Snap selection handles to text

 Bug 6198286
 Webkit Change: I55604f3ec28586beaec5fd98a27c9f4b8a59a8a5

Change-Id: I3c51ed5f6988d58440badfbe8b076fd83d48ae2a

Author: George Mount

core/java/android/webkit/QuadF.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package android.webkit;
+
+import android.graphics.PointF;
+
+/**
+ * A quadrilateral, determined by four points, clockwise order. Typically
+ * p1 is "top-left" and p4 is "bottom-left" following webkit's rectangle-to-
+ * FloatQuad conversion.
+ */
+class QuadF {
+    public PointF p1;
+    public PointF p2;
+    public PointF p3;
+    public PointF p4;
+
+    public QuadF() {
+        p1 = new PointF();
+        p2 = new PointF();
+        p3 = new PointF();
+        p4 = new PointF();
+    }
+
+    public void offset(float dx, float dy) {
+        p1.offset(dx, dy);
+        p2.offset(dx, dy);
+        p3.offset(dx, dy);
+        p4.offset(dx, dy);
+    }
+
+    /**
+     * Determines if the quadrilateral contains the given point. This does
+     * not work if the quadrilateral is self-intersecting or if any inner
+     * angle is reflex (greater than 180 degrees).
+     */
+    public boolean containsPoint(float x, float y) {
+        return isPointInTriangle(x, y, p1, p2, p3) ||
+                isPointInTriangle(x, y, p1, p3, p4);
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder s = new StringBuilder("QuadF(");
+        s.append(p1.x).append(",").append(p1.y);
+        s.append(" - ");
+        s.append(p2.x).append(",").append(p2.y);
+        s.append(" - ");
+        s.append(p3.x).append(",").append(p3.y);
+        s.append(" - ");
+        s.append(p4.x).append(",").append(p4.y);
+        s.append(")");
+        return s.toString();
+    }
+
+    private static boolean isPointInTriangle(float x0, float y0,
+            PointF r1, PointF r2, PointF r3) {
+        // Use the barycentric technique
+        float x13 = r1.x - r3.x;
+        float y13 = r1.y - r3.y;
+        float x23 = r2.x - r3.x;
+        float y23 = r2.y - r3.y;
+        float x03 = x0 - r3.x;
+        float y03 = y0 - r3.y;
+
+        float determinant = (y23 * x13) - (x23 * y13);
+        float lambda1 = ((y23 * x03) - (x23 * y03))/determinant;
+        float lambda2 = ((x13 * y03) - (y13 * x03))/determinant;
+        float lambda3 = 1 - lambda1 - lambda2;
+        return lambda1 >= 0.0f && lambda2 >= 0.0f && lambda3 >= 0.0f;
+    }
+}