1. CIS 338: VB.NET Components Dr. Ralph D. Westfall April, 2011

2. Components = Building Blocks form is the fundamental VB.NET component = interface between user and other code parts of a form control box (click or double-click upper left corner) Text (title) property title bar small buttons: minimize, maximize, close follow along on laptops

3. Form Methods if only one form, shows at Startup can stop it by clicking small Close (x) button at top right, or run Close in code do NOT use [frmName].Hide with only one form! [frmName.]Close closes form, and also shuts down the project if there is only one form End shuts down the project if there is more than one form

4. Controls visible objects on forms or elsewhere built into Visual Basic.NET or available from 3 rd parties examples of built in form controls  Button, TextBox, Label, CheckBox, RadioButtons, ListBox, ComboBox, etc. (view names on Visual Studio.NET Toolbox buttons)

5. Commonly Used VB.NET Controls Label – puts text on a form TextBox – accepts inputs, displays outputs (Command) Button – causes code to run CheckBox – accepts Yes/No inputs (Option) RadioButtons – selects only one from multiple choices ListBox – select from a list of choices ComboBox – select from list or enter value

6. Sample Properties of Controls properties = variables e.g., (Name) of form or control Location.X.Y = # of pixels from left and top edges of “container”  sets position on screen  container = what item is inside  a form is the container for Button, etc. Size: Width Height are also in pixels Anchor – attaches to side(s) of the form

7. Sample Properties of Controls - 2 more properties Enabled – True means user can change  for a Text Box that shows a calculated output, set Enabled = False (or show output in a Label instead) Visible = True (or False)  guess what this does  where use? why? 'code

8. Using Properties of Controls can set during development (“design time”) can also use code to change (“run time”) example: disable a Go to Next Form button until after user has entered inputs and clicked Enter button use “dot notation” to reference properties txtPayment.Text = CStr(decPayment) decPayment = CDec(txtPayment.Text) conversions needed with Option Strict On

9. Some Label Control Properties can set in Properties window or in code AutoSize – label’s “box” expands to fit text Font – size (points), font (typeface), style (bold, italic, etc.) ForeColor – text color BackColor – background color (behind text)  can use a white background color to make Label look like a TextBox (but why?)

10. Some TextBox Control Properties setting content value (default) txtName.Text = "Bubba" for handling larger quantities of text MultiLine – True enables text wrapping  goes to next line when reaches right side ScrollBars determines if a scroll bar is used on a text box, and what type(s)  (None | Horizontal | Vertical | Both)

11. (Command) Button Properties can use & in Text property to set shortcut key [Alt] e runs &Exit, [Alt] r runs G&rin may see an underline if & is before a letter in the middle of the word e.g., Grin Enabled if =True button is usable, but not if =False  when would you set it =False?

12. CheckBox Properties 2 possible Checked (Boolean) Values: False (not checked) True (checked) 3 possible CheckState Properties: Unchecked Indeterminate (checked and grayed; try it) Checked

13. (Option) RadioButtons only one radio button at a time can be selected clicking one "unclicks" the other different than clicking 2+ checkboxes can use a GroupBox (container) to set up separate groups of radio buttons user can only select one from each group

14. (Option) RadioButtons - 2 Checked property is either True or False two ways to run (checkboxes also) can use [name]_Click method to cause code to run as soon as user clicks one can use If … Then … Else or a Select Case structure to test a user choice later, instead of triggering an immediate action

15. GroupBoxes (are Containers) can put other controls in a GroupBox need to 1 st put GroupBox on form, then put controls into it GroupBox will not include controls already on form, even if you put it over them can change appearance Text – present or absent FlatStyle – Standard, Popup, or System ForeColor, BackColor, BackGroundImage

16. ListBoxes 2 different kinds of ListBox ListBox: selection is highlighted CheckedListBox: selection is checked lst[name].SelectedIndex property item number of selected item in list (zero- based, starts at 0, but is -1 if unselected) lst[name].Items.Count property (2 dots) total number of items in ListBox 'code

17. Other List Box Properties can use Sorted = True to sort, but this only sorts by left side of list if leftmost characters are the same numbers are handled as text characters (lexical sort), so don't sort correctly e.g., 1191-9 (or a-9) 56492-64 (or b-64, etc.) 943-119 9 4-5649 'prefix gives order 'or use leading zeros (0009, 0064 …)

18. ListBox Multiple Selection 0, 1, or many based on SelectionMode  works on ListBox, not on CheckedListBox 0 None – disabled 1 One – can select only one item 2 MultiSimple – can select with mouse, or arrow key followed by spacebar 3 MultiExtended – also use Shift, Ctrl keys if no item is selected, then SelectedIndex value is -1 regardless of SelectionMode

19. ListBox Multiple Selection - 2 total number of selected items = lst[name].SelectedItems.Count VB.NET creates a collection of specific selected items can cycle through in a for loop e.g., For Each item inListBox1.SelectedItems MsgBox(item) Next

20. ListBox Properties that Are Useable in Code.SelectedItem property shows user's 1 st selected item (simple approach) str[variable] = lst[name].SelectedItem.SelectedIndex property shows the sequential identifier of selected item collection of items in the ListBox (1 st ) selected item # is lst[name].ListIndex  lst[name].Items(lst[name].ListIndex)

21. Programmable List Box Properties - 2 can set default selection in code with SelectedIndex property 1 st item in ListBox has SelectedIndex of 0 2 nd item has 1 SelectedIndex of -1 means that none is selected lst[name].SelectedIndex = 2 'which item? can't set this in Properties window

22. ListBox & Collection Together lst[name].Items(lst[name]._ SelectedIndex) or lst[name].Items.SelectedItem als[name](lst[name]._ SelectedIndex) Joe lst[name].Items(Items(lst[n ame].SelectedIndex) 123456789 als[name](Items(lst[n ame].SelectedIndex) Ana lst[name].Items(1) ' hard coded 345678901 als[name](1) ' hard coded

23. Adding Items to ListBox using Items editor via Properties window type in items, then click OK can also paste into the editor window programmatically lst[name].Items.Add("CIS") lst[name].Items.Add(str[variable]) can load values into a parallel ArrayList (unlike an array, don't need to use a counter) als[name].Add(191919) 'code

24. ComboBox like a combination (combo) of a TextBox and a ListBox user can type information into the TextBox part to either enter an item not in the list or scroll down to item(s) in the (Sorted = True) list that start with the same letters properties and methods are usually same or similar to those of a ListBox

25. ComboBox Properties DropDownStyle property 0 Simple (TextBox on top of a ListBox)  can select an item or type in something not in the ListBox part (Prof. Westfall's FAVORITE!!) 1 Dropdown (ListBox drops down on a click)  can type in an item or initial letter(s), but don't see any match from the ListBox until it drops down 2 DropdownList (ListBox drops down on click)  can't type anything in the TextBox part, but must click to drop down the ListBox to select an item

26. ComboBox Properties - 2 Text property (for Styles Simple or DropDown) can set it as a default selection, or make it be an instruction to the user when it runs, or leave it blank code can access.Text property to get user inputs that are not in the list(box)

27. ComboBox Properties - 3 can add objects to a ComboBox and make one attribute the DisplayItem can then access other attributes of selected item e.g., select name, get Social Security # 'code

28. Controlling Tab Sequence if a control's TabStop property = True, user can use tab key to move from one control to the next sequence is initially determined by order that item was added to form set TabStop = False for items that will not be used for input (e.g. a Label or a TextBox or ListBox that displays outputs)

29. Changing Tab Sequence can change by changing TabIndex use a large number to make an item last VB 6 changed tab indices to compensate for other changes  Visual Basic.NET seems to keep track of this in another way  tutorial (click Types of Windows>Tab Order) tutorial set TabStop=True for Radio Buttons

30. Clicking to Change Tab Stops in VB.NET, can mouse click items to change their tab sequence View>Tab Order then click each item in the order that you want for the tab sequence repeated clicks on same item cycles through the TabIndex values then click View>Tab Order (toggle it off) to set new values

31. Clicking to Change Tab Stops - 2 note that Labels have a TabIndex property too, but not a TabStop property so can't tab to them could click them repeatedly to set all the values to 0, but not necessary note that tab values in View>Tab Order don't match with TabIndex properties

32. Clearing Common Controls sometimes need to clear (remove contents) of a control txtName.Text = Nothing or txtName = "" chkComputerOwner.Checked = False rdoCategory.Checked = False lstPersons.ClearSelected() cboCities.SelectedItem = Nothing

33. Design Tips for Controls hold down left mouse button and use cursor to select multiple controls or hold Ctrl key and click items after multiple items are selected, can move them as a group can change properties of all selected controls by changing in one control e.g., Font on Labels, Format>Align

34. Visual Studio's Format Menu horizontal or vertical spacing increase/decrease, make equal, remove make same size size to grid (all corners on grid points) alignment tops, lefts, etc.

35. Showing Grid Lines on Form it can be helpful in designing a form to have grid lines showing during design Tools>Options>Windows Forms Designer>General>Layout Settings>click Show Grid option SnapToGrid LayoutMode forces controls to space themselves based on grid

36. Exercise put a Button on a Form, and several other input controls covered today click the Button, write code to put the keyboard inputs from one control into a different kind of control that takes Text test, and then repeat with another pair of controls