ResizableImageView.java

import android.content.Context;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.widget.ImageView;

/*
 * An ImageView that scales its bounds while following the aspect ratio
 * of its drawable. This is useful for showing images in fill_parent
 * situations when the drawable itself is smaller than the dimensions of
 * the view.
 * 
 * Normal ImageView with fill_parent and 20x20 image:
 * 
 * 	 10px	 20px    10px
 * -----------------------
 * |      |       |      |
 * | view | image | view | 20px
 * |      |       |      |
 * ----------------------- *obviously not drawn to scale
 * 
 * This ImageView with fill_parent and 20x20 image:
 * 
 * 	    40px
 * ---------------------
 * |			|
 * |			|
 * |			|
 * |	image		| 40px
 * |			|
 * |			|
 * |			|
 * ---------------------  *not drawn to scale as well
 * 
 */
public class ResizableImageView extends ImageView {

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

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

	public ResizableImageView(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		Drawable drawable = getDrawable();
		if (drawable != null) {
			int width = MeasureSpec.getSize(widthMeasureSpec);
			int diw = drawable.getIntrinsicWidth();
			if (diw > 0) {
				int height = width * drawable.getIntrinsicHeight() / diw;
				setMeasuredDimension(width, height);
			} else
				super.onMeasure(widthMeasureSpec, heightMeasureSpec);
		} else
			super.onMeasure(widthMeasureSpec, heightMeasureSpec);
	}
}