/** 计算两点间距离,结果取数的级别 */
private static float calculateDistance(PointBean start, PointBean end) {
float result = 1;
float x = Math.abs(start.getX() - end.getX());
float y = Math.abs(start.getY() - end.getY());
String dis = (int) Math.sqrt(x * x + y * y) + "";
int level = dis.trim().length();
for (int i = 1; i < level; ++i) {
result *= 10;
}
return result;
}
/** 用两个点算他们的中点，完成一次贝塞尔曲线计算 */
private static void addMidPoint() {
PointBean one = mScreenPoints.get(0);
PointBean three = mScreenPoints.get(1);
PointBean mid =
new PointBean(((one.getX() + three.getX()) / 2), (one.getY() + three.getY()) / 2);
if (mBezierPoints.size() == 2) { // 前面已经完成一次中点计算了
mBezierPoints.add(mid);
calculateBezier();
mBezierPoints.clear(); // 计算完之后，要将这一次的中点和屏幕点记下来，给下一个中点完成贝塞尔曲线
mBezierPoints.add(mid);
mBezierPoints.add(three);
} else { // 第一次完成中点计算
mBezierPoints.add(one); // 第一个点，以线性的贝塞尔曲线连接
mBezierPoints.add(mid);
mBezierPoints.add(three);
calculateBezier();
releasePoints();
// 添加点，等下一次用
mBezierPoints.add(mid);
mBezierPoints.add(three);
}
}
/** 计算贝塞尔曲线点 */
private static void calculateBezier() {
PointBean mControlPoint; // 贝塞尔控制点
PointBean mBezierPoint; // 贝塞尔曲线上的点
PointBean mStartPoint; // 贝塞尔曲线起点
PointBean mEndPoint; // 贝塞尔曲线终点
float t = 0.01f; // 默认t取0.01
float BezierX;
float BezierY;
mControlPoint = mBezierPoints.get(1);
mStartPoint = mBezierPoints.get(0);
mEndPoint = mBezierPoints.get(2);
mBezierResult.add(mStartPoint);
// 先计算两点之间距离，根据距离选择t
float distance; // 起点和终点两点间距离
distance = calculateDistance(mStartPoint, mEndPoint);
t = 1 / distance; // 再根据距离选取t的取值 100->0.01, 10->0.1, 1->1
float step = t / 2; // 除以2再取多一点的点
if (t > 0 && t < 1) { // t取值范围
// 公式 (1-t)^2 * x1 + 2 * t * (1-t) * x0 + t^2 * x2 = x
for (; t <= 1.0f; t += step) {
BezierX =
(float) Math.pow(1 - t, 2) * mBezierPoints.get(0).getX()
+ 2 * t * (1 - t) * mControlPoint.getX()
+ (float) Math.pow(t, 2) * mBezierPoints.get(2).getX();
BezierY =
(float) Math.pow(1 - t, 2) * mBezierPoints.get(0).getY()
+ 2 * t * (1 - t) * mControlPoint.getY()
+ (float) Math.pow(t, 2) * mBezierPoints.get(2).getY();
mBezierPoint = new PointBean(BezierX, BezierY);
mBezierResult.add(mBezierPoint);
}
}
mBezierResult.add(mEndPoint);
switch (Constant.CURRENT_USE_TYPE) {
case Constant.PAINT:
ObjectUtil.createBezierLine(mBezierResult);
break;
case Constant.FIREWORKS:
// 需要每个点位置刚好接上，不能重叠
mDeleteLeftPoints = splicePoints(mBezierResult);
ObjectUtil.createBezierLine(mDeleteLeftPoints);
break;
case Constant.WALLPAPER:
// 需要先除去一些点
mDeleteLeftPoints = deletePoints(mBezierResult);
ObjectUtil.createBezierLine(mDeleteLeftPoints);
break;
case Constant.MOSAIC:
ObjectUtil.createBezierLine(mBezierResult);
break;
case Constant.ERASER:
ObjectUtil.createBezierLine(mBezierResult);
break;
default:
break;
}
}
/**
* 也是计算两点间距离，但是这个是结果准确的
*
* @param start
* @param end
* @return
*/
private static float calculateExactDistance(PointBean start, PointBean end) {
float x = Math.abs(start.getX() - end.getX());
float y = Math.abs(start.getY() - end.getY());
return (float) Math.sqrt((x * x + y * y));
}