将行动态添加到TableLayoutPanel会在不同的行号（位置）上显示

Question

我正在尝试通过单击按钮将TextBox动态添加到TableLayoutPanel。通过单击鼠标选择一行。在选择行之后，单击按钮会在所选行号上插入TextBox。 问题是在不同选择的行上正确地[文本框3或4次后，单击以下按钮将开始在随机行上显示文本框，即使调试显示正确的行号也是如此。需要帮助请，这里是完整的代码：

public partial class Form1 : Form
    {
        private TableLayoutPanel _tableLayout;
        private int _selectedRow = -1;
        public Form1()
        {
            InitializeComponent();

            var button = new Button()
            {
                Text = "Add Text"
            };
            button.MouseClick += AddText;

            this.Controls.Add(button);

            _tableLayout = new TableLayoutPanel()
            {
                Dock = DockStyle.Fill,
                AutoScroll = true,
                AutoSize = true,
                AutoSizeMode = AutoSizeMode.GrowAndShrink,
                CellBorderStyle = TableLayoutPanelCellBorderStyle.Single
            };
            _tableLayout.MouseClick += SelectRow;

            this.Controls.Add(_tableLayout);
        }

        private void SelectRow(object sender, MouseEventArgs e)
        {
            _selectedRow = GetRowColIndex(_tableLayout, e.Location).Value.Y;
        }

        private void AddText(object sender, MouseEventArgs e)
        {
            _tableLayout.ColumnStyles.Add(new ColumnStyle() { SizeType = SizeType.AutoSize });
            _tableLayout.RowStyles.Add(new RowStyle() { SizeType = SizeType.AutoSize });
            _tableLayout.Controls.Add(new TextBox(), 0, _selectedRow);
        }

        Point? GetRowColIndex(TableLayoutPanel tlp, Point point)
        {
            if (point.X > tlp.Width || point.Y > tlp.Height)
                return null;

            int w = tlp.Width;
            int h = tlp.Height;
            int[] widths = tlp.GetColumnWidths();

            int i;
            for (i = widths.Length - 1; i >= 0 && point.X < w; i--)
                w -= widths[i];
            int col = i + 1;

            int[] heights = tlp.GetRowHeights();
            for (i = heights.Length - 1; i >= 0 && point.Y < h; i--)
                h -= heights[i];

            int row = i + 1;

            return new Point(col, row);
        }
    }

Answer 1

当前代码中缺少某些部分。它不考虑滚动条和当前TableLayoutPanel的DisplayRectangle。如您在.Net源代码中所看到的，TableLayoutPanel's OnPaintBackGround方法已经执行了这些计算，以获取每个单元格的坐标，并调用使用当前单元格的Bounds和ClipBounds初始化的OnPaintCell() with a TableLayoutCellPaintEventArgs类。

您可以在代码中使用相同的逻辑，也可以使用已知的方法，从e.CellBounds事件中的

CellPaint参数检索单击的单元格边界。

这里的例子，从TLP的MouseClick事件中获取鼠标位置，并使用

Rectangle.Contains(Point)

中的e.CellBounds.Contains(currentPointerLocation)方法在单元格的边界包含鼠标指针并更新几个具有当前坐标的标签，存储在2个字段中，以方便显示：

Point currentPointerLocation = Point.Empty;
Rectangle currentCellBounds = Rectangle.Empty;
Point currentCell = Point.Empty;

private void tableLayoutPanel1_CellPaint(object sender, TableLayoutCellPaintEventArgs e)
{
    if (e.CellBounds.Contains(currentPointerLocation)) {
        currentCellBounds = e.CellBounds;
        currentCell = new Point(e.Row, e.Column);
        e.Graphics.FillRectangle(Brushes.Red, e.CellBounds);
    }
    else {
        using (var brush = new SolidBrush(tableLayoutPanel1.BackColor)) {
            e.Graphics.FillRectangle(brush, e.CellBounds);
        }
    }
}

private void tableLayoutPanel1_MouseClick(object sender, MouseEventArgs e)
{
    currentPointerLocation = e.Location;

    this.tableLayoutPanel1.Invalidate();
    this.tableLayoutPanel1.Update();

    lblCurrentCell.Text = currentCell.ToString();
    lblCellBounds.Text = currentCellBounds.ToString();
}

有了这些值，在将控件添加到使用鼠标指针选定的单元格时，确定当前单元格的坐标并使用它们就更加容易。 
例如，使用按钮（btnAddControl）和ContextMenuStrip向TableLayoutPanel添加不同的控件：
private void btnAddControl_Click(object sender, EventArgs e)
{
    tableLayoutPanel1.Controls.Add(new TextBox() {
        Multiline = true, Text = "TextBox from Button", Dock = DockStyle.Fill }, currentCell.Y, currentCell.X);
}

// Each ToolStripMenuItem sub-item subscribes to the event using this handler
private void contextTLPMenu_Clicked(object sender, EventArgs e)
{
    Control ctl = null;
    switch ((sender as ToolStripMenuItem).Text)
    {
        case "TextBox":
            ctl = new TextBox() { Multiline = true, Text = "TextBox from ContextMenu" };
            break;
        case "Button":
            ctl = new Button() { Text = "A Button", ForeColor = Color.White };
            break;
        case "Panel":
            ctl = new Panel() { BackColor = Color.LightGreen };
            break;
        default:
            break;
    }
    if (ctl != null) {
        ctl.Dock = DockStyle.Fill;
        tableLayoutPanel1.Controls.Add(ctl, currentCell.Y, currentCell.X);
    }
}

视觉结果：