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

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

Index: third_party/WebKit/Source/core/layout/svg/SVGLayoutSupport.cpp
diff --git a/third_party/WebKit/Source/core/layout/svg/SVGLayoutSupport.cpp b/third_party/WebKit/Source/core/layout/svg/SVGLayoutSupport.cpp
index 32073042bd914cd8999f8fd2c593feade0f70a23..4c109b2ae26434a6930074a0d4b0096e57909ea1 100644
--- a/third_party/WebKit/Source/core/layout/svg/SVGLayoutSupport.cpp
+++ b/third_party/WebKit/Source/core/layout/svg/SVGLayoutSupport.cpp
@@ -476,4 +476,60 @@ float SVGLayoutSupport::calculateScreenFontSizeScalingFactor(const LayoutObject*
     return narrowPrecisionToFloat(sqrt((pow(ctm.xScale(), 2) + pow(ctm.yScale(), 2)) / 2));
 }
 
+bool SVGLayoutSupport::compareCandidateDistance(const SearchCandidate r1, const SearchCandidate r2)
+{
+    return r1.distance < r2.distance;
+}
+
+LayoutObject* SVGLayoutSupport::findClosestLayoutSVGText(LayoutObject* layoutObject, const FloatPoint& point)
+{
+    // Try to search closest LayoutSVGText on sub-tree of |layoutObject|.
+    // On this level of tree, try to find the closest LayoutSVGText. If not find this level, try to search
+    // next level which is candidates.
+    LayoutObject* closestLayoutObject = nullptr;
+    float closestDistance = std::numeric_limits<float>::max();
+    Vector<SearchCandidate> candidates;
+    for (LayoutObject* child = layoutObject->slowLastChild(); child; child = child->previousSibling()) {
+        if (child->isSVGHiddenContainer() || !child->localToParentTransform().isInvertible())

[fs, 2016/01/21 14:27:15]

Marginally better than before. I think it'd better to explicitly handle the
cases we're interested in and "continue" for the rest.

[hyunjunekim2, 2016/01/21 15:14:05]

I separated it.

+            continue;
+
+        FloatRect boundingBox = child->objectBoundingBox();
+        FloatPoint childLocalPoint = child->localToParentTransform().inverse().mapPoint(point);
+        float distance = boundingBox.squaredDistanceTo(childLocalPoint);
+
+        if (distance >= closestDistance)

[fs, 2016/01/21 14:27:16]

If distance == closestDistance and !child->isSVGText() don't you want to include
the candidate in that case?

[hyunjunekim2, 2016/01/21 15:14:05]

I contained it in that case.

+            continue;
+
+        if (child->isSVGText()) {
+            candidates.clear();
+            closestLayoutObject = child;
+            closestDistance = distance;
+            continue;
+        }
+
+        if (child->isSVGContainer())
+            candidates.append(SearchCandidate(child, distance));
+    }
+
+    // If find LayoutSVGText this level of tree, return it.
+    if (closestLayoutObject && closestLayoutObject->isSVGText())
+        return closestLayoutObject;
+
+    // Sort using the distance between the mouse point and a candidate.
+    // Because if the distance is close, It is high priority to search LayoutSVGText.
+    std::stable_sort(candidates.begin(), candidates.end(), compareCandidateDistance);
+
+    // If not find LayoutSVGText on this level of tree, try to search it on sub-tree of |condidate|.
+    // This vector called |candidates| is the sort in order of distance from the mouse point.
+    // If can not find the LayoutSVGText on |candidates|, after all return nullptr.
+    for (SearchCandidate searchCandidate : candidates) {

[fs, 2016/01/21 14:27:16]

Use reference.

+        LayoutObject* candidateLayoutObject = searchCandidate.candidateLayoutObject;
+        FloatPoint candidateLocalPoint = candidateLayoutObject->localToParentTransform().inverse().mapPoint(point);
+        if (LayoutObject* result = findClosestLayoutSVGText(candidateLayoutObject, candidateLocalPoint))
+            return result;
+    }
+
+    return nullptr;
+}
+
 }