我对安卓动画不太熟悉。我正在使用在YouTube上找到的教程进行学习。该应用程序在画布上绘制了一个球的图片,然后将其对角线移动。我想让球按圆形轨迹移动。我已经找到了一些有关圆周运动基本数学的信息,但是我无法实现它。有人能看看我的代码并告诉我哪里出了问题吗?谢谢。
以下是我的代码:
public class DrawingTheBall extends View {
Bitmap bball;
int x,y;
public DrawingTheBall(Context context) {
super(context);
// TODO Auto-generated constructor stub
bball = BitmapFactory.decodeResource(getResources(), R.drawable.blueball);
x = 0;
y = 0;
}
@Override
public void onDraw(Canvas canvas){
super.onDraw(canvas);
Rect ourRect = new Rect();
ourRect.set(0, 0, canvas.getWidth(), canvas.getHeight()/2);
float a = 10;
float b = 10;
float r = 20;
double theta = 0;
theta = Math.toRadians(45);
Paint blue = new Paint();
blue.setColor(Color.BLUE);
blue.setStyle(Paint.Style.FILL);
canvas.drawRect(ourRect, blue);
if(x < canvas.getWidth()){
//x += 10;
x = (int) (a +r*Math.cos(theta));
}else{
x = 0;
}
if(y < canvas.getHeight()){
//y += 10;
y = (int) (b +r*Math.sin(theta));
}else{
y = 0;
}
Paint p = new Paint();
canvas.drawBitmap(bball, x, y, p);
invalidate();
}
}