如何将一个可绘制的图像放入此画布中并让它在此图像上画线？

Question

我该如何将一个可绘制的图像放入此画布中并让它在此图像上画线？下面 代码：谢谢

package com.tutorialforandroid; 

import java.util.ArrayList; 

import android.app.Activity; 
import android.content.Context; 
import android.content.res.Resources; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.graphics.Canvas; 
import android.graphics.Paint; 
import android.graphics.Path; 
import android.os.Bundle; 
import android.view.MotionEvent; 
import android.view.SurfaceHolder; 
import android.view.SurfaceView; 

/** 
* 
* @author mendoza, almond joseph 
* From tutorial 
* http://www.tutorialforandroid.com/2009/06/drawing-with-canvas-in-android.html 
*/ 
public class CanvasDrawingActivity extends Activity { 
    private ArrayList<Path> _graphics = new ArrayList<Path>(); 
    private Paint mPaint; 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(new DrawingPanel(this)); 
    mPaint = new Paint(); 
    mPaint.setDither(true); 
    mPaint.setColor(0xFFFFFF00); 
    mPaint.setStyle(Paint.Style.STROKE); 
    mPaint.setStrokeJoin(Paint.Join.ROUND); 
    mPaint.setStrokeCap(Paint.Cap.ROUND); 
    mPaint.setStrokeWidth(3); 


} 
class DrawingPanel extends SurfaceView implements SurfaceHolder.Callback { 
    private DrawingThread _thread; 
    private Path path; 

    public DrawingPanel(Context context) { 
     super(context); 
     getHolder().addCallback(this); 
     _thread = new DrawingThread(getHolder(), this); 
    } 


    public boolean onTouchEvent(MotionEvent event) { 
     synchronized (_thread.getSurfaceHolder()) { 
      if(event.getAction() == MotionEvent.ACTION_DOWN){ 
       path = new Path(); 
       path.moveTo(event.getX(), event.getY()); 
       path.lineTo(event.getX(), event.getY()); 
      }else if(event.getAction() == MotionEvent.ACTION_MOVE){ 
       path.lineTo(event.getX(), event.getY()); 
      }else if(event.getAction() == MotionEvent.ACTION_UP){ 
       path.lineTo(event.getX(), event.getY()); 
       _graphics.add(path); 
      } 

      return true; 
     } 
    } 

    @Override 
    public void onDraw(Canvas canvas) { 
     for (Path path : _graphics) { 
      //canvas.drawPoint(graphic.x, graphic.y, mPaint); 
      canvas.drawPath(path, mPaint); 

     } 
    } 

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

    } 

    public void surfaceCreated(SurfaceHolder holder) { 
     // TODO Auto-generated method stub 
     _thread.setRunning(true); 
     _thread.start(); 
    } 

    public void surfaceDestroyed(SurfaceHolder holder) { 
     // TODO Auto-generated method stub 
     boolean retry = true; 
     _thread.setRunning(false); 
     while (retry) { 
      try { 
       _thread.join(); 
       retry = false; 
      } catch (InterruptedException e) { 
       // we will try it again and again... 
      } 
     } 
    } 
} 

class DrawingThread extends Thread { 
    private SurfaceHolder _surfaceHolder; 
    private DrawingPanel _panel; 
    private boolean _run = false; 

    public DrawingThread(SurfaceHolder surfaceHolder, DrawingPanel panel) { 
     _surfaceHolder = surfaceHolder; 
     _panel = panel; 
    } 

    public void setRunning(boolean run) { 
     _run = run; 
    } 

    public SurfaceHolder getSurfaceHolder() { 
     return _surfaceHolder; 
    } 

    @Override 
    public void run() { 
     Canvas c; 
     while (_run) { 
      c = null; 
      try { 
       c = _surfaceHolder.lockCanvas(null); 
       synchronized (_surfaceHolder) { 
        _panel.onDraw(c); 
       } 
      } finally { 
       // do this in a finally so that if an exception is thrown 
       // during the above, we don't leave the Surface in an 
       // inconsistent state 
       if (c != null) { 
        _surfaceHolder.unlockCanvasAndPost(c); 
       } 
      } 
     } 
    } 
} 

}

Answer 1

内onDraw(Canvas canvas)

Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.icon); 
canvas.drawBitmap(bitmap, x, y, null); 

只要画一条线在图像上，我不知道，但我认为

canvas.drawRect(); 

应该可以做到，bitmap.getWidth()和bitmap.getheight()应该可以帮你解决这个问题。