AndroidBug5497Workaround.java

package com.jasonchen.microlang.utils;

import android.app.Activity;
import android.graphics.Rect;
import android.view.View;
import android.view.ViewTreeObserver;
import android.widget.FrameLayout;

import java.lang.reflect.Field;

/**
 * jasonchen
 * 2015/04/10
 */
public class AndroidBug5497Workaround {

    // For more information, see https://code.google.com/p/android/issues/detail?id=5497
    // To use this class, simply invoke assistActivity() on an Activity that already has its content view set.

    public static void assistActivity (Activity activity) {
        new AndroidBug5497Workaround(activity);
    }

    private View mChildOfContent;
    private int usableHeightPrevious;
    private FrameLayout.LayoutParams frameLayoutParams;

    private AndroidBug5497Workaround(Activity activity) {
        FrameLayout content = (FrameLayout) activity.findViewById(android.R.id.content);
        mChildOfContent = content.getChildAt(0);
        mChildOfContent.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            public void onGlobalLayout() {
                possiblyResizeChildOfContent();
            }
        });
        frameLayoutParams = (FrameLayout.LayoutParams) mChildOfContent.getLayoutParams();
    }

    private void possiblyResizeChildOfContent() {
        int usableHeightNow = computeUsableHeight();
        if (usableHeightNow != usableHeightPrevious) {
            int usableHeightSansKeyboard = mChildOfContent.getRootView().getHeight();
            int heightDifference = usableHeightSansKeyboard - usableHeightNow;
            if (heightDifference > (usableHeightSansKeyboard/4)) {
                // keyboard probably just became visible
                frameLayoutParams.height = usableHeightSansKeyboard - heightDifference + getStatusBarHeight();
            } else {
                // keyboard probably just became hidden
                frameLayoutParams.height = usableHeightSansKeyboard;
            }
            mChildOfContent.requestLayout();
            usableHeightPrevious = usableHeightNow;
        }
    }

    private int computeUsableHeight() {
        Rect r = new Rect();
        mChildOfContent.getWindowVisibleDisplayFrame(r);
        return (r.bottom - r.top);
    }
    
    public int getStatusBarHeight() {
		Class<?> c = null;
		Object obj = null;
		Field field = null;
		int x = 0, statusBarHeight = 0;
		try {
			c = Class.forName("com.android.internal.R$dimen");
			obj = c.newInstance();
			field = c.getField("status_bar_height");
			x = Integer.parseInt(field.get(obj).toString());
			statusBarHeight = GlobalContext.getInstance().getResources().getDimensionPixelSize(x);
		} catch (Exception e1) {
			e1.printStackTrace();
		}
		return statusBarHeight;
	}

}