今天带大家实现简书的滑动返回效果.
先看看效果图:
最终效果图.gif因为没有具体内容,也没有简书的图片资源,所以稍微简陋了点.但是依然不妨碍我们的效果展示~
OK,接下来惯例,通过阅读本文你能学习到:
- ViewDragHelper的使用(如果你想学习自定义View,那么ViewDragHelper你绝对不能错过)
- 好像也没有什么了....
这个效果,难度不大,会ViewDragHelper的同学应该10分钟就能写出来了吧~如果不会也没关系~
1. 我们自定义一个SwipeBackFrameLayout继承自FrameLayout1.1 因为看到左边黄色的View是被遮住的,而另外一个View的宽度是MatchParent的,所以FrameLayout是不错的选择.顺便增加一个回调,通知activity去finish
[Java] 纯文本查看 复制代码
| 1 2 3 4 5 6 7 | public void setCallback(Callback mCallback){ this .mCallback = mCallback; } private Callback mCallback; public interface Callback{ void onShouldFinish(); } |
1.2 Xml布局,非常简单:
[XML] 纯文本查看 复制代码
| 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 | < yifeiyuan.practice.practicedemos.drager.SwipeBackFrameLayout xmlns:android = "http://schemas.android.com/apk/res/android" xmlns:tools = "http://schemas.android.com/tools" android:id = "@+id/swipe_back" android:layout_width = "match_parent" android:layout_height = "match_parent" tools:context = "yifeiyuan.practice.practicedemos.drager.SwipeBackActivity" > < TextView android:layout_width = "40dp" android:layout_height = "match_parent" android:text = "@string/hello_world" android:gravity = "center" android:background = "#ffff00" /> < View android:layout_width = "match_parent" android:layout_height = "match_parent" android:background = "#ff00ff" /> </ yifeiyuan.practice.practicedemos.drager.SwipeBackFrameLayout > |
1.3 实例化一个ViewDragHelper
[Java] 纯文本查看 复制代码
| 1 2 3 4 5 6 7 8 9 | //1f代表灵敏度 mDragHelper = ViewDragHelper.create( this , 1f, new ViewDragHelper.Callback() { @Override public boolean tryCaptureView(View child, int pointerId) { return false ; } } //因为我们是从左向右滑动 所以设置EDGE_LEFT mDragHelper.setEdgeTrackingEnabled(ViewDragHelper.EDGE_LEFT); |
1.4 在SwipeBackFrameLayout里实例化xml里的子View
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| 1 2 3 4 5 6 7 8 9 | private View mDividerView; private View mContentView; @Override protected void onFinishInflate() { super .onFinishInflate(); mDividerView = getChildAt( 0 ); mDividerView.setAlpha(0f); mContentView = getChildAt( 1 ); } |
1.5 让ViewDragHelper处理touch事件
[Java] 纯文本查看 复制代码
| 1 2 3 4 5 6 7 8 9 | @Override public boolean onInterceptTouchEvent(MotionEvent ev) { return mDragHelper.shouldInterceptTouchEvent(ev); } @Override public boolean onTouchEvent(MotionEvent event) { mDragHelper.processTouchEvent(event); return true ; } |
1.6重写ViewDragHelper的一些处理方法
已附上详细注释
[Java] 纯文本查看 复制代码
| 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 | @Override public void onEdgeTouched( int edgeFlags, int pointerId) { super .onEdgeTouched(edgeFlags, pointerId); //触摸到左边界的时候 我们capture住mContentView mDragHelper.captureChildView(mContentView, pointerId); } @Override public int getViewHorizontalDragRange(View child) { return 1 ; } [url=home.php?mod=space&uid= 389554 ] @Override [/url] public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) { super .onViewPositionChanged(changedView, left, top, dx, dy); Log.d(TAG, "onViewPositionChanged() called with left = [" + left + "], top = [" + top + "], dx = [" + dx + "], dy = [" + dy + "]" ); //0.0 - 1.0 //Notice 这边可以给个接口回调出去,就可以做各种炫酷的效果了 float alpha = ( float ) (left* 1.0 /mDividerWidth); mDividerView.setAlpha(alpha); } @Override public int clampViewPositionHorizontal(View child, int left, int dx) { // Log.d(TAG, "clampViewPositionHorizontal() called with dx = [" + dx + "]"); // 计算left 我们的目标范围是0-dividerwidth的宽度 mLastdx = dx; int newLeft = Math.min(mDividerWidth, Math.max(left, 0 )); return newLeft; } @Override public void onViewReleased(View releasedChild, float xvel, float yvel) { //>0代表用户想关闭 if (mLastdx> 0 ){ // 还不到关闭条件,我们让view滑动过去,再关闭 if (mDividerWidth != releasedChild.getLeft()) { mDragHelper.settleCapturedViewAt(mDividerWidth,releasedChild.getTop(); invalidate(); } else { if (mCallback != null ) { mCallback.onShouldFinish(); } } } else { //用户不想关闭 ,则滑动到最左边 if (mDividerWidth != 0 ) { mDragHelper.settleCapturedViewAt( 0 , releasedChild.getTop()); invalidate(); } } } @Override public void onViewDragStateChanged( int state) { super .onViewDragStateChanged(state); //滑动停止,并且到达了滑动的判断条件 则回调关闭 if (mDragHelper.getViewDragState()==ViewDragHelper.STATE_IDLE&&mCallback != null &&mDividerWidth==mContentView.getLeft()&&mLastdx> 0 ) { mCallback.onShouldFinish(); } } }); |
1.7 增加对view滑动事件处理,对于以上mDividerWidth我们在onLayout里获取
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| 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 | private int mDividerWidth; @Override protected void onLayout( boolean changed, int left, int top, int right, int bottom) { super .onLayout(changed, left, top, right, bottom); mDividerWidth = mDividerView.getWidth(); } //Notice view 刚初始化的时候就会被调用一次 @Override public void computeScroll() { super .computeScroll(); // Log.d(TAG, "computeScroll() called with " + ""); if (mDragHelper.continueSettling( true )) { invalidate(); } } |
我们写完自定义view后还需要自定义一下activity的退出动画~
2.定义activity的finish动画2.1 在anim目录下,创建两个动画xml:
[XML] 纯文本查看 复制代码
| 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 | //no_anim < alpha android:duration = "300" xmlns:android = "http://schemas.android.com/apk/res/android" android:fromAlpha = "1.0" android:toAlpha = "1.0" ></ alpha > //out_to_right < translate xmlns:android = "http://schemas.android.com/apk/res/android" android:duration = "300" android:fromXDelta = "0%" android:toXDelta = "100%" ></ translate > |
2.2 在activity里设置callback监听,并运用动画
[Java] 纯文本查看 复制代码
| 1 2 3 4 5 6 7 | mSwipeBack.setCallback( new SwipeBackFrameLayout.Callback() { @Override public void onShouldFinish() { finish(); overridePendingTransition(R.anim.no_anim, R.anim.out_to_right); } }); |
好了!!~代码量非常少!~就是这么简单~
吐槽一下,简书对代码块的支持太差了,代码复制过来全是乱的!!
同学们还是去看源码吧:
源码在我的 Github (https://github.com/AlanCheen/PracticeDemo)上
如果你觉得喜欢,举手之劳,给我点个赞吧!~
如果有什么不好的,不对的欢迎指出!~
如果有什么更好的方式,也欢迎指导!!!!
下次见!~
