AndroidSwipeLayout 分析

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https://github.com/daimajia/AndroidSwipeLayout

侧滑的删除按钮在右边为例分析：

核心函数：

ViewDragHelper //拉动效果的函数。

打开app，初始化view

<?xml version="1.0" encoding="utf-8"?><com.daimajia.swipe.SwipeLayout    xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/godfather"    android:layout_width="match_parent"    android:layout_height="match_parent">    <ImageView        android:layout_gravity="right"        android:src="@drawable/bird"        android:layout_width="100dp"        android:layout_height="100dp" />    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="nihao"/></com.daimajia.swipe.SwipeLayout>

1. addView ImageView

2. addView TextView

3. 调了两次onLayout

protected void onLayout(boolean changed, int l, int t, int r, int b) {

07-20 19:30:37.926 25279-25279/com.daimajia.swipedemo D/SwipeLayout: onLayout() called with: changed = [true], l = [0], t = [0], r = [480], b = [672]
07-20 19:30:37.976 25279-25279/com.daimajia.swipedemo D/SwipeLayout: onLayout() called with: changed = [false], l = [0], t = [0], r = [480], b = [672]

void layoutPullOut() { // 如果两个view，拼成一个view的。    View surfaceView = getSurfaceView(); // TextView    Log.d(TAG, "layoutPullOut: surfaceView:"+surfaceView);    Rect surfaceRect = mViewBoundCache.get(surfaceView);    if(surfaceRect == null) surfaceRect = computeSurfaceLayoutArea(false); //Rect(0, 0 - 480, 672)  左上（0，0）右下（480，672）    if (surfaceView != null) {        surfaceView.layout(surfaceRect.left, surfaceRect.top, surfaceRect.right, surfaceRect.bottom);        bringChildToFront(surfaceView);    }    View currentBottomView = getCurrentBottomView();//imageview    Rect bottomViewRect = mViewBoundCache.get(currentBottomView);    if(bottomViewRect == null) bottomViewRect = computeBottomLayoutAreaViaSurface(ShowMode.PullOut, surfaceRect);//Rect(480, 0 - 630, 672)    if (currentBottomView != null) {        currentBottomView.layout(bottomViewRect.left, bottomViewRect.top, bottomViewRect.right, bottomViewRect.bottom);    }}

layoutPullout效果就是这样的。

onTouchEvent ACTION_DOWN

按第一下，全局变量记录这个点。

2.滑动：

MotionEvent.ACTION_MOVE

1.判断滑动方向

mDragHelper.processTouchEvent(ev);

clampViewPositionHorizontal

case Right:    if (left > getPaddingLeft()) return getPaddingLeft();    if (left < getPaddingLeft() - mDragDistance)        return getPaddingLeft() - mDragDistance;    breakreturn left；

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