问题
I am having problems with a requirement on one of my projects at work. What I am doing is binding a datatable to a DataGridView(DGV)'s datasource. I then loop through the DataGridView and check if the cell as either 1 * or 2 ** in its value and format those cells with a tooltip and a red background. If I use a button event to trigger this everything works perfectly fine. But if I want this to occur automatically when the form loads using the DataBindingComplete event it does not work correctly. The problem was DataBindingComplete was firing multiple times. I read this SO question which gave me a couple options to try and none worked. Here is the code:
public partial class TestForm2 : Form
{
private DataTable dt;
private int methodCalls = 0;
private bool isFormatted = false;
public TestForm2()
{
InitializeComponent();
buildDataTable();
dataGridView1.DataBindingComplete += dataGridView1_DataBindingComplete;
}
private void TestForm2_Load(object sender, EventArgs e)
{
bindData();
}
private void button1_Click(object sender, EventArgs e)
{
formatDataGridView();
}
private void bindData()
{
dataGridView1.DataSource = dt;
}
private void dataGridView1_DataBindingComplete(object sender, DataGridViewBindingCompleteEventArgs e)
{
//If this code is commented out the program will work just fine
//by just clicking the button
//This was added to prevent formatDataGridView from executing more
//than once. Even though I unreg and rereg the event handler, the
//method was still being called 3 - 4 times. This successfully
//prevented that but only the *'s were removed and no red back color
//added to the cells.
if(!isFormatted)
{
formatDataGridView();
}
}
private void buildDataTable()
{
dt = new DataTable();
dt.Columns.Add("col1");
dt.Columns.Add("col2");
dt.Columns.Add("col3");
dt.Columns.Add("col4");
Random randNum = new Random();
for(int i = 0; i < 10; i++)
{
DataRow dr;
object[] rowItems = new object[dt.Columns.Count];
for(int j = 0; j < dt.Columns.Count; j++)
{
int number = randNum.Next(1, 20);
if(number % 7 == 0)
{
rowItems[j] = number + "*";
}
else if(number % 5 == 0)
{
rowItems[j] = number + "**";
}
else
{
rowItems[j] = number;
}
}
dr = dt.NewRow();
dr.ItemArray = rowItems;
dt.Rows.Add(dr);
}
}
private void formatDataGridView()
{
// I noticed that I needed to unregister the event handler to
// prevent DataBindingComplete from firing during the format
dataGridView1.DataBindingComplete -= dataGridView1_DataBindingComplete;
foreach(DataGridViewRow row in dataGridView1.Rows)
{
string originalCell;
string reformattedCell;
if(row.Cells["col1"].Value != null)
{
originalCell = row.Cells["col1"].Value.ToString();
if (originalCell.Count(c => c == '*') == 2)
{
reformattedCell = originalCell.Replace("**", "");
row.Cells["col1"].Value = reformattedCell;
row.Cells["col1"].Style.BackColor = Color.Red;
row.Cells["col1"].ToolTipText = "Divisible by 5";
}
else if (originalCell.Count(c => c == '*') == 1)
{
reformattedCell = originalCell.Replace("*", "");
row.Cells["col1"].Value = reformattedCell;
row.Cells["col1"].Style.BackColor = Color.Red;
row.Cells["col1"].ToolTipText = "Divisible by 7";
}
else
{
//do nothing
}
}
if (row.Cells["col2"].Value != null)
{
originalCell = row.Cells["col2"].Value.ToString();
if (originalCell.Count(c => c == '*') == 2)
{
reformattedCell = originalCell.Replace("**", "");
row.Cells["col2"].Value = reformattedCell;
row.Cells["col2"].Style.BackColor = Color.Red;
row.Cells["col2"].ToolTipText = "Divisible by 5";
}
if (originalCell.Count(c => c == '*') == 1)
{
reformattedCell = originalCell.Replace("*", "");
row.Cells["col2"].Value = reformattedCell;
row.Cells["col2"].Style.BackColor = Color.Red;
row.Cells["col2"].ToolTipText = "Divisible by 7";
}
else
{
//do nothing
}
}
if (row.Cells["col3"].Value != null)
{
originalCell = row.Cells["col3"].Value.ToString();
if (originalCell.Count(c => c == '*') == 2)
{
reformattedCell = originalCell.Replace("**", "");
row.Cells["col3"].Value = reformattedCell;
row.Cells["col3"].Style.BackColor = Color.Red;
row.Cells["col3"].ToolTipText = "Divisible by 5";
}
else if (originalCell.Count(c => c == '*') == 1)
{
reformattedCell = originalCell.Replace("*", "");
row.Cells["col3"].Value = reformattedCell;
row.Cells["col3"].Style.BackColor = Color.Red;
row.Cells["col3"].ToolTipText = "Divisible by 7";
}
else
{
//do nothing
}
}
if (row.Cells["col4"].Value != null)
{
originalCell = row.Cells["col4"].Value.ToString();
if (originalCell.Count(c => c == '*') == 2)
{
reformattedCell = originalCell.Replace("**", "");
row.Cells["col4"].Value = reformattedCell;
row.Cells["col4"].Style.BackColor = Color.Red;
row.Cells["col4"].ToolTipText = "Divisible by 5";
}
else if (originalCell.Count(c => c == '*') == 1)
{
reformattedCell = originalCell.Replace("*", "");
row.Cells["col4"].Value = reformattedCell;
row.Cells["col4"].Style.BackColor = Color.Red;
row.Cells["col4"].ToolTipText = "Divisible by 7";
}
else
{
//do nothing
}
}
}
// Reregistering the event handler
dataGridView1.DataBindingComplete += dataGridView1_DataBindingComplete;
isFormatted = true;
methodCalls++;
MessageBox.Show("Method Calls: " + methodCalls);
}
}
I am not sure how to get around this problem but there has to be a way. I am unfamiliar with DataBindingComplete until recently so I am sure to learn something here. Thanks for the help everyone and helping me learn something new!
回答1:
CellFormatting event handler was the route I ended up taking to resolve my issue.
private void dataGridView1_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
{
string originalCell;
string reformattedCell;
if (this.dataGridView1.Columns[e.ColumnIndex].Name == "col1")
{
if(e.Value != null)
{
DataGridViewCell cell =
this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex];
originalCell = e.Value.ToString();
if (originalCell.Count(c => c == '*') == 2)
{
reformattedCell = originalCell.Replace("**", "");
cell.Value = reformattedCell;
cell.Style.BackColor = Color.Red;
cell.ToolTipText = "Divisible by 5";
}
else if (originalCell.Count(c => c == '*') == 1)
{
reformattedCell = originalCell.Replace("*", "");
cell.Value = reformattedCell;
cell.Style.BackColor = Color.Red;
cell.ToolTipText = "Divisible by 7";
}
else
{
//do nothing
}
}
}
if (this.dataGridView1.Columns[e.ColumnIndex].Name == "col2")
{
if (e.Value != null)
{
DataGridViewCell cell =
this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex];
originalCell = e.Value.ToString();
if (originalCell.Count(c => c == '*') == 2)
{
reformattedCell = originalCell.Replace("**", "");
cell.Value = reformattedCell;
cell.Style.BackColor = Color.Red;
cell.ToolTipText = "Divisible by 5";
}
else if (originalCell.Count(c => c == '*') == 1)
{
reformattedCell = originalCell.Replace("*", "");
cell.Value = reformattedCell;
cell.Style.BackColor = Color.Red;
cell.ToolTipText = "Divisible by 7";
}
else
{
//do nothing
}
}
}
if (this.dataGridView1.Columns[e.ColumnIndex].Name == "col3")
{
if (e.Value != null)
{
DataGridViewCell cell =
this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex];
originalCell = e.Value.ToString();
if (originalCell.Count(c => c == '*') == 2)
{
reformattedCell = originalCell.Replace("**", "");
cell.Value = reformattedCell;
cell.Style.BackColor = Color.Red;
cell.ToolTipText = "Divisible by 5";
}
else if (originalCell.Count(c => c == '*') == 1)
{
reformattedCell = originalCell.Replace("*", "");
cell.Value = reformattedCell;
cell.Style.BackColor = Color.Red;
cell.ToolTipText = "Divisible by 7";
}
else
{
//do nothing
}
}
}
if (this.dataGridView1.Columns[e.ColumnIndex].Name == "col4")
{
if (e.Value != null)
{
DataGridViewCell cell =
this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex];
originalCell = e.Value.ToString();
if (originalCell.Count(c => c == '*') == 2)
{
reformattedCell = originalCell.Replace("**", "");
cell.Value = reformattedCell;
cell.Style.BackColor = Color.Red;
cell.ToolTipText = "Divisible by 5";
}
else if (originalCell.Count(c => c == '*') == 1)
{
reformattedCell = originalCell.Replace("*", "");
cell.Value = reformattedCell;
cell.Style.BackColor = Color.Red;
cell.ToolTipText = "Divisible by 7";
}
else
{
//do nothing
}
}
}
}
回答2:
You need to change:
- the formatting in the DataBindingComplete event, but not the value
- supply a "clean" value to display in the CellFormatting Event (e.Value) which does not change the underlying value stored in the dataviewgrid cell, just what value is passed to the painting event to show on the screen
Remember that when going through the data to set the formating, for efficiency if the types of CellStyles are limited e.g Good Result, Bad Result (my code has actually about 11 default styles) create the styles first.
Then assign them as you check you cell values and work out which style to use.
The only caveat of this is that later on if you change e.g Column = 12, Row = 4 cellstyle in some way it will affect all cells "sharing" the same default DataGridViewCellstyle.
e.g
Font bFont = new Font("Calibri", defFontSize, FontStyle.Bold); // Bold font
Font iFont = new Font("Calibri", defFontSize, FontStyle.Italic); // Italic font
Font nFont = new Font("Calibri", defFontSize); // Normal font
DataGridViewCellStyle dgvcsOKRESULT = new DataGridViewCellStyle()
{
Font = nFont,
ForeColor = Color.White,
BackColor = Color.Green,
};
DataGridViewCellStyle dgvcsBADRESULT = new DataGridViewCellStyle()
{
Font = bFont,
ForeColor = Color.White,
BackColor = Color.Red,
};
回答3:
Call formatDataGridView from the bindData method and forget about the DataBinding event:
private void bindData()
{
dataGridView1.DataSource = dt;
formatDataGridView();
}
Or is there a reason this is not possible?
来源：https://stackoverflow.com/questions/25192961/cell-formatting-in-datagridview-on-databindingcomplete