Do not SchedulePaint() inside views::Label::OnPaint()

ui/views/controls/label_unittest.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/controls/label.h"
 
 #include <stddef.h>
 
 #include "base/i18n/rtl.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/accessibility/ax_view_state.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/compositor/canvas_painter.h"
 #include "ui/gfx/canvas.h"
 #include "ui/views/border.h"
 #include "ui/views/test/focus_manager_test.h"
 #include "ui/views/test/views_test_base.h"
 #include "ui/views/widget/widget.h"
 
 using base::ASCIIToUTF16;
 
 namespace views {
+namespace {
 
-typedef ViewsTestBase LabelTest;
+// All text sizing measurements (width and height) should be greater than this.
+const int kMinTextDimension = 4;
+
+using LabelTest = ViewsTestBase;
 
 class LabelFocusTest : public FocusManagerTest {
  public:
   LabelFocusTest() {}
   ~LabelFocusTest() override {}
 
  protected:
-  views::Label* label() { return label_; }
+  Label* label() { return label_; }
 
  private:
   // FocusManagerTest:
   void InitContentView() override {
     label_ = new views::Label();
     GetContentsView()->AddChildView(label_);
   }
 
-  views::Label* label_;
+  Label* label_;
 };
 
-// All text sizing measurements (width and height) should be greater than this.
-const int kMinTextDimension = 4;
+class TestLabel : public Label {
+ public:
+  TestLabel() : Label(ASCIIToUTF16("TestLabel")) { SizeToPreferredSize(); }
+
+  int schedule_paint_count() const { return schedule_paint_count_; }
+
+  void SimulatePaint() {
+    gfx::Canvas canvas(bounds().size(), 1.0, false /* is_opaque */);
+    Paint(ui::CanvasPainter(&canvas, 1.f).context());
+  }
+
+  // View:
+  void SchedulePaintInRect(const gfx::Rect& r) override {
+    ++schedule_paint_count_;
+    Label::SchedulePaintInRect(r);
+  }
+
+ private:
+  int schedule_paint_count_ = 0;
+
+  DISALLOW_COPY_AND_ASSIGN(TestLabel);
+};
 
 // A test utility function to set the application default text direction.
 void SetRTL(bool rtl) {
   // Override the current locale/direction.
   base::i18n::SetICUDefaultLocale(rtl ? "he" : "en");
   EXPECT_EQ(rtl, base::i18n::IsRTL());
 }
 
+// Returns true if |current| is bigger than |last|. Sets |last| to |current|.
+bool Increased(int current, int* last) {
+  bool increased = current > *last;
+  *last = current;
+  return increased;
+}
+
+}  // namespace
+
 // Crashes on Linux only. http://crbug.com/612406
 #if defined(OS_LINUX)
 #define MAYBE_FontPropertySymbol DISABLED_FontPropertySymbol
 #else
 #define MAYBE_FontPropertySymbol FontPropertySymbol
 #endif
 TEST_F(LabelTest, MAYBE_FontPropertySymbol) {
   Label label;
   std::string font_name("symbol");
   gfx::Font font(font_name, 26);
@@ skipping 539 matching lines @@
   label.SizeToPreferredSize();
 
   gfx::Canvas canvas(label.GetPreferredSize(), 1.0f, true);
   label.Paint(ui::CanvasPainter(&canvas, 1.f).context());
 
   // There's only one 'line', RenderText itself supports multiple lines.
   EXPECT_EQ(1u, label.lines_.size());
 }
 #endif
 
+// Ensures SchedulePaint() calls are not made in OnPaint().
+TEST_F(LabelTest, NoSchedulePaintInOnPaint) {
+  TestLabel label;
+
+  // Initialization should schedule at least one paint, but the precise number
+  // doesn't really matter.
+  int count = label.schedule_paint_count();
+  EXPECT_LT(0, count);
+
+  // Painting should never schedule another paint.
+  label.SimulatePaint();
+  EXPECT_EQ(count, label.schedule_paint_count());
+
+  // Test a few things that should schedule paints. Multiple times is OK.
+  label.SetEnabled(false);
+  EXPECT_TRUE(Increased(label.schedule_paint_count(), &count));
+
+  label.SetText(label.text() + ASCIIToUTF16("Changed"));
+  EXPECT_TRUE(Increased(label.schedule_paint_count(), &count));
+
+  label.SizeToPreferredSize();
+  EXPECT_TRUE(Increased(label.schedule_paint_count(), &count));
+
+  label.SetEnabledColor(SK_ColorBLUE);
+  EXPECT_TRUE(Increased(label.schedule_paint_count(), &count));
+
+  label.SimulatePaint();
+  EXPECT_EQ(count, label.schedule_paint_count());  // Unchanged.
+}
+
 TEST_F(LabelFocusTest, FocusBounds) {
   label()->SetText(ASCIIToUTF16("Example"));
   gfx::Size normal_size = label()->GetPreferredSize();
 
   label()->SetFocusBehavior(View::FocusBehavior::ALWAYS);
   label()->RequestFocus();
   gfx::Size focusable_size = label()->GetPreferredSize();
   // Focusable label requires larger size to paint the focus rectangle.
   EXPECT_GT(focusable_size.width(), normal_size.width());
   EXPECT_GT(focusable_size.height(), normal_size.height());
@@ skipping 31 matching lines @@
   label()->SetFocusBehavior(View::FocusBehavior::ALWAYS);
   label()->RequestFocus();
   label()->SizeToPreferredSize();
 
   gfx::Rect focus_bounds = label()->GetFocusBounds();
   EXPECT_FALSE(focus_bounds.IsEmpty());
   EXPECT_LT(label()->font_list().GetHeight(), focus_bounds.height());
 }
 
 }  // namespace views