package com.stu.assistant.uitls;

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

/**
 * 解决沉浸式状态栏下 输入框不顶上去的冲突
* 实现顶部状态栏沉浸式后，点击底部自定义的输入框，弹出软键盘后，输入框被遮挡
* */
public class ChenJingEditUil {

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

    private Activity activity;
    private View mChildOfContent;
    private int usableHeightPrevious;
    private FrameLayout.LayoutParams frameLayoutParams;
    private int contentHeight;//获取setContentView本来view的高度
    private boolean isfirst = true;//只用获取一次
    private int statusBarHeight;//状态栏高度

    private ChenJingEditUil(Activity activity) {
        this.activity = activity;
        //1､找到Activity的最外层布局控件，它其实是一个DecorView,它所用的控件就是FrameLayout
        FrameLayout content = (FrameLayout) activity.findViewById(android.R.id.content);
        //2､获取到setContentView放进去的View
        mChildOfContent = content.getChildAt(0);
        //3､给Activity的xml布局设置View树监听，当布局有变化，如键盘弹出或收起时，都会回调此监听
        mChildOfContent.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            //4､软键盘弹起会使GlobalLayout发生变化
            public void onGlobalLayout() {
                if (isfirst) {
                    contentHeight = mChildOfContent.getHeight();//兼容华为等机型
                    isfirst = false;
                }
                //5､当前布局发生变化时，对Activity的xml布局进行重绘
                possiblyResizeChildOfContent();
            }
        });
        //6､获取到Activity的xml布局的放置参数
        frameLayoutParams = (FrameLayout.LayoutParams) mChildOfContent.getLayoutParams();
    }

    // 获取界面可用高度，如果软键盘弹起后，Activity的xml布局可用高度需要减去键盘高度
    private void possiblyResizeChildOfContent() {
        //1､获取当前界面可用高度，键盘弹起后，当前界面可用布局会减少键盘的高度
        int usableHeightNow = computeUsableHeight(activity);
        //2､如果当前可用高度和原始值不一样
        if (usableHeightNow != usableHeightPrevious) {
            //3､获取Activity中xml中布局在当前界面显示的高度
            int usableHeightSansKeyboard = mChildOfContent.getRootView().getHeight();
            //4､Activity中xml布局的高度-当前可用高度
            int heightDifference = usableHeightSansKeyboard - usableHeightNow;
            //5､高度差大于屏幕1/4时，说明键盘弹出
            if (heightDifference > (usableHeightSansKeyboard / 4)) {
                // 6､键盘弹出了，Activity的xml布局高度应当减去键盘高度
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
                    frameLayoutParams.height = usableHeightSansKeyboard - heightDifference + statusBarHeight;
                } else {
                    frameLayoutParams.height = usableHeightSansKeyboard - heightDifference;
                }

            } else {
                frameLayoutParams.height=contentHeight;

            }
            //7､ 重绘Activity的xml布局
            mChildOfContent.requestLayout();
            usableHeightPrevious = usableHeightNow;
        }
    }

    private int computeUsableHeight(Activity activity) {
        Rect frame = new Rect();
        activity.getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);
        int statusBarHeight = frame.top;
        Rect r = new Rect();
        mChildOfContent.getWindowVisibleDisplayFrame(r);
        //这个判断是为了解决19之后的版本在弹出软键盘时，键盘和推上去的布局（adjustResize）之间有白色区域的问题
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            return (r.bottom - r.top) + statusBarHeight;
        }
        return (r.bottom - r.top);
    }

}
