Android - 連續繪製形狀到隨機位置

Question

我對android動畫有點新。我正在製作一個項目，該項目將一個球的圖片放置在一個隨機位置，之後它將循環移動。到目前爲止，我已經取得了成功，但現在我想在不同的隨機座標上不斷繪製新形狀。我想過使用一個線程來繪製形狀每隔幾秒鐘，但我似乎無法實現它，而不是把所有東西搞砸。

有誰知道我該如何解決這個問題？另外我知道我每次都必須不斷重置我的隨機座標。有誰知道我該怎麼做？謝謝你的幫助。我的代碼如下：

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

理念：

1. 實現Runnable和處理

2. 創建通過隨機隨機座標。

   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); 
       } 
   } 
   

   }