图像视图不动

Question

我试图让 Imageview（一个球）在布局中移动并弹跳多次，然后在按下按钮时停止。问题是虽然 logcat 说它正在发生，但我看不到它在移动。

在这里

public class BallPhisics {
int x =400;
int y = 0;
boolean bounceX = false;
boolean bounceY= false;
int counter =0;
ImageView object;
public BallPhisics(ImageView i){
    object=i;
}

public void applyMovement() {
    while (true) {
        object.setLeft((int) object.getX()+x); //i know i shouldnt use pixels
        Log.d("EVENT", "X moved");        Log.d("Ended",Integer.toString(object.getLeft()));

        object.setBottom((int)(object.getY() + y));
        Log.d("EVENT", "Y moved");
        try {
            Thread.sleep(1000);
            Log.d("EVENT", "Time 1 used");
        } catch(InterruptedException ex) {
            Thread.currentThread().interrupt();
        }

        if (object.getX()<=50||(object.getRight()<=50)){
            bounceX =true;
            break;
        }
        if (object.getY()<=50||object.getTop()<=50){
            bounceY=true;
            break;
        }
    }
    this.bouncing();

}
public void bouncing(){
    Log.d("EVENT", "Bouncing!!");
    if (bounceX&&bounceY){
        x=-x;
        y=-y;
    }
    else if (bounceX){
        x=-x;
        y=(int)(Math.random()*100- 50 +y);
    }
    else if (bounceY) {
        x = (int) (Math.random() * 100 - 50 + x);
        y = -y;
    }
    counter++;
    if(counter==5){return;}
    this.applyMovement();
}

并且在 mainActivity 上的 onclick 事件。

 public void StartBall (View view){
    ImageView imageview=(ImageView) findViewById(R.id.imageView);
    BallPhisics phisics = new BallPhisics(imageview);
    Log.d("EVENT", Integer.toString(imageview.getLeft() )+" before");
    phisics.applyMovement();
    Log.d("EVENT",Integer.toString(imageview.getLeft())+" after" );

}

抱歉，如果阅读量很大。顺便问一下，有人知道移动视图的正确方法吗？

提前致谢

Answer 1

首先要移动视图，使用 setLeft (int left) 或 setBottom (int bottom) 可能不是一个好主意，因为此方法旨在由布局系统调用，否则通常不应调用, according to the documentation.

要动态移动视图，您应该查看 LayoutParams 或 setX (float x) 和 setY (float Y)，如果您可以限制对 Honeycomb 的支持（API 级别 11 ).

无论使用哪一种，您都可能会发现很难实现流畅的移动。因此，我建议您使用视图动画系统来执行 ImageView 的补间动画。

下面是一个链式动画示例，它使用任意 y 坐标从左向右移动 ImageView。每次从一个 x 边界转换到下一个 x 边界后，onAnimationEnd 将被调用并开始另一个方向的动画。

public class MainActivity extends Activity {

  //the ImageView you want to animate
  private ImageView imageview; 

  private Animation mAnimation;

  //The coordinates the view moved to in the last animation 
  private float lastX=0;
  private float lastY=0;
  private float secondlastY;
 
  //Listener that implements a translate animation chain
  AnimationListener animationListener=new AnimationListener() {
        @Override
        public void onAnimationEnd(Animation animation) {
            
            float newY=(float)(Math.random()*0.75);

            //this prevents that we move back to the position we came from
            // to get a more natural bounce animation
            while(newY<=secondlastY+0.15 && newY>=secondlastY-0.15){
                newY=(float)(Math.random()*0.75);
            }
            
            if(lastX==0.75f){
              //test if we are on the right border of the parent
                mAnimation=newAnimation(lastX,lastY,0f,newY);
                mAnimation.setAnimationListener(animationListener);
                lastX=0f;
                
            }else if(lastX==0.0f){
                //test if we are on the left border of the parent
                mAnimation=newAnimation(lastX,lastY,0.75f,newY);
                mAnimation.setAnimationListener(animationListener);
                lastX=0.75f;
            }
            
            secondlastY=lastY;
            lastY=newY;
            imageview.startAnimation(mAnimation);
        }
  };
    
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    
    imageview=(ImageView) findViewById(R.id.imageView);

    //the coordinates the first animation should move to
    lastY=(float)(Math.random()*0.75);
    lastX=0.75f;

    mAnimation=newAnimation(0f,0f,lastX,lastY); 
    mAnimation.setAnimationListener(animationListener);
    imageview.startAnimation(mAnimation);
 }

  //Method that returns a new animation with given start and end coordinates
  private Animation newAnimation(float startX, float startY, float endX, float endY){
     Animation mAnimation = new TranslateAnimation(
              TranslateAnimation.RELATIVE_TO_PARENT, startX,
              TranslateAnimation.RELATIVE_TO_PARENT, endX,
              TranslateAnimation.RELATIVE_TO_PARENT, startY,
              TranslateAnimation.RELATIVE_TO_PARENT, endY );
     mAnimation.setDuration(2500);
     mAnimation.setRepeatCount(0);
     mAnimation.setRepeatMode(Animation.REVERSE);
     mAnimation.setFillAfter(true);
          
     return mAnimation;
 }

}

注：平移动画是相对于父类的宽高的。如果将视图一直移动到 x=1.0 或 y=1.0，您会将部分视图移出父布局。因为对于这个例子来说已经足够了，所以我选择将 0.75 设置为任一方向的最大位置。但是您可能应该根据 ImageView 和 ParentLayout 的宽度和高度动态设置它。

图像视图不动

Imageview not moving

android

view