Home / Community & Support / Developer Productivity Tools Forums / WinForms > GridView > Virtual Mode Cell Update

• Hesham Desouky

  Posted on Jan 23, 2012 (permalink)

  Hello,
  
  I am implementing virtual mode for WinForms RadGridView
  
  Everything working ok except one thing, in my virtual mode implementation user may required additional data from slow data source in such case the data will not be available when grid needs the cell value.
  In this case the cells displays a "Loading..." text until the data is retrieved from the slow source.
  
  The problem is how to tell the GridView to reread the cells values to update the cells with real content.
  
  I tried the MasterTemplate.Refresh but this cause the grid scroll returns to the top again and display the first item.
  
  Is there any method to call to force the grid to re-read the visisble cells values without reseting the scroll?
  
  I am using 2011 Q2 SP1
  
  
  

  Attached files

  • grid-with-data-available-but-after-scrolling.png
  • grid-with-data-available.png

  Reply

• Answer Julian Benkov Julian Benkov

  Posted on Jan 26, 2012 (permalink)

  Hi Heshman,
  
  You should call the Update method of GridTableElement to solve this issue. Consider the sample below:
  
  

  public partial class VirtualGridForm : Form

  {

      private Random random = new Random((int)DateTime.Now.Ticks);

   

      public VirtualGridForm()

      {

          InitializeComponent();

           

          radGridView.VirtualMode = true;

          radGridView.CellValueNeeded += new GridViewCellValueEventHandler(radGridView_CellValueNeeded);

          radGridView.RowCount = 1000;

          radGridView.ColumnCount = 10;

      }

   

      void radGridView_CellValueNeeded(object sender, GridViewCellValueEventArgs e)

      {

          e.Value = random.Next(1000);

      }

   

      private void button1_Click(object sender, EventArgs e)

      {

          radGridView.TableElement.Update(GridUINotifyAction.DataChanged);

      }

  }

  
  I hope this helps.
  
  Kind regards,
  Julian Benkov
  the Telerik team

  SP1 of Q3’11 of RadControls for WinForms is available for download (see what's new).

  Reply



• Hesham Desouky

  Posted on Jan 29, 2012 (permalink)

  thanks for your reply,
  
  I am implementing this solution:
  

  var visibleRows = gridStudy.TableElement.VisualRows.Select(r=>r.RowInfo).ToArray();
  gridStudy.TableElement.Update(GridUINotifyAction.DataChanged, visibleRows); 
  
  It works but I don't know whether the extra code I add to update the visible rows only enhance performanfce or not?

  Reply

• Answer Julian Benkov Julian Benkov

  Posted on Feb 1, 2012 (permalink)

  Hello Hesham,

  This additional logic is not needed in virtual mode. RadGridView is optimized for this behavior and CellValueNeeded event will be fired only for the visible cells on the screen.

  Kind regards,
  Julian Benkov
  the Telerik team

  SP1 of Q3’11 of RadControls for WinForms is available for download (see what's new).

  Reply

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