Украшение RecyclerView (с помощью GridLayoutManager) для отображения разделителя между элементами

Ответ 1

Я не знаю, зачем вам это нужно, но этот пользовательский интерфейс довольно легко реализовать с помощью декоратора RecyclerView.

mRecylerView.addItemDecoration(new ItemDecorationAlbumColumns(
    getResources().getDimensionPixelSize(R.dimen.photos_list_spacing), 
    getResources().getInteger(R.integer.photo_list_preview_columns)));

и декоратор (требуется некоторый рефаторирование)

import android.graphics.Rect;
import android.support.v7.widget.RecyclerView;
import android.view.View;

public class ItemDecorationAlbumColumns extends RecyclerView.ItemDecoration {

    private int mSizeGridSpacingPx;
    private int mGridSize;

    private boolean mNeedLeftSpacing = false;

    public ItemDecorationAlbumColumns(int gridSpacingPx, int gridSize) {
        mSizeGridSpacingPx = gridSpacingPx;
        mGridSize = gridSize;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        int frameWidth = (int) ((parent.getWidth() - (float) mSizeGridSpacingPx * (mGridSize - 1)) / mGridSize);
        int padding = parent.getWidth() / mGridSize - frameWidth;
        int itemPosition = ((RecyclerView.LayoutParams) view.getLayoutParams()).getViewAdapterPosition();
        if (itemPosition < mGridSize) {
            outRect.top = 0;
        } else {
            outRect.top = mSizeGridSpacingPx;
        }
        if (itemPosition % mGridSize == 0) {
            outRect.left = 0;
            outRect.right = padding;
            mNeedLeftSpacing = true;
        } else if ((itemPosition + 1) % mGridSize == 0) {
            mNeedLeftSpacing = false;
            outRect.right = 0;
            outRect.left = padding;
        } else if (mNeedLeftSpacing) {
            mNeedLeftSpacing = false;
            outRect.left = mSizeGridSpacingPx - padding;
            if ((itemPosition + 2) % mGridSize == 0) {
                outRect.right = mSizeGridSpacingPx - padding;
            } else {
                outRect.right = mSizeGridSpacingPx / 2;
            }
        } else if ((itemPosition + 2) % mGridSize == 0) {
            mNeedLeftSpacing = false;
            outRect.left = mSizeGridSpacingPx / 2;
            outRect.right = mSizeGridSpacingPx - padding;
        } else {
            mNeedLeftSpacing = false;
            outRect.left = mSizeGridSpacingPx / 2;
            outRect.right = mSizeGridSpacingPx / 2;
        }
        outRect.bottom = 0;
    }
}

Ответ 2

Вот более простая и удобная реализация:

public class MediaSpaceDecoration extends RecyclerView.ItemDecoration {
    private final int spacing;
    private final List<Integer> allowedViewTypes = Arrays.asList(
            R.layout.item_image,
            R.layout.item_blur);

    public MediaSpaceDecoration(int spacing) {
        this.spacing = spacing;
    }

    @Override
    public void getItemOffsets(Rect outRect,
                               View view,
                               RecyclerView parent,
                               RecyclerView.State state) {
        final int position = parent.getChildAdapterPosition(view);
        if (!isMedia(parent, position)) {
            return;
        }

        final int totalSpanCount = getTotalSpanCount(parent);
        int spanSize = getItemSpanSize(parent, position);
        if (totalSpanCount == spanSize) {
            return;
        }

        outRect.top = isInTheFirstRow(position, totalSpanCount) ? 0 : spacing;
        outRect.left = isFirstInRow(position, totalSpanCount) ? 0 : spacing / 2;
        outRect.right = isLastInRow(position, totalSpanCount) ? 0 : spacing / 2;
        outRect.bottom = 0; // don't need
    }

    private boolean isInTheFirstRow(int position, int spanCount) {
        return position < spanCount;
    }

    private boolean isFirstInRow(int position, int spanCount) {
        return position % spanCount == 0;
    }

    private boolean isLastInRow(int position, int spanCount) {
        return isFirstInRow(position + 1, spanCount);
    }

    private int getTotalSpanCount(RecyclerView parent) {
        final RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
        return layoutManager instanceof GridLayoutManager
            ? ((GridLayoutManager) layoutManager).getSpanCount()
            : 1;
    }

    private int getItemSpanSize(RecyclerView parent, int position) {
        final RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
        return layoutManager instanceof GridLayoutManager
            ? ((GridLayoutManager) layoutManager).getSpanSizeLookup().getSpanSize(position)
            : 1;
    }

    private boolean isMedia(RecyclerView parent, int viewPosition) {
        final RecyclerView.Adapter adapter = parent.getAdapter();
        final int viewType = adapter.getItemViewType(viewPosition);
        return allowedViewTypes.contains(viewType);
    }
}

Я также проверяю перед установкой outRect, потому что у меня есть различные spanSize для каждого viewType, и мне нужно добавить дополнительный пробел только для allowedViewTypes. Вы можете легко удалить эту проверку, и код будет еще проще. Для меня это выглядит так:

Ответ 3

Вы можете получить свой ответ, но я все равно отправляю свое решение, которое может помочь другим. Это можно использовать для вертикальных, горизонтальных списков или видов сетки, передавая ориентацию.

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;

public class DividerItemDecoration extends RecyclerView.ItemDecoration {

    private static final int[] ATTRS = new int[]{
            android.R.attr.listDivider
    };

    public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;
    public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;
    public static final int GRID = 2;

    private Drawable mDivider;

    private int mOrientation;

    public DividerItemDecoration(Context context, int orientation) {
        final TypedArray a = context.obtainStyledAttributes(ATTRS);
        mDivider = a.getDrawable(0);
        a.recycle();
        setOrientation(orientation);
    }

    public void setOrientation(int orientation) {
        if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST && orientation != GRID) {
            throw new IllegalArgumentException("invalid orientation");
        }
        mOrientation = orientation;
    }

    @Override
    public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
        if (mOrientation == VERTICAL_LIST) {
            drawVertical(c, parent);
        } else if(mOrientation == HORIZONTAL_LIST){
            drawHorizontal(c, parent);
        } else {
            drawVertical(c, parent);
            drawHorizontal(c, parent);
        }
    }

    public void drawVertical(Canvas c, RecyclerView parent) {
        if (parent.getChildCount() == 0) return;

        final int left = parent.getPaddingLeft();
        final int right = parent.getWidth() - parent.getPaddingRight();

        final View child = parent.getChildAt(0);
        if (child.getHeight() == 0) return;

        final RecyclerView.LayoutParams params =
                (RecyclerView.LayoutParams) child.getLayoutParams();
        int top = child.getBottom() + params.bottomMargin + mDivider.getIntrinsicHeight();
        int bottom = top + mDivider.getIntrinsicHeight();

        final int parentBottom = parent.getHeight() - parent.getPaddingBottom();
        while (bottom < parentBottom) {
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);

            top += mDivider.getIntrinsicHeight() + params.topMargin + child.getHeight() + params.bottomMargin + mDivider.getIntrinsicHeight();
            bottom = top + mDivider.getIntrinsicHeight();
        }
    }

    public void drawHorizontal(Canvas c, RecyclerView parent) {
        final int top = parent.getPaddingTop();
        final int bottom = parent.getHeight() - parent.getPaddingBottom();

        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params =
                    (RecyclerView.LayoutParams) child.getLayoutParams();
            final int left = child.getRight() + params.rightMargin + mDivider.getIntrinsicHeight();
            final int right = left + mDivider.getIntrinsicWidth();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        if (mOrientation == VERTICAL_LIST) {
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else if(mOrientation == HORIZONTAL_LIST) {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        } else {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), mDivider.getIntrinsicHeight());
        }
    }
}

Ответ 4

Еще одно простое решение, которое сработало для меня. Надеюсь, это может быть полезно.

class GridItemDecorator(val context: Context, private val spacingDp: Int, private val mGridSize: Int) : RecyclerView.ItemDecoration() {

    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {

        val resources = context.resources
        val spacingPx = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, spacingDp.toFloat(), resources.displayMetrics)

        val bit = if (spacingPx > mGridSize) Math.round(spacingPx / mGridSize) else 1
        val itemPosition = (view.layoutParams as RecyclerView.LayoutParams).viewAdapterPosition

        outRect.top = if (itemPosition < mGridSize) 0 else  bit * mGridSize
        outRect.bottom = 0

        val rowPosition = itemPosition % mGridSize
        outRect.left = rowPosition * bit
        outRect.right = (mGridSize - rowPosition - 1) * bit

    }
}

Ответ 5

  @BindingAdapter({"bind:adapter"})
    public static void bind(RecyclerView view, RecyclerView.Adapter<BaseViewHolder> adapter) {
        view.setLayoutManager(new GridLayoutManager(view.getContext(), 3));
        view.addItemDecoration(new SpacesItemDecorationGrid(view.getContext(), 4, 3));
        view.setItemAnimator(new DefaultItemAnimator());
        view.setAdapter(adapter);
    }


public class SpacesItemDecorationGrid extends RecyclerView.ItemDecoration {

    private int mSizeGridSpacingPx;
    private int mGridSize;
    private boolean mNeedLeftSpacing = false;

    /**
     * @param gridSpacingPx
     * @param gridSize
     */
    SpacesItemDecorationGrid(Context context, int gridSpacingPx, int gridSize) {
        mSizeGridSpacingPx = (int) Util.convertDpToPixel(gridSpacingPx, context);
        mGridSize = gridSize;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        int frameWidth = (int) ((parent.getWidth() - (float) mSizeGridSpacingPx * (mGridSize - 1)) / mGridSize);
        int padding = parent.getWidth() / mGridSize - frameWidth;
        int itemPosition = ((RecyclerView.LayoutParams) view.getLayoutParams()).getViewAdapterPosition();
        int itemCount = parent.getAdapter().getItemCount() - mGridSize;


   /*     if (itemPosition < mGridSize) {
            outRect.top = mSizeGridSpacingPx;
        } else {
                   outRect.top = mSizeGridSpacingPx;
        }*/
        outRect.top = mSizeGridSpacingPx;
        if (itemPosition % mGridSize == 0) {
            outRect.left = mSizeGridSpacingPx;
            outRect.right = padding;
            mNeedLeftSpacing = true;
        } else if ((itemPosition + 1) % mGridSize == 0) {
            mNeedLeftSpacing = false;
            outRect.right = mSizeGridSpacingPx;
            outRect.left = padding;
        } else if (mNeedLeftSpacing) {
            mNeedLeftSpacing = false;
            outRect.left = mSizeGridSpacingPx - padding;
            if ((itemPosition + 2) % mGridSize == 0) {
                outRect.right = mSizeGridSpacingPx - padding;
            } else {
                outRect.right = mSizeGridSpacingPx / 2;
            }
        } else if ((itemPosition + 2) % mGridSize == 0) {
            mNeedLeftSpacing = false;
            outRect.left = mSizeGridSpacingPx / 2;
            outRect.right = mSizeGridSpacingPx - padding;
        } else {
            mNeedLeftSpacing = false;
            outRect.left = mSizeGridSpacingPx / 2;
            outRect.right = mSizeGridSpacingPx / 2;
        }
        if (itemPosition > itemCount) {
            outRect.bottom = mSizeGridSpacingPx;
        } else {
            outRect.bottom = 0;
        }

    }

}

Ответ 6

Вот моя реализация в Котлине. Я изменил код из других ответов, чтобы разделитель отображался и для полных составных элементов.

import android.graphics.Rect
import android.view.View
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.RecyclerView

class GridDividerItemDecoration(private val spacing: Int) : RecyclerView.ItemDecoration() {

    override fun getItemOffsets(
        outRect: Rect,
        view: View,
        parent: RecyclerView,
        state: RecyclerView.State
    ) {
        val position = parent.getChildAdapterPosition(view)

        val totalSpanCount = getTotalSpanCount(parent)
        val spanSize = getItemSpanSize(parent, position)

        outRect.top = if (isInTheFirstRow(position, totalSpanCount)) 0 else spacing
        outRect.left = if (isFirstInRow(position, totalSpanCount, spanSize)) 0 else spacing / 2
        outRect.right = if (isLastInRow(position, totalSpanCount, spanSize)) 0 else spacing / 2
        outRect.bottom = 0
    }

    private fun isInTheFirstRow(position: Int, totalSpanCount: Int): Boolean =
        position < totalSpanCount

    private fun isFirstInRow(position: Int, totalSpanCount: Int, spanSize: Int): Boolean =
        if (totalSpanCount != spanSize) {
            position % totalSpanCount == 0
        } else true

    private fun isLastInRow(position: Int, totalSpanCount: Int, spanSize: Int): Boolean =
        isFirstInRow(position + 1, totalSpanCount, spanSize)

    private fun getTotalSpanCount(parent: RecyclerView): Int =
        (parent.layoutManager as? GridLayoutManager)?.spanCount ?: 1

    private fun getItemSpanSize(parent: RecyclerView, position: Int): Int =
        (parent.layoutManager as? GridLayoutManager)?.spanSizeLookup?.getSpanSize(position) ?: 1
}

Результат: