1. C# Programming: From Problem Analysis to Program Design1 Introduction to Windows Programming C# Programming: From Problem Analysis to Program Design 3 rd Edition 9

2. COS240 O-O Languages AUBG, COS dept Lecture 33 Title: C# vs. Java (GUI Programming) Reference: COS240 Syllabus

3. Lecture Contents: Contrasting Windows and Console Applications Graphical User Interfaces Using C# & Visual Studio to Create Windows based Applications Windows Forms Controls

4. Contrasting Windows and Console Applications Console applications –Each line in Main( ) method executed sequentially – then the program halts –Method calls might branch to different locations in the program, however control always returns back to Main –Program initiates interaction with the user by calling the OS to get data using ReadLine() method –Program calls OS to output data through method calls like WriteLine() or Write() Console applications run IPO model of computing process

5. Contrasting Windows and Console Applications Windows applications –Instead of the program executing sequential statements from top to bottom, the application, once launched, sits in what is called a process loop and waits for an event –Sits in a process loop, waiting for event to execute Windows applications run Event-driven model of a computing process

6. Contrasting Windows and Console Applications Event: notification from OS that an action, such as the user clicking the mouse or the user pressing a key, has occurred Instead of calling the OS with IO request as console applications, Windows applications receive messages from OS that event has occurred It is must to write methods, called Event Handlers to indicate what should be done when an event occurs

7. Graphical User Interfaces Windows applications also look different from console applications User Interface: front end of a program –Visual image you see when you run a program –Algorithmic functionality stays behind GUI –Often users of programs actually identify the interface of the program itself, when in reality, the interface is just one facet of the program. –Algorithmic complexity is hidden behind GUI.

8. Graphical User Interfaces Graphical user interface (GUI) includes: –Menus, labels, text boxes, list boxes, –Other controls (pictures, buttons, etc.) –Text in many different colors and sizes Controls are objects that can display and respond to user interaction. Controls are placed in a container, called form, which is an object as well. It is instance of a class derived from predefined class Form

9. C# Programming: From Problem Analysis to Program Design9 Windows Applications Reference and import System.Windows.Forms namespace Class heading definition –Includes not only the class name, but a colon followed by another class name Derived class (first class) Colon ( : ) – delimiter, separator Base class (second class) public class Form1 : Form Derived classes inherit from base class

10. C# Programming: From Problem Analysis to Program Design10 Windows Applications ( continued ) Text –A property for setting/getting title bar caption –Can be used in constructor Windows forms/controls offer many properties including Text, Color, Font, and Location Execution begins in Main( ) method –Main( ) is located in Program.cs file for the application –Call to Run( ) method places application in process loop

11. C# Programming: From Problem Analysis to Program Design11 // Windows0.cs Author: Doyle using System.Windows.Forms; // Line 1 namespace Windows0 { public class Form1 : Form // Line 2 { public Form1( ) // Line 3 { Text = "Simple Windows Application"; // Line 4 } static void Main( ) { Form1 winForm = new Form1( ); // Line 5 Application.Run(winForm); // Line 6 } New namespace referenced Constructor Base class Sets title bar caption Starts process loop

12. C# Programming: From Problem Analysis to Program Design12 Windows Application ( continued ) Figure 9-1 Windows-based form Output generated from Windows0 application

13. C# Programming: From Problem Analysis to Program Design13 Elements of Good Design Appearance matters –Human-computer interaction (HCI) research Design considerations –Consistency –Alignment –Avoid clutter –Color –Target audience

14. Using C# & Visual Studio to Create Windows based Applications Primitive approach –Manually create Win based application in C# using a text editor like Notepad, or Textpad etc Professional approach –Using IDE like MS Visual Studio –Select File Menu: New >> Project –Select Visual C#, Windows and Windows Forms Application from Visual Studio Installed Templates pane, see next 3 slides

15. C# Programming: From Problem Analysis to Program Design15 Use Visual Studio to Create Windows-Based Applications Windows Forms Application template Browse to location to store your work Select File New Project Name Figure 9-2 Visual Studio New Windows application

16. C# Programming: From Problem Analysis to Program Design16 Windows-Based Applications Properties Window Design View Toolbox Figure 9-3 Initial design screen

17. C# Programming: From Problem Analysis to Program Design17 Windows-Based Applications ( continued ) Figure 9-4 Dockable windows

18. Windows Based Applications MS VS automatically generates code to create a blank Windows Form object. The IDE opens the Form Designer pane showing the form If you see Code Editor pane instead, you press Shift+F7 to view Designer. F7 reveals Code Editor Other panes used at application design time: Toolbox, Solution Explorer, Properties Other panes used at application run time: Error List pane and Output pane Pushpin icon and dockable panes (auto hide state)

19. Windows Based Applications How to run Windows based application? Like console applications –Select from Debug menu Start Debugging (shortcut F5) Or Start Without Debugging (Ctrl+F5)

20. Windows Based Applications Task: create a new project named pureFCLForm to display a pure empty form Build the solution Run the application

21. C# Programming: From Problem Analysis to Program Design21 Windows Forms Extensive collection of Control classes Top-level window for an application is called a Form Each control has large collection of properties and methods –Select property from an alphabetized list (Properties window) –Change property by clicking in the box and selecting or typing the new entry

22. C# Programming: From Problem Analysis to Program Design22 Windows Form Properties Properties Property value Figure 9-5 Properties window

23. C# Programming: From Problem Analysis to Program Design23 Windows Form Properties ( continued )

24. Windows Forms Task: Modify the PureFCLForm application Find appropriate property and type a new value –Change the following Form properties: –Text –BackColor –Size –FormBorderStyle

25. C# Programming: From Problem Analysis to Program Design25 Windows Form Events Add code to respond to events, like button clicks From the Properties window, select the lightning bolt (Events) –Double-click on the event name to generate code Registers the event as being of interest Adds a heading for event-handler method

26. C# Programming: From Problem Analysis to Program Design26 Windows Form Properties ( continued ) Events button selected Figure 9-6 Form1 events

27. C# Programming: From Problem Analysis to Program Design27 Windows Form – Closing Event Code automatically added to register event this.Closing += new System.ComponentModel.CancelEventHandler (this.Form1_Closing); Code automatically added for method heading private void Form1_Closing(object sender, System.ComponentModel.CancelEventArgs e) { } You add statement to event-handler method body MessageBox.Show("Hope you are having fun!");

28. Windows Forms Task: Modify the PureFCLForm application Write your user reaction (fill the body of corresponding event handlers with C# statements) in order to process the following events associated with the form: –Load form event –Mouse entering form event For example, type a statement like MessageBox.Show("Message at form loading time"); MessageBox.Show("Message at mouse entering form");

29. C# Programming: From Problem Analysis to Program Design29 Simple Windows Application IDE separates the source code into three separate files –Form1.cs: normally this is the only one you edit –Form1.Designer.cs: holds the auto generated code –Program.cs: contains the Main( ) method, where execution always begins Form1.cs and Form1.Designer.cs both include partial class definitions for the Form1 class

30. C# Programming: From Problem Analysis to Program Design30 Windows Form Events ( continued ) Figure 9-7 Solution Explorer window Expand Form1.cs node to reveal the Form1.Designer.cs file

31. C# Programming: From Problem Analysis to Program Design31 Controls Controls are all classes –Button, Label, TextBox, ComboBox, MainMenu, ListBox, CheckBox, PictureBox, MenuStrip, RadioButton, and MonthCalendar Each comes with its own predefined properties and methods Each fires events Each is derived from the System.Windows.Forms.Control class

32. C# Programming: From Problem Analysis to Program Design32 Controls ( continued ) Dots indicate other classes are derived from the class Figure 9-9 Control class hierarchy

33. C# Programming: From Problem Analysis to Program Design33 Standard Controls Figure 9-10 Windows Forms controls

34. C# Programming: From Problem Analysis to Program Design34 Controls ( continued ) Two procedures to place controls –From Toolbox, double-click on control or drag and drop Move, resize, and delete controls Format controls –Align controls –Make same size –Horizontal and vertical spacing

35. C# Programming: From Problem Analysis to Program Design35 Properties of the Control Class

36. C# Programming: From Problem Analysis to Program Design36 Methods of the Control Class

37. C# Programming: From Problem Analysis to Program Design37 Controls ( continued ) Figure 9-11 GUI controls

38. C# Programming: From Problem Analysis to Program Design38 Label Objects Provide descriptive text or labels for other controls Instantiate object Label labelName = new Label( ); Add control to Form this.Controls.Add(labelName); Set property values (some from Control class) –Text; TextAlign; Font; Location

39. C# Programming: From Problem Analysis to Program Design39 Creating a TaxApp Properties set for the Form container

40. C# Programming: From Problem Analysis to Program Design40 Creating a TaxApp Form Figure 9-12 Formatting Label objects Add Label objects to Form object, then format

41. C# Programming: From Problem Analysis to Program Design41 Adding Labels to TaxApp Form Add Label objects, then set their properties using the Properties window (View Properties window)

42. C# Programming: From Problem Analysis to Program Design42 TextBox Objects Used to enter data or display text during run time –Used for both input and output Instantiate object TextBox textBoxName = new TextBox( ); Add control to Form this.Controls.Add(TextBoxName); Interesting properties –MultiLine, ScrollBars, MaxLength, PasswordChar, CharacterCasing

43. C# Programming: From Problem Analysis to Program Design43 TextBox Objects ( continued )

44. C# Programming: From Problem Analysis to Program Design44 Adding TextBox Objects to TaxApp Form Add TextBox objects, then set their property values

45. C# Programming: From Problem Analysis to Program Design45 Button Enables user to click button to perform task –If button has event-handler method and is registered as an event to which your program is planning to respond, event-handler method is called automatically when button clicked Button object’s properties, methods, and events –Inherits from Control (Table 9-2 & 9-3) Text, Enabled, Focused, TabIndex

46. C# Programming: From Problem Analysis to Program Design46 Adding Button Objects to TaxApp Form Add Button objects, then set their property values

47. C# Programming: From Problem Analysis to Program Design47 Adding Button Objects to TaxApp Form ( continued ) Figure 9-14 Events

48. C# Programming: From Problem Analysis to Program Design48 Adding Button Objects to TaxApp Form ( continued ) When you double-click on event, an event-handler method is created: private void btnCompute_Click(object sender, System.EventArgs e) { } AND registers click event: this.btnCompute.Click += new System.EventHandler (this.btnCompute_Click);

49. C# Programming: From Problem Analysis to Program Design49 Adding Button Objects to TaxApp Form ( continued ) private void btnCompute_Click(object sender, System.EventArgs e) { string inValue; double purchaseAmt, percent, ans; inValue = txtPurchase.Text; purchaseAmt = Int32.Parse(inValue); inValue = label5.Text; //inValue previously declared as string inValue = inValue.Remove(inValue.Length-1, 1); percent = double.Parse(inValue) / 100; percent = (double.Parse(label5.Text.Remove(label5.Text.Length-1,1))) / 100; ans = (purchaseAmt * percent) + purchaseAmt; txtTotalDue.Text = String.Format("{0:C}",ans).ToString(); }

50. C# Programming: From Problem Analysis to Program Design50 TaxApp Form Figure 9-15 Tax calculator output

51. Tasks Windows Based Application Start from scratch and develop your own version of the TAX CALCULATOR program

52. Tasks Windows Based Application Start from scratch and develop your own program Input: separate text box for each one of your names Output: text box or label or both to display all your names concatenated to one string.

53. Tasks Windows Based Application Start from scratch and develop your own program Input: separate text box to enter two numeric values Output: text boxes to display result of addition, subtraction, multiplication and division of the input values.

54. Tasks Windows Based Application Start from scratch and develop your own CURRENCY CONVERTER program GUI design on your choice.

55. Tasks Windows Based Application Start from scratch and develop your own LINEAR EQUATION SOLVER program GUI design on your choice.

56. Coding Standards Guidelines for Naming Controls –Consistency –Use appropriate prefix for controls C# Programming: From Problem Analysis to Program Design56

57. Thank You For Your attention