Place a transparent surface view over a map

Question

I am developing an android application using google map, in this i need to place a surface view over a map so that i can draw shapes above the map. i have DrawingSurface.java as below

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.util.AttributeSet;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;


import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

public class DrawingSurface extends SurfaceView implements SurfaceHolder.Callback {
    private Boolean _run;
    protected DrawThread thread;
    private Bitmap mBitmap;
    public boolean isDrawing = true;


    public DrawingSurface(Context context, AttributeSet attrs) {
        super(context, attrs);

        getHolder().addCallback(this);


        thread = new DrawThread(getHolder());
    }


    class DrawThread extends  Thread{
        private SurfaceHolder mSurfaceHolder;


        public DrawThread(SurfaceHolder surfaceHolder){
            mSurfaceHolder = surfaceHolder;

        }

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


        @Override
        public void run() {
            Canvas canvas = null;
            while (_run){
                if(isDrawing == true){
                    try{
                        canvas = mSurfaceHolder.lockCanvas(null);
                        if(mBitmap == null){
                            mBitmap =  Bitmap.createBitmap (1, 1, Bitmap.Config.ARGB_8888);
                        }
                        final Canvas c = new Canvas (mBitmap);

                        c.drawColor(0, PorterDuff.Mode.CLEAR);
                        canvas.drawColor(0, PorterDuff.Mode.CLEAR);


                        canvas.drawBitmap (mBitmap, 0,  0,null);
                    } finally {
                        mSurfaceHolder.unlockCanvasAndPost(canvas);
                    }
                    isDrawing = false;
                }

            }

        }
    }






    public Bitmap getBitmap(){
        return mBitmap;
    }


    public void surfaceChanged(SurfaceHolder holder, int format, int width,  int height) {
        // TODO Auto-generated method stub
        mBitmap =  Bitmap.createBitmap (width, height, Bitmap.Config.ARGB_8888);;
    }


    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...
            }
        }
    }

}

and the lay out as

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:id="@+id/lay">
            <com.google.android.maps.MapView
            android:id="@+id/mapview"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:apiKey="0VD9w_GZnvQYr8v0KDuVHYn0DTw_ZXwqHnnP7CA"
            android:clickable="true" />
             <com.experion.test.DrawingSurface
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:id="@+id/surfaceView"
        />

</FrameLayout>

i need to draw shapes on my DrawingSurface on that time the map need to disable the scroll.

Whether i need to use canvas??

thanks in advance

Answer 1

    drawingSurface = (DrawingSurface) findViewById(R.id.drawingSurface);
    drawingSurface.setZOrderOnTop(true);    // necessary
    SurfaceHolder drawingSurface1 = drawingSurface.getHolder();
    drawingSurface1.setFormat(PixelFormat.TRANSPARENT);