How To Scale Canvas In Android

Question

I am writing a android game using Canvas as the way to draw everything, the problem is that when i run it on different android phones the canvas dosn't change size i tried using canvas.scale() but that didn't make a i difference. The code i use for drawing is ...

public void draw( Canvas c, int score )
{   
    Obstical2[] obstmp = Queue.toArray(this.o);
    Coin[] cointmp = QueueC.toArray(this.c);

    for( int i = 0; i < obstmp.length; i++ )
    {
        obstmp[i].draw(c);
    }

    for( int i = 0; i < cointmp.length; i++ )
    {
        cointmp[i].draw(c);
    }
    c.drawText(String.format("%d", score ), 20, 50, textPaint);

    if( isWon && isStarted ) c.drawText("YOU WON", 20, 400, resPaint);
    else if( isLost && isStarted ) c.drawText("YOU LOST", 20, 400, resPaint);
}

The function above calls the draw functions for the entity's on the screen, theses function are as follows

Draw Function For Obstical :

public void draw( Canvas c )
{
    Log.i("D", "COIN");
    coin.draw(c);
}

Draw Function For Coin :

public void draw( Canvas c )
{
     obstical.draw(c);
}

The on create function is :

protected void onCreate(Bundle savedInstanceState) 
{
    player = new Player(this);
    //map = new Map(this, );
    WindowManager w = this.getWindowManager();
    Display d = w.getDefaultDisplay();

    float sy = d.getHeight()/800;
    float sx = d.getWidth()/480;

    super.onCreate(savedInstanceState);

    Intent intent = getIntent();
    String type = intent.getStringExtra(CUBEMenuActivity.EXTRA_MESSAGE);

    Log.i("MENU", type);

    mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
    //mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_GRAVITY);
    mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);

       // Remove the title bar from the window.
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);

        // Make the windows into full screen mode.
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

    map = new Map( this, type, sy, sx );

    canvasView = new CanvasSurfaceView(this, map, player, sx, sy );
    setContentView(canvasView);

    Log.i("C", "Canvas View Set");

}

i am using a canvasSurfaceView instead of an XML layout, the canvasSurfaceView constructor method is

public CanvasSurfaceView(Context context, Map map, Player player, float sx, float sy) 
{
    super(context);
    holder = getHolder();

    gestures = new GestureDetector(new GestureListener(this));

    this.map = map;
    this.player = player;
    this.background = Bitmap.createScaledBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.background1), 480, 10000, false);
    this.sx = sx;
    this.sy = sy;
} 

when the game is running the run() method is called repeatedly this is where the canvas class is initialized

public void run()
{
    while( run == true )
    {
        if( !holder.getSurface().isValid() )
        {
            continue;
        }

        Canvas c = holder.lockCanvas();

        if( ( map.isWon || map.isLost ) && map.isStarted ) setCompleated();
        //c.scale(sx, sy);

        if( notCompleated == false )    
        {

            if( map.map.bottomOfLevel != 800 ) by += player.terminalVelosity / 2;
            update();
        }
        c.drawBitmap(background, 0, by, null);
        map.draw(c, player.score);
        player.draw(c);

        holder.unlockCanvasAndPost(c);
    }
}

How could i make the canvas re-size to it would look the same on any screen ?

Cheers Daniel

Answer 1

To do this, change the size of your paint object. Also, scale the bitmaps. Scaling the canvas doesn't do anything.

paint.setTextSize(textSize);

and for bitmaps

bitmap=Bitmap.createScaledBitmap(src, dstWidth, dstHeight, filter) 

where filter is whether the bilinear filtering is enabled

Answer 2

in run method when you want draw canvas you can use :

//out of run method
Rect dstRect = new Rect();
//in run method
canvas.getClipBounds(dstRect);
canvas.drawBitmap(background, null, dstRect, null); 

it force canvas to draw & scale your final bitmap(background) for any device resolation (may strech in som device).