Introduction to Windows Presentation Foundation (WPF)

Dr. Frank McCownCOMP 445 – GUI Programming

WPF History

• Work began in early 2000’s by Microsoft under code name “Avalon”

• Effort to provide a clearer separation between the interface and business logic

• Avalon renamed WPF in July 2005• WPF released in 2006 as part of .NET Framework 3.0• Silverlight (released in 2007) is a subset of WPF • Windows Phone 7 (released in 2010) uses Silverlight or

XNA to write apps

http://channel9.msdn.com/posts/Charles/Michael-Wallent-Advent-and-Evolution-of-WPF/ http://www.eweek.com/c/a/Windows/Microsoft-Gives-Avalon-Indigo-Official-Names/

WPF Features

• Works on top of DirectX to provide more advanced UI features

• Support for 2D and 3D graphics, audio, and video• GUI appearance and content manipulated with XAML• WPF controls can be embedded in Windows Forms

app and vice versa• Uses vector-based graphics for resolution

independence• WPF apps can stand alone or run in Internet Explorer

Bringing it all together…

http://windowsclient.net/wpf/white-papers/when-to-adopt-wpf.aspx

Extensible Application Markup Language (XAML)

• Pronounced “zammel”• XML-based markup language for defining and

arranging GUI controls• Can be manually generated/edited or edited

by Visual Studio

Example XAML Document

<Window x:Class="WPF_HelloWindows.Window1” xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"Title="Hello WPF" Height="150" Width="250">

<Grid Background="AntiqueWhite" > <Label Name="label1" VerticalAlignment="Center"

HorizontalAlignment="Center">Hello, WPF!</Label> </Grid></Window>

Window1.xaml

Control Layout

• Windows Forms: Set absolute (x,y) position• WPF: Set relative position in its layout container• Controls grow/shrink as window grows/shrinks• Control properties:

– Width, Height– MinWidth, MinHeight, MaxWidth, MaxHeight– Margin: space around control’s edges (L,T,R,B)– HorizontalAlignment (Left, Center, Right, or Stretch)– VerticalAlignment (Top, Center, Bottom, or Stretch)

Alignment

Introduction to WPF Layout by Christian Moserhttp://www.wpftutorial.net/LayoutProperties.html

Padding and Margin

Introduction to WPF Layout by Christian Moserhttp://www.wpftutorial.net/LayoutProperties.html

• The Margin is the extra space around the control.• The Padding is extra space inside the control.• The Padding of an outer control is the Margin of an inner control.

Common Layouts

• Grid• Canvas• StackPanel• DockPanel• WrapPanel

Grid Layout

Grid Panel by Christian Moserhttp://www.wpftutorial.net/GridLayout.html

Layout is defined by a grid of rows and columns with elements placed in cells.

Canvas Layout

Canvas Panel by Christian Moserhttp://www.wpftutorial.net/Canvas.html

Elements are placed in relation to the distance from the top and left edges of the Canvas.

StackPanel Layout

StackPanel by Christian Moserhttp://www.wpftutorial.net/StackPanel.html

Elements are arranged in a single column or row.

DockPanel Layout

Dock Panel by Christian Moserhttp://www.wpftutorial.net/DockPanel.html

Elements are positioned based on the edge they are docked to.

WrapPanel Layout

Wrap Panel by Christian Moserhttp://www.wpftutorial.net/WrapPanel.html

A wrapping StackPanel where elements are wrapped to the next row or column.

Event Handling<Button Height="23" Margin="78,12,78,0" Name="button1" VerticalAlignment="Top" Click="button1_Click">Press Me</Button>

// Code from Windows1.xaml.cspublic partial class Window1 : Window { public Window1() { InitializeComponent(); }

private void button1_Click(object sender, RoutedEventArgs e) { label1.Content = "Button pressed!"; }}

Event Routing

• All WPF events are routed events– Can travel up (from child to parent)– Can travel down (from parent to child)

• Three types of routed events– Direct events: Don’t travel up or down– Bubbling events: Travel up (Source to Window)– Tunneling events: Travel down (top of

containment hierarchy to Source)

Bubbling Event Example<GroupBox Name="myGroupBox" Header="Bubbling Example“ MouseLeftButtonUp="MyCallback"> <Label Name="myLabel"

MouseLeftButtonUp=“MyCallback">Click Me</Label>

</GroupBox>

private void MyCallback(object sender, MouseButtonEventArgs e){ // Label notified of event first, then GroupBox}

Bubbling event

Tunneling Event Example<GroupBox Name="myGroupBox" Header="Bubbling Example“ PreviewMouseLeftButtonUp ="Tunneling"> <Label Name="myLabel"

PreviewMouseLeftButtonUp="Tunneling">Click Me</Label>

</GroupBox>

private void Tunneling(object sender, MouseButtonEventArgs e){ // GroupBox notified of event first, then Label}

Tunneling event

Commands• Any action or task that may be triggered by different user

interactions– Example: File Exit from the menu and Exit button may both

need to execute the same command• Commands can better synchronize a tasks’ availability

– Example: If copy command requires text to be highlighted, all controls using this command can be disabled if no text is highlighted

• Some common built-in commands: New, Open, Save, Close, Cut, Copy, Paste

• Can create your own custom commands

Command Example<Window x:Class="WPF_HelloWindows.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Hello WPF" Height="150" Width="250"> <Window.CommandBindings> <CommandBinding Command="Close" Executed="closeCommand_Executed" /> </Window.CommandBindings> <Grid Background="AntiqueWhite" > <Button Height="23" Margin=“80,0,80,14" Name="button1" VerticalAlignment="Bottom“ Command="Close">Press Me</Button> <Menu Name="menu1" Height="23" VerticalAlignment="Top"> <MenuItem Header="File" > <MenuItem Header="Exit" Command="Close"/> </MenuItem> </Menu> </Grid></Window>

Called by Menu and Button

Styles

• WPF style is a collection of reusable property-value & event-handler definitions

• Concept is similar to style sheets for HTML• Same Style might be applied to different types

of controls• Styles are WPF resources– Reusable objects defined for entire application

Styles Example 1<Window.Resources> <Style x:Key="WashedOut" TargetType="{x:Type FrameworkElement}" > <Setter Property="Opacity" Value="0.5" /> </Style></Window.Resources>

<Slider Name="button1" Content="Button" Style="{StaticResource WashedOut}" /><Slider Name="label1" Content="Label" Style="{StaticResource WashedOut}" /><Slider Name="checkBox1" Content="CheckBox" Style="{StaticResource WashedOut}" />

Same style applied to

different controls

Styles Example 2<Window.Resources> <Style x:Key="SliderStyle"> <Setter Property="Slider.Minimum" Value="0" /> <Setter Property="Slider.Maximum" Value="255" /> <Setter Property="Slider.IsSnapToTickEnabled" Value="True" /> <EventSetter Event="Slider.ValueChanged" Handler="slider_ValueChanged" /> </Style></Window.Resources>

<Slider Name="redSlider" Style="{StaticResource SliderStyle}" /><Slider Name="greenSlider" Style="{StaticResource SliderStyle}" /><Slider Name="blueSlider" Style="{StaticResource SliderStyle}" />

Control Templates

• Appearance of WPF controls determined by a control template

• Control template is a hierarchy of visual elements

• All visual controls use a default control template

• Changes to a control’s control template can redefine the appearance of the control without changing its functionality

Button|

Border|

ContentPresenter|

String

Displays single element

Control Template Example<Window.Resources> <ControlTemplate x:Key=“MyButtonTemplate" TargetType="Button"> <Border Name="Border" BorderThickness="2" CornerRadius="10" BorderBrush="BlueViolet"> <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center" TextBlock.FontWeight="Bold" TextBlock.Foreground="Firebrick" Content="{TemplateBinding Content}" /> </Border> </ControlTemplate></Window.Resources>

<Button Name="button1" Width="100" Height="30"> Button 1</Button><Button Name="button2" Width="100" Height="30" Template="{StaticResource MyButtonTemplate}"> Button 2</Button>

Triggers

• Triggers can be used to change a control’s appearance when it enters a certain state

• Can be used with Styles or Control Templates• Must be defined in Style.Triggers or ControlTemplate.Triggers

Style with Trigger Example<Window.Resources> <Style x:Key="MyButtonStyle" > <Setter Property="Button.Opacity" Value="0.5" /> <Style.Triggers> <Trigger Property="Button.IsMouseOver" Value="True"> <Setter Property="Button.Opacity" Value="1" /> </Trigger> </Style.Triggers> </Style></Window.Resources>

<Button Name="mybutton" Width="100" Height="30" Style="{StaticResource MyButtonStyle}">Push Me</Button>

Control Template with Trigger Example <Window.Resources> <ControlTemplate x:Key=“MyButtonTemplate" TargetType="Button"> <Border Name="Border" BorderThickness="2" CornerRadius="10" BorderBrush="BlueViolet"> <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center" TextBlock.FontWeight="Bold" TextBlock.Foreground="Firebrick" Content="{TemplateBinding Content}" /> </Border> <ControlTemplate.Triggers> <Trigger Property="IsMouseOver" Value="True"> <Setter TargetName="Border" Property="Background" Value="LightBlue" /> </Trigger> </ControlTemplate.Triggers> </ControlTemplate></Window.Resources>

<Button Name="button2" Width="100" Height="30" Template="{StaticResource MyButtonTemplate}">Button 2</Button>

trigger