Android实现背景图滑动变大松开回弹效果 Android实现背景图滑动变大松开

本文实例为大家分享了Android实现背景图滑动变大松开回弹的具体代码，供大家参考，具体内容如下
【Android实现背景图滑动变大松开回弹效果】原图

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1、自定义view继承ScrollView实现效果

public class HeadZoomScrollView extends ScrollView {private View mZoomView; private int mZoomViewWidth; private int mZoomViewHeight; private float firstPosition; //记录第一次按下的位置private boolean isScrolling; //是否正在缩放private float mScrollRate = 0.3f; //缩放系数，缩放系数越大，变化的越大private float mReplyRate = 0.5f; //回调系数，越大，回调越慢public HeadZoomScrollView(Context context) {super(context); }public HeadZoomScrollView(Context context, AttributeSet attrs) {super(context, attrs); }public HeadZoomScrollView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr); }public void setmZoomView(View mZoomView) {this.mZoomView = mZoomView; }public void setmScrollRate(float mScrollRate) {this.mScrollRate = mScrollRate; }public void setmReplyRate(float mReplyRate) {this.mReplyRate = mReplyRate; }@Overrideprotected void onFinishInflate() {super.onFinishInflate(); init(); }private void init() {setOverScrollMode(OVER_SCROLL_NEVER); if (getChildAt(0) != null) {ViewGroup vg = (ViewGroup) getChildAt(0); if (vg.getChildAt(0) != null) {mZoomView = vg.getChildAt(0); }}}@Overridepublic boolean onTouchEvent(MotionEvent ev) {if (mZoomViewWidth <= 0 || mZoomViewHeight <= 0) {mZoomViewWidth = mZoomView.getMeasuredWidth(); mZoomViewHeight = mZoomView.getMeasuredHeight(); }switch (ev.getAction()) {case MotionEvent.ACTION_UP://手指离开后恢复图片isScrolling = false; replyImage(); break; case MotionEvent.ACTION_MOVE:if (!isScrolling) {if (getScrollY() == 0) {firstPosition = ev.getY(); // 滚动到顶部时记录位置，否则正常返回} else {break; }}int distance = (int) ((ev.getY() - firstPosition) * mScrollRate); // 滚动距离乘以一个系数if (distance < 0) { // 当前位置比记录位置要小，正常返回break; }// 处理放大isScrolling = true; setZoom(distance); return true; // 返回true表示已经完成触摸事件，不再处理}return true; }//回弹动画private void replyImage() {float distance = mZoomView.getMeasuredWidth() - mZoomViewWidth; ValueAnimator valueAnimator = ValueAnimator.ofFloat(distance, 0f).setDuration((long) (distance * mReplyRate)); valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {@Overridepublic void onAnimationUpdate(ValueAnimator animation) {setZoom((Float) animation.getAnimatedValue()); }}); valueAnimator.start(); }public void setZoom(float zoom) {if (mZoomViewWidth <= 0 || mZoomViewHeight <= 0) {return; }ViewGroup.LayoutParams lp = mZoomView.getLayoutParams(); lp.width = (int) (mZoomViewWidth + zoom); lp.height = (int) (mZoomViewHeight * ((mZoomViewWidth + zoom) / mZoomViewWidth)); ((MarginLayoutParams) lp).setMargins(-(lp.width - mZoomViewWidth) / 2, 0, -(lp.width - mZoomViewWidth) / 2, 0); mZoomView.setLayoutParams(lp); }}

2、直接布局中使用这个view就可以，要注意的是在布局中需要在自定义view下写一个子控件才能使用

<你的包名.HeadZoomScrollView xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"xmlns:tools="http://schemas.android.com/tools"android:id="@+id/drop_down_menu"android:layout_width="match_parent"android:layout_height="match_parent">

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。