FlexGrid for WPF | ComponentOne
Features / Selection / Select Cells and Objects
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    Select Cells and Objects
    In This Topic

     In the the following section learn how to implement Cell and Objects Selection in FlexGrid .NET 4.5.2 and .NET 5 versions.

    The Selection property is read-write, so you can select cell ranges using code. You can also perform selections using the Select method. The Select method allows you to select cells or ranges, and optionally scroll the new selection into view so the user can see it. The following code example illustrates selecting the first cell in FlexGrid and ensures the selection is visible to the user.

    C#
    Copy Code
    // select row zero, column zero, make sure the cell is visible
    grid.Select(0, 0, true);
    

    The selection methods are based on row and column indices. But these methods can be used to make selections based on cell content. For example, the code below selects the first row that contains a given string in the grid's "Name" column.

    C#
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    bool SelectName(string name)
    {
      // find row that contains the given string in the "Name" column
      int col = _flexGroup.Columns["Name"].Index;
      int row = FindRow(grid, name, grid.Selection.Row, col, true);
      if (row > -1)
      {
        grid.Select(row, col);
        return true;
      }
      // not found...
      return false;
    }
    

    The code uses the FindRow helper method defined below:

    C#
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    // look for a row that contains some text in a specific column
    int FindRow(C1FlexGrid grid, string text,
                int startRow, int col, bool wrap)
    {
      int count = grid.Rows.Count;
      for (int off = 0; off <= count; off++)
      {
        // reached the bottom and not wrapping? quit now
        if (!wrap && startRow + off >= count)
        {
          break;
        }
    
        // get text from row
        int row = (startRow + off) % count;
        var content = grid[row, col];
    
        // found? return row index
        if (content != null &&
            content.ToString().IndexOf(text,
            StringComparison.OrdinalIgnoreCase) > -1)
        {
          return row;
        }
      }
    
      // not found...
      return -1;
    }
    

    The FindRow method searches the specified column for a string, starting at a given row and optionally wrapping the search to start from the top if the string is not found. It is flexible enough to be used in many scenarios. Another common selection scenario is the case where you want to select a specific object in the data source. Your first impulse might be to find the index of the object in the source collection using the PagedDataCollection.IndexOf method, then use the index to select the row. The problem with that approach is that it works only if the data is not grouped. If the data is grouped, the group rows also count, so the indices of items in the data source do not match the row indices on the grid.

    The easy way to solve this problem is to enumerate the rows and compare each row's DataItem property to the item you are looking for. The code below shows how this is done.

    C#
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    var customer = GetSomeCustomer;
    
    #if false // ** don't use this, won't work with grouped data
    
      int index = view.IndexOf(customer);
      if (index > -1)
      {
        grid.Select(index, 0);
      }
    
    #else // this is the safe way to look for objects in the grid
    
      for (int row = 0; row <= grid.Rows.Count; row++)
      {
        if (row.DataItem == customer)
        {
          grid.Select(row, 0);
          break;
        }
      }
    #endif
    

    The Selection property is read-write, so you can select cell ranges using code. You can also perform selections using the Select method. The Select method allows you to select cells or ranges, and optionally scroll the new selection into view so the user can see it. The following code example illustrates selecting the first cell in FlexGrid and ensures the selection is visible to the user.

    C#
    Copy Code
    // select row zero, column zero, make sure the cell is visible
    grid.Select(0, 0, true);
    

    The selection methods are based on row and column indices. But these methods can be used to make selections based on cell content. For example, the code below selects the first row that contains a given string in the grid's "Name" column.

    C#
    Copy Code
    bool SelectName(string name)
    {
        // find row that contains the given string in the "Name" column
        int col = grid.Columns["Name"].Index;
        int row = FindRow(grid, name, grid.Selection.Row, col, true);
        if (row > -1)
        {
            grid.Select(row, col);
            return true;
        }
        // not found...
        return false;
    }
    

    The code uses the FindRow helper method defined below:

    C#
    Copy Code
    // look for a row that contains some text in a specific column
    int FindRow(FlexGrid grid, string text,
                int startRow, int col, bool wrap)
    {
        int count = grid.Rows.Count;
        for (int off = 0; off <= count; off++)
        {
            // reached the bottom and not wrapping? quit now
            if (!wrap && startRow + off >= count)
            {
                break;
            }
    
            // get text from row
            int row = (startRow + off) % count;
            var content = grid[row, col];
    
            // found? return row index
            if (content != null &&
                content.ToString().IndexOf(text,
                StringComparison.OrdinalIgnoreCase) > -1)
            {
                return row;
            }
        }
    
        // not found...
        return -1;
    

    The FindRow method searches the specified column for a string, starting at a given row and optionally wrapping the search to start from the top if the string is not found. It is flexible enough to be used in many scenarios. Another common selection scenario is the case where you want to select a specific object in the data source. Your first impulse might be to find the index of the object in the source collection using the PagedDataCollection.IndexOf method, then use the index to select the row. The problem with that approach is that it works only if the data is not grouped. If the data is grouped, the group rows also count, so the indices of items in the data source do not match the row indices on the grid.

    The easy way to solve this problem is to enumerate the rows and compare each row's DataItem property to the item you are looking for. The code below shows how this is done.

    C#
    Copy Code
        var customer = grid.Rows[1].DataItem;
    
        #if false // ** don't use this, won't work with grouped data
    
        int index = view.IndexOf(customer);
        if (index > -1)
        {
            grid.Select(index, 0);
        }
    
       #else // this is the safe way to look for objects in the grid
    
        for (int row = 0; row <= grid.Rows.Count; row++)
        {
            if (grid.Rows[row].DataItem == customer)
            {
                grid.Select(row, 0);
                break;
            }
        }
    #endif
    
    See Also