c# - 当 Scroll 在 DataGridView 中发生时，单元格会重叠并绘制

Question

最初我在用户滚动时在单元格中显示数据，我需要在 DataGridView 中加载更多数据。

我正在使用 DataGridView CellPainting 来绘制线条。 当我开始在 datagridview 中滚动时，单元格重叠并且它完全改变了输出。

public partial class Display : Form
{
    public Display()
    {
        InitializeComponent();
        LoadData();
    }

    // To create the rows and columns and fill some data
    private void LoadData()
    {
        int columnSize = 10;

        DataGridViewColumn[] columnName = new DataGridViewColumn[columnSize];

        for (int index = 0; index < columnSize; index++)
        {
            columnName[index] = new DataGridViewTextBoxColumn();

            if (index == 0)
            {
                columnName[index].Name = "Name";
                columnName[index].HeaderText = "Name";
            }
            else
            {
                columnName[index].Name = (index).ToString();
                columnName[index].HeaderText = (index).ToString();
            }
            columnName[index].FillWeight = 0.00001f;
            columnName[index].AutoSizeMode = DataGridViewAutoSizeColumnMode.None;

            dataGridView1.Columns.Add(columnName[index]);
        }

        for (int rowIndex = 0; rowIndex < columnSize; rowIndex++)
        {
            dataGridView1.Rows.Add((rowIndex + 1).ToString());
            dataGridView1.Rows[rowIndex].HeaderCell.Value = (rowIndex + 1).ToString();
        }
    }

    private void dataGridView1_CellPainting(object sender, DataGridViewCellPaintingEventArgs e)
    {
        Rectangle rectPos1 = this.dataGridView1.GetCellDisplayRectangle(e.ColumnIndex, e.RowIndex, false);
        Pen graphPen = new Pen(Color.Red, 1);
        Graphics graphics = this.dataGridView1.CreateGraphics();
        Point[] points =
        {
                new Point(rectPos1.Left , rectPos1.Bottom), 
                new Point(rectPos1.Right, rectPos1.Bottom),
                new Point(rectPos1.Right, rectPos1.Top)
        };
        graphics.DrawLines(graphPen, points);
        e.PaintContent(rectPos1);
        e.Handled = true;
    }
}

Sample Download Link

我已经在下图中显示了

我怎样才能避免它，请帮我解决这个问题。

Answer 1

几个问题。首先也是最重要的，您应该几乎总是使用从 PaintEventArgs 获得的提供的 Graphics 对象。 CreateGraphics 是一个可以轻松删除的临时 Canvas 。您获得的参数之一是 CellBounds 矩形，因此您可以使用它。您的线条实际上是在矩形之外绘制的，并且您没有清除以前的内容，因此您的代码应该如下所示:

Rectangle rectPos1 = e.CellBounds;
e.Graphics.FillRectangle(Brushes.White, rectPos1);
Graphics graphics = e.Graphics; // this.dataGridView1.CreateGraphics();
Point[] points =
  {
    new Point(rectPos1.Left , rectPos1.Bottom - 1), 
    new Point(rectPos1.Right - 1, rectPos1.Bottom - 1),
    new Point(rectPos1.Right - 1, rectPos1.Top)
  };
graphics.DrawLines(Pens.Red, points);
e.PaintContent(rectPos1);
e.Handled = true;