cardview及下定义scrollview实现下拉头部放大

文件来源：http://blog.csdn.net/anyfive/article/details/52575262

//自定义scrollview

package com.example.administrator.myscrollview;import android.animation.ObjectAnimator;import android.animation.ValueAnimator;import android.content.Context;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.View;import android.view.ViewGroup;import android.widget.ScrollView;/** * Created by Administrator on 2016/12/9. */public class MyScrollView extends ScrollView {    public MyScrollView(Context context) {        super(context);    }    public MyScrollView(Context context, AttributeSet attrs) {        super(context, attrs);    }    public MyScrollView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);    }    //    用于记录下拉位置    private float y = 0f;    //    zoomView原本的宽高    private int zoomViewWidth = 0;    private int zoomViewHeight = 0;    //    是否正在放大    private boolean mScaling = false;    //    放大的view，默认为第一个子view    private View zoomView;    public void setZoomView(View zoomView) {        this.zoomView = zoomView;    }    //    滑动放大系数，系数越大，滑动时放大程度越大    private float mScaleRatio = 0.4f;    public void setmScaleRatio(float mScaleRatio) {        this.mScaleRatio = mScaleRatio;    }    //    最大的放大倍数    private float mScaleTimes = 2f;    public void setmScaleTimes(float mScaleTimes) {        this.mScaleTimes = mScaleTimes;    }    //    回弹时间系数，系数越小，回弹越快    private float mReplyRatio = 0.5f;    public void setmReplyRatio(float mReplyRatio) {        this.mReplyRatio = mReplyRatio;    }    @Override    protected void onFinishInflate() {        super.onFinishInflate();//        不可过度滚动，否则上移后下拉会出现部分空白的情况        setOverScrollMode(OVER_SCROLL_NEVER);//        获得默认第一个view        if (getChildAt(0) != null && getChildAt(0) instanceof ViewGroup && zoomView == null) {            ViewGroup vg = (ViewGroup) getChildAt(0);            if (vg.getChildCount() > 0) {                zoomView = vg.getChildAt(0);            }        }    }    @Override    public boolean onTouchEvent(MotionEvent ev) {        if (zoomViewWidth <= 0 || zoomViewHeight <=0) {            zoomViewWidth = zoomView.getMeasuredWidth();            zoomViewHeight = zoomView.getMeasuredHeight();        }        if (zoomView == null || zoomViewWidth <= 0 || zoomViewHeight <= 0) {            return super.onTouchEvent(ev);        }        switch (ev.getAction()) {            case MotionEvent.ACTION_MOVE:                if (!mScaling) {                    if (getScrollY() == 0) {                        y = ev.getY();//滑动到顶部时，记录位置                    } else {                        break;                    }                }                int distance = (int) ((ev.getY() - y)*mScaleRatio);                if (distance < 0) break;//若往下滑动                mScaling = true;                setZoom(distance);                return true;            case MotionEvent.ACTION_UP:                mScaling = false;                replyView();                break;        }        return super.onTouchEvent(ev);    }    /**放大view*/    private void setZoom(float s) {        float scaleTimes = (float) ((zoomViewWidth+s)/(zoomViewWidth*1.0));//        如超过最大放大倍数，直接返回        if (scaleTimes > mScaleTimes) return;        ViewGroup.LayoutParams layoutParams = zoomView.getLayoutParams();        layoutParams.width = (int) (zoomViewWidth + s);        layoutParams.height = (int)(zoomViewHeight*((zoomViewWidth+s)/zoomViewWidth));//        设置控件水平居中        ((MarginLayoutParams) layoutParams).setMargins(-(layoutParams.width - zoomViewWidth) / 2, 0, 0, 0);        zoomView.setLayoutParams(layoutParams);    }    /**回弹*/    private void replyView() {        final float distance = zoomView.getMeasuredWidth() - zoomViewWidth;        // 设置动画        ValueAnimator anim = ObjectAnimator.ofFloat(distance, 0.0F).setDuration((long) (distance * mReplyRatio));        anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {            @Override            public void onAnimationUpdate(ValueAnimator animation) {                setZoom((Float) animation.getAnimatedValue());            }        });        anim.start();    }    @Override    protected void onScrollChanged(int l, int t, int oldl, int oldt) {        super.onScrollChanged(l, t, oldl, oldt);        if (onScrollListener!=null) onScrollListener.onScroll(l,t,oldl,oldt);    }    private OnScrollListener onScrollListener;    public void setOnScrollListener(OnScrollListener onScrollListener) {        this.onScrollListener = onScrollListener;    }    /**滑动监听*/    public  interface OnScrollListener{        void onScroll(int scrollX,int scrollY,int oldScrollX, int oldScrollY);    }}

//cardview的使用

<android.support.v7.widget.CardView    android:clickable="true"

<!--设置可点击和点击出现button类似的波纹效果-->    android:foreground="?attr/selectableItemBackground"    android:layout_marginTop="50dp"    android:layout_marginLeft="20dp"    android:layout_marginRight="20dp"    android:layout_width="match_parent"    android:layout_height="250dp"    xmlns:card_view="http://schemas.android.com/apk/res-auto"    card_view:cardBackgroundColor="#ffffff"    card_view:contentPadding="5dp"    card_view:cardCornerRadius="10dp"<!--定义圆角弧度-->

<!--定义阴影程度-->
    card_view:cardElevation="20dp">
<!--cardview继承fragment，内容布局需要自己添加包裹-->    <LinearLayout        android:layout_width="match_parent"        android:layout_height="match_parent"        android:orientation="vertical">        <ImageView            android:layout_width="match_parent"            android:layout_height="200dp"            android:src="@mipmap/a0003"            android:layout_centerHorizontal="true"            android:scaleType="fitCenter" />        <TextView            android:layout_width="wrap_content"            android:layout_height="50dp"            android:layout_below="@+id/img"            android:layout_centerHorizontal="true"            android:text="This is a card view"            android:paddingLeft="@dimen/activity_horizontal_margin"            android:paddingRight="@dimen/activity_horizontal_margin" />    </LinearLayout></android.support.v7.widget.CardView>