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Windows Forms

Windows Forms. A new plattform for Windows-based application development. Overview. Section 1: Introduction Section 2: Forms Section 3: Using Controls Section 4: Data bound Controls Section 5: User Controls Section 6: Miscellaneous Summary. Introduction. Basic concepts

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Windows Forms

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  1. Windows Forms A new plattform for Windows-based application development

  2. Overview • Section 1: Introduction • Section 2: Forms • Section 3: Using Controls • Section 4: Data bound Controls • Section 5: User Controls • Section 6: Miscellaneous • Summary

  3. Introduction • Basic concepts • From Window to Control to Form • Delegates and Events • The Control class • Forms • Inheritance • Creating and using instances • The System.Drawing namespace

  4. Basic concepts • A window is the core component of Windows • Configured via attributes • SendMessage is the most important function • Not really object oriented • MFC as C++ oriented improvement • New library for the .NET framework • Windows Forms

  5. From Window to Control to Form • One common base class: Control • Represents a window • Offers properties and methods • The Form class is derived from Control • New Controls and Forms through Inheritance

  6. Delegates and Events • The control‘s way to send a message: an event • Delegates • Object oriented function pointers • The base of modern callback functions • Delegates are type safe • Events are based on delegates • Act as connection points • More than one handler possible Windows Forms: Overridable methods

  7. The Control Class • Implements basic functionality • Base class for predefined classes • Indirect base class for user controls • A lot of properties and methods • Color, position, size, child controls • Enhanced functionality • Docking, special message handling • No painting implemented

  8. Forms • Application windows • Different forms: standard, tool, dialog • Own forms through inheritance • Special attributes • DesktopLocation, AcceptButton, ShowDialog

  9. Inheritance • New window types through inheritance • Old methods: • API: WNDCLASS • VB: Form class or User Control (ActiveX) • .NET method • Inherited from (User)Control or Form • Really object oriented

  10. Creating and using Instances • Very familiar to Visual Basic programmers • Form • Create instance • Call the Show or ShowDialog method • Use properties and methods • Control • Create instance • Add to the containers Controls collection • Use properties and methods

  11. The System.Drawing namespace • Special data structures for position and so on • Defined in the System.Drawing namespace • Point for position • Rectangle and Size for dimensions • Color für Color values • Graphics encapsulate a Device Context • Drawing functions and elements

  12. Forms • GUI based applications • Forms • Forms and contained Controls • Dialogs • MDI applications

  13. GUI based applications • Use SYSTEM.WINDOWS.FORMS.DLL • Main function as entry point • Application class for message loop • The Run method opens the main form • User defined Form class for the main window • Override OnPaint for output • Override other event method for input handling

  14. Forms • New concepts • ClientSize instead of ScaleWidth, ScaleHeight • New names for known elements • Unload goes to Closing • New properties and functions • DesktopLocation, DesktopBounds

  15. Forms and contained Controls • Adding a control to a form • create the control instance • set the attributes of the control (Text, BackColor,…) • set the location and dimensions of the control • add event handlers for the control • add the control to the controls collection of the form

  16. Dialogs • Use ShowDialog to open a dialog • Returns a DialogResult value • How is the dialog closed • OK, Cancel, Yes, ... • AcceptButton, CancelButton properties • Extra OK and Cancel button handling • Return input values via • Public Controls • Public properties • Special dialog type: MessageBox

  17. MDI applications • Combination of Container and Child Form • IsMdiContainer property indicates the container • MdiParent property refers to the Container • Used by the Child Form • Other elements • ActiveMdiChild: active child form • MdiChildren: child forms array

  18. Using Controls • Layout • Buttons • Text Controls • List Controls • Menus • Common Dialogs • More controls

  19. Layout • Dynamic position of controls • Old: Calculate and move • New: Anchoring and Docking • Anchor • Fixed distance to borders • Dock • Connecting to an edge • Splitter

  20. Buttons • Abstract base class: ButtonBase • Button class for push buttons • DialogResult property • CheckBox • ThreeState, AutoCheck property • RadioButton • AutoCheck property

  21. Text Controls • Base class TextBoxBase • New functions • Lines property gets, sets a string array • Select method selects a range of text in the text box • AppendText method appends text • TextBox and RichTextBox are inherited classes • TextBox • Character casing, Password handling • RichTextBox • Supports RTF • DetectUrls, AutoWordSelection properties

  22. Simple List Controls • ListBox • Items are stored in an ObjectCollection • Additional collections for selected items • SelectedIndexCollection, SelectedObjectCollection • Enhanced and new functions • ComboBox • Combination of ListBox and TextBox • CheckedListBox • Owner Draw Mode

  23. Complex List Controls • ListView • (Multi column) list of items • Collections for Columns, Items and so on • More values as columns possible • TreeView • Hierarchical list of items • ImageList • Stores images for other controls

  24. Menus • Realized by a class hierarchy • Abstract base class Menu • MenuItem class for single items • MainMenu class for the forms main menu • ContextMenu class for shortcut menus • Useful events • Popup, MenuStart: context dependant states • Select: User feedback

  25. Toolbars • 2 classes: ToolBar + ToolBarButton • Buttons with different styles • Dropdown menus supported • Toggle buttons supported • ButtonClick + ButtonDropDown events • No events for status handling • Use the Application.Idle event instead

  26. Common Dialogs • OpenFileDialog, SaveFileDialog • Derived from FileDialog • Offers the OpenFile method • FontDialog • Raises an Apply event for preview functionality • ColorDialog • PageSetupDialog • PrintDialog

  27. More Controls • Tabbed views • TabControl and TabPage • StatusBar • Bar and Panels • Miscellaneous • PictureBox, LinkLabel, Timer, UpDown • TrackBar, Scrollbars, ProgressBar • MonthCalendar, DateTimePicker

  28. Data bound Controls • ADO.NET • Managed Providers • Using the OLE DB .NET Provider • Data Binding • Simple data binding • Complex data binding

  29. ADO.NET • New data access technology • Two core components • DataSet • .NET Managed Providers • DataSet contains other components • DataTable • DataRelation • Tight integration with XML

  30. Managed Providers • Data Source/Database access • Connection: Access to a data source • Command: SQL statements • DataAdapter • Bridge between DataSet and Database • OLE DB .NET Provider • Native OLE DB through COM Interop • SQL Client .NET Provider • SQL Server specific protocol

  31. Using the OLE DB .NET Provider • OleDbConnection • ADO like connection string • OleDbCommand • SQL statements: Select, Insert, Update • OleDbDataReader • Read only, forward only, fast • OleDbDataSet • Fill a DataSet

  32. Data Binding • Two types • Simple data binding • Label, TextBox, PictureBox • Complex data binding • DataGrid, ComboBox • Possible data sources • DataSet, DataTable, DataView, DataSetView • 1-dimensional Array, Collection

  33. Simple data binding • Binding a control to a data source • Binds one data field • Binds a property of the control • The Binding classes • Binding • BindingContext • BindingManagerBase • CurrencyManager

  34. Complex data binding • Bind more than one data field • Properties • DataSource • DataMember • Method • SetDataBinding • Updates by DataSet operations

  35. User Controls • Reusing existing controls • Extending standard controls • Composite controls • Custom Controls • Implemented from scratch • Design time support • Attributes • Type converter and editor, designer

  36. Reusing Existing Controls • Extending existing controls • Using standard controls as base class • Rich base functionality • Focus on new functions • Composite controls • Derived from UserControl • Combines standard controls • LabelTextbox: Label + TextBox

  37. Custom Controls • „Normal“ .NET Controls • Implementation is straightforward • Derived from System.Control • Sometimes from UserControl • Implemented from scratch • Overrides OnPaint for display • Special property support • ShouldSerialize, Reset

  38. Design time support (1) • Better cooperation with designers • Support for UDTs • Converter + editor • For properties and events • Based on attributes • Browsable: displayed in the property browser • Description: describes the property • DefaultValue: a simple default value • TypeConverter: a special converter

  39. Design time support (2) • Type converter • Converts from and to UDTs • UI Type Editor • Visual editing of UDTs • Type specific Dialogs • Custom Designer • Supports special design time demands

  40. Miscellaneous • ActiveX Controls • Special message handling • IMessageFilter interface • PreProcessMessage • Related classes • Keys • Cursors • System Information

  41. ActiveX Controls • Usable through wrappers • Aximp.exe generates control class • Creation via New statement • Usage like other controls • Special initialisation • BeginInit, EndInit • Main function requirers STAThread attribute

  42. Special Message Handling • IMessageFilter interface • Early message handling • 1 method: PreFilterMessage • Used by the Splitter control • PreProcessMessage • After PreFilterMessage, before any event • Some related functions • ProcessCmdKey, ProcessDialogKey • IsInputKey, IsInputChar

  43. Related classes • Keys • Cursors • SystemInformation

  44. Summary • Windows Form is • Straightforward • Really object oriented • Feature rich • Easy to use

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