Fix invalid selection produced when dragging mouse outside the SVG text element

third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp

Index: third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
diff --git a/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp b/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
index fbe5909f7a0917a37e843ac9a56c9a385ae59861..88950ebfdd429ea49d5ba6c08200b0fe63cf9b57 100644
--- a/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
+++ b/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
@@ -28,6 +28,7 @@
 #include "core/layout/LayoutAnalyzer.h"
 #include "core/layout/LayoutPart.h"
 #include "core/layout/LayoutView.h"
+#include "core/layout/svg/LayoutSVGText.h"
 #include "core/layout/svg/SVGLayoutSupport.h"
 #include "core/layout/svg/SVGResourcesCache.h"
 #include "core/paint/PaintLayer.h"
@@ -281,6 +282,56 @@ void LayoutSVGRoot::willBeRemovedFromTree()
     LayoutReplaced::willBeRemovedFromTree();
 }
 
+PositionWithAffinity LayoutSVGRoot::positionForPoint(const LayoutPoint& point)
+{
+    LayoutObject* closestDescendant = nullptr;
+    float closestDistance = std::numeric_limits<float>::max();
+    FloatPoint absolutePoint(point);
+
+    for (LayoutObject* descendant = firstChild(); descendant; descendant = descendant->nextInPreOrder(this)) {
+        if (descendant->isSVGText()) {
+            FloatRect boundaries = toLayoutSVGText(descendant)->objectBoundingBox();
+            FloatPoint closestPoint;
+            closestPoint.setX(std::max(std::min(absolutePoint.x(), boundaries.maxX()), boundaries.x()));
+            closestPoint.setY(std::max(std::min(absolutePoint.y(), boundaries.maxY()), boundaries.y()));
+            float distance = (absolutePoint - closestPoint).diagonalLengthSquared();
+
+            if (distance < closestDistance) {
+                closestDistance = distance;
+                closestDescendant = descendant;

[hyunjunekim2, 2016/01/11 09:13:17]

1. Find closest LayoutSVGText from mouse which is local coordinate of
LayoutSVGRoot.

+            }
+        }
+    }
+
+    if (!closestDescendant)
+        return createPositionWithAffinity(0);

[hyunjunekim2, 2016/01/11 09:13:16]

2. If no has LayoutSVGText, return 0.

+
+    AffineTransform transform;
+    transform.makeIdentity();
+    if (toLayoutSVGText(closestDescendant)->location().x())
+        transform.setE(toLayoutSVGText(closestDescendant)->location().x());
+    if (toLayoutSVGText(closestDescendant)->location().y())
+        transform.setF(toLayoutSVGText(closestDescendant)->location().y());
+
+    LayoutObject* layoutObject = closestDescendant;
+    while (layoutObject) {
+        layoutObject = layoutObject->parent();
+        if (layoutObject->isSVGRoot())
+            break;
+        transform = layoutObject->localToParentTransform() * transform;
+    }
+
+    transform = m_localToBorderBoxTransform * transform;

[hyunjunekim2, 2016/01/11 09:13:16]

3. Make a Matrix M. M is (Root's child Matrix) * (Root's's child Matrix) *
(Root's's's child Matirx) * ....;
4. M = (ViewBox Matrix) * M

+    absolutePoint = transform.inverse().mapPoint(absolutePoint);

[hyunjunekim2, 2016/01/11 09:13:16]

5. LayoutSVGText's local coordinate = M^-1 * point(local coodinate of SVG Root).

+
+    if (absolutePoint.x() < 0)
+        absolutePoint.setX(0);
+    if (absolutePoint.y() < 0)
+        absolutePoint.setY(0);
+
+    return closestDescendant->positionForPoint(LayoutPoint(absolutePoint.x(), absolutePoint.y()));

[hyunjunekim2, 2016/01/11 09:13:16]

6. After calculate position For Point on LayoutSVGText, return value.

+}
+
 // LayoutBox methods will expect coordinates w/o any transforms in coordinates
 // relative to our borderBox origin.  This method gives us exactly that.
 void LayoutSVGRoot::buildLocalToBorderBoxTransform()