Android-->如何將RecyclerView打造成ViewPager的效果
阿新 • • 發佈：2019-01-08
更新於:2017-2-16
以前的實現方式, 雖然面前可以達到效果, 但是著實有點low,
現在提供一種體驗相當好的解決方案:SnapHelper
以下是實現程式碼: 其實就是同時處理OnScrollListener事件和OnFlingListener事件.
比我之前的方法多了一個OnFlingListener事件的監聽.
public class ViewPagerSnapHelper extends SnapHelper {
/**
* 每一頁中, 含有多少個item
*/
int mPageItemCount = 1;
/**
* 當前頁面索引
*/ 使用方法:
new ViewPagerSnapHelper(getItemCount()).setPageListener(new ViewPagerSnapHelper.PageListener() {
@Override
public void onPageSelector(int position) {
onViewPagerSelect(position);
}
}).attachToRecyclerView(recyclerView);在配合我之前寫的RecyclerViewPagerAdapter(必須), 就可以輕鬆實現效果了.
如題所示,
都支援橫向和縱向, 暫不支援StaggeredGridLayoutManager佈局管理.
如圖:
在LinearLayoutManager中:
在GridLayoutManager中:
1:當adapter中Item的數量不足時, 需要用假資料填充.
否則最後一頁顯示不全, 達不到頁面的效果.
@Override
public int getItemCount() {
rawSize = mAllDatas == null ? 0 : mAllDatas.size();
final int itemCount = mRecyclerViewPager.getItemCount();
final double ceil = Math.ceil(rawSize * 1f / itemCount);//當給定的item個數不足以填充一屏時, 使用佔位item
return (int) (ceil * itemCount);
}2:為了達到沾滿整屏的效果, 需要動態計算每一個Item的寬高
@Override
protected void onBindView(RBaseViewHolder holder, int position, T bean) {
holder.itemView.setLayoutParams(new ViewGroup.LayoutParams(mRecyclerViewPager.getItemWidth(),
mRecyclerViewPager.getItemHeight()));
if (holder.getItemViewType() == 200) {
onBindRawView(holder, position, bean);
}
}
/**
* 計算每個Item的寬度
*/
public int getItemWidth() {
final LayoutManager layoutManager = getLayoutManager();
int itemWidth = 0;
if (layoutManager instanceof GridLayoutManager) {
final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
final int spanCount = gridLayoutManager.getSpanCount();
if (gridLayoutManager.getOrientation() == LinearLayoutManager.HORIZONTAL) {
itemWidth = getRawWidth() / (mItemCount / spanCount);
} else {
itemWidth = getRawWidth() / spanCount;
}
} else if (layoutManager instanceof LinearLayoutManager) {
final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
if (linearLayoutManager.getOrientation() == LinearLayoutManager.HORIZONTAL) {
itemWidth = getRawWidth() / mItemCount;
} else {
itemWidth = getRawWidth();
}
}
return itemWidth;
}
public int getItemHeight() {
final LayoutManager layoutManager = getLayoutManager();
int itemHeight = 0;
if (layoutManager instanceof GridLayoutManager) {
final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
final int spanCount = gridLayoutManager.getSpanCount();
if (gridLayoutManager.getOrientation() == LinearLayoutManager.HORIZONTAL) {
itemHeight = getRawHeight() / spanCount;
} else {
itemHeight = getRawHeight() / (mItemCount / spanCount);
}
} else if (layoutManager instanceof LinearLayoutManager) {
final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
if (linearLayoutManager.getOrientation() == LinearLayoutManager.HORIZONTAL) {
itemHeight = getRawHeight();
} else {
itemHeight = getRawHeight() / mItemCount;
}
}
return itemHeight;
}3:一切準備好了之後,核心的滾動計算要開始了.
private OnScrollListener mOnScrollListener = new OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
if (newState == SCROLL_STATE_DRAGGING) {
//開始滾動
mVerticalScrollOffsetStart = recyclerView.computeVerticalScrollOffset();
mHorizontalScrollOffsetStart = recyclerView.computeHorizontalScrollOffset();
} else if (newState == SCROLL_STATE_IDLE) {
//滾動結束之後
final int verticalScrollOffset = recyclerView.computeVerticalScrollOffset();
final int horizontalScrollOffset = recyclerView.computeHorizontalScrollOffset();
final int rawWidth = getRawWidth();
final int rawHeight = getRawHeight();
int pagerIndex = mCurrentPager;
int dx = 0, dy = 0;
if (verticalScrollOffset == 0 && horizontalScrollOffset != 0) {
//橫向滾動
final float page = horizontalScrollOffset * 1.f / rawWidth;//當前滾動到了第幾頁
final double floor = Math.floor(page);//前一頁
final double ceil = Math.ceil(page);//後一頁
final int offset;
final int offsetWidth;//滑動之後, 剩餘螢幕的寬度
if (horizontalScrollOffset > mHorizontalScrollOffsetStart) {
pagerIndex = (int) floor;
//左滑動
offset = (int) (horizontalScrollOffset - floor * rawWidth);
offsetWidth = rawWidth - offset;
if (offset >= rawWidth / 3) {
dx = offsetWidth;
} else {
dx = -offset;
}
} else if (mHorizontalScrollOffsetStart > horizontalScrollOffset) {
pagerIndex = (int) ceil;
//右滑動
offset = (int) (ceil * rawWidth - horizontalScrollOffset);//橫向滾動了多少距離
offsetWidth = rawWidth - offset;
if (offset >= rawWidth / 3) {
dx = -offsetWidth;
} else {
dx = offset;
}
}
} else if (horizontalScrollOffset == 0 && verticalScrollOffset != 0) {
//豎向滾動
final float page = verticalScrollOffset * 1.f / rawHeight;//當前滾動到了第幾頁
final double floor = Math.floor(page);//前一頁
final double ceil = Math.ceil(page);//後一頁
final int offset;
final int offsetHeight;//滑動之後, 剩餘螢幕的高度
if (verticalScrollOffset > mVerticalScrollOffsetStart) {
pagerIndex = (int) floor;
//上滑動
offset = (int) (verticalScrollOffset - floor * rawHeight);
offsetHeight = rawHeight - offset;
if (offset >= rawHeight / 3) {
dy = offsetHeight;
} else {
dy = -offset;
}
} else if (mVerticalScrollOffsetStart > verticalScrollOffset) {
pagerIndex = (int) ceil;
//下滑動
offset = (int) (ceil * rawHeight - verticalScrollOffset);//橫向滾動了多少距離
offsetHeight = rawHeight - offset;
if (offset >= rawHeight / 3) {
dy = -offsetHeight;
} else {
dy = offset;
}
}
} else {
pagerIndex = 0;
}
to(dx, dy);
onViewPagerSelect(pagerIndex);
}
}
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
}
};4:其他需要注意的東西
//重寫此方法, 讓手指快速滑動的時候, 慢一點...
@Override
public boolean fling(int velocityX, int velocityY) {
return super.fling((int) (velocityX * 0.3f), (int) (velocityY * 0.3f));
}
至此: 文章就結束了,如有疑問: QQ群 Android:274306954 Swift:399799363 歡迎您的加入.