RecyclerView使用GridLayoutManager尝试解决wrap_content问题

Question

我尝试解决以下问题：

• 使用RecyclerView
• 使用GridLayoutManager
• 使用固定的单元格宽度
• 让RecyclerView只调整到必要的高度（wrap_content）

我尝试使用以下代码，但问题是它不起作用，我没有找到任何工作示例，也没有提到在方向更改时如何正确重绘。

public class AutofitRecyclerView extends RecyclerView {
    private MyGridLayoutManager manager;
    private int columnWidth = -1;

    public AutofitRecyclerView(Context context) {
        super(context);
        init(context, null);
    }

    public AutofitRecyclerView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context, attrs);
    }

    public AutofitRecyclerView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context, attrs);
    }

    private void init(Context context, AttributeSet attrs) {
        if (attrs != null) {
            int[] attrsArray = {
                    android.R.attr.columnWidth
            };
            TypedArray array = context.obtainStyledAttributes(attrs, attrsArray);
            columnWidth = array.getDimensionPixelSize(0, -1);
            array.recycle();
        }

        manager = new MyGridLayoutManager(getContext(), 1);
        setLayoutManager(manager);
    }

    @Override
    protected void onMeasure(int widthSpec, int heightSpec) {
        super.onMeasure(widthSpec, heightSpec);
        if (columnWidth > 0) {

            int mw = getMeasuredWidth();

            int spanCount = Math.max(1, mw / columnWidth);
            manager.setSpanCount(spanCount);
        }

        int numOfFullRows = manager.getItemCount() / manager.getSpanCount();

        if(manager.getItemCount() % manager.getSpanCount() > 0)
        {
            numOfFullRows++;
        }

        if(getChildCount() > 0) {
            int h = 0;
            try {
                h = manager.getChildAt(0).getMeasuredHeight();
            } catch (Exception e) {
                e.printStackTrace();
            }

            if(h != 0) {
                getLayoutParams().height = numOfFullRows * h;
            }
        }
    }
}

- Csabi

Answer 1

基于 connector 发布的代码，我设计了以下解决方案，支持不同的行/列大小（尽管我承认尚未测试），考虑到装饰项的大小，并正确处理不同的测量模式。

以下是代码：

import android.content.Context;
import android.graphics.Rect;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.view.ViewGroup;

public class WrappableGridLayoutManager extends GridLayoutManager {

    public WrappableGridLayoutManager(Context context, int spanCount) {
        super(context, spanCount);
    }

    private int[] measuredSize = new int[2];

    @Override
    public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state, int widthSpec, int heightSpec) {
        final int widthMode = View.MeasureSpec.getMode(widthSpec);
        final int heightMode = View.MeasureSpec.getMode(heightSpec);
        final int widthSize = View.MeasureSpec.getSize(widthSpec);
        final int heightSize = View.MeasureSpec.getSize(heightSpec);

        int spanWidth = 0;
        int spanHeight = 0;

        int viewWidth = 0;
        int viewHeight = 0;

        int spanCount = getSpanCount();

        for (int i = 0; i < getItemCount(); i++) {

            measureScrapChild(recycler, i, View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED), View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED), measuredSize);

            if (i % spanCount == 0) {
                spanWidth = measuredSize[0];
                spanHeight = measuredSize[1];
            } else {
                if (getOrientation() == VERTICAL) {
                    spanWidth += measuredSize[0];
                    spanHeight = Math.max(spanHeight, measuredSize[1]);
                } else {
                    spanWidth = Math.max(spanWidth, measuredSize[0]);
                    spanHeight += measuredSize[1];
                }
            }

            if (i % spanCount == spanCount - 1 || i == getItemCount() - 1) {
                if (getOrientation() == VERTICAL) {
                    viewWidth = Math.max(viewWidth, spanWidth);
                    viewHeight += spanHeight;
                } else {
                    viewWidth += spanWidth;
                    viewHeight = Math.max(viewHeight, spanHeight);
                }
            }
        }

        int finalWidth;
        int finalHeight;

        switch (widthMode) {
            case View.MeasureSpec.EXACTLY:
                finalWidth = widthSize;
                break;
            case View.MeasureSpec.AT_MOST:
                finalWidth = Math.min(widthSize, viewWidth);
                break;
            case View.MeasureSpec.UNSPECIFIED:
                finalWidth = viewWidth;
                break;
            default:
                finalWidth = widthSize;
                break;
        }

        switch (heightMode) {
            case View.MeasureSpec.EXACTLY:
                finalHeight = heightSize;
                break;
            case View.MeasureSpec.AT_MOST:
                finalHeight = Math.min(heightSize, viewHeight);
                break;
            case View.MeasureSpec.UNSPECIFIED:
                finalHeight = viewHeight;
                break;
            default:
                finalHeight = heightSize;
                break;
        }

        setMeasuredDimension(finalWidth, finalHeight);
    }


    private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec, int heightSpec, int[] measuredDimension) {

        View view = null;
        try {
            view = recycler.getViewForPosition(position);
        } catch (Exception ex) {
          // try - catch is needed since support library version 24
        }


        if (view != null) {

            RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();

            int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec, getPaddingLeft() + getPaddingRight(), p.width);
            int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec, getPaddingTop() + getPaddingBottom(), p.height);

            view.measure(childWidthSpec, childHeightSpec);

            measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin;
            measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin;

            Rect decoratorRect = new Rect();
            calculateItemDecorationsForChild(view, decoratorRect);
            measuredDimension[0] += decoratorRect.left;
            measuredDimension[0] += decoratorRect.right;
            measuredDimension[1] += decoratorRect.top;
            measuredDimension[1] += decoratorRect.bottom;

            recycler.recycleView(view);
        }
    }
}

- Nantoka

---

为什么会被踩？这是连接器代码的改进版本，是从我为一个已发布的应用程序编写的代码中复制而来的，所以我知道它是有效的。 - Nantoka

下降的票数可能来自于只有一个项目和例如2列的人-在这种情况下，您的经理将回收视图的高度设置为0（6.0 Nexus 7）。上面的其他答案中的Git链接完美地工作（我没有使用装饰）。 - snachmsm

谢谢你告诉我。我一找到时间就会调查这个问题。 - Nantoka

我更新了我的回答，并提供了解决这个问题的方法。 - Nantoka

我的答案已更新，修复了Android SDK 24的问题。 - Nantoka

我目前不需要你的解决方案，但感谢保持代码更新... :) - snachmsm

Answer 2

您需要添加自定义的GridlayoutManager。 请查看此链接：https://gist.github.com/ArthurSav/5f80e19d9ba6d562fbd5

- Arthur

Answer 3

感谢@nantoka和@arthur提供的代码，它给了我一个很好的起点。不幸的是，它在不同的spanCount下表现不佳，所以这里是我的更新（Kotlin）：

import android.content.Context
import android.util.AttributeSet
import android.view.View
import android.view.ViewGroup
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.RecyclerView
import androidx.recyclerview.widget.RecyclerView.Recycler
import com.baziliqo.app.bar.utils.takeIfInstance

class WrappableGridLayoutManager(context: Context?, val preferedSpanCount: Int, @RecyclerView.Orientation orientation: Int = RecyclerView.VERTICAL) :
    GridLayoutManager(context, preferedSpanCount, orientation, false) {

    private val mMeasuredDimension = IntArray(2)

    var measuredWidth = 0
    var measuredHeight = 0


    override fun onMeasure(recycler: Recycler, state: RecyclerView.State, widthSpec: Int, heightSpec: Int) {
        val suitableSpanCount = preferedSpanCount.coerceAtMost(itemCount)
        if (spanCount != suitableSpanCount) {
            spanCount = suitableSpanCount
            return
        }
        val widthMode = View.MeasureSpec.getMode(widthSpec)
        val heightMode = View.MeasureSpec.getMode(heightSpec)
        val widthSize = View.MeasureSpec.getSize(widthSpec)
        val heightSize = View.MeasureSpec.getSize(heightSpec)
        measuredWidth = 0
        measuredHeight = 0
        for (i in 0 until itemCount) {
            measureScrapChild(
                recycler, i,
                View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                mMeasuredDimension
            )
            if (orientation == HORIZONTAL) {
                if (i % spanCount == 0) {
                    measuredWidth += mMeasuredDimension[0]
                }
                if (i < spanCount) {
                    measuredHeight += mMeasuredDimension[1]
                }
            } else {
                if (i % spanCount == 0) {
                    measuredHeight += mMeasuredDimension[1]
                }
                if (i < spanCount) {
                    measuredWidth += mMeasuredDimension[0]
                }
            }
        }
        when (widthMode) {
            View.MeasureSpec.EXACTLY -> measuredWidth = widthSize
            View.MeasureSpec.AT_MOST, View.MeasureSpec.UNSPECIFIED -> {
            }
        }
        when (heightMode) {
            View.MeasureSpec.EXACTLY -> measuredHeight = heightSize
            View.MeasureSpec.AT_MOST, View.MeasureSpec.UNSPECIFIED -> {
            }
        }
        setMeasuredDimension(measuredWidth, measuredHeight)
    }

    private fun measureScrapChild(recycler: Recycler, position: Int, widthSpec: Int, heightSpec: Int, measuredDimension: IntArray) {
        try {
            var view = recycler.getViewForPosition(position) ?: return
            val p = view.layoutParams as RecyclerView.LayoutParams
            val childWidthSpec = ViewGroup.getChildMeasureSpec(
                widthSpec,
                paddingLeft + paddingRight, p.width
            )
            val childHeightSpec = ViewGroup.getChildMeasureSpec(
                heightSpec,
                paddingTop + paddingBottom, p.height
            )
            view.measure(childWidthSpec, childHeightSpec)
            measuredDimension[0] = view.measuredWidth + p.leftMargin + p.rightMargin
            measuredDimension[1] = view.measuredHeight + p.bottomMargin + p.topMargin
            recycler.recycleView(view)
        } catch (e: Exception) {
        }
    }
}

- Nikola Minoski