Android 下拉阻尼效果_At_Swim

废话不多说直接上代码

自定义ListView

HeaderListView 类

package com.example.headerlistview;

import android.animation.ObjectAnimator;
import android.animation.ValueAnimator;
import android.annotation.SuppressLint;
import android.content.Context;
import android.os.Build;
import android.support.annotation.RequiresApi;
import android.text.Layout;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.ViewTreeObserver;
import android.view.animation.OvershootInterpolator;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ListView;

import com.nineoldandroids.view.ViewHelper;

/**
 * Created by Lenovo on 2018/5/14.
 */

public class HeaderListView extends ListView {

    private ImageView mIv;

    public HeaderListView(Context context) {
        this(context, null);
    }

    public HeaderListView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public HeaderListView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    private int picHeight, mImageViewHeight, maxHeight;//图片高度| 控件高度

    public void setImageView(ImageView imageView) {
        mIv = imageView;
        picHeight = mIv.getDrawable().getIntrinsicHeight();   // 688
        Log.e("TAG", "图片高度：=======" + picHeight);
        mIv.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            @SuppressLint("NewApi")
            @Override
            public void onGlobalLayout() {
                mIv.getViewTreeObserver().removeOnGlobalLayoutListener(this);
                mImageViewHeight = mIv.getHeight();
                Log.e("TAG", "图片控件的高度：=======" + mImageViewHeight); //240
            }
        });

        maxHeight = mImageViewHeight > picHeight ? mImageViewHeight * 2 : picHeight;

    }

    //判断滚动的View是否滑动到了顶端或者底端
    //maxOverScrollX  X轴滑动的最大范围
    //maxOverScrollY  Y轴滑动的最大范围
    //isTouchEvent  是否是拖动滑动，  true 代表是拖动状态，false 代表惯性滑动状态
    @Override
    protected boolean overScrollBy(int deltaX, int deltaY, int scrollX,
                                   int scrollY, int scrollRangeX, int scrollRangeY,
                                   int maxOverScrollX, int maxOverScrollY,
                                   boolean isTouchEvent) {
        if (deltaY < 0 && isTouchEvent) {
            if (mIv != null) {
                mIv.getLayoutParams().height = mIv.getHeight() + (-deltaY) / 3;
                if (mIv.getLayoutParams().height > maxHeight) {
                    mIv.getLayoutParams().height = maxHeight;
                }
                mIv.requestLayout();
            }
        }

        return super.overScrollBy(deltaX, deltaY, scrollX, scrollY, scrollRangeX,
                scrollRangeY, maxOverScrollX, maxOverScrollY, isTouchEvent);
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        super.onTouchEvent(ev);
        switch (ev.getAction()) {
            case MotionEvent.ACTION_UP:
                ValueAnimator valueAnimator = ValueAnimator.ofFloat(mIv.getHeight(), mImageViewHeight);
                valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                    @Override
                    public void onAnimationUpdate(ValueAnimator value) {
                        float i = (float) value.getAnimatedValue();
                        if (mIv != null) {
                            mIv.getLayoutParams().height = (int) i;
                            mIv.requestLayout();
                        }
                    }
                });
                valueAnimator.setDuration(1000);
                valueAnimator.setInterpolator(new OvershootInterpolator(3));
                valueAnimator.start();
                break;
        }
        return true;
    }
}

HeaderListView布局

<?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="wrap_content">

    <ImageView
        android:id="@+id/header_iv"
        android:layout_width="match_parent"
        android:layout_height="200dp"
        android:scaleType="centerCrop"
        android:src="@drawable/e" />

</LinearLayout>

MainActivity 代码

package com.example.headerlistview;

import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    private HeaderListView mListView;
    private String[] mStrArr = new String[20];

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        for (int i = 0; i < mStrArr.length; i++) {
            mStrArr[i] = "数据" + i;
        }
        mListView = findViewById(R.id.lv);
        View view = View.inflate(MainActivity.this, R.layout.header_view, null);
        ImageView ImageView = view.findViewById(R.id.header_iv);
        mListView.addHeaderView(view);
        mListView.setImageView(ImageView);
        mListView.setAdapter(new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_1, mStrArr) {
            @Override
            public View getView(int position, View convertView, ViewGroup parent) {
                convertView = View.inflate(MainActivity.this, R.layout.list_item, null);
                TextView tv_item = convertView.findViewById(R.id.item_tv);
                tv_item.setText(mStrArr[position]);
                return convertView;
            }
        });


    }
}

MainActivity 布局

<?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:orientation="vertical">

    <com.example.headerlistview.HeaderListView
        android:id="@+id/lv"
        android:layout_width="match_parent"
        android:overScrollMode="never"
        android:layout_height="match_parent" />

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:paddingBottom="15dp"
    android:paddingTop="15dp">

    <TextView
        android:id="@+id/item_tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="哈哈" />

</RelativeLayout>

最后呢libs里添加架包

nineoldandroids-2.4.0.jar

如果帮到你了，请评论