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Cell Blink for DataGridView

, 4 May 2008 Zlib
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An article on adding a cell blink feature for DataGridView
Screenshot - DataGridViewCellBlink.jpg


After reading many articles on The Code Project, I realized that it's my time to contribute. Few months ago, I came across a requirement for cells in a DataGridView control to blink when the cell value changed. The code presented here can be applied to any other grid.

The blinking of the grid cell is achieved in the following manner. When we update the value of a cell, we also change the background color of that cell to a blink color. To restore the cell background color to its original value, we run a background thread that iterates through a list of cells that are blinking and resets them to their original non blinking state.

The Code

The sample project has two functions. The first function DataInputThreadFunc() is used to generate random values to be filled / updated in the grid. The second function GridBlinkThreadFunc() is used to restore the cells to the non blink state.

Let's take a look at the first function DataInputThreadFunc():

private void DataInputThreadFunc()
    Random rand = new Random();
    while (true)
        if (dataGridView1.IsDisposed)

        CellData data = new CellData();
        data.Row = rand.Next(0, 7);
        data.Col = rand.Next(0, 3);
        data.Time = DateTime.Now;

        int value = rand.Next(0, 101);

            dataGridView1.Rows[data.Row].Cells[data.Col].Value = value;
              .BackColor = Color.Salmon;

        lock (_blinkData)


The function uses a while (true) loop as it's a background thread and will be shutdown automatically when the application is closed. if (dataGridView1.IsDisposed) check is done to make sure we do not call dataGridView1.Invoke() on a disposed object. This can happen when the user closes the application.

Next, we initialize an object of the class CellData to store the blink data:

class CellData
     public int Row;
     public int Col;
     public DateTime Time;

This class is used to store the row number, column number and the time when the value changed.

Next we use dataGridView1.Invoke() to make a call to the user interface thread and set the grid properties. We save the blink data in a generic list to be used later by the blink thread function. Since the list is altered by more than one thread, we synchronize access by locking the list on each access.

Now let's take a look at the blink thread function:

private void GridBlinkThreadFunc()
    while (true)
        // Make a copy to avoid invalid operation exception
        // while iterating through the map
        List<CellData> tempBlinkData;
        lock (_blinkData)
            tempBlinkData = new List<CellData>(_blinkData);

        foreach (CellData data in tempBlinkData)
            TimeSpan elapsed = DateTime.Now - data.Time;
            if (elapsed.TotalMilliseconds > 500) // 500 is the Blink delay
                if (dataGridView1.IsDisposed)

                      .Style.BackColor = dataGridView1.Columns[data.Col]

                lock (_blinkData)

        Thread.Sleep(250); // Blink frequency

At the very beginning, we make a copy of the _blinkData list. This helps us to modify the list while we iterate through the contents of the temporary copy. For each cell we find in the list, we check to make sure whether the blink time has elapsed or not. In this case, the blink time is 500 milliseconds. Any cell that has elapsed the blink time gets its background color reset to the default cell style background color and is removed from the list.

Again we make sure that we set the grid property only in the user interface thread. In addition, we lock the _blinkData list before altering it. Thread.Sleep(250) is the frequency with which we go through the list to turn off the cells. Ideally, it should be half the value of blink delay.

Points of Interest

You will notice that this code can be applied to any grid. This code can also be hidden in a class that extends a DataGridView control.

One thing I love about .NET 2.0 is dataGridView1.Invoke((MethodInvoker)delegate(). This statement lets you get away from writing a function and declaring a delegate.

A good point was made by "Kristof Verbiest" about the use of BeginInvoke() instead of Invoke(). The GridBlinkThreadFunc() uses BeginInvoke() to avoid unnecessary context switch.


  • 09/06/2007: First published
  • 09/11/2007: Changed the GridBlinkThreadFunc() to use BeginInvoke() instead of Invoke()
  • 05/02/2008: Edited the "Points of Interest" section


This article, along with any associated source code and files, is licensed under The zlib/libpng License


About the Author

Rammohan Raja
United States United States
Nothing to brag about, just another passionate software developer.

Work to make a living, don't live to work!

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Comments and Discussions

GeneralPerformance issue Pin
Hoa Le10-Nov-08 15:19
memberHoa Le10-Nov-08 15:19 
GeneralRe: Performance issue Pin
Raghavan Ram Raja14-Nov-08 3:21
memberRaghavan Ram Raja14-Nov-08 3:21 
GeneralRe: Performance issue Pin
Hoa Le20-Nov-08 17:27
memberHoa Le20-Nov-08 17:27 
GeneralVB.NET Version Here (Visual Studio 2005) Pin
gratro14-Oct-08 2:26
membergratro14-Oct-08 2:26 
GeneralRe: VB.NET Version Here (Visual Studio 2005) Pin
Raghavan Ram Raja14-Oct-08 3:07
memberRaghavan Ram Raja14-Oct-08 3:07 
GeneralBlink Pin
txALI29-Jan-08 4:16
membertxALI29-Jan-08 4:16 
GeneralSome comments Pin
Kristof Verbiest10-Sep-07 20:16
memberKristof Verbiest10-Sep-07 20:16 
GeneralRe: Some comments Pin
Ram Mohan Raja11-Sep-07 4:42
memberRam Mohan Raja11-Sep-07 4:42 
GeneralRe: Some comments Pin
Kristof Verbiest11-Sep-07 21:11
memberKristof Verbiest11-Sep-07 21:11 
GeneralRe: Some comments Pin
Ram Mohan Raja12-Sep-07 4:46
memberRam Mohan Raja12-Sep-07 4:46 
GeneralRe: Some comments Pin
Kristof Verbiest12-Sep-07 21:06
memberKristof Verbiest12-Sep-07 21:06 
GeneralRe: Some comments Pin
Ram Mohan Raja13-Sep-07 4:05
memberRam Mohan Raja13-Sep-07 4:05 
1) You have to realize that many people take the sample code presented in the article and use it directly. And many times more processing code (functionality) is added. Just because my sample code does not do much does not mean that a person using my code will also not have any processing. The two functions present in my sample code are used to highlight the difference between using Invoke() and BeginInvoke(). I have to keep in mind a broad audience.
The reason I keep referring to financial applications is because 90% of all financial applications use cell blink. These are the kinds of applications that push the GUI thread to its limits with constant real time updates.

2) If you look at the GridBlinkThreadFunc() there is only one line of code that has to be executed in the GUI thread. Everything else is not required to run in the GUI thread. Suppose the for-loop executes and finds out that there is no cell that has its blink time expired, then there is no need to call the GUI thread.
When you write code you have to go over all the possibilities not just one or two obvious ones.

GeneralRe: Some comments Pin
Kristof Verbiest13-Sep-07 4:40
memberKristof Verbiest13-Sep-07 4:40 
GeneralRe: Some comments [modified] Pin
Ram Mohan Raja13-Sep-07 5:40
memberRam Mohan Raja13-Sep-07 5:40 
GeneralRe: Some comments Pin 0:26 0:26 
GeneralRe: Some comments Pin
Ram Mohan Raja31-Oct-07 3:33
memberRam Mohan Raja31-Oct-07 3:33 

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