Android的：如何获得当前X RecyclerView偏移？ [英] Android: How to get the current X offset of RecyclerView?
问题描述
我使用了一个滚动型对于无限时间选取旋转木马，并发现了，这是不是最好的方法（<一href="http://stackoverflow.com/questions/26341587/horizontalscrollview-customadapter-with-getview-doesnt-reuse-convertviews-li">last问题）
现在，我发现回收站视图但我无法获得当前滚动的recyclerView的X方向的偏移？ （比方说，每一项都是100px的宽度，而第二项是唯一可见的50％，所以滚动偏移量为150像素）
- 在所有项目具有相同的宽度，但therer一定的差距之前，首先，在最后一个项目之后
-
recyclerView.getScrollX（）返回0（文档说：初始滚动值） - 的
布局管理的findFirstVisibleItemPosition，但我不能计算出的X轴偏移与
更新
我刚刚找到一种方法来保持跟踪X位置，同时更新与 onScrolled 回调的价值，但我想preFER得到实际的值，而不是跟踪这一切的时候！
私人INT overallXScrol = 0;
// ...
mRecyclerView.setOnScrollListener（新RecyclerView.OnScrollListener（）{
@覆盖
公共无效onScrolled（RecyclerView recyclerView，诠释DX，诠释DY）{
super.onScrolled（recyclerView，DX，DY）;
overallXScroll = overallXScroll + DX;
Log.i（检查，overall-＆GT;+ overallXScroll）;
}
}）;
解决方案1： setOnScrollListener
保存的X定位为类变量和更新中的 onScrollListener 每一个变化。确保你不重置 overallXScroll （FE onScreenRotationChange ）
私人INT overallXScroll = 0;
// ...
mRecyclerView.setOnScrollListener（新RecyclerView.OnScrollListener（）{
@覆盖
公共无效onScrolled（RecyclerView recyclerView，诠释DX，诠释DY）{
super.onScrolled（recyclerView，DX，DY）;
overallXScroll = overallXScroll + DX;
Log.i（检查，整体X =+ overallXScroll）;
}
}）;
解决方案2：计算当前位置
在我的情况，我有一个充满了时间值（0:00，0:30，1:00，1:30 ... 23:00，23:30）水平列表。我计算从时间项，这是在屏幕（计算点）的中间位置的时间。这就是为什么我需要的精确的X滚动位置我 RecycleView
- 在每次项目有60dp相同的宽度（供参考：60dp = 30分钟，2DP = 1分）
-
第一项（标题项）有一个微胖，设置0min到中心
私人INT mScreenWidth = 0; 私人诠释mHeaderItemWidth = 0; 私人诠释mCellWidth = 0; @覆盖 保护无效的onCreate（包savedInstanceState）{ super.onCreate（savedInstanceState）; //初始化循环意见 // ... DisplayMetrics displaymetrics =新DisplayMetrics（）; 。this.getWindowManager（）getDefaultDisplay（）getMetrics（displaymetrics）。 this.mScreenWidth = displaymetrics.widthPixels; //计算值在当前设备 mCellWidth =（INT）TypedValue.applyDimension（TypedValue.COMPLEX_UNIT_DIP，60，getResources（） .getDisplayMetrics（））; 列表中的权利（差距缩小到屏幕的左边，从第一个项目的左侧）//得到补偿 最终诠释mOffset =（this.mScreenWidth / 2） - （mCellWidth / 2）; // HeaderItem宽度（图形蓝色矩形） mHeaderItemWidth = mOffset + mCellWidth; mRecyclerView.setOnScrollListener（新RecyclerView.OnScrollListener（）{ @覆盖 公共无效onScrolled（RecyclerView recyclerView，诠释DX，诠释DY）{ super.onScrolled（recyclerView，DX，DY）; //获取第一个可见项目 视图firstVisibleItem = mLLM.findViewByPosition（mLLM.findFirstVisibleItemPosition（））; INT leftScrollXCalculated = 0; 如果（firstItemPosition == 0）{ //如果第一个项目，得到宽度headerview的（getLeft（）℃的，这就是为什么我使用Math.abs（）） leftScrollXCalculated = Math.abs（firstVisibleItem.getLeft（））; } 其他{ // X坐标=峡向右+细胞数*宽度 - 当前的第一个可见项目的偏移量电池 //（mHeaderItemWidth包括已经宽度一格的，这就是为什么我必须再减去它） leftScrollXCalculated =（mHeaderItemWidth - mCellWidth）+ firstItemPosition * mCellWidth + firstVisibleItem.getLeft（）; } Log.i（ASDF，计算出的X要离开=+ leftScrollXCalculated）; } }）;}
I'm using a Scrollview for an infinite "Time Picker Carousel" and found out, that it is not the best approach (last question)
Now, I found the Recycler View but I am unable to get the current scroll offset in X direction of the recyclerView? (Let's say each item is 100px width, and the second item is only visible to 50%, so the scroll-offset is 150px)
- all items have the same width, but therer is some gap before the first, after the last item
recyclerView.getScrollX()returns0(docs say: initial scroll value)- the
LayoutManagerhasfindFirstVisibleItemPosition, but I cannot calculate the X offset with that
UPDATE
I just found a way to keep tracking the X-Position, while updating the value with the onScrolled callback, but I would prefer getting the actual value instead of tracking it all the time!
private int overallXScrol = 0;
//...
mRecyclerView.setOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
overallXScroll = overallXScroll + dx;
Log.i("check","overall->" + overallXScroll);
}
});
Solution 1: setOnScrollListener
Save your X-Position as class variable and update each change within the onScrollListener. Ensure you don't reset overallXScroll (f.e. onScreenRotationChange)
private int overallXScroll = 0;
//...
mRecyclerView.setOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
overallXScroll = overallXScroll + dx;
Log.i("check","overall X = " + overallXScroll);
}
});
Solution 2: Calculate current position.
In my case, I have a horizontal List which is filled with time values (0:00, 0:30, 1:00, 1:30 ... 23:00, 23:30). I'm calculating the time from the time-item, which is in the middle of the screen (calculation point). That's why I need the exact X-Scroll Position of my RecycleView
- Each time item has the same width of 60dp (fyi: 60dp = 30min, 2dp = 1min)
First item (Header item) has an extra padding, to set 0min to the center
private int mScreenWidth = 0; private int mHeaderItemWidth = 0; private int mCellWidth = 0; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //init recycle views //... DisplayMetrics displaymetrics = new DisplayMetrics(); this.getWindowManager().getDefaultDisplay().getMetrics(displaymetrics); this.mScreenWidth = displaymetrics.widthPixels; //calculate value on current device mCellWidth = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 60, getResources() .getDisplayMetrics()); //get offset of list to the right (gap to the left of the screen from the left side of first item) final int mOffset = (this.mScreenWidth / 2) - (mCellWidth / 2); //HeaderItem width (blue rectangle in graphic) mHeaderItemWidth = mOffset + mCellWidth; mRecyclerView.setOnScrollListener(new RecyclerView.OnScrollListener() { @Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) { super.onScrolled(recyclerView, dx, dy); //get first visible item View firstVisibleItem = mLLM.findViewByPosition(mLLM.findFirstVisibleItemPosition()); int leftScrollXCalculated = 0; if (firstItemPosition == 0){ //if first item, get width of headerview (getLeft() < 0, that's why I Use Math.abs()) leftScrollXCalculated = Math.abs(firstVisibleItem.getLeft()); } else{ //X-Position = Gap to the right + Number of cells * width - cell offset of current first visible item //(mHeaderItemWidth includes already width of one cell, that's why I have to subtract it again) leftScrollXCalculated = (mHeaderItemWidth - mCellWidth) + firstItemPosition * mCellWidth + firstVisibleItem.getLeft(); } Log.i("asdf","calculated X to left = " + leftScrollXCalculated); } });}
这篇关于Android的：如何获得当前X RecyclerView偏移？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
