Question

Please see this i have similar vertical recycler view but i want an effect similar to smart tab layout link below on scroll 我有两个垂直的回收站视图。每当在Recycler视图2中滚动10个项目时，我都会将Recycler View 1滚动到下一个位置。

使用此

rec2.addOnScrollListener(new RecyclerView.OnScrollListener() {


        @Override
        public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
            super.onScrolled(recyclerView, dx, dy);

            int currFirstPos = mLayoutManager4.findFirstCompletelyVisibleItemPosition();
            int currLastPos = mLayoutManager4.findLastCompletelyVisibleItemPosition();
            if (oldFirstPos==-1){
                totalItemsViewed = totalItemsViewed+currLastPos - currFirstPos + 1;
            }
            else{
                if (dy>0){
                    totalItemsViewed= totalItemsViewed+currLastPos - oldLastPos;
                 //   Toast.makeText(getContext(), "total item viewed"+totalItemsViewed, Toast.LENGTH_SHORT).show();
                    changeState(totalItemsViewed,"up");
                }else {
                    totalItemsViewed=totalItemsViewed+currFirstPos - oldFirstPos;
                 //   Toast.makeText(getContext(), "total item viewed"+totalItemsViewed, Toast.LENGTH_SHORT).show();
                    changeState(totalItemsViewed,"down");
                }
            }
            oldLastPos = currLastPos;
            oldFirstPos = currFirstPos;
        }
    });

更改状态方法，将imageRecycler视图滚动到一个位置，然后更改图像以在recycler视图中显示选定的图像。

private void changeState(int position,String direction){
    if (position<7){
        adapter.changeImage(1);
        catImageRec.scrollToPosition(1);
    }
  // and the rest of the code 
}

我想为我的Recycler View1创建一个垂直指示器以实现这种效果。！[Indicator] https://raw.githubusercontent.com/ogaclejapan/SmartTabLayout/master/art/demo4.gif

因此，我想到了使用物品装饰，并在此处找到了这段代码，但这是用于水平指示器的，并且不在回收站视图中而是在回收站视图中显示指示器

public class CirclePagerIndicatorDecoration extends RecyclerView.ItemDecoration {
private int colorActive = 0xDE000000;
private int colorInactive = 0x33000000;

private static final float DP = Resources.getSystem().getDisplayMetrics().density;

/**
 * Height of the space the indicator takes up at the bottom of the view.
 */
private final int mIndicatorHeight = (int) (DP * 16);

/**
 * Indicator stroke width.
 */
private final float mIndicatorStrokeWidth = DP * 4;

/**
 * Indicator width.
 */
private final float mIndicatorItemLength = DP * 4;
/**
 * Padding between indicators.
 */
private final float mIndicatorItemPadding = DP * 8;

/**
 * Some more natural animation interpolation
 */
private final Interpolator mInterpolator = new AccelerateDecelerateInterpolator();

private final Paint mPaint = new Paint();

public CirclePagerIndicatorDecoration() {

    mPaint.setStrokeWidth(mIndicatorStrokeWidth);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setAntiAlias(true);
}

@Override
public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
    super.onDrawOver(c, parent, state);

    int itemCount = parent.getAdapter().getItemCount();

    // center horizontally, calculate width and subtract half from center
    float totalLength = mIndicatorItemLength * itemCount;
    float paddingBetweenItems = Math.max(0, itemCount - 1) * mIndicatorItemPadding;
    float indicatorTotalWidth = totalLength + paddingBetweenItems;
    float indicatorStartX = (parent.getWidth() - indicatorTotalWidth) / 2F;

    // center vertically in the allotted space
    float indicatorPosY = parent.getHeight() - mIndicatorHeight / 2F;

    drawInactiveIndicators(c, indicatorStartX, indicatorPosY, itemCount);

    // find active page (which should be highlighted)
    LinearLayoutManager layoutManager = (LinearLayoutManager) parent.getLayoutManager();
    int activePosition = layoutManager.findFirstVisibleItemPosition();
    if (activePosition == RecyclerView.NO_POSITION) {
        return;
    }

    // find offset of active page (if the user is scrolling)
    final View activeChild = layoutManager.findViewByPosition(activePosition);
    int left = activeChild.getLeft();
    int width = activeChild.getWidth();
    int right = activeChild.getRight();

    // on swipe the active item will be positioned from [-width, 0]
    // interpolate offset for smooth animation
    float progress = mInterpolator.getInterpolation(left * -1 / (float) width);

    drawHighlights(c, indicatorStartX, indicatorPosY, activePosition, progress);
}

private void drawInactiveIndicators(Canvas c, float indicatorStartX, float indicatorPosY, int itemCount) {
    mPaint.setColor(colorInactive);

    // width of item indicator including padding
    final float itemWidth = mIndicatorItemLength + mIndicatorItemPadding;

    float start = indicatorStartX;
    for (int i = 0; i < itemCount; i++) {

        c.drawCircle(start, indicatorPosY, mIndicatorItemLength / 2F, mPaint);

        start += itemWidth;
    }
}

private void drawHighlights(Canvas c, float indicatorStartX, float indicatorPosY,
                            int highlightPosition, float progress) {
    mPaint.setColor(colorActive);

    // width of item indicator including padding
    final float itemWidth = mIndicatorItemLength + mIndicatorItemPadding;

    if (progress == 0F) {
        // no swipe, draw a normal indicator
        float highlightStart = indicatorStartX + itemWidth * highlightPosition;

        c.drawCircle(highlightStart, indicatorPosY, mIndicatorItemLength / 2F, mPaint);

    } else {
        float highlightStart = indicatorStartX + itemWidth * highlightPosition;
        // calculate partial highlight
        float partialLength = mIndicatorItemLength * progress + mIndicatorItemPadding*progress;

        c.drawCircle(highlightStart + partialLength, indicatorPosY, mIndicatorItemLength / 2F, mPaint);
    }
}

@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
    super.getItemOffsets(outRect, view, parent, state);
    outRect.bottom = mIndicatorHeight;
}

}

Answer 1

尝试这种方式

<android.support.v7.widget.RecyclerView
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:scrollbars="vertical" />

回收站视图的垂直指示器

1 个答案: