Windows Presentation Foundation (WPF) and Dyalog APL

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Windows Presentation Foundation (WPF) and Dyalog
APL

• A new era
• Dan Baronet and Michael Hughes
• Boston 2011
• V1.00

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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

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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

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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 doesnt.

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Goal
The 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 computers CPU).
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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

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The Evolution of WPF
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 werent 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.
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Divide and conquer

• Separating 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.

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XAML
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. Youre not locked into Visual
Studio for ex. XML was designed to be logical,
readable, and straightforwardnot
compact Everything done with XAML can be done
entirely in your favorite .NET language (but note
that the reverse is not true).
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XAML Namespaces

• http//schemas.microsoft.com/winfx/2006/xaml/prese
  ntation 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

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XAML Attributes vs Properties

• Attribute
• ltButton ContentOK BackgroundWhite/gt
• Property
• ltButtongt
• ltButton.ContentgtOKlt/Button.Contentgt
• ltButton.BackgroundgtWhitelt/Button.Backgroundgt
• lt/Buttongt

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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.

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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.

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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 thats existed
  since .NET 1.0.

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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

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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.

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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.

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DockPanel

• Aligns elements against an entire edge of the
  container.

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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

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Grid

• Arranges elements in rows and columns according
  to an invisible table.
• This is one of the most flexible and commonly
  used layout containers

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UniformGrid

• Places elements in an invisible table but forces
  all cells to have the same size.
• This layout container is used infrequently.

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Canvas

• Allows elements to be positioned absolutely using
  fixed coordinates.
• This layout container is the most similar to
  traditional Windows Forms, but it doesnt provide
  anchoring or docking features. As a result, its
  an unsuitable choice for a resizable window
  unless youre willing to do a fair bit of work.

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Other features

• There are many features not found in WC objects

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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
  its handled by your code.

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Routed Events

• Routed events actually come in the following
  three flavors
• Direct events are like ordinary .NET events. They
  originate in one element and dont 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. Its raised first by the
  element that is clicked. Next, its raised by
  that elements parent, and then by that elements
  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

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Dependency Properties

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

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Styles?

• ltButton MinWidth75 Margin10gt
• ltButton.Stylegt
• ltStyle TargetTypexType Buttongt
• ltStyle.Triggersgt
• ltTrigger PropertyIsMouseOver ValueTruegt
• ltSetter PropertyForeground ValueBlue/gt
• lt/Triggergt
• lt/Style.Triggersgt
• lt/Stylegt
• lt/Button.Stylegt
• OK
• lt/Buttongt

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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.

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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.

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Triggers

• Property triggersInvoked when the value of a
  dependency property changes
• Data triggersInvoked when the value of a plain
  .NET property changes
• Event triggersInvoked when a routed event is
  raised

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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).

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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.

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• Class Name Usage
• HwndHost Hosting an HWND in WPF
• WindowsFormsHost Hosting Windows Forms in WPF
• HwndSource Hosting WPF in an HWND
• ElementHost Hosting WPF in Windows Forms

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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

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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.