Berühren und ziehen Bild in Android

Question

Ich arbeite an einem Beispiel, in dem ich das Bild entsprechend Touch in Android ziehen möchten. Hat jemand eine Idee, wie ich das machen kann?

Answer 1

public class TouchBall extends Activity { 


@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 

    int w=getWindowManager().getDefaultDisplay().getWidth()-25; 
    int h=getWindowManager().getDefaultDisplay().getHeight()-25; 

    BallView ballView=new BallView(this,w,h); 
    setContentView(ballView); 
} 


} 
public class BallView extends SurfaceView implements SurfaceHolder.Callback { 

    private Bitmap bitmap ; 
    private MyThread thread; 
    private int x=20,y=20;int width,height; 

    public BallView(Context context,int w,int h) { 
     super(context); 

     width=w; 
     height=h; 
     thread=new MyThread(getHolder(),this); 
     getHolder().addCallback(this); 
     setFocusable(true); 
    } 

    @Override 
    protected void onDraw(Canvas canvas) { 
     super.onDraw(canvas); 

     bitmap =BitmapFactory.decodeResource(getResources(), R.drawable.ball_green); 
     canvas.drawColor(Color.BLUE);//To make background 
     canvas.drawBitmap(bitmap,x-(bitmap.getWidth()/2),y-(bitmap.getHeight()/2),null); 


    } 

    @Override 
    public boolean onTouchEvent(MotionEvent event) { 

     x=(int)event.getX(); 
     y=(int)event.getY(); 

     if(x<25) 
       x=25; 
     if(x> width) 
       x=width; 
     if(y <25) 
       y=25; 
     if(y > 405) 
       y=405;  
     return true; 
    } 

    @Override 
    public void surfaceChanged(SurfaceHolder holder, int format, int width,int height) { 
     // TODO Auto-generated method stub 

    } 

    @Override 
    public void surfaceCreated(SurfaceHolder holder) { 

     thread.startrun(true); 
     thread.start(); 

    } 

    @Override 
    public void surfaceDestroyed(SurfaceHolder holder) { 


     thread.startrun(false); 
     thread.stop(); 

    } 
} 

thread:

public class MyThread extends Thread { 

private SurfaceHolder msurfaceHolder; 
private BallView mballView; 
private boolean mrun =false; 

public MyThread(SurfaceHolder holder, BallView ballView) { 

    msurfaceHolder = holder; 
    mballView=ballView; 
} 

public void startrun(boolean run) { 

    mrun=run; 
} 

@Override 
public void run() { 

    super.run(); 
    Canvas canvas; 
    while (mrun) { 
     canvas=null; 
     try { 
      canvas = msurfaceHolder.lockCanvas(null); 
       synchronized (msurfaceHolder) { 
       mballView.onDraw(canvas); 
      } 
     } finally { 
       if (canvas != null) { 
       msurfaceHolder.unlockCanvasAndPost(canvas); 
      } 
     } 
    } 
    } 

} 

Answer 2

Als leichte Modifikation der TouchBall Antwort - wenn Sie nicht wirklich eine Spielschleife haben - in anderen Worten, die nur Änderungen am Bildschirm direkt aufgrund Benutzereingabe - dann könnte es sinnvoller sein, den Thread wegzulassen. Sonst wird nur ständig geblättert und neu gezeichnet, auch wenn sich nichts geändert hat. Also:

public class TouchBall extends Activity { 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 

     int w=getWindowManager().getDefaultDisplay().getWidth()-25; 
     int h=getWindowManager().getDefaultDisplay().getHeight()-25; 

     BallView ballView=new BallView(this,w,h); 
     setContentView(ballView); 
    } 
} 

public class BallView extends SurfaceView implements SurfaceHolder.Callback { 
    private Bitmap bitmap ; 
    private int x=20,y=20;int width,height; 

    public BallView(Context context,int w,int h) { 
     super(context); 

     width=w; 
     height=h; 
     getHolder().addCallback(this); 
     setFocusable(true); 
    } 

    @Override 
    protected void onDraw(Canvas canvas) { 
     super.onDraw(canvas); 

     bitmap =BitmapFactory.decodeResource(getResources(), R.drawable.ball_green); 
     canvas.drawColor(Color.BLUE);//To make background 
     canvas.drawBitmap(bitmap,x-(bitmap.getWidth()/2),y-(bitmap.getHeight()/2),null); 
    } 

    @Override 
    public boolean onTouchEvent(MotionEvent event) { 
     x=(int)event.getX(); 
     y=(int)event.getY(); 

     if(x<25) 
      x=25; 
     if(x> width) 
      x=width; 
     if(y <25) 
      y=25; 
     if(y > 405) 
      y=405; 

     updateBall(); 

     return true; 
    } 

    @Override 
    public void surfaceChanged(SurfaceHolder holder, int format, int width,int height) { 
     // TODO Auto-generated method stub 
    } 

    @Override 
    public void surfaceCreated(SurfaceHolder holder) { 
     // TODO Auto-generated method stub 
    } 

    @Override 
    public void surfaceDestroyed(SurfaceHolder holder) { 
     // TODO Auto-generated method stub 
    } 

    private void updateBall() { 
     Canvas canvas = null; 
     try { 
      canvas = getHolder().lockCanvas(null); 
      synchronized (getHolder()) { 
       this.onDraw(canvas); 
      } 
     } 
     finally { 
      if (canvas != null) { 
       getHolder().unlockCanvasAndPost(canvas); 
      } 
     } 
    } 
} 

Zugegeben, ich bin neu in der Android-Entwicklung, daher kann mir hier etwas fehlen.