User interface development based on Windows Forms class library

MINISTRY OF SCIENCE AND HIGHER EDUCATION OF THE RUSSIAN FEDERATION SOUTHERN FEDERAL UNIVERSITY








Mikhail E. Abramyan




USER INTERFACE DEVELOPMENT
BASED ON WINDOWS FORMS CLASS LIBRARY



Textbook for students of computer science and programming











Rostov-on-Don - Taganrog
Southern Federal University Press
2021

УДК 004.438.NET
ББК 32.973.202
А16
Published by decision of the Educational-Methodical Commission of the I. I. Vorovich Institute of Mathematics, Mechanics, and Computer Science of the Southern Federal University (minutes No. 5 dated April 12, 2021)

Reviewers:
doctor of Technical Sciences, Professor of the Department of Computer Science of the Rostov State Transport University, Professor M. A. Butakova;
candidate of Physical and Mathematical Sciences, Head of the Department of Computer Science and Computational Experiment of the I. I. Vorovich Institute of Mathematics, Mechanics, and Computer Science
of the Southern Federal University, Docent S. S. Mikhalkovich
Публикуется с разрешения издательства БХВ, являющегося владельцем прав на первое издание книги на русском языке:
Абрамян М.Э., Visual C# на примерах, 2008.
Published with the permission of the publishing house BHV, which is the copyright holder of the first edition of the book in Russian:
Абрамян М.Э., Visual C# на примерах, 2008.

        Abramyan, M. E.
А16 User interface development based on Windows Forms class library : textbook / M. E. Abramyan ; Southern Federal University. - Rostov-on-Don ; Taganrog : Southern Federal University Press, 2021. - 278 p.
      ISBN 978-5-9275-3830-0

    The tutorial focuses on developing a graphical user interface based on the Microsoft Windows Forms class library, which is a part of the .NET Framework since version 1.0. The tutorial is presented in the form of detailed descriptions of 23 projects that demonstrate various aspects of user interface development for Windows applications. Projects can be implemented in the Microsoft Visual Studio 2015-2019 IDE. Description of projects is accompanied by numerous comments. Typical errors that arise during the development of Windows applications are considered, ways to fix them are indicated. The final section contains 65 study assignments designed to consolidate the learning material.
    The textbook is intended for students specializing in science and engineering.
УДК 004.438.NET
ISBN 978-5-9275-3830-0                                      ББК 32.973.202
                                          © ООО “БХВ”, 2017
                                          © Southern Federal University, 2021

C

Preface ................................................................. 8
1.  Developing projects in Microsoft Visual Studio environment ......... 10
   1.1. Creating, saving, and opening a project ........................ 10
   1.2. Adding a new form to the project and placing a new control on the form ........................................................... 12
   1.3. Setting properties of forms and controls ....................... 16
   1.4. Defining event handlers......................................... 18
   1.5. Making changes to the program text ............................. 19
   1.6. Application launch...............................................20
2.  Console application: DISKINFO project .............................. 22
   2.1. Creating a console application ..................................22
   2.2. Receiving the information about current disk ....................24
   2.3. Using command line arguments ................................... 28
3. Exception handling: EXCEP  project....................................30
   3.1. Handling a specific exception and exception groups ............. 30
   3.2. Handling any exception...........................................34
   3.3. Re-throwing a handled exception..................................35
4. Events: EVENTS project................................................37
   4.1. Connecting an event to a handler ................................37
   4.2. Disconnecting a handler from an event............................41
   4.3. Connecting another handler to an event ......................... 43
5.  Forms: WINDOWS project..............................................46
   5.1. Setting the visual properties of forms. Opening forms in normal and modal mode .......................................................46
   5.2. Checking the state of the subordinate form.......................49
   5.3. Controls adapting to fit the window ............................ 51
   5.4. Modal and non-modal buttons of the dialog window ................52
   5.5. Setting the active form control .................................54
   5.6. Request for confirmation of closing the form ....................54
6.  Sharing event handlers and working with keyboard: CALC project ..... 57
   6.1. Event handler for multiple controls..............................57
   6.2. Calculations with control of the correctness of the input data . 58
   6.3. The simplest techniques to speed up work using keyboard .........60
   6.4. Using a keyboard event handler .................................61
   6.5. Control over changes to the input data..........................62

7.  Working with date and time: CLOCK project......................... 64
   7.1. Displaying the current time on the form ...................... 64
   7.2. Implementation of the stopwatch capabilities ................. 66
   7.3. Alternative options for executing commands using the mouse ... 70
7.4.  Displaying the current status of the clock and stopwatch on the taskbar..................................................... 71
8.  Text input: TEXTBOXES project .................................... 72
   8.1. Additional highlighting of the active text box ............... 72
   8.2. Changing the tab order of text boxes ......................... 74
   8.3. Blocking exit from an empty text box ......................... 76
   8.4. Informing the user about the error ........................... 77
   8.5. Providing additional information about the error ............. 78
   8.6. Form-level error checking..................................... 78
9.  Mouse event handling: MOUSE project............................... 80
   9.1. Dragging with the mouse. Setting the z-order of controls on a form.......................................................... 80
   9.2. Resizing with the mouse ...................................... 84
   9.3. Using additional cursors ..................................... 86
   9.4. Handling a situation with simultaneous pressing of several mouse buttons........................................... 87
   9.5. Dragging and resizing a control of any type. Using the find and replace tool ................................... 90
10.  Drag-and-drop: ZOO project ...................................... 93
   10.1. Dragging labels on a form.................................... 93
   10.2. Dragging labels to text boxes................................ 96
   10.3. Interaction oflabels......................................... 97
   10.4. Actions in case of dragging to invalid target ............... 99
   10.5. Additional coloring of source and target while dragging .... 100
   10.6. Customizing the cursor in drag-and-drop mode ............... 101
   10.7. Information about the current state of the program. Buttons with images............................................... 102
   10.8. Restoring the initial state ................................ 105
11.  Cursors and icons: CURSORS project ............................. 107
   11.1. Using standard cursors ..................................... 107
   11.2. Setting the cursor for a form and waiting mode indication .. 109
   11.3. Connecting new cursors to the project and saving them as embedded resources............................................. 111
   11.4. Working with icons.......................................... 112
   11.5. Placing an icon of application in the notification area .... 113
12.  Menus and processing of text files: TEXTEDIT1 project........... 116
   12.1. Menu creation .............................................. 116
   12.2. Saving text to a file ...................................... 119

12.3.  Clearing the editing area and opening an existing file ..... 121
  12.4.  Request to save changes .................................... 124
13.  Advanced menu options, color and font setting: TEXTEDIT2 project .......................................................... 126
  13.1.  Setting the font style (menu items as checkboxes) .......... 126
  13.2.  Setting text alignment (menu items as radio buttons) ....... 128
  13.3.  Setting the color of symbols and background color (third-level menu commands and the Color dialog box)................... 130
  13.4.  Setting font properties using the Font dialog box .......... 131
14.  Editing commands, context menus: TEXTEDIT3 project ............. 134
  14.1.  Editing commands ........................................... 134
  14.2.  Special visualization of unavailable editing commands. Working with the clipboard...................................... 136
  14.3.  Creating a context menu..................................... 138
15.  Toolbar: TEXTEDIT4 project.......................................140
  15.1.  Creation a toolbar and shortcut buttons. Adding images to menu items .................................................. 140
  15.2.  Using shortcut buttons that behave as checkboxes and radio buttons .............................................. 143
16.  Status bar and hints: TEXTEDIT5 project ........................ 147
  16.1.  Using the status bar ....................................... 147
  16.2.  Inaccessible shortcut buttons............................... 148
  16.3.  Hiding the toolbar and status bar........................... 149
  16.4.  Displaying hints on the status bar.......................... 149
17.  Formatting a document: TEXTEDIT6 project ....................... 152
  17.1.  Replacing the TextBox control with the RichTextBox control . 152
  17.2.  Correcting the state of shortcut buttons and menu commands when changing the current format................................ 155
  17.3.  Setting paragraph properties................................ 157
  17.4.  Display the current row and column ......................... 159
  17.5.  Loading and saving text without format settings ............ 161
18.  Colors: COLORS project ..........................................163
  18.1.  Defining a color as a combination of four color components. Track bars and scroll bars...................................... 163
  18.2. Inverting colors and output color constants ................. 167
  18.3. Grayscale colors ............................................ 168
  18.4. Displaying color names ...................................... 169
  18.5. Controls and their associated labels ........................ 171
  18.6. Anchoring controls .......................................... 172
19.  Drop-down list and list box: LISTBOXES project ................. 175
  19.1. Creating and using drop-down lists........................... 175
  19.2. List box: adding and removing items ......................... 177

19.3. Additional list operations................................... 179
   19.4. Performing list operations with the mouse ................... 182
20.  Checkboxes and checked list boxes: CHECKBOXES project............ 186
   20.1. Checkboxes and checking their state ......................... 186
   20.2. Global setting of CheckedListBox items ...................... 189
   20.3. Using checkboxes with three states .......................... 190
21.  Viewing images: IMGVIEW project.................................. 193
   21.1. Displaying a directory tree.................................. 193
   21.2. View images from image files in the selected directory....... 200
   21.3. Docking of controls and its features ........................ 206
   21.4. Setting the image view mode.................................. 208
   21.5. Saving information about the state of the program in the Windows registry............................................. 211
   21.6. Restoring information from the Windows registry.............. 213
22.  MDI application: JPEGVIEW project ............................... 216
   22.1. Opening and closing child forms in MDI application .......... 216
   22.2. Standard actions with child forms ........................... 220
   22.3. Adding a list of open child forms to the menu ............... 222
   22.4. Closing all child forms at the same time .................... 223
   22.5. Image scaling ............................................... 223
   22.6. Automatic resizing of child forms ........................... 224
   22.7. Additional control tools .................................... 225
   22.8. Scrolling the image using the keyboard....................... 228
23.  Splash screen application: TRIGFUNC project ..................... 231
   23.1. Creating a table of trigonometric function values ........... 231
   23.2. Displaying the splash window when loading the program........ 235
   23.3. Using the splash window as an information window ............ 237
   23.4. Displaying the progress of the program loading............... 238
   23.5. Early termination of the program............................. 240
   23.6. Dragging the splash window................................... 241
24.  Creating controls at runtime: HTOWERS project.................... 243
   24.1. Creating a start position ................................... 243
   24.2. Redrawing the tower when changing the number of blocks ...... 244
   24.3. Dragging blocks to a new location ........................... 245
   24.4. Restoring the start position and counting the number of block movings ................................................... 248
   24.5. Information about solving the problem ....................... 249
   24.6. Demo mode implementation..................................... 250
25.  Study assignments................................................ 253
   25.1. General requirements ........................................ 253
   25.2. CONSOLE project: console applications, file and directory processing....................................... 253

25.3. DIALOGS project: form interaction ............................256
   25.4. SYNC project: control synchronization ........................259
   25.5. DRAGDROP project: drag-and-drop mode..........................262
   25.6. TIMER project: timer-controlled programs .....................265
   25.7. REGISTRY project: dialog boxes and working with the Windows registry ...........................................269
   25.8. MDIFORMS project: MDI applications ...........................273
References.............................................................277

Preface




     This textbook focuses on developing a graphical user interface based on the Windows Forms class library. This library appeared in .NET Framework 1.0 (the Microsoft Visual Studio .NET 2003 IDE), was significantly improved in .NET Framework 2.0 (the Microsoft Visual Studio 2005 IDE) and after that practically did not change; nevertheless, it was included in all subsequent versions of Microsoft Visual Studio. Despite the presence of the newer Windows Presentation Foundation class library, which is related to the development of the graphical interface and provides more features, the Windows Forms library retains its position, due to greater ease of use and convenient visual design tools. At the same time, the capabilities of this library are quite enough for the development of fully functional Windows desktop applications of medium complexity. In addition, the Windows Forms library contains a number of important concepts related to GUI design. Therefore, studying it in a course on the basics of user interface development seems to be quite justified.
     The learning material of the book is presented in the form of descriptions of 23 examples, which are fully functional software projects. Each of the examples focuses on a specific topic indicated in its name, but much additional information is provided in the description of the project development process and accompanying comments. We focuse on best practices for developing event-driven applications and the efficient use of Windows Forms library components. The tools providing a convenient and reliable dialogue between the program and the user are discussed in detail. We also discuss common errors that occur when using the various Windows Forms library classes and show how to fix them.
     Most of the examples are slightly modified versions of the examples given in [1]. The exception is the IMGVIEW example, which has been changed more significantly by eliminating several obsolete controls (DriveListBox, DirListBox, and FileListBox) and using the TreeView control instead, which allows visualizing hierarchical lists of data.
     The book assumes an acquaintance with the basics of programming in the C# language at the level of knowledge of the system of basic types and control statements (see, for instance, [2]). The in-depth knowledge of the .NET object model is not required. Mostly C# 3.0 is used, which allows you to develop projects in the Visual Studio 2008 and higher. Among the innovations, only interpolated strings are used, which appeared in C# 6.0 (Visual Studio 2015); in earlier versions, you can use the string.Format function instead. The LINQ queries (implemented in C# 3.0) are used only in the projects LISTBOXES and IMGVIEW

(Chapters 19 and 21) and are commented in detail. Chapter 1 provides a detailed description of the Microsoft Visual Studio tools used to develop Windows applications.
     The last chapter of the book contains 65 study assignments divided into 7 groups related to the following topics:
     •   developing console applications,
     •   interaction between windows of an application,
     •   synchronizing controls and sharing event handlers,
     •   implementing the drag-and-drop mode,
     •   creating timer-driven programs,
     •   use of standard dialog boxes and the Windows registry,
     •   developing MDI applications.
     Most assignments contain references to sections of the book that describe the required controls and how to use them.

1.    Developing projects in Microsoft Visual Studio environment




     Currently, the most common version of Microsoft Visual Studio is version 2019, targeting the .NET 4.8 platform and the C# 8.0 language, although most of the features discussed are available for earlier versions. In particular, the Windows Forms library itself has remained unchanged since the release of .NET 3.5, C# 3.0, and Visual Studio 2008.


            1.1.  Creating, saving, and opening a project


     When you start Visual Studio, the Start Page is automatically loaded into it, which allows you to quickly load one of the previously developed projects (the Open recent list), open any other existing project (the Open a project or solution item), and also create a new project (the Create a new project item). All these actions are also available from the menu of the Visual Studio environment:
     •  File | New | Project... or Ctrl+Shift+N - create a new project;
     •  File | Open | Project/Solution... or Ctrl+Shift+O - open an existing project;
     •  File | Recent Projects and Solutions - open one of the recently developed projects.
     The Visual Studio environment is organized in such a way that you cannot create a “stand alone” project. Each project must be contained in a special entity called a solution, which can be described as a group of related projects. Only one solution can be loaded into the Visual Studio environment at a time; loading another solution leads to automatic closing of the previous solution.
     When creating a new project, a dialog box appears on the screen, in which first of all you need to select the language used (in our case, C# or Visual C#), and then the project template and its name. As a template for all considered projects (except for the first two projects DISKINFO and EXCEP), you should choose Windows Forms App (or Windows Forms Application). As to the name, it is recommended to use the name of the example given in the title of the corresponding chapter, for example, EVENTS (see Chapter 4). Note that the project name can contain not only digits and Latin letters, but also other characters allowed in file names, including spaces, although this feature is not recommended for use.
     In Visual Studio, when creating a new project, you must immediately specify the directory to save it (the Location text box). Project placement is also affected by information related to the solution in which the project will be placed,