Loading images to different screen sizes and densities in game development?

Question

The code below draws a square and circle on different screen sizes distance between images changes. It would be more messed up with actual bitmaps and different screen sizes and densities. Here is the code

package com.badlogic.androidgames;

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;

public class ShapeTest extends Activity {
class RenderView extends View {        
    Paint paint;

    public RenderView(Context context) {
        super(context);
        paint = new Paint();            
    }

    protected void onDraw(Canvas canvas) {
        canvas.drawRGB(255, 255, 255);            
        paint.setColor(Color.RED);
        canvas.drawLine(0, 0, canvas.getWidth()-1, canvas.getHeight()-1, paint);

        paint.setStyle(Style.STROKE);
        paint.setColor(0xff00ff00);            
        canvas.drawCircle(canvas.getWidth() / 2, canvas.getHeight() / 2, 40, paint);

        paint.setStyle(Style.FILL);
        paint.setColor(0x770000ff);
        canvas.drawRect(100, 100, 200, 200, paint);
        invalidate();
    }
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                         WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(new RenderView(this));
}
}

Here is a pic:

How should i proceed?

Answer 1

The problem is that the bounds of your rectangle are not depending on the screen size.

canvas.drawRect(100, 100, 200, 200, paint);

will draw in pixels.

What you need is an appropriate multiplier for the width, height, top and left. (float)(height / width) or (float)(width / height) - depending on wich is larger.

canvas.drawRect(leftOffset* ratio, topOffset * ratio, baseWidth * ratio, baseHeight * ratio, paint);

If you use real Bitmaps, you would also need to scale it to the correct size.

Answer 2

I think this code gets the apropriately sized bitmap:

Bitmap bm = BitmapFactory.decodeResource(getResources(), R.drawable.image);

according to this post: Android - does decodeResource scale the bitmap for screen density?