C

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Windows Forms
A new plattform for Windows-based application
development
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Overview

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

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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

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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

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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

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Delegates and Events

• The controls 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

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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

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Forms

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

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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

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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

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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

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Forms

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

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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

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Forms

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

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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

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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

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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

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Using Controls

• Layout
• Buttons
• Text Controls
• List Controls
• Menus
• Common Dialogs
• More controls

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Layout

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

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Buttons

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

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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

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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

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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

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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

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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

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Common Dialogs

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

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More Controls

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

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Data bound Controls

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

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ADO.NET

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

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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

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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

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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

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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

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Complex data binding

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

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User Controls

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

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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

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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

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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

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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

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Miscellaneous

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

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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

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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

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Related classes

• Keys
• Cursors
• SystemInformation

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Summary

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