Calculate correct cull rect for SVG inline text boxes.

Cull rects were larger than needed when text was selected.

Identified while investigating test failure of:

svg/text/text-selection-align-06-b.svg

as part of http://crrev.com/2073563002 for crbug.com/616600, though
fixing these did not actually fix any issues for that patch or bug.

Reland of http://crrev.com/2137753002 with updated test to
approximate expected rects to allow for minor font metrics differences
across platforms. Notably, previous patch failed on Android Nexus 4
due to 1 - 2 pixel deltas.

BUG=627233
TBR=pdr

Review-Url: https://codereview.chromium.org/2151323004
Cr-Commit-Position: refs/heads/master@{#405920}

third_party/WebKit/Source/core/core.gypi

@@ -4189,6 +4189,7 @@
             'paint/PaintLayerPainterTest.cpp',
             'paint/PaintPropertyTreeBuilderTest.cpp',
             'paint/StubChromeClientForSPv2.h',
+            'paint/SVGInlineTextBoxPainterTest.cpp',
             'paint/TableCellPainterTest.cpp',
             'paint/TextPainterTest.cpp',
             'paint/VideoPainterTest.cpp',

third_party/WebKit/Source/core/editing/DOMSelection.h

@@ -45,7 +45,7 @@ class Node;
 class Range;
 class TreeScope;
 
-class DOMSelection final : public GarbageCollected<DOMSelection>, public ScriptWrappable, public DOMWindowProperty {
+class CORE_EXPORT DOMSelection final : public GarbageCollected<DOMSelection>, public ScriptWrappable, public DOMWindowProperty {
     DEFINE_WRAPPERTYPEINFO();
     USING_GARBAGE_COLLECTED_MIXIN(DOMSelection);
 public:

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

@@ -45,13 +45,12 @@ FloatRect SVGInlineTextBoxPainter::boundsForDrawingRecorder(
     // computation in SVGInlineTextBox::calculateBoundaries, and the fact that vertical (etc)
     // layouts are handled by SVGTextLayoutEngine.
     LayoutRect bounds(
-        m_svgInlineTextBox.topLeft(),
+        LayoutPoint(m_svgInlineTextBox.topLeft() + paintOffset),
         LayoutSize(m_svgInlineTextBox.logicalWidth(), m_svgInlineTextBox.logicalHeight()));
     if (includeSelectionRect) {
         bounds.unite(m_svgInlineTextBox.localSelectionRect(
             m_svgInlineTextBox.start(), m_svgInlineTextBox.start() + m_svgInlineTextBox.len()));
     }
-    bounds.moveBy(paintOffset);
     return FloatRect(bounds);
 }
 

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

+// 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/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 = 4;
+
+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(delta, delta);
+    IntRect innerRect(expectedRect);
+    // Rect contains is inclusive of edge, so shrink by one extra pixel.
+    innerRect.contract(delta + 1, delta + 1);
+
+    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