1. Controls, Events, and More
More Windows Material
Controls, Events, and more
November 7, 2018

2. AssemblyInfo.cs
Separating version, title, product, and author information from the executable code
Controls, Events, and more
November 7, 2018

3. AssemblyInfo.cs
Each C# project has a file named AssemblyInfo.cs in a project folder named Properties
This file contains attributes in square brackets [ ] that give information about the project including
Title
Author
Copyright
Version
And so forth
Controls, Events, and more
November 7, 2018

4. AssemblyInfo.cs Example
Author
Version information
Controls, Events, and more
November 7, 2018

5. The Application Class
The information from AssemblyInfo.cs is available to your Windows Forms application to use during execution
Primarily accessed through a .NET class named Application using static methods and properties such as
CompanyName
CurrentCulture
ProductName
ProductVersion
OpenForms
And so forth
If the AssemblyInfo.cs file is up-to-date with version information and so forth, the application code need not be updated when versions change, and so forth
Controls, Events, and more
November 7, 2018

6. Like Java’s JOptionPane dialogs
Example
Like Java’s JOptionPane dialogs
Controls, Events, and more
November 7, 2018

7. Docking, anchoring, and resizing
Be in control of how windows look once resized
Controls, Events, and more
November 7, 2018

8. Docking and Anchoring
Controls may be placed on a form at any point the designer wishes
They can be dragged/dropped from the tool box
They can be moved in the design view
The buttons on the Layout toolbar may be used to align, center, and resize controls
Panels can be used as in Java to isolate and group some components of a window from others
The alignment and centering then applies to the panel
Their properties can be set to change the position either in the design view or at run time
Controls, Events, and more
November 7, 2018

9. Docking and Anchoring
When controls are placed in a fixed position on a form, they stay there even when the window is resized
Controls, Events, and more
November 7, 2018

10. Anchoring
The client area of the window is the part of the window that does not include the caption bar, the borders around the window, …
Controls may be anchored to the top, bottom, left, or right sides of the client area of the window
Controls may be anchored to more than one side of the client area
By default, most controls are anchored to both the top and the left sides of the client area
When the window is resized, they stay in a fixed position relative to their anchors as illustrated on the previous slide
Controls, Events, and more
November 7, 2018

11. Anchoring
In the design view, one may set the Anchor property as shown in this diagram
… top, …
… right, …
Anchored on the left …
… but not the bottom
Clicking on one of the 4 rectangles creates or removes the respective anchor
Controls, Events, and more
November 7, 2018

12. Effects of Anchoring
If the textboxes in this window are anchored to the top and right, resizing the window keeps them in a fixed position relative to their anchors
Controls, Events, and more
November 7, 2018

13. Effects of Anchoring
If a control is anchored to opposite sides of the window (top and bottom or to the left and right), resizing the window in that direction stretches/shrinks the control in that direction if the control is stretchable in that direction – a label is not stretchable, for example
Controls, Events, and more
November 7, 2018

14. Docking
When appropriate, some controls may be “docked” to one of the 4 sides of the client area of a window
This attaches the docked control to that side
The control is sized appropriately
A control may be docked to Fill the remaining space as well
When the window is resized, the docked controls may be resized as appropriate for their docked position
Controls, Events, and more
November 7, 2018

15. Five panel controls with different background colors shown docked
Docking
Five panel controls with different background colors shown docked
Controls, Events, and more
November 7, 2018

16. Docking
Docking properties may be set at design time using the properties tab
Dock at top
Fill remaining area
Dock on right
Dock at left
Dock at bottom
Do not dock
Controls, Events, and more
November 7, 2018

17. Prevent Resizing by User
There are two ways in which a user typically resizes a window
Maximize button
Drag the border of the window
Each of these ways may be enabled or disabled
At design time
At run time
Controls, Events, and more
November 7, 2018

18. Disable the Maximize Button
At design time, select the form in the design view
Open the properties tab
Set the Maximize Box property to False
May also disable the minimize button
Controls, Events, and more
November 7, 2018

19. Disable Resizing by Dragging Border
In the design view, select the form
Open the properties tab
Set the FormBorderStyle to one of the Fixed types such as Fixed3D
Choose a Fixed Style
Controls, Events, and more
November 7, 2018

20. Disable Resizing: A Caveat
Often, windows can be made to look very unprofessional or even unusable if resized incorrectly by the user
We can prevent the user from doing so
We should be careful in deciding whether to do so
There are MANY different monitors with MANY different resolutions
A fixed size window may look great on the designer’s monitor but be totally unusable on another – because a button or a text box or a list control is off the visible window
Be careful in choosing colors for the same reason – the designer may have a black wallpaper so a white font looks good while the user may have a white wallpaper, for example
What looks good on one monitor may not be usable on another
The solution: test, test, test on many different resolutions and color schemes
Controls, Events, and more
November 7, 2018

21. Controls Without Visual Representations
Controls that perform a service but do not have visual representations
Controls, Events, and more
November 7, 2018

22. Non-Visual Controls
Most Windows controls have a visual representation on a Windows form
Label
TextBox
Button
And so forth
A few controls, however, provide a service without having a visual representation
One example is the timer control
Controls, Events, and more
November 7, 2018

23. Timer Control Many applications may use a timer
Network or database connection “times out” if inactive for some designated period
An operating system “shares” processor time among multiple applications
Educational software may give a timed test
Some electronic card or board games may give each player a time limit in which to make a play
Some applications may need a “clock” display
The timer control may be used to facilitate some of these types of activities
Controls, Events, and more
November 7, 2018

24. Using the Timer Control
Drag the Timer Control from the Toolbox onto the form and drop it anywhere
The timer control “bounces off” the form and lands in the tray below the form
Drag and Drop
Controls, Events, and more
November 7, 2018

25. Using the Timer Control
Like other controls, the timer control has a set of properties that may be set/used
Object name in program
Must enable the timer to use it
Interval until a “Tick” event occurs. Measured in milliseconds (5000 represents 5 seconds)
Controls, Events, and more
November 7, 2018

26. Using the Timer
When the timer is enabled during program execution, the timer runs
When the timer interval expires, a Tick event occurs
This event may be handled or ignored like other events
As long as the timer is enabled, it starts timing again immediately so that the Tick event will occur periodically – at the end of each specified interval
Controls, Events, and more
November 7, 2018

27. Tick Event Handler
Double-clicking on the timer in the tray in the design view generates a skeleton Tick event handler
One may add code to take appropriate action
No need to reset the timer – that is automatic unless the timer is disabled or stopped by the program
A digital clock application takes only a few lines of code
Controls, Events, and more
November 7, 2018

28. Digital Clock Application
Form below has one Label with a Blue Background and Gold Foreground (for ETSU)
The Label is docked (its Dock property is set to Fill) to Fill the client area of the Form with the Form sized appropriately for the application
Fill
Blue area is the Label’s background
Controls, Events, and more
November 7, 2018

29. Digital Clock Application
Form_Load event initializes the clock: sets form caption with the date and sets clock to current time
Update the date and time every time the timer expires (set to one second interval)
Controls, Events, and more
November 7, 2018

30. Digital Clock Application
Controls, Events, and more
November 7, 2018

31. More on events and event handlers
Enter and KeyPress events; using the handler arguments; doing double duty
Controls, Events, and more
November 7, 2018

32. The Enter Event
For some controls such as TextBox, the Enter event occurs when they gain the focus (i.e., when program control or the “input” focus “enters” them)
The Leave event occurs when the control loses focus
The handler for the Enter event may take appropriate actions such as SelectAll the text, Clear the text box, or validate its contents
The Enter event is just one of many in the event list found in the Properties window for many controls
Controls, Events, and more
November 7, 2018

33. Double-click any event to generate a skeleton of its event-handler
Enter Event
Return to properties
Double-click any event to generate a skeleton of its event-handler
Event List
Enter Event
Controls, Events, and more
November 7, 2018

34. Now we can use TextBox methods on tb
Enter Event Handler
The code below was intended for use with the TextBox named txtPoints as seen from the name of the handler
However, we can make it more general by determining what control was “entered” from the sender argument
As an “Object”, we have to cast the sender as a more specific type (TextBox) in this case before we can use it as such (using the unique methods of the more specific type, for example)
Cast sender as TextBox
Now we can use TextBox methods on tb
Controls, Events, and more
November 7, 2018

35. Kill 2 birds with one stone
In the previous example, we can make the same event handler handle the same event for other TextBoxes as well
We wrote the body of the handler to be general enough to handle any TextBox in this case
Now, we simply need to register this handler for other TextBox Enter events
Go to the .Designer.cs file for this form
Locate the txtPoints Enter event handler registration in the generated code
Copy to any other TextBox control and rename as needed
Controls, Events, and more
November 7, 2018

36. … 2 birds … Copy this line Paste here
Now, one event handler handles the Enter event for both txtPoints and txtHours
Change to txtHours
Controls, Events, and more
November 7, 2018

37. One handler worked for both TextBoxes
See Results
After calculating one GPA, if we want to do another … it helps to have this value “selected” so that typing replaces what is here
Both TextBox contents are selected as the focus “enters” them, allowing easy editing
One handler worked for both TextBoxes
Controls, Events, and more
November 7, 2018

38. KeyPress Event
One way to help avoid situations in which bad input causes program crashes is to limit what the user is allowed to type into a TextBox or other control
For example, if a user is to type the number of credits earned, then only digits should be typed
If a user is to enter a number, then only characters such as digits, +, -, and . are allowed
Should also allow a backspace in case the user types something incorrect and wants to erase and correct it
The KeyPress event occurs each time the user presses a key
Controls, Events, and more
November 7, 2018

39. KeyPress Event
The KeyPressEventArgs argument e to the handler for this event has a string property named KeyChar that identifies the key pressed
One may interrogate this value to determine whether to process or ignore the pressed key - typically, an if statement is used
To ignore a character, set the (already) Handled property of e to true
The character will not even be echoed to the screen since the event has been marked as completely handled in this case
Controls, Events, and more
November 7, 2018

40. KeyPress Event Handler Example
If character typed is less than ‘0’ …
… or greater than ‘9’ ( then it cannot be a digit) …
… and it is not a backspace …
… THEN we mark it as completely handled since we are discarding the offending character
Controls, Events, and more
November 7, 2018

41. Register KeyPress Handler for Other TextBoxes
Copy this line …
… to here and change object name to txtHours
Register this handler for any other TextBoxes to which it applies
Controls, Events, and more
November 7, 2018

42. More Complex KeyPress Event Handler
Should be == instead of !=
Controls, Events, and more
November 7, 2018

43. Other controls Many different controls are available …
Controls, Events, and more
November 7, 2018

44. Some other controls Datetime picker Month Calendar Menu Strip Groupbox
Checkboxes
Numeric up-down
Combo Box
Progress Bar
Picture Box
List Box
Status Strip
Controls, Events, and more
November 7, 2018

45. For a “tabbed” interface on a form
Controls
Windows Forms Controls listed in the Toolbar … others can be added to the Toolbar
For a “tabbed” interface on a form
Controls, Events, and more
November 7, 2018

46. MenuStrip
MenuStrip
One can add a new Menu item by simply typing it here
An item can be added to the drop down by typing it here
From the right-click context menu, one can add a separator line, a TextBox, or a ComboBox to the menu
Once all items have been added, double click on a menu item to generate skeleton of an event handler for it
Controls, Events, and more
November 7, 2018

47. A ListBox is designed to display a list of strings
An item may be selected by clicking on it. Depending on ListBox properties, one may select multiple items
Scroll bar is only visible if there are too many items in the list to show all at one time
A ListBox is designed to display a list of strings
Controls, Events, and more
November 7, 2018

48. ListBox
One may manually add items to the ListBox in the code (or in the design view)
This example shows adding items in code
Programmatically selects the first item in the list – exception if list is empty
Controls, Events, and more
November 7, 2018

49. List Contents at Design Time
ListBox
Initialize items in the ListBox in the design view
Collection Editor
List Contents at Design Time
Select Items
Controls, Events, and more
November 7, 2018

50. Set the DataSource for MyListBox to be the array named MyData
ListBox – Data Binding
One may bind the contents of a ListBox to a collection object such as an array or List<type>
Set the DataSource for MyListBox to be the array named MyData
Controls, Events, and more
November 7, 2018

51. Changing the DataSource
Controls, Events, and more
November 7, 2018

52. Selection Changed Handling
When an item in a ListBox is selected by clicking on it, a SelectedIndexChanged event occurs
It may be handled to take some action
Retrieve the selected item
Controls, Events, and more
November 7, 2018

53. This picture is displayed in a PictureBox control
The PictureBox control is designed to make it easy to display a picture as illustrated here
PictureBox control
This picture is displayed in a PictureBox control
Controls, Events, and more
November 7, 2018

54. Using a Picture Box Control
The image may be set at design time using a property
Some PictureBox properties are shown here
This picture comes from the Resources file
Set the image property
Controls, Events, and more
November 7, 2018

55. Resources Can be Set from Project Properties
May Add new Resources
Resources tab of the Project Properties Dialog
Controls, Events, and more
November 7, 2018

56. Adding an Image to a Resource
Can add existing files
Can add new pictures in any of these formats
Controls, Events, and more
November 7, 2018

57. Internationalizing a Program
Controls, Events, and more
November 7, 2018

58. Internationalizing a Program
Replace EVERY literal string in the code by a reference to a string resource
Replace the resources but not the code to have the program run in a different language
Controls, Events, and more
November 7, 2018

59. Setting the Picture from Code
One may also set the Image property of the control at runtime
Controls, Events, and more
November 7, 2018

60. Create Your Own Web Browser
You may use the WebBrowser control to create your own web browser or to create web browsing capability as part of a larger desktop application
Controls, Events, and more
November 7, 2018

61. The Web Browser Application
WebBrowser control – docked to fill rest of the form
Panel control with a Label, TextBox, and Button on it – docked at the top of the form
Controls, Events, and more
November 7, 2018

62. Code for the WebBrowser App
This is all of the code required…
When user types a new URL and clicks Go, update the WebBrowser’s URL from the TextBox
When user clicks a link, update the TextBox
Controls, Events, and more
November 7, 2018