Android Activity侧滑返回怎么实现

本篇内容主要讲解"Android Activity侧滑返回怎么实现"，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习"Android Activity侧滑返回怎么实现"吧!

Slidr使用示例

它的使用很简单，首先要设置透明的窗口背景

然后

//setContent(View view)后Slidr.attach(this);

下面可以从三个步骤看其原理

步骤一 重新包裹界面

Slidr.class

 public static SlidrInterface attach(final Activity activity, final int statusBarColor1, final int statusBarColor2){        //0  创建滑动嵌套界面SliderPanel                final SliderPanel panel = initSliderPanel(activity, null);        //7 Set the panel slide listener for when it becomes closed or opened        // 监听回调        panel.setOnPanelSlideListener(new SliderPanel.OnPanelSlideListener() {                        ...            //open close等        });                // Return the lock interface                return initInterface(panel);    }        private static SliderPanel initSliderPanel(final Activity activity, final SlidrConfig config) {                //3 获取decorview                ViewGroup decorView = (ViewGroup)activity.getWindow().getDecorView();                //4 获取我们布局的内容并删除                View oldScreen = decorView.getChildAt(0);                decorView.removeViewAt(0);                //5 Setup the slider panel and attach it to the decor        // 建立滑动嵌套视图SliderPanel并且添加到DecorView中                SliderPanel panel = new SliderPanel(activity, oldScreen, config);                panel.setId(R.id.slidable_panel);                oldScreen.setId(R.id.slidable_content);                //6 把我们的界面布局添加到SliderPanel，并且把SliderPanel添加到decorView中                panel.addView(oldScreen);                decorView.addView(panel, 0);                return panel;        }

步骤二 使用ViewDragHelper.class处理滑动手势

SliderPanel.class

private void init(){    ...    //1 ViewDragHelper创建    mDragHelper = ViewDragHelper.create(this, mConfig.getSensitivity(), callback);    mDragHelper.setMinVelocity(minVel);    mDragHelper.setEdgeTrackingEnabled(mEdgePosition);    //2 Setup the dimmer view 添加用于指示滑动过程的View到底层    mDimView = new View(getContext());    mDimView.setBackgroundColor(mConfig.getScrimColor());    mDimView.setAlpha(mConfig.getScrimStartAlpha());    addView(mDimView);}

步骤三 在ViewDragHelper.Callback中处理我们的界面的拖动

我们首先明确ViewDragHelper仅仅是处理ParentView与它子View的关系，不会一直遍历到最顶层的View。ViewDragHelper的捕获capture是这样实现的

  @Nullable    public View findTopChildUnder(int x, int y) {        final int childCount = mParentView.getChildCount();        for (int i = childCount - 1; i >= 0; i--) {            final View child = mParentView.getChildAt(mCallback.getOrderedChildIndex(i));            if (x >= child.getLeft() && x < child.getRight()                    && y >= child.getTop() && y < child.getBottom()) {                return child;            }        }        return null;    }

重点在SliderPanel.class的ViewDragHelper.Callback callback的实现，作者实现实现了很多个方向的滑动处理mLeftCallback、mRightCallback、mTopCallback、mBottomCallback、mVerticalCallback、mHorizontalCallback, 我们取mLeftCallback来分析

private ViewDragHelper.Callback mLeftCallback = new ViewDragHelper.Callback() {    //捕获View    @Override    public boolean tryCaptureView(View child, int pointerId) {        boolean edgeCase = !mConfig.isEdgeOnly() || mDragHelper.isEdgeTouched(mEdgePosition, pointerId);        //像前面说的，我们的内容是最上层子View，mDecorView这里指的是我们的contentView        return child.getId() == mDecorView.getId() && edgeCase;    }    //拖动， 最终是通过view.offsetLeftAndRight(offset)实现移动    @Override    public int clampViewPositionHorizontal(View child, int left, int dx) {        return clamp(left, 0, mScreenWidth);    }    //滑动范围    @Override    public int getViewHorizontalDragRange(View child) {        return mScreenWidth;    }    //释放处理，判断是滚回屏幕    @Override    public void onViewReleased(View releasedChild, float xvel, float yvel) {        super.onViewReleased(releasedChild, xvel, yvel);        int left = releasedChild.getLeft();        int settleLeft = 0;        int leftThreshold = (int) (getWidth() * mConfig.getDistanceThreshold());        boolean isVerticalSwiping = Math.abs(yvel) > mConfig.getVelocityThreshold();        if(xvel > 0){            if(Math.abs(xvel) > mConfig.getVelocityThreshold() && !isVerticalSwiping){                settleLeft = mScreenWidth;            }else if(left > leftThreshold){                settleLeft = mScreenWidth;            }        }else if(xvel == 0){            if(left > leftThreshold){                settleLeft = mScreenWidth;            }        }                        //滚动到left=0(正常布局) 或者 滚动到left=mScreenWidth（滚出屏幕）关闭Activity        mDragHelper.settleCapturedViewAt(settleLeft, releasedChild.getTop());        invalidate();    }    //转换位置百分比，确定指示层的透明度    @Override    public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) {        super.onViewPositionChanged(changedView, left, top, dx, dy);        float percent = 1f - ((float)left / (float)mScreenWidth);        if(mListener != null) mListener.onSlideChange(percent);        // Update the dimmer alpha        applyScrim(percent);    }    //回调到Slidr处理Activity状态    @Override    public void onViewDragStateChanged(int state) {        super.onViewDragStateChanged(state);        if(mListener != null) mListener.onStateChanged(state);        switch (state){            case ViewDragHelper.STATE_IDLE:                if(mDecorView.getLeft() == 0){                    // State Open                    if(mListener != null) mListener.onOpened();                }else{                    // State Closed  这里回调到Slidr处理activity.finish()                    if(mListener != null) mListener.onClosed();                }                break;            case ViewDragHelper.STATE_DRAGGING:                break;            case ViewDragHelper.STATE_SETTLING:                break;        }    }};

对于mDragHelper.settleCapturedViewAt(settleLeft, releasedChild.getTop());内部是使用Scroller.class辅助滚动，所以要在SliderPanel中重写View.computeScroll()

@Overridepublic void computeScroll() {    super.computeScroll();    if(mDragHelper.continueSettling(true)){        ViewCompat.postInvalidateOnAnimation(this);    }}

到此，相信大家对"Android Activity侧滑返回怎么实现"有了更深的了解，不妨来实际操作一番吧！这里是网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！