1 files changed, 40 insertions, 0 deletions
diff --git a/Source/WebCore/platform/graphics/FloatPoint.cpp b/Source/WebCore/platform/graphics/FloatPoint.cpp
index 226ae71..abe9b86 100644
--- a/Source/WebCore/platform/graphics/FloatPoint.cpp
+++ b/Source/WebCore/platform/graphics/FloatPoint.cpp
@@ -31,6 +31,7 @@
 #include "TransformationMatrix.h"
 #include "FloatConversion.h"
 #include "IntPoint.h"
+#include <limits>
 #include <math.h>
 
 namespace WebCore {
@@ -73,4 +74,43 @@ FloatPoint FloatPoint::narrowPrecision(double x, double y)
     return FloatPoint(narrowPrecisionToFloat(x), narrowPrecisionToFloat(y));
 }
 
+float findSlope(const FloatPoint& p1, const FloatPoint& p2, float& c)
+{
+    if (p2.x() == p1.x())
+        return std::numeric_limits<float>::infinity();
+
+    // y = mx + c
+    float slope = (p2.y() - p1.y()) / (p2.x() - p1.x());
+    c = p1.y() - slope * p1.x();
+    return slope;
+}
+
+bool findIntersection(const FloatPoint& p1, const FloatPoint& p2, const FloatPoint& d1, const FloatPoint& d2, FloatPoint& intersection) 
+{
+    float pOffset = 0;
+    float pSlope = findSlope(p1, p2, pOffset);
+
+    float dOffset = 0;
+    float dSlope = findSlope(d1, d2, dOffset);
+
+    if (dSlope == pSlope)
+        return false;
+    
+    if (pSlope == std::numeric_limits<float>::infinity()) {
+        intersection.setX(p1.x());
+        intersection.setY(dSlope * intersection.x() + dOffset);
+        return true;
+    }
+    if (dSlope == std::numeric_limits<float>::infinity()) {
+        intersection.setX(d1.x());
+        intersection.setY(pSlope * intersection.x() + pOffset);
+        return true;
+    }
+    
+    // Find x at intersection, where ys overlap; x = (c' - c) / (m - m')
+    intersection.setX((dOffset - pOffset) / (pSlope - dSlope));
+    intersection.setY(pSlope * intersection.x() + pOffset);
+    return true;
+}
+
 }