我已经进行了几天的尝试,但没能找到一个好的解决方案(至少对我来说是这样)。
基本上我需要做的是绘制一条动态虚线曲线,用于表示基础游戏的导弹轨迹。这条轨迹将接受起始、中间和最终的x、y坐标。我读了很多有关动画曲线甚至直线绘制的问答,但与我要做的相比,它们看起来非常复杂。
我有一个带有onclick
监听器的按钮,触发导弹发射,但到目前为止,它只能绘制静态线条,没有任何动画效果。
你还记得这个吗?那就是我想要实现的效果: http://www.youtube.com/watch?v=UDc3ZEKl-Wc
香蕉轨迹没有被绘制出来,但你已经有了这个想法。
在您的示例的基础上,我尝试使用数组和for循环同时绘制曲线,但有时候,不总是,应用程序会因为nullpointer异常而崩溃,我不知道原因。我在这里发布了我的代码:
public class DrawDottedCurve extends View {
Path[] path = new Path[8];
Path[] drawingPath = new Path[8];
PathMeasure[] measure = new PathMeasure[8];
Path[] segmentPath = new Path[8];
float[] length = new float[8];
float[] start = new float[8];
float[] percent = new float[8];
Paint paint = new Paint();
float x1;
float y1;
float x3;
float y3;
long k = 0;
Canvas canvas;
Random r = new Random();
public DrawDottedCurve(Context context, int a, int b, int c, int d) {
super(context);
x1 = a;
y1 = b;
x3 = c;
y3 = d;
paint.setAlpha(255);
paint.setStrokeWidth(2);
paint.setColor(Color.RED);
paint.setStyle(Style.STROKE);
paint.setPathEffect(new DashPathEffect(new float[] { 2, 4 }, 50));
for (int i = 0; i < 8; i++) {
k = r.nextInt(100 - 30) + 30;
path[i] = new Path();
path[i].moveTo(x1 + k, y1 + k); //
path[i].quadTo((x3 + k - x1 + k) / 2, (y3 + k - y1 + k) / 2,
x3 + k, y3 + k); // Calculate Bezier Curves
}
final long DRAW_TIME = 10000;
CountDownTimer timer = new CountDownTimer(DRAW_TIME, 100) {
@Override
public void onTick(long millisUntilFinished) {
Log.d("Timer", "Inizio");
for (int i = 0; i < 8; i++) {
start[i] = 0;
measure[i] = new PathMeasure();
measure[i].setPath(path[i], false);
percent[i] = ((float) (DRAW_TIME - millisUntilFinished))
/ (float) DRAW_TIME;
segmentPath[i] = new Path();
drawingPath[i] = new Path();
length[i] = measure[i].getLength() * percent[i];
measure[i].getSegment(start[i], length[i], segmentPath[i],
true);
start[i] = length[i];
drawingPath[i].addPath(segmentPath[i]);
}
invalidate();
;
}
@Override
public void onFinish() {
for (int i = 0; i < 8; i++) {
measure[i].getSegment(start[i], measure[i].getLength(),
segmentPath[i], true);
drawingPath[i].addPath(segmentPath[i]);
}
invalidate();
Log.d("Timer", "Fine");
}
};
timer.start();
}
@Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
for (int i = 0; i < 8; i++) {
canvas.drawPath(drawingPath[i], paint);
invalidate();
}
}
}