/*
* 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;
}
}