Windows Presentation Foundation (WPF) and Dyalog APL

Windows Presentation

Foundation (WPF) and

Dyalog APLA new era

Dan Baronet and Michael HughesBoston 2011

V1.00

1Dyalog’11 - BostonWPF and APL

Why WPF?

It is difficult to stay on top of the latest changes in the GUI world.

Windows Presentation Foundation (WPF) is a framework (based on .NET) for describing all kinds of GUI

Easy to use from APL


DirectX ±= assembler of graphicsWPF ±= APL DirectX takes care of all the nitty gritty details such as drawing.WPF uses DirectX (and User32 for some services, eg screen areas)Does not use GDI/GDI32/GDI+ - essentially replaces win32

WPF is a replacement, not a new wrapper.

DirectX is the technology used underneath

DirectX

• DirectX is more efficient because it understands higher-level ingredients such as textures and gradients that can be rendered directly by the video card. GDI/GDI+ doesn’t.

WPF and APL Dyalog’11 - Boston 4

PresentationCore.dll

ApplicationsControls

Styling

Layout Data Content

Action

Presentation Framework

MilCore.dll

DirectX

Driver


GoalThe goal of WPF is to offload as much of the work as possible on the video card so that complex graphics routines are render-bound (limited by the GPU) rather than processor-bound (limited by your computer’s CPU).


An ideal choice

• WPF is an ideal choice and it offers the best prospects for future enhancements and longevity

• Win32 is a general bucket that includes any technology that runs on Windows: DirectX, MFC, WTL, OpenGL, and so on.

• Resolution Independence 7Dyalog’11 - BostonWPF and APL



Although WPF is a relatively new technology, it already exists in two versions:

• WPF 3.0. The first version of WPF was released with two other new technologies:Windows Communication Foundation (WCF) and Windows Workflow Foundation (WF). Together, these three technologies were called the .NET Framework 3.0 (even though the core bits of .NET weren’t changed).• WPF 3.5. A year later, a new version of WPF was released as part of the .NET Framework 3.5. The new features in WPF are mostly minor refinements. Some of these bug fixes and performance improvements are available to .NET Framework 3.0 applications through the .NET Framework 3.0 Service Pack 1.

The Evolution of WPF


Divide and conquerSeparating the design from the code

should be done.The premise of combining designers and

developers to create a better experience is not new, but it has also never been an efficient collaboration.

With the introduction of XAML, walls that may have existed between designers and developers are no longer in place.


XAML (short for Extensible Application Markup Language, and pronounced “zammel”) is a markup language used to instantiate .NET objects

XAML documents define the arrangement of panels, buttons, and controls that make up the windows in a WPF application

XML-based formats such as XAML are flexible and easily portable to other tools and platforms. You’re not locked into Visual Studio for ex.

XML was designed to be logical, readable, and straightforward—not compact

Everything done with XAML can be done entirely in your favorite .NET language (but note that the reverse is not true).

XAML


XAML: Namespaces

• http://schemas.microsoft.com/winfx/2006/xaml/presentation maps to the .NET namespace System.Windows.Controls

• http://schemas.microsoft.com/winfx/2006/xaml is the XAML language namespace, which maps to types in the System.Windows.Markup namespace


XAML: Attributes vs PropertiesAttribute:<Button Content=”OK”

Background=”White”/>

Property:<Button> <Button.Content>OK</Button.Content>…<Button.Background>White</

Button.Background></Button>


No size/pos

Hard-coded sizes are usually not the ideal approach to creating user interfaces.

They limit your ability to handle dynamic content and they make it more difficult to localize your application into other languages.


No fixed coordinates

• Instead, the emphasis is on creating more flexible layouts that can adapt to changing content, different languages, and a variety of window sizes.

• Hard-coded sizes and positions are evil because they limit your ability to localize your interface, and they make it much more difficult to deal with dynamic content.


Matching arguments with real values

In order to bridge the gap between string values and nonstring properties (e.g. a number) , the XAML parser needs to perform a conversion.

The conversion is performed by type converters, a basic piece of .NET infrastructure that’s existed since .NET 1.0.


Panels

• Panels are containers• Panels may contain several

elements• There are many kinds of panels,

each with their own layout logic• WPF uses Panels extensively


Panels

• They are parent elements that support the arrangement of multiple children, and derive from the abstract System.Windows.Controls.Panel class.

• All the elements involved in the layout process (both parents and children) derive from System.Windows.UIElement.


StackPanel

• StackPanel Places elements in a horizontal or vertical stack. This layout container is typically used for small sections of a larger, more complex window.


DockPanel

Aligns elements against an entire edge of the container.


WrapPanel

• Places elements in a series of wrapped lines. In horizontal orientation, the WrapPanel lays items out in a row from left to right and then onto subsequent lines. In vertical orientation, the WrapPanel lays out items in a top-to-bottom column and then uses additional columns to fit the remaining items


Grid

• Arranges elements in rows and columns according to an invisible table.

• This is one of the most flexible and commonly used layout containers


UniformGrid

• Places elements in an invisible table but forces all cells to have the same size.

• This layout container is used infrequently.


Canvas

• Allows elements to be positioned absolutely using fixed coordinates.

• This layout container is the most similar to traditional Windows Forms, but it doesn’t provide anchoring or docking features. As a result, it’s an unsuitable choice for a resizable window unless you’re willing to do a fair bit of work.


Other features

• There are many features not found in []WC objects


Routed Events

• It allows an event to originate in one element but be raised by another one.

• For example, event routing allows a click that begins in a toolbar button to rise up to the toolbar and then to the containing window before it’s handled by your code.


Routed EventsRouted events actually come in the following three flavors:

• Direct events are like ordinary .NET events. They originate in one element and don’t pass to any other. For example, MouseEnter (which fires when the mouse pointer moves over an element) is a direct event.

• Bubbling events are events that travel up the containment hierarchy. For example, MouseDown is a bubbling event. It’s raised first by the element that is clicked. Next, it’s raised by that element’s parent, and then by that element’s parent, and so on, until WPF reaches the top of the element tree.

• Tunneling events are events that travel down the containment hierarchy. They give you the chance to preview (and possibly stop) an event before it reaches the appropriate control. For example, PreviewKeyDown allows you to intercept a key press, first at the window level, and then in increasingly more specific containers until you reach the element


Dependency Properties

• Change notification• Property value inheritance• Support for multiple providers


Styles?• <Button MinWidth=”75” Margin=”10”>• <Button.Style>• <Style TargetType=”{x:Type Button}”>• <Style.Triggers>• <Trigger Property=”IsMouseOver”

Value=”True”>• <Setter Property=”Foreground” Value=”Blue”/>• </Trigger>• </Style.Triggers>• </Style>• </Button.Style>• OK• </Button>


Data Binding• Data binding is about tying together arbitrary .NET

objects. The classic scenario is providing a visual representation (for example, in a ListBox or ListView) of items in an XML file, database, or an in-memory collection.

• For example, instead of iterating through a data source and manually adding a ListBoxItem to a ListBox for each one, it would be nice to just say, “Hey, ListBox! Get your items from over here. And keep them up to date, please. Oh yeah, and format them to look like this.” Data binding enables this and much more.


Data Binding

• XmlDataProvider could be considered a “killer app” for data binding, as it makes retrieving, parsing, navigating, and displaying remote XML data incredibly easy.

• The ability to get asynchronous behavior on any Binding or data provider simply by setting a Boolean property also makes data binding a compelling alternative to performing such work manually.


Triggers

• Property triggers—Invoked when the value of a dependency property changes

• Data triggers—Invoked when the value of a plain .NET property changes

• Event triggers—Invoked when a routed event is raised


Expressing More Complex Logic with Triggers

• Multiple triggers can be applied to the same element (to get a logical OR).

• Multiple properties can be evaluated for the same trigger (to get a logical AND).


Easy Graphics

• The ability to create and use vector-based 2D graphics is not unique to WPF; even GDI enabled the drawing of paths and shapes.

• The main difference with drawing in WPF versus GDI or any previous Window technology is that WPF is a completely retained-mode graphics system rather than an immediate-mode graphics system.


SilverLight

SilverLight is a slightly cut-down version of WPF, which can run in most popular browsers & includes a small .NET Framework.

Applications built on SilverLight (like ”APL#”) can run in the browser ”without installation” on the client (Windows only) computer


3 examples

• A windows application• A web app• A Silverlight app

+ how to store XAML in e.g. SVN and use it other dev interfaces.


Documents

Windows Presentation Foundation (WPF) and Dyalog APL