横向加载更多（查看更多）RecyclerView
实现方式是不改变RecyclerView本身，定义了一个父控件装载，查看更多和架子更多的view也同样作为该父控件的子控件。有简单的阻尼回弹效果。
实现代码：
public class PulToLeftViewGroupl extends LinearLayout implements ViewTreeObserver.OnGlobalLayoutListener {
OnPullToLeftListener mOnPullToLeftListener;
public void setOnPullToLeftListener(OnPullToLeftListener leftListener){
this.mOnPullToLeftListener = leftListener;
}
public interface OnPullToLeftListener{
/**
* 松开手指去更新-可能需要动画在此函数实现
*/
void onReleaseFingerToUpload();
/**
* 开始拉出查看更多-可能需要动画在此函数实现
*/
void onStartToUpload();
}
/**
* 动画时间
*/
private static final long ANIM_TIME = 200;
//recyclerview
private View childView;
// 用于记录正常的布局位置
private Rect originalRect = new Rect();
//滚动时，移动的view和位置
private List mMoveViews = new ArrayList<>();
private List mMoveRects = new ArrayList<>();
// 在手指滑动的过程中记录是否移动了布局
private boolean isMoved = false;
// 如果按下时不能上拉和下拉， 会在手指移动时更新为当前手指的Y值
private float startY;
//阻尼
private static final float OFFSET_RADIO = 0.6f;
private boolean isRecyclerReuslt = false;
public PulToLeftViewGroupl(Context context) {
super(context);
}
public PulToLeftViewGroupl(Context context, AttributeSet attrs) {
super(context, attrs);
}
public PulToLeftViewGroupl(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
/**
* 完成更新调用
*/
public void completeToUpload(){
postDelayed(new Runnable() {
@Override
public void run() {
recoverLayout();
}
}, 1500);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
originalRect.set(childView.getLeft(), childView.getTop(), childView.getRight(), childView.getBottom());
for (int i = 0; i < mMoveViews.size(); i++) {
final View v = mMoveViews.get(i);
v.addOnLayoutChangeListener(new OnLayoutChangeListener() {
@Override
public void onLayoutChange(View v, int left, int top, int right, int bottom, int oldLeft, int oldTop, int oldRight, int oldBottom) {
Rect rect = new Rect();
rect.set(v.getLeft(), v.getTop(), v.getRight(), v.getBottom());
mMoveRects.add(rect);
v.removeOnLayoutChangeListener(this);
}
});
}
}
/**
* 加载布局后初始化,这个方法会在加载完布局后调用
*/
@Override
protected void onFinishInflate() {
if (getChildCount() > 0) {
for (int i = 0; i < getChildCount(); i++) {
if (getChildAt(i) instanceof RecyclerView) {
if (childView == null) {
childView = getChildAt(i);
} else {
throw new RuntimeException("只能存在一个RecyclerView");
}
}
}
}
if (childView == null) {
throw new RuntimeException("子容器中必须有一个RecyclerView");
}
//布局重绘监听，比如华为屏幕键盘可以弹出和隐藏，改变布局，加监听就可以虽键盘弹出关闭的变化而变化
getViewTreeObserver().addOnGlobalLayoutListener(this);
super.onFinishInflate();
}
@RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
@Override
public void onGlobalLayout() {
requestLayout();
getViewTreeObserver().removeOnGlobalLayoutListener(this);
}
/**
* 跟随弹性移动的view
* @param view
*/
public void setMoveViews(View view) {
this.mMoveViews.add(view);
requestLayout();
}
/**
* 位置还原
*/
private void recoverLayout() {
if (!isMoved) {
return;//如果没有移动布局，则跳过执行
}
for (int i = 0; i < mMoveViews.size(); i++) {
if (i < mMoveRects.size()) {
if (mMoveRects.get(i) != null) {
final int indexAt = i;
TranslateAnimation anims = new TranslateAnimation(mMoveViews.get(i).getRight(), mMoveRects.get(i).right, 0, 0);
anims.setDuration(ANIM_TIME);
mMoveViews.get(i).startAnimation(anims);
mMoveViews.get(indexAt).layout(
mMoveRects.get(indexAt).left,
mMoveRects.get(indexAt).top,
mMoveRects.get(indexAt).right,
mMoveRects.get(indexAt).bottom);
}
}
}
TranslateAnimation anim = new TranslateAnimation(childView.getRight() - originalRect.right, 0, 0,0);
anim.setDuration(ANIM_TIME);
childView.startAnimation(anim);
childView.layout(originalRect.left, originalRect.top, originalRect.right, originalRect.bottom);
isMoved = false;
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
return false; //不拦截 直接传递给子的view
}
/**
* 判断是否可以上拉
* @return
*/
private boolean isCanPullUp() {
final RecyclerView.Adapter adapter = ((RecyclerView) childView).getAdapter();
if (null == adapter) {
return true;
}
final int lastItemPosition = adapter.getItemCount() - 1;
final int lastVisiblePosition = ((LinearLayoutManager) ((RecyclerView) childView)
.getLayoutManager()).findLastVisibleItemPosition();
if (lastVisiblePosition >= lastItemPosition) {
final int childIndex = lastVisiblePosition - ((LinearLayoutManager) ((RecyclerView) childView)
.getLayoutManager()).findFirstVisibleItemPosition();
final int childCount = ((RecyclerView) childView).getChildCount();
final int index = Math.max(childIndex, childCount - 1);
final View lastVisibleChild = ((RecyclerView) childView).getChildAt(index);
if (lastVisibleChild != null) {
return lastVisibleChild.getRight() <= childView.getRight() - childView.getLeft();
}
}
return false;
}
/**
* 事件分发
*/
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
if (childView == null) {
return super.dispatchTouchEvent(ev);
}
boolean isTouchOutOfScrollView = ev.getX() >= originalRect.right || ev.getX() <= originalRect.left; //如果当前view的Y上的位置
if (isTouchOutOfScrollView) {//如果不在view的范围内
if (isMoved) { //当前容器已经被移动
recoverLayout();
}
return true;
}
int action = ev.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
//记录按下时的X
startY = ev.getX();
case MotionEvent.ACTION_MOVE:
float nowX = ev.getX();
int scrollX = (int) (nowX - startY);
if ((isCanPullUp() && scrollX < 0)) {
int offset = (int) (scrollX * OFFSET_RADIO);
childView.layout(originalRect.left + offset, originalRect.top, originalRect.right + offset, originalRect.bottom);
for (int i = 0; i < mMoveViews.size(); i++) {
if (i < mMoveRects.size()) {
if (mMoveViews.get(i) != null && mMoveRects.get(i) != null) {
mMoveViews.get(i).layout(mMoveRects.get(i).left + offset,
mMoveRects.get(i).top,
mMoveRects.get(i).right + offset,
mMoveRects.get(i).bottom);
}
}
}
isMoved = true;
isRecyclerReuslt = false;
if (mOnPullToLeftListener!=null){
mOnPullToLeftListener.onStartToUpload();
}
return true;
} else {
startY = ev.getX();
isMoved = false;
isRecyclerReuslt = true;
recoverLayout();
return super.dispatchTouchEvent(ev);
}
case MotionEvent.ACTION_UP:
if (isMoved && mOnPullToLeftListener!=null) {
//recoverLayout();
mOnPullToLeftListener.onReleaseFingerToUpload();
}
if (isRecyclerReuslt) {
return super.dispatchTouchEvent(ev);
} else {
return true;
}
default:
return true;
}
}
}
需要注意的地方有RecyclerView的Manager只处理了LinearLayoutManager.如果需要其他类型的Manager,请自行改写isCanPullUp()函数。
eg使用例子：
布局文件xml中代码：
.PulToLeftViewGroupl
android:id="@+id/pull_group"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content">
.support.v7.widget.RecyclerView
android:scrollbars="none"
android:background="#FFFFFF"
android:overScrollMode="never"
android:id="@+id/rv_hsv_type_content"
android:layout_width="match_parent"
android:layout_height="wrap_content"> .support.v7.widget.RecyclerView>
"@layout/include_left_layout"/>
.PulToLeftViewGroupl>Activity中代码：
mRecyclerView = (RecyclerView) findViewById(R.id.rv_hsv_type_content);
moved_view = (RelativeLayout) findViewById(R.id.moved_view);
pull_group = (PulToLeftViewGroupl) findViewById(R.id.pull_group) ;
pull_group.setMoveViews(moved_view);
List strings = new LinkedList<>();
for (int ii=0; ii<6; ii++) {
String str = "";
strings.add(str);
}
mAdapter = new Adapter(strings);
mRecyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));
mRecyclerView.addItemDecoration(new Adapter.SpacesItemDecoration(0, 50, 0, 0));
mRecyclerView.setAdapter(mAdapter);
pull_group.setOnPullToLeftListener(new PulToLeftViewGroupl.OnPullToLeftListener() {
@Override
public void onReleaseFingerToUpload() {
for (int ii=0; ii<6; ii++) {
String str = "";
mAdapter.addItem(str);
}
mAdapter.notifyDataSetChanged();
pull_group.completeToUpload();
}
@Override
public void onStartToUpload() {
}
});
} include对应布局就是pull_group.setMoveViews…的注入View。