Question

Can any1 tell me why I cant add a bitmap onto my surfaceView like this:

    steering = new Steering(BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher), getWidth()-50,getHeight()-50);

if I use integers instead of the “getHeight()”-method, the bitmap is added just fine. But since I want this game to run on more then 1 phone without looking weird I want to add it using those 2 methods.

can any1 help?

thanks!

Answer 1

where exactly you are adding that line? if its on your onCreate then it wouldnt display you the image since the method getWidth() and getHeight() would return 0. So to paint it you have to wait until the system have actually created the view.
To test that you are actually receiving a value try changing the code you actually have for something like this:

final int width = getWidth();
final int height = getHeight();
final Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
steering = new Steering(bitmap, width-50,height-50);

and add a breakpoint to the steering line and debugg it. If you are getting 0 in the width and height then you will have to wait for the view to draw.

Edit:
on your Activity/Fragment you can add a tree observer like this:

 myView.getViewTreeObserver().addOnGlobalLayoutListener( new ViewTreeObserver.OnGlobalLayoutListener() {
                @Override
                public void onGlobalLayout() {
                    //Do something here since now you have the width and height of your view
                }
            });

Here is a small example on how you would do it in your classes:

My Steering Class:

public class Steering {

    private Bitmap mBitmap;
    private int mWidth;
    private int mHeight;

    public Steering(Bitmap bitmap, int width, int height) {
        this.mBitmap = bitmap;
        this.mWidth = width;
        this.mHeight = height;
    }

    public Bitmap getBitmap() {
        //reescaling from anddev.org/resize_and_rotate_image_-_example-t621
        final int imageWidth = mBitmap.getWidth();
        final int imageHeight = mBitmap.getHeight();
        // calculate the scale -
        float scaleWidth = ((float) mWidth) / imageWidth;
        float scaleHeight = ((float) mHeight) / imageHeight;
        // createa matrix for the manipulation
        Matrix matrix = new Matrix();
        // resize the bit map
        matrix.postScale(scaleWidth, scaleHeight);

        Bitmap resizedBitmap = Bitmap.createBitmap(mBitmap, 0, 0, imageWidth, imageHeight, matrix, true);
        return resizedBitmap;
    }

}

My Activity

public class MainActivity extends Activity {

    MyView mView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mView = (MyView) findViewById(R.id.viewid);
        OnGlobalLayoutListener listener = new OnGlobalLayoutListener() {

            @Override
            public void onGlobalLayout() {
                final int width = mView.getWidth();
                final int height = mView.getHeight();
                final Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.android);
                //image from anddev
                final Steering steering = new Steering(bitmap, width-50,height-50);
                mView.setObject(steering);
            }
        };
        mView.getViewTreeObserver().addOnGlobalLayoutListener(listener);
    }

}

and my View Class

public class MyView extends View{

    Steering steering = null;

    public MyView(Context context) {
        super(context);
    }

    public MyView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public void setObject(Steering steering){
        this.steering = steering;
    }

    final Paint paint = new Paint();

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.save();
        if(steering!=null){
            canvas.drawBitmap(steering.getBitmap(), 0, 0, paint);
        }
        canvas.restore();
    }

}

You can use this for a normal view or a surfaceView, either way works.
Sorry if the answer is a bit too long 😛