Android Databinding

BindingUtil.java

public class BindingUtil {

    /**
     * 四方形是基准。none：不做任何调整，width：基于宽度调整成四方形
     */
    public enum Size {
        none, width, height
    }

    /**
     * 和Picasso不合。Picasso拿不到新的Layout尺寸。
     * @param view
     * @param by
     */
    @BindingAdapter("android:squareBy")
    public static void bindSquare(final View view, final Size by) {
        if (by == Size.none) return;
        view.getViewTreeObserver().addOnGlobalLayoutListener(
            new ViewTreeObserver.OnGlobalLayoutListener() {
                @Override
                public void onGlobalLayout() {
                    int size = by == Size.height ? view.getHeight() : view.getWidth();
                    ViewGroup.LayoutParams params = view.getLayoutParams();
                    params.width = size;
                    params.height = size;
                    view.setLayoutParams(params);
                    view.getViewTreeObserver().removeOnGlobalLayoutListener(this);
                }
            }
        );
    }

    /**
     * 和Picasso不合。Picasso拿不到新的Layout尺寸。
     * @param view
     * @param by
     */
    @BindingAdapter("android:squareBy")
    public static void bindSquare(final View view, final int by) {
        bindSquare(view, Size.values()[by]);
    }

    private BindingUtil() {
    }
}