java - Android - 连续绘制形状到随机位置

Question

我对安卓动画有点陌生。我正在做一个项目，该项目将球的图片放在随机位置 - 之后它会绕圈移动。到目前为止，我一直很成功，但现在我想在不同的随机坐标上不断绘制新形状。我考虑过使用线程每隔几秒绘制一次形状，但我似乎无法在不搞砸一切的情况下实现它。

有谁知道我该如何解决这个问题？我也知道每次我都必须不断地重新设置我的随机坐标。有谁知道我该怎么做？谢谢你的帮助。我的代码如下:

public class DrawingTheBall extends View {

Bitmap bball; 
int randX, randY;
double theta;


public DrawingTheBall(Context context) {
    super(context);
    // TODO Auto-generated constructor stub
    bball = BitmapFactory.decodeResource(getResources(), R.drawable.blueball);  
    randX = 1 + (int)(Math.random()*500); 
    randY = 1 + (int)(Math.random()*500);
    theta = 45;
}

public void onDraw(Canvas canvas){
    super.onDraw(canvas);
    //Radius, angle, and coordinates for circle motion  
    float a = 50;
    float b = 50;
    float r = 50;
    int x = 0;
    int y = 0;
    theta = theta + Math.toRadians(2);

    //move ball in circle
    if(x < canvas.getWidth()){
        x = randX + (int) (a +r*Math.cos(theta));
    }else{
        x = 0;
    }
    if(y < canvas.getHeight()){
        y = randY + (int) (b +r*Math.sin(theta));
    }else{
        y = 0;
    }
    Paint p = new Paint();

    //Implement Thread here
      thread = new Thread(new Runnable(){

                  @Override
                  public void run(){

                    for(int j = 0; j <= 60; j++){

                          //It tells me to change variables to Final
                        //But if I do that it messes up my if statements above
                            canvas.drawBitmap(bball, x, y, p);

                         }
                      };
                      try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } //wait one second
                    }
                  }

                });
                thread.start();

    //canvas.drawBitmap(bball, x, y, p);
    invalidate();
}

Answer 1

想法:

1. 实现 Runnable 和处理程序

2. 通过Random创建随机坐标。

   public class DrawingTheBall extends View implements Runnable {
   
   final Bitmap bball;
   Random randX, randY;
   double theta;
   Handler handler = new Handler(){
       public void handleMessage(android.os.Message msg) {
           invalidate();
           System.out.println("redraw");
       };
   };
   
   public DrawingTheBall(Context context) {
       super(context);
       bball = BitmapFactory.decodeResource(getResources(),
               R.drawable.ic_launcher);
       randX = new Random();
       randY = new Random();
       theta = 45;
       new Thread(this).start();
   }
   
   public void onDraw(Canvas canvas) {
       super.onDraw(canvas);
       // Radius, angle, and coordinates for circle motion
       float a = 50;
       float b = 50;
       float r = 50;
       int x = 0;
       int y = 0;
       theta = theta + Math.toRadians(2);
   
       // move ball in circle
       if (x < canvas.getWidth()) {
           x = randX.nextInt(100) + (int) (a + r * Math.cos(theta)); // create
                                                                   // randX
                                                                   // integer
       } else {
           x = 0;
       }
       if (y < canvas.getHeight()) {
           y = randY.nextInt(100) + (int) (b + r * Math.sin(theta));// create
                                                                   // randX
                                                                   // integer
       } else {
           y = 0;
       }
       Paint p = new Paint();
       canvas.drawBitmap(bball, x, y, p);
   }
   
   public void run() {
       while (true) {
           try {
               Thread.sleep(1000);
           } catch (InterruptedException e) {
               e.printStackTrace();
           }
           handler.sendEmptyMessage(0);
       }
   }