RenderTextHarfBuzz: Add support for multi line text selection.

ui/views/examples/label_example.cc

 // 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.
 
 #include "ui/views/examples/label_example.h"
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "ui/gfx/geometry/vector2d.h"
@@ skipping 114 matching lines @@
 void LabelExample::ButtonPressed(Button* button, const ui::Event& event) {
   if (button == multiline_) {
     custom_label_->SetMultiLine(multiline_->checked());
   } else if (button == shadows_) {
     gfx::ShadowValues shadows;
     if (shadows_->checked()) {
       shadows.push_back(gfx::ShadowValue(gfx::Vector2d(), 1, SK_ColorRED));
       shadows.push_back(gfx::ShadowValue(gfx::Vector2d(2, 2), 0, SK_ColorGRAY));
     }
     custom_label_->SetShadows(shadows);
+  } else if (button == text_selection_) {
+    custom_label_->SetSelectable(text_selection_->checked());
   }
   custom_label_->parent()->parent()->Layout();
   custom_label_->SchedulePaint();
 }
 
 void LabelExample::OnPerformAction(Combobox* combobox) {
   if (combobox == alignment_) {
     custom_label_->SetHorizontalAlignment(
         static_cast<gfx::HorizontalAlignment>(combobox->selected_index()));
   } else if (combobox == elide_behavior_) {
@@ skipping 34 matching lines @@
   alignment_ = AddCombobox(layout, "Alignment: ", kAlignments,
                            arraysize(kAlignments));
   elide_behavior_ = AddCombobox(layout, "Elide Behavior: ", kElideBehaviors,
                                 arraysize(kElideBehaviors));
 
   column_set = layout->AddColumnSet(1);
   column_set->AddColumn(GridLayout::LEADING, GridLayout::LEADING,
                         0, GridLayout::USE_PREF, 0, 0);
   column_set->AddColumn(GridLayout::LEADING, GridLayout::LEADING,
                         0, GridLayout::USE_PREF, 0, 0);
+  column_set->AddColumn(GridLayout::LEADING, GridLayout::LEADING, 0,
+                        GridLayout::USE_PREF, 0, 0);
   layout->StartRow(0, 1);
   multiline_ = new Checkbox(base::ASCIIToUTF16("Multiline"));
   multiline_->set_listener(this);
   layout->AddView(multiline_);
   shadows_ = new Checkbox(base::ASCIIToUTF16("Shadows"));
   shadows_->set_listener(this);
   layout->AddView(shadows_);
+  text_selection_ = new Checkbox(base::ASCIIToUTF16("Text selection"));

[msw, 2016/12/07 20:20:35]

nit: rename the identifier |selectable_| and change this string to "Selectable"

[karandeepb, 2016/12/12 10:36:19]

Done.

+  text_selection_->set_listener(this);
+  layout->AddView(text_selection_);
   layout->AddPaddingRow(0, 8);
 
   column_set = layout->AddColumnSet(2);
   column_set->AddColumn(GridLayout::FILL, GridLayout::FILL,
                         1, GridLayout::USE_PREF, 0, 0);
   layout->StartRow(0, 2);
   custom_label_ = new PreferredSizeLabel();
   custom_label_->SetHorizontalAlignment(gfx::ALIGN_LEFT);
   custom_label_->SetElideBehavior(gfx::NO_ELIDE);
   custom_label_->SetText(textfield_->text());
   layout->AddView(custom_label_);
 
+  // Disable the text selection checkbox if |custom_label_| does not support
+  // text selection.
+  if (custom_label_->SetSelectable(true))
+    text_selection_->SetChecked(true);

[msw, 2016/12/07 20:20:35]

Don't set selectable and check by default, just disable the checkbox if
!custom_label_->IsSelectionSupported() instead

[karandeepb, 2016/12/12 10:36:19]

Done. This required making Label::IsSelectionSupported public, which sort of
makes sense.

+  else
+    text_selection_->SetEnabled(false);
+
   container->AddChildView(control_container);
 }
 
 Combobox* LabelExample::AddCombobox(GridLayout* layout,
                                     const char* name,
                                     const char** strings,
                                     int count) {
   layout->StartRow(0, 0);
   layout->AddView(new Label(base::ASCIIToUTF16(name)));
   ExampleComboboxModel* model = new ExampleComboboxModel(strings, count);
   example_combobox_models_.push_back(base::WrapUnique(model));
   Combobox* combobox = new Combobox(model);
   combobox->SetSelectedIndex(0);
   combobox->set_listener(this);
   layout->AddView(combobox);
   return combobox;
 }
 
 }  // namespace examples
 }  // namespace views