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public static List<LatLong> narrowTest(List<LatLong> oldLatLongs, List<Float> dis){
//计算地块的顺逆时针
boolean wise = isClockwise(oldLatLongs);
//原始边界点
List<LatLong> originalLatLongs = new ArrayList<>(oldLatLongs);
for (int i = 0; i < dis.size(); i++) {
originalLatLongs = narrowSingle(oldLatLongs,originalLatLongs, i, dis.get(i), wise);
}
return originalLatLongs;
}
/**
*
* @param oldLatLongs 内缩边界点
* @param originalLatLongs 原始边界点
* @param index 内缩边序号
* @param dis 内缩距离
* @param clockwise 顺逆时针
* @return
*/
private static List<LatLong> narrowSingle(List<LatLong> oldLatLongs,List<LatLong> originalLatLongs, int index, float dis, boolean clockwise) {
LatLong origin = oldLatLongs.get(0);
List<Point2D> point2DS = loc2Point2D(origin, oldLatLongs);
List<Line2D> line2DS = point2Line(point2DS);
Line2D midLine = line2DS.get(index);
Vector2D vector = new Vector2D(midLine.endPoint.x - midLine.startPoint.x,
midLine.endPoint.y - midLine.startPoint.y);
//平行线
Line2D ParallelLine;
if (vector.getRadian() == Math.PI / 2 || vector.getRadian() == -Math.PI / 2) {
double space = dis * 100.0f;//对应的Y轴截距
ParallelLine = new Line2D(midLine.a, midLine.b, midLine.c - midLine.a * space);
} else {
double cos = Math.abs(Math.cos(vector.getRadian()));
double space = dis * 100.0f / cos;//对应的Y轴截距
ParallelLine = new Line2D(midLine.a, midLine.b, midLine.c - midLine.b * space);
}
Point2D pointT= ParallelLine.getIntersectPoint2(new Line2D(1,0,-(midLine.endPoint.x+midLine.startPoint.x)/2));
Vector2D vectorT = new Vector2D(pointT.x-midLine.startPoint.x,pointT.y-midLine.startPoint.y);
double T = vector.crossProduct(vectorT);//T != 0
if ((clockwise && T > 0) || (!clockwise && T < 0)) {//顺逆不相同
if (vector.getRadian() == Math.PI / 2 || vector.getRadian() == -Math.PI / 2) {
double space = -dis * 100.0f;//对应的Y轴截距
ParallelLine = new Line2D(midLine.a, midLine.b, midLine.c - midLine.a * space);
} else {
double cos = Math.abs(Math.cos(vector.getRadian()));
double space = -dis * 100.0f / cos;//对应的Y轴截距
ParallelLine = new Line2D(midLine.a, midLine.b, midLine.c - midLine.b * space);
}
}
Pair<Point2D, Integer> pointLeftPair = null;
Pair<Point2D, Integer> pointRightPair = null;
List<Point2D> pointActual = loc2Point2D(origin, originalLatLongs);
List<Line2D> lineActual = point2Line(pointActual);
//用于计算原始边界与内缩边界的差值
int temp = oldLatLongs.size() - originalLatLongs.size();
for (int i = 1; i < originalLatLongs.size() - 1; i++) {
//左侧邻边序号，递减
int leftIndex = (index + originalLatLongs.size() - i - temp) % originalLatLongs.size();
//右邻边序号，递增
int rightIndex = (index + i - temp) % originalLatLongs.size();
if (pointLeftPair == null){
Point2D point1 = ParallelLine.getIntersectPoint2(line2DS.get(leftIndex));
//判断point1是否在多边形内部
if (point1 != null && isInPolygon(point2D2Latlong(origin, point1), oldLatLongs)){
pointLeftPair = new Pair<>(point1, leftIndex);
}
}
if (pointRightPair == null){
Point2D point2 = ParallelLine.getIntersectPoint2(line2DS.get(rightIndex));
//判断point2是否在多边形内部
if (point2 != null && isInPolygon(point2D2Latlong(origin, point2), oldLatLongs)){
pointRightPair = new Pair<>(point2, rightIndex);
}
}
//遍历所有边后还是无交点
if (pointLeftPair != null && pointRightPair != null){
break;
}
//左侧边与右侧边重合，结束遍历
if (Math.abs(leftIndex - rightIndex) <= 1) {
break;
}
}
if (pointLeftPair == null || pointRightPair == null) {
//如果无交点则返回上一次的边界点
return originalLatLongs;
} else {
int leftPairIndex = pointLeftPair.second;
int rightPairIndex = pointRightPair.second;
int max = Math.max(leftPairIndex, rightPairIndex);
int min = Math.min(leftPairIndex, rightPairIndex);
//内缩边与其他边的两个交点正好在当前边的左右邻边上
if ((max - 1) % originalLatLongs.size() == (min + 1) % originalLatLongs.size()) {
pointActual.set((pointLeftPair.second + 1) % originalLatLongs.size(), pointLeftPair.first);
pointActual.set(pointRightPair.second, pointRightPair.first);
} else {
pointActual.set((pointLeftPair.second + 1) % originalLatLongs.size(), pointLeftPair.first);
pointActual.set(pointRightPair.second, pointRightPair.first);
if (rightPairIndex < leftPairIndex) {
rightPairIndex = rightPairIndex + originalLatLongs.size();
}
for (int i = rightPairIndex - 1; i > leftPairIndex + 1; i--) {
pointActual.remove((i - 1) % originalLatLongs.size() + 1);
}
}
}
return point2D2Latlong(origin, pointActual);
}
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代码示例：