Question

我在我的主要活动布局中使用了多个RecyclerView，并且从此处https://github.com/rubensousa/RecyclerViewSnap/使用捕捉来水平或垂直滚动显示recyclerview。很好。

但是，当我水平滚动时，最后一个Recycleview本身会滚动回到项目或位置之一，而在此上方的其他或其他Recycleview则不是这种情况。

这是图片

如何防止这种情况。这是我的助手类，用于处理滚动行为

public class GravitySnapHelper extends LinearSnapHelper {

    private OrientationHelper verticalHelper;
    private OrientationHelper horizontalHelper;
    private int gravity;
    private boolean isSupportRtL;

    @SuppressLint("RtlHardcoded")
    public GravitySnapHelper(int gravity) {
        this.gravity = gravity;
        if (this.gravity == Gravity.LEFT) {
            this.gravity = Gravity.START;
        } else if (this.gravity == Gravity.RIGHT) {
            this.gravity = Gravity.END;
        }
    }

    @Override
    public void attachToRecyclerView(@Nullable RecyclerView recyclerView)
            throws IllegalStateException {
        if (recyclerView != null) {
            isSupportRtL = recyclerView.getContext().getResources().getBoolean(R.bool.is_rtl);
        }
        super.attachToRecyclerView(recyclerView);
    }

    @Override
    public int[] calculateDistanceToFinalSnap(@NonNull RecyclerView.LayoutManager layoutManager,
                                              @NonNull View targetView) {
        int[] out = new int[2];

        if (layoutManager.canScrollHorizontally()) {
            if (gravity == Gravity.START) {
                out[0] = distanceToStart(targetView, getHorizontalHelper(layoutManager));
            } else { // END
                out[0] = distanceToEnd(targetView, getHorizontalHelper(layoutManager));
            }
        } else {
            out[0] = 0;
        }

        if (layoutManager.canScrollVertically()) {
            if (gravity == Gravity.TOP) {
                out[1] = distanceToStart(targetView, getVerticalHelper(layoutManager));
            } else { // BOTTOM
                out[1] = distanceToEnd(targetView, getVerticalHelper(layoutManager));
            }
        } else {
            out[1] = 0;
        }
        return out;
    }

    @Override
    public View findSnapView(RecyclerView.LayoutManager layoutManager) {
        if (layoutManager instanceof LinearLayoutManager) {
            switch (gravity) {
                case Gravity.START:
                    return findStartView(layoutManager, getHorizontalHelper(layoutManager));
                case Gravity.TOP:
                    return findStartView(layoutManager, getVerticalHelper(layoutManager));
                case Gravity.END:
                    return findEndView(layoutManager, getHorizontalHelper(layoutManager));
                case Gravity.BOTTOM:
                    return findEndView(layoutManager, getVerticalHelper(layoutManager));
            }
        }

        return super.findSnapView(layoutManager);
    }

    private int distanceToStart(View targetView, OrientationHelper helper) {
        if (isSupportRtL) {
            return distanceToEnd(targetView, helper);
        }
        return helper.getDecoratedStart(targetView) - helper.getStartAfterPadding();
    }

    private int distanceToEnd(View targetView, OrientationHelper helper) {
        if (isSupportRtL) {
            return helper.getDecoratedStart(targetView) - helper.getStartAfterPadding();
        }
        return helper.getDecoratedEnd(targetView) - helper.getEndAfterPadding();
    }

    private View findStartView(RecyclerView.LayoutManager layoutManager,
                               OrientationHelper helper) {

        if (layoutManager instanceof LinearLayoutManager) {
            int firstChild = ((LinearLayoutManager) layoutManager).findFirstVisibleItemPosition();

            if (firstChild == RecyclerView.NO_POSITION) {
                return null;
            }

            View child = layoutManager.findViewByPosition(firstChild);

            if (helper.getDecoratedEnd(child) >= helper.getDecoratedMeasurement(child) / 2
                    && helper.getDecoratedEnd(child) > 0) {
                return child;
            } else {
                if (((LinearLayoutManager) layoutManager).findLastCompletelyVisibleItemPosition()
                        == layoutManager.getItemCount() - 1) {
                    return null;
                } else {
                    return layoutManager.findViewByPosition(firstChild + 1);
                }
            }
        }

        return super.findSnapView(layoutManager);
    }

    private View findEndView(RecyclerView.LayoutManager layoutManager,
                             OrientationHelper helper) {

        if (layoutManager instanceof LinearLayoutManager) {
            int lastChild = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();

            if (lastChild == RecyclerView.NO_POSITION) {
                return null;
            }

            View child = layoutManager.findViewByPosition(lastChild);

            if (helper.getDecoratedStart(child) + helper.getDecoratedMeasurement(child) / 2
                    <= helper.getTotalSpace()) {
                return child;
            } else {
                if (((LinearLayoutManager) layoutManager).findFirstCompletelyVisibleItemPosition()
                        == 0) {
                    return null;
                } else {
                    return layoutManager.findViewByPosition(lastChild - 1);
                }
            }
        }

        return super.findSnapView(layoutManager);
    }

    private OrientationHelper getVerticalHelper(RecyclerView.LayoutManager layoutManager) {
        if (verticalHelper == null) {
            verticalHelper = OrientationHelper.createVerticalHelper(layoutManager);
        }
        return verticalHelper;
    }

    private OrientationHelper getHorizontalHelper(RecyclerView.LayoutManager layoutManager) {
        if (horizontalHelper == null) {
            horizontalHelper = OrientationHelper.createHorizontalHelper(layoutManager);
        }
        return horizontalHelper;
    }

}

我的主要活动是

public class MainActivity extends AppCompatActivity {

    private ArrayList<Item> items;
    private RecyclerView science, engineering;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        science = (RecyclerView) findViewById(R.id.science);
        engineering = (RecyclerView) findViewById(R.id.engineering);


        createApps();

        /**
         * Center snapping
         */
        //SnapHelper snapHelper = new LinearSnapHelper();
        //snapHelper.attachToRecyclerView(recyclerView);

        /**
         * Start snapping
         */
        //SnapHelper snapHelper = new GravitySnapHelper(Gravity.START);
        //snapHelper.attachToRecyclerView(recyclerView);

        /**
         * End snapping
         */
        //SnapHelper snapHelper = new GravitySnapHelper(Gravity.END);
        //snapHelper.attachToRecyclerView(recyclerView);

        /**
         * Top snapping
         */
        //SnapHelper snapHelper = new GravitySnapHelper(Gravity.TOP);
        //snapHelper.attachToRecyclerView(recyclerView);

        /**
         * Bottom snapping
         */
        SnapHelper snapHelper = new GravitySnapHelper(Gravity.CENTER);
        snapHelper.attachToRecyclerView(science);
        snapHelper.attachToRecyclerView(medical);
        snapHelper.attachToRecyclerView(engineering);
        snapHelper.attachToRecyclerView(account);
        snapHelper.attachToRecyclerView(others);

        // HORIZONTAL for Gravity START/END and VERTICAL for TOP/BOTTOM SCIENCE
        science.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));
        science.setHasFixedSize(true);

        SnapRecyclerAdapter adapter = new SnapRecyclerAdapter(this, items);
        science.setAdapter(adapter);

//Engineering
        engineering.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));
        engineering.setHasFixedSize(true);

        SnapRecyclerAdapter engi = new SnapRecyclerAdapter(this, items);
        engineering.setAdapter(engi);




    }

    private void createApps() {
        items = new ArrayList<>();
        items.add(new Item("Google+", R.drawable.google_plus));
        items.add(new Item("Facebook", R.drawable.facebook));
        items.add(new Item("LinkedIn", R.drawable.linkedin));
        items.add(new Item("Youtube", R.drawable.youtube));
        items.add(new Item("Instagram", R.drawable.instagram));
        items.add(new Item("Skype", R.drawable.skype));
        items.add(new Item("Twitter", R.drawable.twitter));
        items.add(new Item("Wikipedia", R.drawable.wikipedia));
        items.add(new Item("Whats app", R.drawable.what_apps));
        items.add(new Item("Pokemon Go", R.drawable.pokemon_go));
    }
}

如果有人需要的话，这里是上述教程的文章 http://www.devexchanges.info/2016/09/android-tip-recyclerview-snapping-with.html

防止Recyclerview自动水平滚动

0 个答案: