example_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android">

	<ImageView
		android:id="@+id/big_image"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"
		/>

	<ImageView
		android:id="@+id/small_image"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"
		/>

</merge>

ExampleLayout.java

package my.package;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

public class ExampleLayout extends ViewGroup {

	public ExampleLayout(Context context, AttributeSet attrs) {
		super(context, attrs);
		inflate(context, R.layout.example_layout, this);
		bigImageView = (ImageView) findViewById(R.id.big_image);
		smallImageView = (ImageView) findViewById(R.id.small_image);
	}

	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		final int width = r - l;
		final int height = b - t;

		final int bigImageViewHeight = Math.round(0.4f * height);
		layoutChild(bigImageView,
			Math.round(0.1f * width),
			0,
			Math.round(0.8f * width),
			bigImageViewHeight);

		final int bigImageViewCenterVertical = bigImageViewHeight / 2;
		final int smallImageViewHeight = smallImageView.getMeasuredHeight(); // for example
		layoutChild(smallImageView,
			Math.round(0.3f * width),
			bigImageViewCenterVertical - smallImageViewHeight / 2,
			Math.round(0.4f * width),
			smallImageViewHeight);

		// etc
	}

	private static void layoutChild(View view, int left, int top, int width, int height) {
		view.layout(left, top, left + width, top + height);
	}

	private final ImageView bigImageView;
	private final ImageView smallImageView;

}