suppressed(subpixel_rendering_suppressed);
   }
 }
@@ -599,6 +816,15 @@ void Label::UpdateColorsFromTheme(const ui::NativeTheme* theme) {
     background_color_ =
         theme->GetSystemColor(ui::NativeTheme::kColorId_DialogBackground);
   }
+  if (!selection_text_color_set_) {
+    // Todo create new default for labels or rename Textfield to Text?
+    requested_selection_text_color_ = theme->GetSystemColor(
+        ui::NativeTheme::kColorId_TextfieldSelectionColor);

[karandeepb, 2016/10/14 09:31:33]

Would it be ok to use the same colors for Textfields and Labels. If yes, is just
renaming it to kColorId_TextSelectionColor fine or should a separate constant be
created for Labels?

+  }
+  if (!selection_background_color_set_) {
+    selection_background_color_ = theme->GetSystemColor(
+        ui::NativeTheme::kColorId_TextfieldSelectionBackgroundFocused);
+  }
   RecalculateColors();
 }
 
@@ -609,4 +835,17 @@ bool Label::ShouldShowDefaultTooltip() const {
                          (multi_line() && text_size.height() > size.height()));
 }
 
+void Label::OnSelectionUpdated() {
+  if (performing_mouse_action_)
+    return;
+  SchedulePaint();
+}
+
+void Label::ClearLines() {
+  // Persist the selection range if there is an active selection.
+  if (HasSelection())
+    last_selection_range_ = GetRenderTextForSelection()->selection();
+  lines_.clear();
+}
+
 }  // namespace views