Lock screen: Show tooltip if text is truncated

Add tootip to LoginShelfButton when the text of the label is truncated.

Bug: 878340
Change-Id: I28441db54bb49e0ba262f820bbf9041993a36683
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1712675
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Roman Aleksandrov <raleksandrov@google.com>
Cr-Commit-Position: refs/heads/master@{#685825}

ash/shelf/login_shelf_view.cc

@@ -218,6 +218,12 @@ class LoginShelfButton : public views::LabelButton {
     return ink_drop;
   }
 
+  base::string16 GetTooltipText(const gfx::Point& p) const override {
+    if (label()->IsDisplayTextTruncated())
+      return label()->GetText();
+    return base::string16();
+  }
+
   void PaintDarkColors() {
     SetEnabledTextColors(gfx::kGoogleGrey600);
     SetImage(views::Button::STATE_NORMAL,

ui/views/controls/label.cc

@@ -252,6 +252,17 @@ void Label::SetObscured(bool obscured) {
   OnPropertyChanged(&full_text_ + kLabelObscured, kPropertyEffectsLayout);
 }
 
+bool Label::IsDisplayTextTruncated() const {
+  MaybeBuildDisplayText();
+  if (!full_text_ || full_text_->text().empty())
+    return false;
+  auto text_bounds = GetTextBounds();
+  return (display_text_ &&
+          display_text_->text() != display_text_->GetDisplayText()) ||
+         text_bounds.width() > GetContentsBounds().width() ||
+         text_bounds.height() > GetContentsBounds().height();
+}
+
 bool Label::GetAllowCharacterBreak() const {
   return full_text_->word_wrap_behavior() == gfx::WRAP_LONG_WORDS ? true
                                                                   : false;

ui/views/controls/label.h

@@ -153,6 +153,10 @@ class VIEWS_EXPORT Label : public View,
   bool GetObscured() const;
   void SetObscured(bool obscured);
 
+  // Returns true if some portion of the text is not displayed, either because
+  // of eliding or clipping.
+  bool IsDisplayTextTruncated() const;
+
   // Gets/Sets whether multi-line text can wrap mid-word; the default is false.
   // TODO(mukai): allow specifying WordWrapBehavior.
   bool GetAllowCharacterBreak() const;
@@ -280,6 +284,7 @@ class VIEWS_EXPORT Label : public View,
   FRIEND_TEST_ALL_PREFIXES(LabelTest, EmptyLabel);
   FRIEND_TEST_ALL_PREFIXES(LabelTest, FocusBounds);
   FRIEND_TEST_ALL_PREFIXES(LabelTest, MultiLineSizingWithElide);
+  FRIEND_TEST_ALL_PREFIXES(LabelTest, IsDisplayTextTruncated);
   friend class LabelSelectionTest;
 
   // ContextMenuController overrides:

ui/views/controls/label_unittest.cc

@@ -944,6 +944,33 @@ TEST_F(LabelTest, DefaultDirectionalityIsFromText) {
             rtl.GetTextDirectionForTesting());
 }
 
+TEST_F(LabelTest, IsDisplayTextTruncated) {
+  const base::string16 text = ASCIIToUTF16("A random string");
+  label()->SetText(text);
+
+  gfx::Size zero_size;
+  label()->SetElideBehavior(gfx::ELIDE_TAIL);
+  label()->SetBoundsRect(gfx::Rect(zero_size));
+  EXPECT_TRUE(label()->IsDisplayTextTruncated());
+
+  label()->SetElideBehavior(gfx::NO_ELIDE);
+  EXPECT_TRUE(label()->IsDisplayTextTruncated());
+
+  gfx::Size minimum_size(1, 1);
+  label()->SetBoundsRect(gfx::Rect(minimum_size));
+  EXPECT_TRUE(label()->IsDisplayTextTruncated());
+
+  gfx::Size enough_size(100, 100);
+  label()->SetBoundsRect(gfx::Rect(enough_size));
+  EXPECT_FALSE(label()->IsDisplayTextTruncated());
+
+  const base::string16 empty_text;
+  label()->SetText(empty_text);
+  EXPECT_FALSE(label()->IsDisplayTextTruncated());
+  label()->SetBoundsRect(gfx::Rect(zero_size));
+  EXPECT_FALSE(label()->IsDisplayTextTruncated());
+}
+
 TEST_F(LabelSelectionTest, Selectable) {
   // By default, labels don't support text selection.
   EXPECT_FALSE(label()->GetSelectable());