add image to surface view in android

问题:

I want to add image to Surface view. So i used below code

public class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback{

     Bitmap myicon;
     Canvas canvas;
     private Paint   mBitmapPaint;

     Paint p= new Paint();


       @Override
        protected void onDraw(Canvas canvas) {
           Bitmap myicon=BitmapFactory.decodeResource(getResources(),R.drawable.icon);
           canvas.drawColor(Color.BLACK);
           canvas.drawBitmap(myicon, 0,0, p);
           // canvas.drawBitmap(myicon, 0,0, null);
           // canvas.drawBitmap(myicon, 25,25, null);
       }
        public MySurfaceView(Context context) {
            super(context);
            // TODO Auto-generated constructor stub
        }

        public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
            // TODO Auto-generated method stub

        }

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

        }

        public void surfaceDestroyed(SurfaceHolder arg0) {
            // TODO Auto-generated method stub

        }
    }

But it shows black screen. I didn't get what i did wrong in above code.

Please solve the problem

Thanks in advance.

回答1:

Here is your solution Buddy, Also look at this link from where I got the solution

MainAct.java

public class MainAct extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mySurfaceView mySurfaceView = new mySurfaceView(getApplicationContext());
        setContentView(mySurfaceView);
    }
}

mySurfaceView.java

public class mySurfaceView extends SurfaceView implements
        SurfaceHolder.Callback {

    private TutorialThread _thread;

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

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        Bitmap _scratch = BitmapFactory.decodeResource(getResources(),
                R.drawable.icon);
        canvas.drawColor(Color.BLACK);
        canvas.drawBitmap(_scratch, 10, 10, null);

    }

    public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
    }

    public void surfaceCreated(SurfaceHolder arg0) {
        _thread.setRunning(true);
        _thread.start();
    }

    public void surfaceDestroyed(SurfaceHolder arg0) {
        boolean retry = true;
        _thread.setRunning(false);
        while (retry) {
            try {
                _thread.join();
                retry = false;
            } catch (InterruptedException e) {
            }
        }
    }

    class TutorialThread extends Thread {
        private SurfaceHolder _surfaceHolder;
        private mySurfaceView _panel;
        private boolean _run = false;

        public TutorialThread(SurfaceHolder surfaceHolder, mySurfaceView panel) {
            _surfaceHolder = surfaceHolder;
            _panel = panel;
        }

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

        @Override
        public void run() {
            Canvas c;
            while (_run) {
                c = null;
                try {
                    c = _surfaceHolder.lockCanvas(null);
                    synchronized (_surfaceHolder) {
                        _panel.onDraw(c);
                    }
                } finally {
                    if (c != null) {
                        _surfaceHolder.unlockCanvasAndPost(c);
                    }
                }
            }
        }
    }
}

EDIT :

droidnova website is not available anymore.I have found alternative website here which is having same source.

I hope it will be helpful !!

回答2:

There are some changes to your class

package com.sample;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class MSurface extends SurfaceView implements SurfaceHolder.Callback {

    public MSurface(Context context) {
        super(context);
        getHolder().addCallback(this);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        Bitmap icon = BitmapFactory.decodeResource(getResources(),R.drawable.icon);
        canvas.drawColor(Color.BLACK);
        canvas.drawBitmap(icon, 10, 10, new Paint());        
    }

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

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        Canvas canvas = null;
        try {
            canvas = holder.lockCanvas(null);
            synchronized (holder) {
                onDraw(canvas);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (canvas != null) {
                holder.unlockCanvasAndPost(canvas);
            }
        }
    }

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

    }
}

But I am not sure you need SurfaceView, cause it used not to draw bitmap once, but to draw a lot of times after user interaction

If your view is not interactive, would be better if you extend View instead of SurfaceView

Cheers