android - Variable number of columns in GridLayoutManager

Question

I wanted to display variable number of columns in a row of GridLayoutManager while using RecyclerView. The number of columns to be displayed depends on the size of the column's TextView.

I don't know the column width as the text is being dynamically put in it.

Can anyone help? StaggeredGridLayoutManager is not solving my purpose as it customizes the height but takes fixed number of columns.

Answer 1

来看看setSpanSizeLookup方法GridLayoutManager。它允许您为RecyclerView. 因此，也许您可​​以使用它来满足您对可变列号的要求。

编辑：

GridLayoutManager manager = new GridLayoutManager(context, 2); // MAX NUMBER OF SPACES
manager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
    @Override
    public int getSpanSize(int position) {
        if (position == 1 || position == 6) {
            return 2; // ITEMS AT POSITION 1 AND 6 OCCUPY 2 SPACES
        } else {
            return 1; // OTHER ITEMS OCCUPY ONLY A SINGLE SPACE
        }
    }
});

使用这种布局时，manager您RecyclerView应该如下所示：

+---+---+
| 0 |   |
+---+---+
|   1   |
+---+---+
| 2 | 3 |
+---+---+
| 4 | 5 |
+---+---+
|   6   |
+---+---+

（只有带数字的框代表您的项目RecyclerView，其他框只是空格）

Answer 2

如果您想进行如下更改：4 列、5 列、6 列...您可以获取此数字 (60) 之间的 MMC（最小公用数）并设置 GridLayoutManager：

    GridLayoutManager manager = new GridLayoutManager(context, 60); // set the grid with the MMC
    manager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
        @Override
        public int getSpanSize(int position) {
            return 12; // 60/12 = 5 Columns
        }
    });

然后您可以在 getSpanSize() 上为 6、5 和 4 列返回 10、12 或 15

Answer 3

您可以根据计算宽度使用跨度。

     public class AutoFitGridLayoutManager extends GridLayoutManager {
                    private boolean columnWidthChanged = true;
                    Context context;

                    public AutoFitGridLayoutManager(Context context) {
                        super(context, 1);
                        this.context = context;
                        setColumnWidth();
                    }

                    public void setColumnWidth() {
                            columnWidthChanged = true;
                    }

                    @Override
                    public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
                        if (columnWidthChanged) {
                          
                            //int spanCount = Math.max(1, totalSpace / columnWidth);
                            //setSpanCount(spanCount);
                            setSpanCount(Utils.calculateNoOfColumns(context));
                            columnWidthChanged = false;
                        }
                        super.onLayoutChildren(recycler, state);
                    }
                }

要计算列，您可以使用此方法：

        public static int calculateNoOfColumns(Context context) {

                DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
                float dpWidth = displayMetrics.widthPixels / displayMetrics.density;
                int scalingFactor = 200; // You can vary the value held by the scalingFactor
                // variable. The smaller it is the more no. of columns you can display, and the
                // larger the value the less no. of columns will be calculated. It is the scaling
                // factor to tweak to your needs.
                int columnCount = (int) (dpWidth / scalingFactor);
                return (columnCount>=2?columnCount:2); // if column no. is less than 2, we still display 2 columns
}