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 »  Home  »  .NET Newbie  »  Chart Success: Second Helpings of Pie. Part 3  »  The User Input Controls
 »  Home  »  Windows Development  »  Graphics  »  Chart Success: Second Helpings of Pie. Part 3  »  The User Input Controls
Chart Success: Second Helpings of Pie. Part 3
by Ged Mead | Published  03/23/2005 | .NET Newbie Graphics | Rating:
The User Input Controls


    Ignoring labels, the first control on the form is a TextBox. If creating your own project, you should name it txtName.

    The next control is a NumericUpDown, named nudValue. You can set the Min, Max and Value settings to whatever values you like.

"Select Color" Button
    Next down the form is a Button. I have named it btnColor, but the name isn't important.

    The button's click event will open a ColorDialog from which the user can select a forecolor for the HatchStyle.
Add a ColorDialog to your Form if necessary (one has already been included in the Skeleton Solution provided).

      The following code will take the user's color choice :

    Private Sub  btnColor_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnColor.Click  
      '  Get user's choice of color      
      Dim  ColorPicker As New ColorDialog    
      Dim  Choice As DialogResult = ColorPicker.ShowDialog 
      If  Choice <> DialogResult.Cancel Then   
         clrPicked = ColorPicker.Color 
      End If       
    End Sub  

"Select Pattern" ComboBox       

          The fourth user input control is a ComboBox, which should be named cboPattern.

      This ComboBox  allows the user to select any of the HatchStyles for use in the pie chart.   We therefore need to populate the combo with that list.   Fortunately VB.Net gives us an extremely easy way of doing this.

       Put this code in the Form_Load event to get each  of the HatchStyle names and populate the ComboBox with them:

    Private Sub  Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load    
       '  Populate the combobox with all available HatchStyles    
          Dim  patts() As String   
          patts = System.Enum.GetNames(GetType(HatchStyle))     
    End Sub

         The ability to get at these Enumerations and manipulate them as a range can be very useful.   The alternative of manually typing  each of them in as an "Items.Add" code line isn't appealing!

   Now  the user can select a HatchStyle from the ComboBox and when this happens we note the user's choice in the variable we created for this purpose earlier on, named Hatchpicked.   This code in the ComboBox's SelectedIndexChanged event does exactly that:

   Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboPattern.SelectedIndexChanged 

      hatchPicked = CType(System.Enum.Parse(GetType(HatchStyle), _     
                cboPattern.Text), HatchStyle)     

    End Sub

       Effectively, it checks the user's choice - which is a string type in the combobox -   finds the equivalent HatchStyle enumeration and stores it.  



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