Calculate correct cull rect for SVG inline text boxes.

third_party/WebKit/Source/core/paint/SVGInlineTextBoxPainterTest.cpp

Index: third_party/WebKit/Source/core/paint/SVGInlineTextBoxPainterTest.cpp
diff --git a/third_party/WebKit/Source/core/paint/SVGInlineTextBoxPainterTest.cpp b/third_party/WebKit/Source/core/paint/SVGInlineTextBoxPainterTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..b969b56420f1ddd6b0d4a4f82a26007bc5ce0afd
--- /dev/null
+++ b/third_party/WebKit/Source/core/paint/SVGInlineTextBoxPainterTest.cpp
@@ -0,0 +1,138 @@
+// Copyright 2016 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 "core/paint/SVGInlineTextBoxPainter.h"
+
+#include "core/dom/Document.h"
+#include "core/dom/Range.h"
+#include "core/editing/DOMSelection.h"
+#include "core/frame/LocalDOMWindow.h"
+#include "core/layout/LayoutTestHelper.h"
+#include "core/layout/line/InlineTextBox.h"
+#include "core/layout/svg/LayoutSVGInlineText.h"
+#include "core/layout/svg/LayoutSVGText.h"
+#include "core/paint/PaintLayer.h"
+#include "platform/geometry/IntRectOutsets.h"
+#include "platform/graphics/GraphicsLayer.h"
+#include "platform/graphics/paint/DisplayItemList.h"
+#include "platform/graphics/paint/DrawingDisplayItem.h"
+#include "platform/graphics/paint/PaintController.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace blink {
+namespace {
+
+class SVGInlineTextBoxPainterTest : public RenderingTest {
+public:
+    const DrawingDisplayItem* getDrawingForSVGTextById(const char* elementName)
+    {
+        // Look up the inline text box that serves as the display item client for the painted text.
+        LayoutSVGText* targetSVGText = toLayoutSVGText(
+            document().getElementById(AtomicString(elementName))->layoutObject());
+        LayoutSVGInlineText* targetInlineText = targetSVGText->descendantTextNodes()[0];
+        const DisplayItemClient* targetClient = static_cast<const DisplayItemClient*>(targetInlineText->firstTextBox());
+
+        // Find the appropriate drawing in the display item list.
+        const DisplayItemList& displayItemList = rootPaintController().getDisplayItemList();
+        for (size_t i = 0; i < displayItemList.size(); i++) {
+            if (displayItemList[i].client() == *targetClient)
+                return static_cast<const DrawingDisplayItem*>(&displayItemList[i]);
+        }
+
+        return nullptr;
+    }
+
+    void selectAllText()
+    {
+        Range* range = document().createRange();
+        range->selectNode(document().documentElement());
+        LocalDOMWindow* window = document().domWindow();
+        DOMSelection* selection = window->getSelection();
+        selection->removeAllRanges();
+        selection->addRange(range);
+    }
+
+private:
+    PaintController& rootPaintController()
+    {
+        return document().view()->layoutView()->layer()->graphicsLayerBacking()->getPaintController();
+    }
+
+    void SetUp() override
+    {
+        RenderingTest::SetUp();
+        enableCompositing();
+    }
+};
+
+static void assertTextDrawingEquals(const DrawingDisplayItem* drawingDisplayItem, const char* str)
+{
+    ASSERT_EQ(str, static_cast<const InlineTextBox*>(&drawingDisplayItem->client())->text());
+}
+
+const static int kAllowedPixelDelta = 8;
+
+static void assertCullRectEquals(const DrawingDisplayItem* drawingDisplayItem, const IntRect& expectedRect)
+{
+    // Text metrics can vary slightly across platforms, so we allow for a small pixel difference.
+    IntRect outerRect(expectedRect);
+    int delta = kAllowedPixelDelta / 2;
+    outerRect.expand(IntRectOutsets(delta, delta, delta, delta));
+    IntRect innerRect(expectedRect);
+    // Rect contains is inclusive of edge, so shrink by one extra pixel.
+    int contractDelta = -delta - 1;
+    innerRect.expand(IntRectOutsets(contractDelta, contractDelta, contractDelta, contractDelta));
+
+    IntRect actualRect(IntRect(drawingDisplayItem->picture()->cullRect()));
+    ASSERT_TRUE(outerRect.contains(actualRect) && !innerRect.contains(actualRect))
+        << "Cull rect not approximately equal [expected=("
+        << expectedRect.x() << "," << expectedRect.y() << " " << expectedRect.width() << "x" << expectedRect.height() << "), actual=("
+        << actualRect.x() << "," << actualRect.y() << " " << actualRect.width() << "x" << actualRect.height() << ")].";
+}
+
+TEST_F(SVGInlineTextBoxPainterTest, TextCullRect_DefaultWritingMode)
+{
+    setBodyInnerHTML(
+        "<svg width='400px' height='400px' font-family='Arial' font-size='30'>"
+        "<text id='target' x='50' y='30'>x</text>"
+        "</svg>");
+    document().view()->updateAllLifecyclePhases();
+
+    const DrawingDisplayItem* drawingDisplayItem = getDrawingForSVGTextById("target");
+    assertTextDrawingEquals(drawingDisplayItem, "x");
+    assertCullRectEquals(drawingDisplayItem, IntRect(50, 3, 15, 33));
+
+    selectAllText();
+    document().view()->updateAllLifecyclePhases();
+
+    drawingDisplayItem = getDrawingForSVGTextById("target");
+    assertTextDrawingEquals(drawingDisplayItem, "x");
+    assertCullRectEquals(drawingDisplayItem, IntRect(50, 3, 15, 33));
+}
+
+TEST_F(SVGInlineTextBoxPainterTest, TextCullRect_WritingModeTopToBottom)
+{
+    setBodyInnerHTML(
+        "<svg width='400px' height='400px' font-family='Arial' font-size='30'>"
+        "<text id='target' x='50' y='30' writing-mode='tb'>x</text>"
+        "</svg>");
+    document().view()->updateAllLifecyclePhases();
+
+    const DrawingDisplayItem* drawingDisplayItem = getDrawingForSVGTextById("target");
+    assertTextDrawingEquals(drawingDisplayItem, "x");
+    assertCullRectEquals(drawingDisplayItem, IntRect(33, 30, 34, 15));
+
+    selectAllText();
+    document().view()->updateAllLifecyclePhases();
+
+    // The selection rect is one pixel taller due to sub-pixel difference
+    // between the text bounds and selection bounds in combination with use of
+    // enclosingIntRect() in SVGInlineTextBox::localSelectionRect().
+    drawingDisplayItem = getDrawingForSVGTextById("target");
+    assertTextDrawingEquals(drawingDisplayItem, "x");
+    assertCullRectEquals(drawingDisplayItem, IntRect(33, 30, 34, 16));
+}
+
+} // namespace
+} // namespace blink