向下滑动效果上ExpandableListView [英] Slide down effect on ExpandableListView

问题描述

是否有可能有一个漂亮的幻灯片向上/向下影响扩大时/折叠一个ExpandableListView的项目？

Is it possible to have a nice slide up/down effect when expanding/collapsing an item of a ExpandableListView?

如果是，如何？

在此先感谢。

推荐答案

所以，这是<一个完整的副本href="http://stackoverflow.com/questions/4541287/animating-the-childs-of-an-expandablelistview-when-collapsing-expanding/10092020#10092020">this.总之，我用了一个常规列表，使我自己的下拉列表视图，使用自定义的下拉动画瞧成功（看看链接查看更多说明）。

So This is a complete duplicate of this. In short, I used a regular list, made my own dropdown view, used a custom drop down animation and voila success (look at link for more description).

编辑：一步一步的指导：

Step by step guide:

首先，我创建XML list_row：

First I create the xml list_row:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/row_parent"
    android:orientation="vertical">
    <RelativeLayout 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/row_simple_parent"
        >
    <View
        android:id="@+id/row_simple_parent_invis_cover"
        android:visibility="gone"
        android:layout_height="something that fills out your content"
        android:layout_width="match_parent"
        android:background="@android:color/transparent"/>
    </RelativeLayout>

    <!-- Dropdown -->
    <RelativeLayout 
        android:id="@+id/row_dropdown"
        android:layout_height="wrap_content"
        android:layout_width="match_parent">
    </RelativeLayout>
</LinearLayout>

动画的下拉列表的以下内容：

The animation for dropdown is following:

import android.app.Activity;
import android.util.DisplayMetrics;
import android.view.View;
import android.view.View.MeasureSpec;
import android.view.animation.Animation;
import android.view.animation.Transformation;

/**
 * Class for handling collapse and expand animations.
 * @author Esben Gaarsmand
 *
 */
public class ExpandCollapseAnimation extends Animation {
    private View mAnimatedView;
    private int mEndHeight;
    private int mStartVisibility;

    /**
     * Initializes expand collapse animation. If the passed view is invisible/gone the animation will be a drop down, 
     * if it is visible the animation will be collapse from bottom
     * @param view The view to animate
     * @param duration
     */ 
    public ExpandCollapseAnimation(View view, int duration) {
        setDuration(duration);
        mAnimatedView = view;
        mEndHeight = mAnimatedView.getLayoutParams().height;
        mStartVisibility = mAnimatedView.getVisibility();
        if(mStartVisibility == View.GONE || mStartVisibility == View.INVISIBLE) {
            mAnimatedView.setVisibility(View.VISIBLE);
            mAnimatedView.getLayoutParams().height = 0;
        }
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        super.applyTransformation(interpolatedTime, t);
        if (interpolatedTime < 1.0f) {
            if(mStartVisibility == View.GONE || mStartVisibility == View.INVISIBLE) {
                mAnimatedView.getLayoutParams().height = (int) (mEndHeight * interpolatedTime);
            } else {
                mAnimatedView.getLayoutParams().height = mEndHeight - (int) (mEndHeight * interpolatedTime);
            }
            mAnimatedView.requestLayout();
        } else {
            if(mStartVisibility == View.GONE || mStartVisibility == View.INVISIBLE) {
                mAnimatedView.getLayoutParams().height = mEndHeight;
                mAnimatedView.requestLayout();
            } else {
                mAnimatedView.getLayoutParams().height = 0;
                mAnimatedView.setVisibility(View.GONE);
                mAnimatedView.requestLayout();
                mAnimatedView.getLayoutParams().height = mEndHeight;
            }
        }
    }

    /**
     * This methode can be used to calculate the height and set itm for views with wrap_content as height. 
     * This should be done before ExpandCollapseAnimation is created.
     * @param activity
     * @param view
     */
    public static void setHeightForWrapContent(Activity activity, View view) {
        DisplayMetrics metrics = new DisplayMetrics();
        activity.getWindowManager().getDefaultDisplay().getMetrics(metrics);

        int screenWidth = metrics.widthPixels;

        int heightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
        int widthMeasureSpec = MeasureSpec.makeMeasureSpec(screenWidth, MeasureSpec.EXACTLY);

        view.measure(widthMeasureSpec, heightMeasureSpec);
        int height = view.getMeasuredHeight();
        view.getLayoutParams().height = height;
    }
}

然后我的适配器内部（你会ofcourse添加更多语法，如果你想在视力在列表中，您需要与某种参数的持有人记得这个问题，以及在下拉列表不关闭）：

Then inside my adapter (you'll ofcourse add more syntax, and if you want the dropdown to not close when out of sight in the list, you need to remember this in the holder with some kind of parameter as well):

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    final ViewHolder holder;
    if(convertView == null) {
        // setup holder
        holder = new ViewHolder();
        convertView = mInflater.inflate(R.layout.list_row, null);
        holder.mDropDown = convertView.findViewById(R.id.row_dropdown);
        convertView.setTag(holder);
    } else {
        // get existing row view
        holder = (ViewHolder) convertView.getTag();
    }
    holder.mDropDown.setVisibility(View.GONE);
    return convertView;
}

然后奇迹发生在你的名单onItemClick：

Then the magic happens in your lists onItemClick:

@Override
public void onListItemClick(ListView list, View view, int position, long id) {
    final ListItem item = (ListItem) list.getAdapter().getItem(position);
    // set dropdown data
    ViewHolder holder = (ViewHolder) view.getTag();
    final View dropDown = holder.mDropDown;

    // set click close on top part of view, this is so you can click the view
    // and it can close or whatever, if you start to add buttons etc. you'll loose
    // the ability to click the view until you set the dropdown view to gone again.
    final View simpleView = view.findViewById(R.id.row_simple_parent_invis_cover);
    simpleView.setVisibility(View.VISIBLE);

    final Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            if(msg.what == 0) {
                // first we measure height, we need to do this because we used wrap_content
                // if we use a fixed height we could just pass that in px.
                ExpandCollapseAnimation.setHeightForWrapContent(getActivity(), dropDown);
                ExpandCollapseAnimation expandAni = new ExpandCollapseAnimation(dropDown, DROP_DOWN_TIME);
                dropDown.startAnimation(expandAni);

                Message newMsg = new Message();

            } else if(msg.what == 1) {
                ExpandCollapseAnimation expandAni = new ExpandCollapseAnimation(dropDown, DROP_DOWN_TIME);
                dropDown.startAnimation(expandAni);

                simpleView.setOnClickListener(null);
                simpleView.setVisibility(View.GONE);
            }
        }
    };

    simpleView.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            handler.sendEmptyMessage(1);
        }
    });

    // start drop down animation
    handler.sendEmptyMessage(0);
}

最后的评论：我不知道这是做的最好的方式，但是这是为我工作。

Final comment: I'm not sure this is the best way of doing it but this is what worked for me.

修改：有不同的解决方案，通过DevBytes在YouTube上，可以在这里查看

Edit: There is a different solution by DevBytes on youtube that can be viewed here.

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