Android: Setting button height in XML based on it's width

Question

I am working on layout in android XML in which I would like to set a buttons height to match it's width when setup to fill parent. Obviously this number will change based on screen size, so I cannot use a set pixel size. Can someone help me with getting the button width based on screen size and then passing that to the height setting?

Thank You, Josh

Answer 1

I once had a similar problem and found no solution which works just from XML. You have to write your own Button-Class and overwrite the [onMeassure][1] method.

Example:

/**
 * @see android.view.View#measure(int, int)
 */
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    setMeasuredDimension(measureWidth(widthMeasureSpec), measureHeight(heightMeasureSpec));
}

private int width; // saves the meassured width


/**
 * Determines the width of this view
 * 
 * @param measureSpec
 *            A measureSpec packed into an int
 * @return The width of the view, honoring constraints from measureSpec
 */
private int measureWidth(int measureSpec) {
    int result = 30;
    int specMode = MeasureSpec.getMode(measureSpec);
    int specSize = MeasureSpec.getSize(measureSpec);

    if (specMode == MeasureSpec.EXACTLY) {
        // We were told how big to be
        result = specSize;
    } else {
        result =1123; // meassure your with here somehow
        if (specMode == MeasureSpec.AT_MOST) {
            // Respect AT_MOST value if that was what is called for by measureSpec
            result = Math.min(result, specSize);
        }
    }
            width = result;
    return result;
}

/**
 * Determines the height of this view
 * 
 * @param measureSpec
 *            A measureSpec packed into an int
 * @return The height of the view, honoring constraints from measureSpec
 */
private int measureHeight(int measureSpec) {
    int result = 0;
    int specMode = MeasureSpec.getMode(measureSpec);
    int specSize = MeasureSpec.getSize(measureSpec);

    if (specMode == MeasureSpec.EXACTLY) {
        // We were told how big to be
        result = specSize;
    } else {
        result = width;
        if (specMode == MeasureSpec.AT_MOST) {
            // Respect AT_MOST value if that was what is called for by measureSpec
            result = Math.min(result, specSize);
        }
    }

    return result;
}

[1]: http://developer.android.com/reference/android/view/View.html#onMeasure(int, int)