1. IMS 3253: Forms, Controls, Properties, Events 1 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Topics Program Elements Assignment Operations Events & Event Procedures Properties Tab Order and Access Keys “Foolproof systems don’t take into account the ingenuity of fools” Gene Brown

2. IMS 3253: Forms, Controls, Properties, Events 2 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Visual Studio & Programming A computer program consists of instructions readable by the computer which direct its operations In modern development, programs begin as instructions readable by (trained) humans… …And end up as instructions readable by the computer (and generally incomprehensible to all but the most sophisticated developers)

3. IMS 3253: Forms, Controls, Properties, Events 3 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Visual Studio & Programming (cont.) Most programs consist of many parts Visual Studio and Visual Basic support: –Authoring the component parts of the programs –Managing the program parts –Converting the parts you write into machine readable format –Combining the parts you write with a huge collection of pre-written instructions –Many other tasks

4. IMS 3253: Forms, Controls, Properties, Events 4 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Projects Projects may consist of many parts –Solution—multiple programs developed together We will not use this –Project—one program All elements are optional… …but it must have at least one

5. IMS 3253: Forms, Controls, Properties, Events 5 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Projects—Forms Forms provide the visual interface for a program Forms contain –Controls –Properties –Methods –Events with code –Non-event code Controls also contain Properties, Methods, and Event Code

6. IMS 3253: Forms, Controls, Properties, Events 6 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Assignment Operations (Our First Code) A common code involves assigning a value to a container Both Container and Value can be –Property –Variable –Object The value portion can also be a literal In this use the equal sign is the assignment operator Container = Value

7. IMS 3253: Forms, Controls, Properties, Events 7 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Assignment Operations (cont.) Examples –intQuantity = 123 places the value 123 into the variable intQuantity –stLastName = “Jones” places the value “Jones” into the variable stLastName –lblLastName.Text = stLastName places the contents of the variable stLastName (whatever they are) into the Text property of the label control lblLastName

8. IMS 3253: Forms, Controls, Properties, Events 8 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Events Forms, Controls, and Classes recognize events Events are predefined (or programmer defined) actions against an object –If the action occurs… –And if there is code written for the event… –Then the code will execute Three kinds of events for forms and controls –Commonly used –Less commonly used –Almost never used

9. IMS 3253: Forms, Controls, Properties, Events 9 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Events (cont.) Our first event—The Click Event for a button Private Sub cmdTransfer_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles cmdTransfer.Click '*************************************************************** '* Places the contents of the txtTransfer text box '* into the lblTransfer label text property '*************************************************************** lblTransfer.Text = txtTransfer.Text End Sub cmdTransfertxtTransferlblTransfer

10. IMS 3253: Forms, Controls, Properties, Events 10 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Events (cont.) Event Arguments are created automatically and are only used for advanced purposes The procedure name and Handles expression are also created automatically The event procedure header (what we are seeing here) is actually created as one long line –Use the line continuation character to break it into two physical lines –But still treated as one logical line Private Sub cmdTransfer_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles cmdTransfer.Click Name of the event procedure Line continuation character Event Arguments Control and event that triggers the code

11. IMS 3253: Forms, Controls, Properties, Events 11 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Creating Event Procedures—Default Events Double-clicking a control or form in design view creates the template for the default event –Form: Load event –Button: Click event –Text Box: TextChanged event –Label: Click event –Check Box & Radio Button: CheckChanged event –Combo Box & List Box: SelectedIndexChanged –Date Time Picker: ValueChanged event –NumericUpDown: ValueChanged event

12. IMS 3253: Forms, Controls, Properties, Events 12 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Creating Event Procedures—Other Events At the top left corner of the code window is a drop-down list of all objects on the form –Select the object whose event you want to program

13. IMS 3253: Forms, Controls, Properties, Events 13 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Creating Event Procedures—Other Events The right side of the code window contains a list of all events supported by the form/control selected in the left box Selecting an event will create the event code template for that control and event combination Selected Object (left side) Supported Events (right side)

14. IMS 3253: Forms, Controls, Properties, Events 14 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Creating Event Procedures—Other Events There can be a dizzying variety of events supported for most objects Most are for events so obscure that you would never use them Some are incredibly useful and you should learn these over time

15. IMS 3253: Forms, Controls, Properties, Events 15 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Event Procedures—Multiple Events You will often want the same code to run for multiple events and/or controls Add the control/event combination to the Handles expression Private Sub txtTransfer_GotFocus … Handles txtTransfer.GotFocus, _ txtTransfer.Click, txtTest.GotFocus, txtTest.Click End Sub

16. IMS 3253: Forms, Controls, Properties, Events 16 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Event Procedures—Multiple Events (cont.) Private Sub txtTransfer_GotFocus(ByVal sender As Object, _ ByVal e As System.EventArgs) Handles txtTransfer.GotFocus, _ txtTransfer.Click, txtTest.GotFocus, txtTest.Click '*************************************************************** '* Handles the GotFocus and Click events of all text boxes on '* the form. '* Automatically selects the contents of the text box so that '* text can be replaced by typing '*************************************************************** '* Create a text box object Dim theTextBox As TextBox '* Set the object to the control that triggered the event theTextBox = sender '* Select the text in the text box theTextBox.SelectionStart = 0 theTextBox.SelectionLength = theTextBox.Text.Length End Sub

17. IMS 3253: Forms, Controls, Properties, Events 17 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Properties Visual design elements (forms and controls) have properties that –Control their behavior –Determine their appearance –Interact with the user Properties may be set at… –Design time –Run time In code With user interaction –Both Design & Run Time

18. IMS 3253: Forms, Controls, Properties, Events 18 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Design Time Properties Selecting an object in form design mode gives access to the object’s properties in the properties window These properties will be the default properties when a form is first created –Changes implemented in code or by user interaction will persist as long as the form is open or until they are changed again

19. IMS 3253: Forms, Controls, Properties, Events 19 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Name Property Every object has a Name property that controls how your object is addressed in code If the object is addressed in code you must rename your object to indicate its: –Type (use a prefix) –Purpose of use (rest of the name) You need not rename labels that are not addressed in code

20. IMS 3253: Forms, Controls, Properties, Events 20 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Name Property (cont.) Examples: –lblLastNamelabel –btnCancelbutton –txtStreetAddresstext box –dtpBirthDatedate time picker –cboStylecombo box –lstDepartmentlist box –chkActivecheck box –rdoMaritalStatusradio button –CustomerFormform

21. IMS 3253: Forms, Controls, Properties, Events 21 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Important Form Properties Accept Button—button whose code will execute if the Enter key is pressed Cancel Button—button whose code will execute if the Escape key is pressed Text*—displays in the title bar ControlBox*, FormBorderStyle, Maximize* & Minimize* Buttons StartPosition—where form will initially load Size—Width & Height of the form * Removing these will give a form with no title bar

22. IMS 3253: Forms, Controls, Properties, Events 22 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Common Control Properties Text—what is displayed in the control Left / Top—coordinates in pixels from the upper left corner of the form for the location of the upper left corner of the control Width / Height—size in pixels of the control Enabled—Control is always visible but can be toggled to active or inactive & dimmed Visible—Control is visible or not TabIndex—sequence of the control in the form’s tab order

23. IMS 3253: Forms, Controls, Properties, Events 23 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Key Interaction Control Value Properties Text Box—Text Check Box—Checked Radio Button—Checked Combo Box & List Box—Text, SelectedIndex, SelectedValue, SelectedText Date Time Picker—Value

24. IMS 3253: Forms, Controls, Properties, Events 24 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Reading & Setting Properties in Code Properties may be read and set in code by referring to them on the appropriate side of an assignment operator (equal sign) Private Sub cmdTransfer_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles cmdTransfer.Click '*************************************************************** '* Places the contents of the txtTransfer text box '* into the lblTransfer label text property '*************************************************************** lblTransfer.Text = txtTransfer.Text End Sub

25. IMS 3253: Forms, Controls, Properties, Events 25 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Properties in Code Private Sub btnCatchMe_MouseMove(ByVal sender As Object, _ ByVal e As System.EventArgs) Handles btnCatchMe.MouseMove '*************************************************************** '* What is going on here? '*************************************************************** If Now.Second < 55 Then If Now.Second < 30 Then btnCatchMe.Top = 20 Else btnCatchMe.Top = Me.Height - btnCatchMe.Height - 30 End If If Now.Second Mod 2 = 1 Then btnCatchMe.Left = 20 Else btnCatchMe.Left = Me.Width - btnCatchMe.Width - 20 End If End Sub

26. IMS 3253: Forms, Controls, Properties, Events 26 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Getting Stupid with Properties You can be VERY stupid with appearance properties –BackColor –ForeColor –Font Experiment and get it out of your system Then stick with the defaults for your work in this class

27. IMS 3253: Forms, Controls, Properties, Events 27 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Setting Tab Order After the form is complete there is an easy to set the whole form’s tab order sequence –Select View | Tab Order from the menu –Click box by each control in the tab order you want –If you screw it up start over –Set individual control Tab Stop properties to False to exclude from the tab order

28. IMS 3253: Forms, Controls, Properties, Events 28 Dr. Lawrence West, MIS Dept., University of Central Florida lwest@bus.ucf.edu Setting Access Keys Putting an “&” in the Text property of a control makes the following letter the hot key for the control. –Gives control focus if Alt-Letter is pressed –Executes button if it is a button’s Access key Text boxes have no permanent Text property –Set the hot key in a label that immediately preceds the text box in the form’s tab order –Labels cannot get focus but focus will shift to the text box