Sep-05 Slide:1 ActiveX Controls in VB ActiveX Controls in VB6

Sep-05 Slide:1ActiveX Controls in VB

ActiveX Controls in VB6


What are ActiveX Controls?

• Custom UI Controls• Which you can design and add to the

toolbox• And then use in applications


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..


The Clock Control 1


Clock Control 2

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


Clock Control 3


Clcok Control 4 - Testing


Clock Control 5 – Normal exe project added


Clock Control 6 – Set Test as Startup

Or when you Run it it will start in a browser


Clock Control 7 – The control in use


Clock control 7 – Give it a name


Clock Control 8 – Make .ocx file


Clock Control 8 – Adding Control in a new project


ActiveX Exercise 1

• Make a Clock control like this but..• Have 3 fields showing hour, minute and

second• Use hour() minute() and second() functions


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


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


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


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


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


End-user code

Private Sub Command1_Click()Text1.Text = CInt(Text1.Text) + StepSizeEnd Sub

Private Sub Command2_Click()Text1.Text = CInt(Text1.Text) - StepSizeEnd Sub


Dim ssize As Integer

Public Property Let StepSize(val As Integer)ssize = valPropertyChanged "StepSize"End Property

Public Property Get StepSize() As IntegerStepSize = ssizeEnd Property

Private Sub UserControl_WriteProperties(PropBag As PropertyBag) PropBag.WriteProperty "StepSize", StepSize, 0End Sub

Private Sub UserControl_ReadProperties(PropBag As PropertyBag) StepSize = PropBag.ReadProperty("StepSize", 0)End Sub

Private Sub UserControl_Initialize()Text1.Text = 0End Sub

Designer-user code


Designer use


.FRM contentsVERSION 5.00Object = "*\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 EndEnd..


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


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..


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 backspaceIf KeyCode < 48 Or KeyCode > 57 Then ' not 0 to 9RaiseEvent BadkeyEnd IfEnd Sub


Designer writes event-handler


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

Documents

Sep-05 Slide:1 ActiveX Controls in VB ActiveX Controls in VB6