Android自定义View之仿知乎滑动删除Activity

先看下具体的实现效果:

上面图片里包含两种效果,一个是向右滑动删除Activity,这个大家可以参考夏神的文章http://blog.csdn.net/xiaanming/article/details/20934541
里面讲解很令人佩服,另一个是向上滑动删除Activity,这个有点类似平时手机的通知栏,滑动删除的知识点和思想基本也是一样的。

项目结构如下:
Android自定义View之仿知乎滑动删除Activity_第1张图片

下面着重讲解如何实现向上滑动删除Activty的自定义View
具体代码如下:

/** * 自定义滑动删除布局 */

public class SildingFinishLayoutVertical extends RelativeLayout implements OnTouchListener,GestureDetector.OnGestureListener {
    /** * SildingFinishLayout布局的父布局 */
    private ViewGroup mParentView;
    /** * 处理滑动逻辑的View */
    private View touchView;
    /** * 滑动的最小距离 */
    private int mTouchSlop;
    /** * 按下点的X坐标 */
    private int downX;
    /** * 按下点的Y坐标 */
    private int downY;
    /** * 临时存储X坐标 */
    private int tempX;
    /** * 临时存储Y坐标 */
    private int tempY;
    /** * 滑动类 */
    private Scroller mScroller;
    /** *SildingFinishLayout的宽度 */
    private int viewWidth;
    /** *SildingFinishLayout的高度 */
    private int viewHeight;
    /** * 记录是否正在滑动 */
    private boolean isSilding;
    private OnSildingFinishListener onSildingFinishListener;
    private boolean isFinish;

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

    public SildingFinishLayoutVertical(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
        mScroller = new Scroller(context);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        super.onLayout(changed, l, t, r, b);
        if (changed) {
            // 获取SildingFinishLayout所在布局的父布局
            mParentView = (ViewGroup) this.getParent();
            //mParentView.getBackground().setAlpha(1);加这行代码会崩溃
            //注意getWidth()和getMeasuredWidth()的区别;
            viewWidth = this.getWidth();
            viewHeight = this.getHeight();//获取布局view的高度
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
    }

    /** * 设置OnSildingFinishListener, 在onSildingFinish()方法中finish Activity * * @param onSildingFinishListener */
    public void setOnSildingFinishListener(OnSildingFinishListener onSildingFinishListener) {
        this.onSildingFinishListener = onSildingFinishListener;
    }

    /** * 设置Touch的View * * @param touchView */
    public void setTouchView(View touchView) {
        this.touchView = touchView;
        touchView.setOnTouchListener(this);
    }

    public View getTouchView() {
        return touchView;
    }

    /** *滚动出界面--从左向右滑出 */
    private void scrollRight() {
        final int delta = (viewWidth + mParentView.getScrollX());
        //getScrollX()是当前view的顶部相对于坐标原点(也就是手机屏幕的左上角的水平偏移量)
        // 调用startScroll方法来设置一些滚动的参数,我们在computeScroll()方法中调用scrollTo来滚动item
        mScroller.startScroll(mParentView.getScrollX(), 0, -delta + 1, 0,
                Math.abs(delta));
        postInvalidate();
    }

    /** *滚动出界面--从下向上滑出 */
    private void scrollTop() {
        final int delta = (viewHeight + mParentView.getScrollY());
        // 调用startScroll方法来设置一些滚动的参数,我们在computeScroll()方法中调用scrollTo来滚动item
        mScroller.startScroll(0,mParentView.getScrollY(), 0, delta - 1, Math.abs(delta));
        postInvalidate();
    }


    /** *滚动到起始位置--从右向左 */
    private void scrollOrigin() {
        int delta = mParentView.getScrollX();
        mScroller.startScroll(mParentView.getScrollX(), 0, -delta, 0,Math.abs(delta));
        postInvalidate();
    }

    /** *滚动到起始位置--从上向下 */
    private void scrollOriginFromTop() {
        int delta = mParentView.getScrollY();//getScrollY是偏移量 无正负之分
        mScroller.startScroll(0,mParentView.getScrollY(), 0,-delta, Math.abs(delta));
        postInvalidate();
    }

    /** * touch的View是否是AbsListView, 例如ListView, GridView等其子类 * * @return */
    private boolean isTouchOnAbsListView() {
        return touchView instanceof AbsListView ? true : false;
    }

    /** * touch的view是否是ScrollView或者其子类 * * @return */
    private boolean isTouchOnScrollView() {
        return touchView instanceof ScrollView ? true : false;
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                downX = tempX = (int) event.getRawX();
                downY = tempY = (int) event.getRawY();
                break;
            case MotionEvent.ACTION_MOVE:
                int moveX = (int) event.getRawX();

                int moveY = (int) event.getRawY();
                int deltaX = tempX - moveX;
                int deltaY = tempY - moveY;
                tempX = moveX;
                tempY = moveY;
                //if (Math.abs(moveX - downX) > mTouchSlop&& Math.abs((int) event.getRawY() - downY) < mTouchSlop) {
                if (Math.abs(moveY - downY) > mTouchSlop&& Math.abs(moveX - downX) < mTouchSlop) {
                    isSilding = true;
                    // 若touchView是AbsListView,
                    // 则当手指滑动,取消item的点击事件,不然我们滑动也伴随着item点击事件的发生
                    if (isTouchOnAbsListView()) {
                        MotionEvent cancelEvent = MotionEvent.obtain(event);
                        cancelEvent
                                .setAction(MotionEvent.ACTION_CANCEL
                                        | (event.getActionIndex() << MotionEvent.ACTION_POINTER_INDEX_SHIFT));
                        v.onTouchEvent(cancelEvent);
                    }

                }
                //if (moveX - downX >= 0 && isSilding) {
                if (moveY - downY <= 0 && isSilding) {
                    //mParentView.scrollBy(deltaX, 0);
                    mParentView.scrollBy(0, deltaY);
                    // 屏蔽在滑动过程中ListView ScrollView等自己的滑动事件
                    if (isTouchOnScrollView() || isTouchOnAbsListView()) {
                        return true;
                    }
                }
                break;
            case MotionEvent.ACTION_UP:
                isSilding = false;
                // if (mParentView.getScrollX() <= -viewWidth / 2) {
                if (Math.abs(mParentView.getScrollY())>= viewHeight /2) {
                    isFinish = true;
                    // scrollRight();
                    scrollTop();
                } else {
                    // scrollOrigin();
                    scrollOriginFromTop();
                    isFinish = false;
                }
                break;
        }

        // 假如touch的view是AbsListView或者ScrollView 我们处理完上面自己的逻辑之后
        // 再交给AbsListView, ScrollView自己处理其自己的逻辑
        if (isTouchOnScrollView() || isTouchOnAbsListView()) {
            return v.onTouchEvent(event);
        }
        // 其他的情况直接返回true
        return true;
    }


    @Override
    public void computeScroll() {
        // 调用startScroll的时候scroller.computeScrollOffset()返回true,//Scroller.computeScrollOffset()方法是判断scroller的移动动画是否完成
        if (mScroller.computeScrollOffset()) {
            mParentView.scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
            postInvalidate();
            //if (mScroller.isFinished()) {
            if (true) {
                if (onSildingFinishListener != null && isFinish) {
                    onSildingFinishListener.onSildingFinish();
                }
            }
        }
    }

    /**GestureDetector.OnGestureListener start**/
    @Override
    public boolean onDown(MotionEvent motionEvent) {
        return false;
    }

    @Override
    public void onShowPress(MotionEvent motionEvent) {

    }

    @Override
    public boolean onSingleTapUp(MotionEvent motionEvent) {
        return false;
    }

    @Override
    public boolean onScroll(MotionEvent motionEvent, MotionEvent motionEvent1, float v, float v1) {
        return false;
    }

    @Override
    public void onLongPress(MotionEvent motionEvent) {

    }

    @Override
    public boolean onFling(MotionEvent motionEvent, MotionEvent motionEvent1, float v, float v1) {

        return false;
    }

    /**GestureDetector.OnGestureListener end**/

    public interface OnSildingFinishListener {
        void onSildingFinish();
    }

}

上面就是是完成整个自定义view的过程,涉及到的知识点总结整理如下:
(1)Android视图坐标系的相对坐标和绝对坐标:
getX()与getRawX()的区别
getY()与getRawY()的区别
(2)mTouchSlop系统认为是滑动的最小距离
mTouchSlop=ViewConfiguration.get(context).getScaledTouchSlop();
(3)关于Scroller的滑动调用方法:
startScroll(int startX, int startY, int dx, int dy, int duration)
表示在duration时间内,从当前的(x,y)点滑动到(x+dx,y+dy)点。
scrollBy (int x, int y) 滑动的偏移量
scrollTo(int x, int y) 滑动到指定的坐标
getCurrX() 返回当前view的x偏移量
getCurrY() 返回当前view的y偏移量
(4)判断当前用户的操作是否是滑动状态:
if (Math.abs(moveY - downY) > mTouchSlop&& Math.abs(moveX - downX) < mTouchSlop) {
isSilding = true;
}

[完成DEMO下载]

(http://download.csdn.net/detail/happy_horse/9521978)

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