Windows Forms FAQ resources

5. Windows Forms Datagrid

Here is a solution suggested by Matthew Benedict. It uses reflection to access the protected DataGridRows collection so he can set the row height.

public void AutoSizeGrid()

{

// DataGrid should be bound to a DataTable for this part to

// work.

int numRows = ((DataTable)gridTasks.DataSource).Rows.Count;

Graphics g = Graphics.FromHwnd(gridTasks.Handle);

StringFormat sf = new StringFormat(StringFormat.GenericTypographic);

SizeF size;

// Since DataGridRows[] is not exposed directly by the DataGrid

// we use reflection to hack internally to it.. There is actually

// a method get_DataGridRows that returns the collection of rows

// that is what we are doing here, and casting it to a System.Array

MethodInfo mi = gridTasks.GetType().GetMethod("get_DataGridRows",

BindingFlags.FlattenHierarchy | BindingFlags.IgnoreCase | BindingFlags.Instance

| BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static);

System.Array dgra = (System.Array)mi.Invoke(gridTasks,null);

// Convert this to an ArrayList, little bit easier to deal with

// that way, plus we can strip out the newrow row.

ArrayList DataGridRows = new ArrayList();

foreach (object dgrr in dgra)

{

if (dgrr.ToString().EndsWith("DataGridRelationshipRow")==true)

DataGridRows.Add(dgrr);

}

// Now loop through all the rows in the grid

for (int i = 0; i < numRows; ++i)

{

// Here we are telling it that the column width is set to

// 400.. so size will contain the Height it needs to be.

size = g.MeasureString(gridTasks[i,1].ToString(),gridTasks.Font,400,sf);

int h = Convert.ToInt32(size.Height);

// Little extra cellpadding space

h = h + 8;

// Now we pick that row out of the DataGridRows[] Array

// that we have and set it's Height property to what we

// think it should be.

PropertyInfo pi = DataGridRows[i].GetType().GetProperty("Height");

pi.SetValue(DataGridRows[i],h,null);

// I have read here that after you set the Height in this manner that you should

// Call the DataGrid Invalidate() method, but I haven't seen any prob with not calling it..

}

g.Dispose();

}