Android RecyclerView模仿探探左右滑动布局

Android-->RecyclerView模仿探探左右

滑动布局

1:这种功能, 首先需要自己管理布局

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 = \ 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)); } } }

} }

2:布局好了之后, 就需要监听鼠标事件了

谷歌官方提供了一个ItemTouchHelper工具类, 对滑动进行了惨无人道的优越封装, 傻x都能用…

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 = \ 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, \ 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, fwww.sm136.comloat 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 = falnc630.comse; 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) {

} } }

看起来不难, 但是真正做的时候, 要处理的地方很多,

并且有些地方要思考很久, 才能实现效果.

总之,做了你才会发现1+1=2的魅力, just do it.

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