之前一段时间，在朋友的推荐下，玩了探探这一款软件，初玩的时候，就发现，这款软件与一般的社交软件如陌陌之类的大相径庭，让我耳目一新，特别是探探里关于图片滑动操作让人觉得非常新鲜。所以在下通过网上之前的前辈的经历加上自己的理解，也来涉涉水。下面是网上找的探探的原界面
当时就非常想通过自己来实现这种仿探探式的效果，然而却没什么思路。不过毋庸置疑的是，这种效果的原理肯定和 ListView /RecyclerView 类似，涉及到 Item View 的回收和重用，否则早就因为大量的 Item View 而 OOM 了。
从View入手，RecyclerView 是自带 Item View 回收和重用功能的，而且，RecyclerView 的布局方式是通过设置 LayoutManager 来实现的，这样就充分地把布局和 RecyclerView 搞定了。
继承 RecyclerView.LayoutManager , 显示自己管理布局, 比如最多显示4个view, 并且都是居中显示.
底部的View还需要进行缩放,平移操作.
public class OverLayCardLayoutManager extends RecyclerView.LayoutManager { private static final String TAG = "swipecard"; public static int MAX_SHOW_COUNT = 4; public static float SCALE_GAP = 0.05f; public static int TRANS_Y_GAP; public OverLayCardLayoutManager(Context context) { //平移时, 需要用到的参考值 TRANS_Y_GAP = (int) (20 * context.getResources().getDisplayMetrics().density); } @Override public RecyclerView.LayoutParams generateDefaultLayoutParams() { //必须要实现的方法 return new RecyclerView.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT); } @Override public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) { //在这个方法中进行View的布局操作.此方法会被调用多次. detachAndScrapAttachedViews(recycler); int itemCount = getItemCount(); if (itemCount < 1) { return; } //top-3View的position int bottomPosition; //边界处理 if (itemCount < MAX_SHOW_COUNT) { bottomPosition = 0; } else { bottomPosition = itemCount - MAX_SHOW_COUNT; } //从可见的最底层View开始layout，依次层叠上去 for (int position = bottomPosition; position < itemCount; position++) { //1:重recycler的缓存机制中拿到一个View View view = recycler.getViewForPosition(position); //2:和自定义ViewGroup一样, 需要先addView addView(view); //3:和自定义ViewGroup一样, 也需要测量View的大小 measureChildWithMargins(view, 0, 0); int widthSpace = getWidth() - getDecoratedMeasuredWidth(view); int heightSpace = getHeight() - getDecoratedMeasuredHeight(view); //4:和自定义ViewGroup的onLayout一样, 需要layout View.对View进行布局 //我们在布局时，将childView居中处理，这里也可以改为只水平居中 layoutDecoratedWithMargins(view, widthSpace / 2, heightSpace / 2, widthSpace / 2 + getDecoratedMeasuredWidth(view), heightSpace / 2 + getDecoratedMeasuredHeight(view)); /** * TopView的Scale 为1，translationY 0 * 每一级Scale相差0.05f，translationY相差7dp左右 * * 观察人人影视的UI，拖动时，topView被拖动，Scale不变，一直为1. * top-1View 的Scale慢慢变化至1，translation也慢慢恢复0 * top-2View的Scale慢慢变化至 top-1View的Scale，translation 也慢慢变化只top-1View的translation * top-3View的Scale要变化，translation岿然不动 */ //第几层,举例子，count =7， 最后一个TopView（6）是第0层， int level = itemCount - position - 1; //如果不需要缩放平移, 那么下面的代码可以注释掉... //除了顶层不需要缩小和位移 if (level > 0 /*&& level < mShowCount - 1*/) { //每一层都需要X方向的缩小 view.setScaleX(1 - SCALE_GAP * level); //前N层，依次向下位移和Y方向的缩小 if (level < MAX_SHOW_COUNT - 1) { view.setTranslationY(TRANS_Y_GAP * level); view.setScaleY(1 - SCALE_GAP * level); } else {//第N层在 向下位移和Y方向的缩小的成都与 N-1层保持一致 view.setTranslationY(TRANS_Y_GAP * (level - 1)); view.setScaleY(1 - SCALE_GAP * (level - 1)); } } } } }
谷歌官方提供了一个ItemTouchHelper工具类, 对滑动进行了优越封装
使用方法: new ItemTouchHelper(callback).attachToRecyclerView(recyclerView);就这么简单,
接下来的操作, 都在回调callback里面进行.
public class RenRenCallback extends ItemTouchHelper.SimpleCallback { private static final String TAG = "RenRen"; private static final int MAX_ROTATION = 15; OnSwipeListener mSwipeListener; boolean isSwipeAnim = false; public RenRenCallback() { //第一个参数决定可以拖动排序的方向, 这里由于不需要拖动排序,所以传0 //第二个参数决定可以支持滑动的方向,这里设置了上下左右都可以滑动. super(0, ItemTouchHelper.DOWN | ItemTouchHelper.UP | ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT); } public void setSwipeListener(OnSwipeListener swipeListener) { mSwipeListener = swipeListener; } //水平方向是否可以被回收掉的阈值 public float getThreshold(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) { //2016 12 26 考虑 探探垂直上下方向滑动，不删除卡片，这里参照源码写死0.5f return recyclerView.getWidth() * /*getSwipeThreshold(viewHolder)*/ 0.5f; } @Override public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) { //由于不支持滑动排序, 所以不需要处理此方法 return false; } @Override public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) { //当view需要滑动的时候,会回调此方法 //但是这个方法只是告诉你View需要滑动, 并不是对View和Adapter进行额外的操作, //所以, 如果你需要实现滑动删除, 那么需要在此方法中remove item等. //我们这里需要对滑动过后的View,进行恢复操作. viewHolder.itemView.setRotation(0);//恢复最后一次的旋转状态 if (mSwipeListener != null) { mSwipeListener.onSwipeTo(viewHolder, 0); } notifyListener(viewHolder.getAdapterPosition(), direction); } private void notifyListener(int position, int direction) { Log.w(TAG, "onSwiped: " + position + " " + direction); if (mSwipeListener != null) { mSwipeListener.onSwiped(position, direction); } } @Override public float getSwipeThreshold(RecyclerView.ViewHolder viewHolder) { //滑动的比例达到多少之后, 视为滑动 return 0.3f; } @Override public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) { super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive); //当你在滑动的过程中, 此方法一直会被回调, 就跟onTouch事件一样... //先根据滑动的dx dy 算出现在动画的比例系数fraction float swipeValue = (float) Math.sqrt(dX * dX + dY * dY); final float threshold = getThreshold(recyclerView, viewHolder); float fraction = swipeValue / threshold; //边界修正 最大为1 if (fraction > 1) { fraction = 1; } else if (fraction < -1) { fraction = -1; } //对每个ChildView进行缩放 位移 int childCount = recyclerView.getChildCount(); for (int i = 0; i < childCount; i++) { View child = recyclerView.getChildAt(i); //第几层,举例子，count =7， 最后一个TopView（6）是第0层， int level = childCount - i - 1; if (level > 0) { child.setScaleX(1 - SCALE_GAP * level + fraction * SCALE_GAP); if (level < MAX_SHOW_COUNT - 1) { child.setScaleY(1 - SCALE_GAP * level + fraction * SCALE_GAP); child.setTranslationY(TRANS_Y_GAP * level - fraction * TRANS_Y_GAP); } else { //child.setTranslationY((float) (mTranslationYGap * (level - 1) - fraction * mTranslationYGap)); } } else { //最上层 //rotate if (dX < -50) { child.setRotation(-fraction * MAX_ROTATION); } else if (dX > 50) { child.setRotation(fraction * MAX_ROTATION); } else { child.setRotation(0); } if (mSwipeListener != null) { RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams(); final int adapterPosition = params.getViewAdapterPosition(); mSwipeListener.onSwipeTo(recyclerView.findViewHolderForAdapterPosition(adapterPosition), dX); } } } } //扩展实现:点击按钮实现左滑效果 public void toLeft(RecyclerView recyclerView) { if (check(recyclerView)) { animTo(recyclerView, false); } } //扩展实现:点击按钮实现右滑效果 public void toRight(RecyclerView recyclerView) { if (check(recyclerView)) { animTo(recyclerView, true); } } private void animTo(final RecyclerView recyclerView, boolean right) { final int position = recyclerView.getAdapter().getItemCount() - 1; final View view = recyclerView.findViewHolderForAdapterPosition(position).itemView; TranslateAnimation translateAnimation = new TranslateAnimation(Animation.RELATIVE_TO_SELF, 0, Animation.RELATIVE_TO_SELF, right ? 1f : -1f, Animation.RELATIVE_TO_SELF, 0f, Animation.RELATIVE_TO_SELF, 1.3f); translateAnimation.setFillAfter(true); translateAnimation.setDuration(300); translateAnimation.setInterpolator(new DecelerateInterpolator()); translateAnimation.setAnimationListener(new Animation.AnimationListener() { @Override public void onAnimationStart(Animation animation) { } @Override public void onAnimationEnd(Animation animation) { isSwipeAnim = false; recyclerView.removeView(view); notifyListener(position, x > view.getMeasuredWidth() / 2 ? ItemTouchHelper.RIGHT : ItemTouchHelper.LEFT); } @Override public void onAnimationRepeat(Animation animation) { } }); view.startAnimation(translateAnimation); } private boolean check(RecyclerView recyclerView) { if (isSwipeAnim) { return false; } if (recyclerView == null || recyclerView.getAdapter() == null) { return false; } if (recyclerView.getAdapter().getItemCount() == 0) { return false; } isSwipeAnim = true; return true; } public interface OnSwipeListener { /** * @param direction {@link ItemTouchHelper#LEFT} / {@link ItemTouchHelper#RIGHT} * {@link ItemTouchHelper#UP} or {@link ItemTouchHelper#DOWN}). */ void onSwiped(int adapterPosition, int direction); /** * 最上层View滑动时回调. * * @param viewHolder 最上层的ViewHolder * @param offset 距离原始位置的偏移量 */ void onSwipeTo(RecyclerView.ViewHolder viewHolder, float offset); } public static class SimpleSwipeCallback implements OnSwipeListener { /** * {@inheritDoc} */ @Override public void onSwiped(int adapterPosition, int direction) { } /** * {@inheritDoc} */ @Override public void onSwipeTo(RecyclerView.ViewHolder viewHolder, float offset) { } } }
布局文件：卡片内容
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal|bottom" android:layout_marginBottom="20dp" android:orientation="horizontal"> <ImageView android:id="@+id/left" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" android:layout_margin="10dp" android:background="@drawable/home_buttons_dislike" android:onClick="left" /> <ImageView android:id="@+id/info" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" android:layout_margin="10dp" android:background="@drawable/home_buttons_info" /> <ImageView android:id="@+id/right" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_margin="10dp" android:background="@drawable/home_buttons_like" /> </LinearLayout>
布局文件：点击按钮
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal|bottom" android:layout_marginBottom="20dp" android:orientation="horizontal"> <ImageView android:id="@+id/left" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" android:layout_margin="10dp" android:background="@drawable/home_buttons_dislike" android:onClick="left" /> <ImageView android:id="@+id/info" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" android:layout_margin="10dp" android:background="@drawable/home_buttons_info" /> <ImageView android:id="@+id/right" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_margin="10dp" android:background="@drawable/home_buttons_like" /> </LinearLayout>
监听函数：
flingContainer = (SwipeFlingAdapterView) findViewById(R.id.frame); //设置适配器 flingContainer.setAdapter(adapter); flingContainer.setFlingListener(new SwipeFlingAdapterView.onFlingListener() { @Override public void removeFirstObjectInAdapter() { al.remove(0); adapter.notifyDataSetChanged(); } @Override public void onLeftCardExit(Object dataObject) { makeToast(MainActivity.this, "不喜欢"); } @Override public void onRightCardExit(Object dataObject) { makeToast(MainActivity.this, "喜欢"); } @Override public void onAdapterAboutToEmpty(int itemsInAdapter) { al.add(new CardMode("循环测试", 18, list.get(itemsInAdapter % imageUrls.length - 1))); adapter.notifyDataSetChanged(); i++; } @Override public void onScroll(float scrollProgressPercent) { View view = flingContainer.getSelectedView(); view.findViewById(R.id.item_swipe_right_indicator).setAlpha(scrollProgressPercent < 0 ? -scrollProgressPercent : 0); view.findViewById(R.id.item_swipe_left_indicator).setAlpha(scrollProgressPercent > 0 ? scrollProgressPercent : 0); } });
总结一下，在这整个代码流程中我们主要是运用了自定义 LayoutManager 以及 ItemTouchHelper.Callback
接下来，我们看看效果：
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。