package com.wuxiaolong.androidsamples.viewdraghelper;
import android.annotation.TargetApi;
import android.content.Context;
import android.os.Build;
import android.support.v4.view.GestureDetectorCompat;
import android.support.v4.view.ViewCompat;
import android.support.v4.widget.ViewDragHelper;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
/**
* Created by WuXiaolong
* on 2015/12/4.
*/
public class ViewDragLayout extends LinearLayout {
/**
* 内容界面
*/
private ViewGroup mContentLayout;
/**
* 遮盖界面
*/
private ViewGroup mBehindLayout;
private ViewDragHelper mViewDragHelper;
/**
* 手势事件类
*/
private GestureDetectorCompat mGestureDetectorCompat;
/**
* 滑动距离
*/
private int mViewDragRange;
/**
* 左滑最大距离
*/
private int mBehindLayoutWidth;
/**
* 宽度
*/
private int mContentLayoutWidth;
private ViewDragListener mViewDragListener;
private boolean isOpen = false;
public ViewDragLayout(Context context) {
super(context);
init();
}
public ViewDragLayout(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public ViewDragLayout(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public ViewDragLayout(Context context, AttributeSet attrs,
int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
init();
}
/**
* View 中所有的子控件均被映射成xml后触发
*/
@Override
protected void onFinishInflate() {
mContentLayout = (ViewGroup) getChildAt(0);
mBehindLayout = (ViewGroup) getChildAt(1);
mBehindLayout.setClickable(true);
mContentLayout.setClickable(true);
super.onFinishInflate();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
mContentLayoutWidth = mContentLayout.getMeasuredWidth();
mBehindLayoutWidth = mBehindLayout.getMeasuredWidth();
}
/**
* 设置监听
*/
public void setOnViewDragListener(ViewDragListener viewDragListener) {
this.mViewDragListener = viewDragListener;
}
public interface ViewDragListener {
void onOpen();
void onClose();
void onDrag(float percent);
}
/**
* 滑动时松手后以一定速率继续自动滑动下去并逐渐停止，
* 类似于扔东西或者松手后自动滑动到指定位置
*/
@Override
public void computeScroll() {
if (mViewDragHelper.continueSettling(true)) {
ViewCompat.postInvalidateOnAnimation(this);
}
}
/**
* 初始化
*/
private void init() {
//创建ViewDragHelper的实例，第一个参数是ViewGroup，传自己，
// 第二个参数就是滑动灵敏度的意思,可以随意设置，第三个是回调
mViewDragHelper = ViewDragHelper.create(this, 1.0f, new DragHelperCallback());
//手势操作，第二参数什么意思看下面
mGestureDetectorCompat = new GestureDetectorCompat(getContext(), new XScrollDetector());
}
/**
* 手势监听回调,
* SimpleOnGestureListener为了不用重写那么多监听的帮助类
*/
private class XScrollDetector extends GestureDetector.SimpleOnGestureListener {
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2,
float distanceX, float distanceY) {
//判断是否是滑动的x距离>y距离
return Math.abs(distanceY) <= Math.abs(distanceX);
}
}
class DragHelperCallback extends ViewDragHelper.Callback {
/**
* 根据返回结果决定当前child是否可以拖拽
*
* @param child 当前被拖拽的view
* @param pointerId 区分多点触摸的id
* @return
*/
@Override
public boolean tryCaptureView(View child, int pointerId) {
return mContentLayout == child;
}
/**
* 返回拖拽的范围，不对拖拽进行真正的限制，仅仅决定了动画执行速度
*
* @param child
* @return
*/
@Override
public int getViewHorizontalDragRange(View child) {
return mContentLayoutWidth;
}
/**
* @param child
* @param left 代表你将要移动到的位置的坐标,返回值就是最终确定的移动的位置,
* 判断如果这个坐标在layout之内,那我们就返回这个坐标值，
* 不能让他超出这个范围, 除此之外就是如果你的layout设置了padding的话，
* 让子view的活动范围在padding之内的
* @param dx
* @return
*/
@Override
public int clampViewPositionHorizontal(View child, int left, int dx) {
//Log.d("wxl", "clampViewPositionHorizontal left=" + left);
if (child == mContentLayout) {
int newLeft = Math.min(
Math.max((-getPaddingLeft() - mBehindLayoutWidth), left), 0);
return newLeft;
} else {
int newLeft = Math.min(
Math.max(left, getPaddingLeft() + mContentLayoutWidth - mBehindLayoutWidth),
(getPaddingLeft() + mContentLayoutWidth + getPaddingRight()));
return newLeft;
}
}
/**
* 位置改变时回调，常用于滑动是更改scale进行缩放等效果
*
* @param changedView
* @param left
* @param top
* @param dx 横向滑动的加速度
* @param dy
*/
@Override
public void onViewPositionChanged(
View changedView, int left, int top, int dx, int dy) {
//Log.d("wxl", "onViewPositionChanged left=" + left);
mViewDragRange = left;
float percent = Math.abs((float) left / (float) mContentLayoutWidth);
if (null != mViewDragListener)
mViewDragListener.onDrag(percent);
if (changedView == mContentLayout) {
mBehindLayout.offsetLeftAndRight(dx);
} else {
mContentLayout.offsetLeftAndRight(dx);
}
invalidate();
}
/**
* 拖动结束后调用
*
* @param releasedChild
* @param xvel 水平方向的速度 向右为正
* @param yvel 竖直方向的速度 向下为正
*/
@Override
public void onViewReleased(View releasedChild, float xvel, float yvel) {
if (releasedChild == mContentLayout) {
if (xvel <= 0) {//向左滑动
if (-mViewDragRange >= mBehindLayoutWidth / 2
&& -mViewDragRange <= mBehindLayoutWidth) {
open();
} else {
close();
}
} else {//向右滑动
if (-mViewDragRange >= 0
&& -mViewDragRange <= mBehindLayoutWidth) {
close();
} else {
open();
}
}
}
}
}
/**
* 打开
*/
public void open() {
if (mViewDragHelper.smoothSlideViewTo(
mContentLayout, -mBehindLayoutWidth, 0)) {
ViewCompat.postInvalidateOnAnimation(this);
}
if (null != mViewDragListener)
mViewDragListener.onOpen();
isOpen = true;
}
/**
* 关闭
*/
public void close() {
if (mViewDragHelper.smoothSlideViewTo(mContentLayout, 0, 0)) {
ViewCompat.postInvalidateOnAnimation(this);
}
if (null != mViewDragListener)
mViewDragListener.onClose();
isOpen = false;
}
public boolean isOpen() {
return isOpen;
}
/**
* 事件拦截下来,相当于把自定义控件的事件交给ViewDragHelper去处理
*
* @param ev
* @return
*/
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
return mViewDragHelper.shouldInterceptTouchEvent(ev)
&& mGestureDetectorCompat.onTouchEvent(ev);
}
/**
* 事件监听，交给ViewDragHelper处理
*
* @param e
* @return
*/
@Override
public boolean onTouchEvent(MotionEvent e) {
try {
mViewDragHelper.processTouchEvent(e);
} catch (Exception ex) {
ex.printStackTrace();
}
return false;
}
}