Android 自定义 侧滑删除

又是新的一年， 又开始了打工人生活， 希望大家在新的一年都能达到自己的预期， 杠把得。

最近项目里会用到侧滑删除的效果， 类似QQ消息侧滑，因为没找到啥比较合适的轮子，功能也比较单一，所以直接手写了。

看一下效果：

007.gif

在xml中怎么使用：

 <!--自定义侧滑容器-->
    <com.example.sliddemo.SlideLayout
        android:id="@+id/slidelayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <!--左部分-->
        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="100dp"
            android:background="#000000"
            >

            <androidx.appcompat.widget.AppCompatTextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="自定义布局"
                android:layout_centerInParent="true"
                android:textColor="#ffffff"
                />

        </RelativeLayout>

        <!--右部分-->
        <androidx.appcompat.widget.AppCompatTextView
            android:id="@+id/tv_delete"
            android:layout_width="140dp"
            android:layout_height="match_parent"
            android:text="删除"
            android:textColor="#ffffff"
            android:background="#ff0000"
            android:gravity="center"
            />

    </com.example.sliddemo.SlideLayout>

再记录一下思路：
1.侧滑效果需要包含两部分， 左边显示区域， 右边隐藏区域， 滑动时显示右部分。
2.滑动未完成时根据滑动距离， 自动滚动到合适位置。
3.单击时不能拦截事件， 滚动时拦截事件。
4.滚动时强制父容器不拦截事件（在RecyclerView中如果不强制 竖直滑动和水平滑动会同时发生）；

代码根据思路写：
1.新建SlideLayout继承ViewGroup， 然后在SlideLayout中放入两个View，这就是左右两部分，
再onMeasure中测量放入View的大小， 在onLayout中将View显示在界面上，代码如下：

 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int count = getChildCount();
        if(count != 2){
            throw new RuntimeException("only can host 2 direct child view");
        }

        measureChildren(widthMeasureSpec, heightMeasureSpec);

        childOne = getChildAt(0);
        childTwo = getChildAt(1);

        childTwo.measure(MeasureSpec.makeMeasureSpec(childTwo.getMeasuredWidth(), MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(childOne.getMeasuredHeight(), MeasureSpec.EXACTLY));

        int ps = getPaddingStart();
        int pt = getPaddingTop();
        int pe = getPaddingEnd();
        int pb = getPaddingBottom();

        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);

        int slideWith = ps + pe;
        int slideHigh = pt + pb;

        switch (widthMode){
            case MeasureSpec.EXACTLY:
                slideWith = widthSize;
                break;
            case MeasureSpec.UNSPECIFIED:
            case MeasureSpec.AT_MOST:
                for (int i=0; i<count; i++){
                    View child = getChildAt(i);
                    slideWith += child.getMeasuredWidth();
                }
                break;
            default:
                break;
        }
        switch (heightMode){
            case MeasureSpec.EXACTLY:
                slideHigh = heightSize;
                break;
            case MeasureSpec.UNSPECIFIED:
            case MeasureSpec.AT_MOST:
                slideHigh += Math.max(childOne.getMeasuredHeight(), childTwo.getMeasuredHeight());
                break;
            default:
                break;
        }
        setMeasuredDimension(slideWith, slideHigh);
    }

    @Override
    protected void onLayout(boolean b, int l, int i1, int i2, int i3) {
        int ps = getPaddingStart();
        int pt = getPaddingTop();
        int pb = getPaddingBottom();

        int childOneWith = childOne.getMeasuredWidth();
        int childOneHigh = childOne.getMeasuredHeight();
        int childTwoWith = childTwo.getMeasuredWidth();
        int childTwoHigjh = childTwo.getMeasuredHeight();

        childOne.layout(ps, pt, ps + childOneWith, pt + childOneHigh + pb);
        childTwo.layout(ps + childOneWith, pt, ps + childOneWith + childTwoWith, pt + Math.max(childOneHigh, childTwoHigjh) + pb);

        scrollLimitSize = childTwoWith;
    }

2，3，4：
在onInterceptTouchEvent中进行事件拦截， 在onTouchEvent中进行View的滚动，在用户手指抬起时记录滚动位置， 并使用Scroller进行自动滚动，代码如下:

  @Override
    public boolean onInterceptTouchEvent(MotionEvent event) {
        switch (event.getAction()){
            case MotionEvent.ACTION_DOWN:
                isClick = true;
                startX = (int) event.getX();
                startY = (int) event.getY();
                return false;
            case MotionEvent.ACTION_MOVE:
                isClick = false;
                return true;
            case MotionEvent.ACTION_UP:
                return !isClick;
            default:
                break;
        }
        return false;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()){
            case MotionEvent.ACTION_DOWN:
                getParent().requestDisallowInterceptTouchEvent(true);
                break;
            case MotionEvent.ACTION_MOVE:
                int endY = (int) (event.getY() - startY);
                int endX = (int) (event.getX() - startX);
                if((Math.abs(endY) > Math.abs(endX)) && !canScrooll){
                    getParent().requestDisallowInterceptTouchEvent(false);
                    resetScroll();
                }else{
                    getParent().requestDisallowInterceptTouchEvent(true);
                    canScrooll = true;
                }
                if(canScrooll){
                    int scroll = currentScroll + endX;
                    if(scroll < -scrollLimitSize){
                        scroll = -scrollLimitSize;
                    }else if(scroll > 0){
                        scroll = 0;
                    }
                    scrollTo(- scroll, 0);
                }
                break;
            case MotionEvent.ACTION_UP:
                int divide = scrollLimitSize >> 1;
                if (getScrollX() > divide){
                    scroller.startScroll(getScrollX(), 0, scrollLimitSize - getScrollX(), 0, TIME);
                }else{
                    scroller.startScroll(getScrollX(), 0, - getScrollX(), 0, TIME);
                }
                invalidate();
                currentScroll = -getScrollX();
                getParent().requestDisallowInterceptTouchEvent(false);
                canScrooll = false;
                return !isClick;
            default:
                break;
        }
        return true;
    }


@Override
    public void computeScroll() {
        super.computeScroll();
        if(scroller.computeScrollOffset()){
            scrollTo(scroller.getCurrX(), scroller.getCurrY());
            invalidate();
        }
    }

重点就这两个， 下面贴全部代码， 就一个类：

public class SlideLayout extends ViewGroup {
    private static final int TIME = 100;
    private static final int LIMIT_MOVE = 20;

    private View childOne, childTwo;

    //最大滑动距离
    private int scrollLimitSize;

    private int startX;
    private int startY;
    private Scroller scroller;

    //当前滑动位置
    private int currentScroll;

    private boolean isClick = true;

    private boolean canScrooll;

    public SlideLayout(Context context) {
        super(context);
        init(context);
    }

    public SlideLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

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

    private void init(Context context){
        scroller = new Scroller(context);
    }

    /**
     * 展开
     */
    public void open(){
        scroller.startScroll(getScrollX(), 0, scrollLimitSize - getScrollX(), 0, TIME);
        invalidate();
    }

    /**
     * 收起
     */
    public void put(boolean isScroll){
        scroller.startScroll(getScrollX(), 0, -getScrollX(), 0, isScroll ? TIME : 0);
        invalidate();
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int count = getChildCount();
        if(count != 2){
            throw new RuntimeException("only can host 2 direct child view");
        }

        measureChildren(widthMeasureSpec, heightMeasureSpec);

        childOne = getChildAt(0);
        childTwo = getChildAt(1);

        childTwo.measure(MeasureSpec.makeMeasureSpec(childTwo.getMeasuredWidth(), MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(childOne.getMeasuredHeight(), MeasureSpec.EXACTLY));

        int ps = getPaddingStart();
        int pt = getPaddingTop();
        int pe = getPaddingEnd();
        int pb = getPaddingBottom();

        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);

        int slideWith = ps + pe;
        int slideHigh = pt + pb;

        switch (widthMode){
            case MeasureSpec.EXACTLY:
                slideWith = widthSize;
                break;
            case MeasureSpec.UNSPECIFIED:
            case MeasureSpec.AT_MOST:
                for (int i=0; i<count; i++){
                    View child = getChildAt(i);
                    slideWith += child.getMeasuredWidth();
                }
                break;
            default:
                break;
        }
        switch (heightMode){
            case MeasureSpec.EXACTLY:
                slideHigh = heightSize;
                break;
            case MeasureSpec.UNSPECIFIED:
            case MeasureSpec.AT_MOST:
                slideHigh += Math.max(childOne.getMeasuredHeight(), childTwo.getMeasuredHeight());
                break;
            default:
                break;
        }
        setMeasuredDimension(slideWith, slideHigh);
    }

    @Override
    protected void onLayout(boolean b, int l, int i1, int i2, int i3) {
        int ps = getPaddingStart();
        int pt = getPaddingTop();
        int pb = getPaddingBottom();

        int childOneWith = childOne.getMeasuredWidth();
        int childOneHigh = childOne.getMeasuredHeight();
        int childTwoWith = childTwo.getMeasuredWidth();
        int childTwoHigjh = childTwo.getMeasuredHeight();

        childOne.layout(ps, pt, ps + childOneWith, pt + childOneHigh + pb);
        childTwo.layout(ps + childOneWith, pt, ps + childOneWith + childTwoWith, pt + Math.max(childOneHigh, childTwoHigjh) + pb);

        scrollLimitSize = childTwoWith;
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent event) {
        switch (event.getAction()){
            case MotionEvent.ACTION_DOWN:
                isClick = true;
                startX = (int) event.getX();
                startY = (int) event.getY();
                return false;
            case MotionEvent.ACTION_MOVE:
                int endY = (int) (event.getY() - startY);
                int endX = (int) (event.getX() - startX);
                if((Math.abs(endY) > LIMIT_MOVE || Math.abs(endX) > LIMIT_MOVE)){
                    isClick = false;
                    return true;
                }else{
                    return false;
                }
            case MotionEvent.ACTION_UP:
                return !isClick;
            default:
                break;
        }
        return false;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()){
            case MotionEvent.ACTION_MOVE:
                int endY = (int) (event.getY() - startY);
                int endX = (int) (event.getX() - startX);
                if((Math.abs(endY) > Math.abs(endX)) && !canScrooll){
                    getParent().requestDisallowInterceptTouchEvent(false);
                    resetScroll();
                }else{
                    getParent().requestDisallowInterceptTouchEvent(true);
                    canScrooll = true;
                }
                if(canScrooll){
                    int scroll = currentScroll + endX;
                    if(scroll < -scrollLimitSize){
                        scroll = -scrollLimitSize;
                    }else if(scroll > 0){
                        scroll = 0;
                    }
                    scrollTo(- scroll, 0);
                }
                break;
            case MotionEvent.ACTION_UP:
                int divide = scrollLimitSize >> 1;
                if (getScrollX() > divide){
                    scroller.startScroll(getScrollX(), 0, scrollLimitSize - getScrollX(), 0, TIME);
                }else{
                    scroller.startScroll(getScrollX(), 0, - getScrollX(), 0, TIME);
                }
                invalidate();
                currentScroll = -getScrollX();
                getParent().requestDisallowInterceptTouchEvent(false);
                canScrooll = false;
                return !isClick;
            default:
                break;
        }
        return true;
    }

    private void resetScroll(){
        scroller.startScroll(getScrollX(), 0, - getScrollX(), 0, TIME);
        invalidate();
        currentScroll = -getScrollX();
    }

    @Override
    public void computeScroll() {
        super.computeScroll();
        if(scroller.computeScrollOffset()){
            scrollTo(scroller.getCurrX(), scroller.getCurrY());
            invalidate();
        }
    }
}

侧滑比较简单，值得注意的是 在作为Recyclerview 的item布局时， 水平和垂直滑动一次只能触发一个，所以通过canScrooll 变量控制滑动冲突，正好解决了这个问题。

end。