Great question! The issue with your padding not taking effect is likely because either you applied it to individual cells without triggering a re-calculation, or the auto-sizing logic wasn't using the updated style. Here are a couple of reliable ways to get the best of both worlds: auto-sized multi-line headers and a decent minimum height for single-line ones.

1. Use Column Header Style Padding (Simplest Approach) #

The easiest fix is to add padding to the default column header cell style. This padding will be included in the auto-size calculation, giving single-line headers extra height while letting multi-line ones expand naturally.

// Add top and bottom padding to all header cells (adjust values as needed)
dataGridView1.ColumnHeadersDefaultCellStyle.Padding = new Padding(0, 5, 0, 5);
// Enable auto-size mode for header heights
dataGridView1.ColumnHeadersHeightSizeMode = DataGridViewColumnHeadersHeightSizeMode.AutoSize;

If you only want specific columns to have this padding, set it on their individual header cells and force a re-calculation:

// Set padding for a specific column's header
dataGridView1.Columns["YourColumnName"].HeaderCell.Style.Padding = new Padding(0, 5, 0, 5);
// Trigger the auto-size logic to apply the new padding
dataGridView1.AutoResizeColumnHeadersHeight();

This works because the auto-size calculation now accounts for the padding, adding it to the text height. For single-line headers, this gives you the desired taller row, and multi-line headers will still fit their content plus padding.

2. Custom Header Cell for Minimum Height Control #

If you want a fixed minimum height regardless of padding (or need more control over sizing), create a custom header cell that enforces a minimum height during the auto-size calculation.

First, define the custom cell class:

public class MinimumHeightHeaderCell : DataGridViewColumnHeaderCell
{
    // Adjust this value to your preferred minimum height
    private const int MinimumHeaderHeight = 30;

    protected override Size GetPreferredSize(Graphics graphics, DataGridViewCellStyle cellStyle, int rowIndex, Size constraintSize)
    {
        // Get the auto-sized size from the base method
        Size preferredSize = base.GetPreferredSize(graphics, cellStyle, rowIndex, constraintSize);
        
        // Enforce the minimum height if needed
        if (preferredSize.Height < MinimumHeaderHeight)
        {
            preferredSize.Height = MinimumHeaderHeight;
        }
        
        return preferredSize;
    }
}

Then assign this cell to your columns (either when creating them or after):

// For an existing column
dataGridView1.Columns["YourColumnName"].HeaderCell = new MinimumHeightHeaderCell();

// For a new column
var newColumn = new DataGridViewTextBoxColumn();
newColumn.HeaderCell = new MinimumHeightHeaderCell();
newColumn.HeaderText = "Single Line Header";
dataGridView1.Columns.Add(newColumn);

// Keep auto-size mode enabled
dataGridView1.ColumnHeadersHeightSizeMode = DataGridViewColumnHeadersHeightSizeMode.AutoSize;

This approach ensures that every header cell will be at least 30 pixels tall, but still expands to fit longer, multi-line text when needed.

内容的提问来源于stack exchange，提问作者user16829390