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 51f3e979d94c282abea135b758f13e1e66e1813a..0ef490f7e6432dad0aebf27ea006d6169130d36a 100644
--- a/third_party/WebKit/Source/core/layout/svg/SVGLayoutSupport.cpp
+++ b/third_party/WebKit/Source/core/layout/svg/SVGLayoutSupport.cpp
@@ -44,6 +44,17 @@
 
 namespace blink {
 
+struct SearchCandidate {
+    SearchCandidate() {}
+    SearchCandidate(LayoutObject* layoutObject, float dist)
+        : candidateLayoutObject(layoutObject)
+        , distance(dist)
+    {
+    }
+    LayoutObject* candidateLayoutObject;
+    float distance;
+};
+
 static inline LayoutRect adjustedEnclosingIntRect(const FloatRect& rect,
     const AffineTransform& rootTransform, float strokeWidthForHairlinePadding)
 {
@@ -476,4 +487,72 @@ float SVGLayoutSupport::calculateScreenFontSizeScalingFactor(const LayoutObject*
     return narrowPrecisionToFloat(sqrt((pow(ctm.xScale(), 2) + pow(ctm.yScale(), 2)) / 2));
 }
 
+static inline bool compareCandidateDistance(const SearchCandidate& r1, const SearchCandidate& r2)
+{
+    return r1.distance < r2.distance;
+}
+
+static inline float distanceToChildLayoutObject(LayoutObject* child, const FloatPoint& point)
+{
+    const AffineTransform& localToParentTransform = child->localToParentTransform();
+    if (!localToParentTransform.isInvertible())
+        return std::numeric_limits<float>::max();
+    FloatPoint childLocalPoint = localToParentTransform.inverse().mapPoint(point);
+    return child->objectBoundingBox().squaredDistanceTo(childLocalPoint);
+}
+
+static SearchCandidate searchTreeForFindClosestLayoutSVGText(LayoutObject* layoutObject, const FloatPoint& point)
+{
+    LayoutObject* closestLayoutObject = nullptr;
+    float closestDistance = std::numeric_limits<float>::max();
+    Vector<SearchCandidate> candidates;
+    for (LayoutObject* child = layoutObject->slowLastChild(); child; child = child->previousSibling()) {
+        if (child->isSVGText()) {
+            float distance = distanceToChildLayoutObject(child, point);
+            if (distance >= closestDistance)
+                continue;
+            candidates.clear();
+            closestLayoutObject = child;
+            closestDistance = distance;
+            continue;
+        }
+
+        if (child->isSVGContainer() && !layoutObject->isSVGHiddenContainer()) {
+            float distance = distanceToChildLayoutObject(child, point);
+            if (distance > closestDistance)
+                continue;
+            candidates.append(SearchCandidate(child, distance));
+        }
+    }
+
+    if (closestLayoutObject && candidates.isEmpty())
+        return SearchCandidate(closestLayoutObject, closestDistance);
+
+    std::stable_sort(candidates.begin(), candidates.end(), compareCandidateDistance);
+
+    SearchCandidate closestSearchCandidateText = SearchCandidate(nullptr, std::numeric_limits<float>::max());
+    for (SearchCandidate& searchCandidate : candidates) {

[hyunjunekim2, 2016/02/08 10:41:01]

We should find the closest LayoutSVGText on condidates.

+        if (closestSearchCandidateText.distance < searchCandidate.distance)

[hyunjunekim2, 2016/02/08 10:41:01]

We are not all traversal. If |closestSearchCandidateText| that is LayoutSVGText
is close then |searchCandidate| that is group,
get out |for| using break.

+            break;
+        LayoutObject* candidateLayoutObject = searchCandidate.candidateLayoutObject;
+        FloatPoint candidateLocalPoint = candidateLayoutObject->localToParentTransform().inverse().mapPoint(point);
+
+        SearchCandidate candidateText = searchTreeForFindClosestLayoutSVGText(candidateLayoutObject, candidateLocalPoint);
+
+        if (candidateText.distance < closestSearchCandidateText.distance)
+            closestSearchCandidateText = candidateText;
+    }
+
+    if (closestDistance <= closestSearchCandidateText.distance)
+        return SearchCandidate(closestLayoutObject, closestDistance);
+
+    return closestSearchCandidateText;
+}
+
+LayoutObject* SVGLayoutSupport::findClosestLayoutSVGText(LayoutObject* layoutObject, const FloatPoint& point)
+{
+    SearchCandidate result = searchTreeForFindClosestLayoutSVGText(layoutObject, point);
+    return result.candidateLayoutObject;
+}
+
 } // namespace blink