ActiveX Controls in VB6

1. ActiveX Controls in VB6

2. What are ActiveX Controls? • Custom UI Controls • Which you can design and add to the toolbox • And then use in applications

3. Creating Simple ActiveX Controls • Start with New Project.. ActiveX Control • Design/program as if a form • Add a project to Group – test it in that • Finally, produce a compiled OCX file • For example, a simple clock control..

4. The Clock Control 1

5. Clock Control 2 • It will work by having a Timer • Which ticks every second • And gets system time • And displays it in a label

6. Clock Control 3

7. Clcok Control 4 - Testing

8. Clock Control 5 – Normal exe project added

9. Clock Control 6 – Set Test as Startup Or when you Run it it will start in a browser

10. Clock Control 7 – The control in use

11. Clock control 7 – Give it a name

12. Clock Control 8 – Make .ocx file

13. Clock Control 8 – Adding Control in a new project

14. ActiveX Exercise 1 • Make a Clock control like this but.. • Have 3 fields showing hour, minute and second • Use hour() minute() and second() functions

15. Controls with properties • Most controls have properties used for design • Example background colour of textbox • And properties for user input • Such as text in a text box • ActiveX usually need the same

16. ActiveX Controls are like Classes (as are forms) • They have methods • They have private data members • They have property let and get routines • Can set up events

17. Two 'users' of custom controls • One user is the programmer who uses the control in a form design • The other is the final end-user who uses that form • You have to write code for both types of user

18. Properties modified at design-time • Need public property Let and Get • and private data member for internal representation • But • property values differ between control instances • and must 'persist' when Form not in memory • so must be written to disc somehow • actually stored in the .frm file • this persistence is not automated

19. Example – a spinner control • Input integer values • Buttons to increase/decrease value • Need a StepSize property

20. End-user code Private Sub Command1_Click() Text1.Text = CInt(Text1.Text) + StepSize End Sub Private Sub Command2_Click() Text1.Text = CInt(Text1.Text) - StepSize End Sub

21. Dim ssize As Integer Public Property Let StepSize(val As Integer) ssize = val PropertyChanged "StepSize" End Property Public Property Get StepSize() As Integer StepSize = ssize End Property Private Sub UserControl_WriteProperties(PropBag As PropertyBag) PropBag.WriteProperty "StepSize", StepSize, 0 End Sub Private Sub UserControl_ReadProperties(PropBag As PropertyBag) StepSize = PropBag.ReadProperty("StepSize", 0) End Sub Private Sub UserControl_Initialize() Text1.Text = 0 End Sub Designer-user code

22. Designer use

23. .FRM contents VERSION 5.00 Object = "*\AspinnerProject.vbp" Begin VB.Form Form1 .. ScaleWidth = 4680 StartUpPosition = 3 'Windows Default Begin Project1.UserControl1 UserControl12 Height = 855 Left = 840 .. _ExtentY = 1508 StepSize = 9 End Begin Project1.UserControl1 UserControl11 Height = 855 .. _ExtentY = 873 StepSize = 5 End End ..

24. ActiveX Exercise 2 • Write a 'slider' control for numeric input • When user drags mouse from area, input is mouse Y • Have textbox and pictureBox • Program the mouseMove event of the PictureBox, use the Y parameter • Once working.. add a scale property set at design-time • Then expose a 'Value' property which allows access to the number in the (Let and Get) and read/write

25. Adding Events to controls • A control can make an event occur • This would be a 'custom' event for the control • Designer can then program an event-handler for it • For example, in the spinner control, could hav ea BadKey event if non-digit key pressed..

26. Control with Event .. Public Event Badkey() .. Private Sub Text1_KeyDown(KeyCode As Integer, Shift As Integer) If KeyCode = 13 Or KeyCode = 8 Then Exit Sub 'Enter or backspace If KeyCode < 48 Or KeyCode > 57 Then ' not 0 to 9 RaiseEvent Badkey End If End Sub

27. Designer writes event-handler

28. ActiveX Control Exercise 3 • Add a 2Click event to the slider control • Triggered when picturebox double-clicked • As designer, use it to zero the value