FixedAspectRatioLayout.java

package com.lettrs.lettrs.view;

import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.widget.RelativeLayout;
import com.lettrs.lettrs.R;
import lombok.Getter;
import lombok.Setter;

/**
 * This class will try to maintain its aspect ratio according to the parameter aspectRatio,
 * (styleable via attribute 'aspect_ratio').
 *
 * If the width is not zero, it will try to change the height to maintain the aspect ratio.
 * Otherwise it tries to change the width. If non of these works, it fallbacks to a regular layout.
 *
 * If the aspectRatio is not present (less than 0.0f), it will fallback to a regular layout
 */
public class FixedAspectRatioLayout extends RelativeLayout {
    /**
     * width / height
     */
    @Getter @Setter
    private float aspectRatio;

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

    public FixedAspectRatioLayout(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

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

        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.FixedAspectRatioLayout, defStyle, 0);
        try {
            aspectRatio = typedArray.getFloat(R.styleable.FixedAspectRatioLayout_aspect_ratio, Float.MIN_VALUE);
        } finally {
            typedArray.recycle();
        }

    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        if (aspectRatio > 0) {
            int width = MeasureSpec.getSize(widthMeasureSpec);
            int height = MeasureSpec.getSize(heightMeasureSpec);

            if (width > 0 && width < height) {
                int measuredHeight = (int) (width / aspectRatio);
                super.onMeasure(widthMeasureSpec,
                        MeasureSpec.makeMeasureSpec(measuredHeight, MeasureSpec.getMode(heightMeasureSpec)));
            } else if (height > 0 && height <= width) {
                int measuredWidth = (int) (height * aspectRatio);
                super.onMeasure(MeasureSpec.makeMeasureSpec(measuredWidth, MeasureSpec.getMode(widthMeasureSpec)),
                        heightMeasureSpec);
            } else {
                super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            }
        } else {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    }
}

Add this to attrs.xml

    <declare-styleable name="FixedAspectRatioLayout">
        <attr name="aspect_ratio" format="float"/>
    </declare-styleable>