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Architectures for Inclusive Design

Architectures for Inclusive Design



An overview of creating accessible user interface architectures. Covers the role of architecture in development, the limitations of traditional Object Oriented and MVC paradigms, and an overview of ...

An overview of creating accessible user interface architectures. Covers the role of architecture in development, the limitations of traditional Object Oriented and MVC paradigms, and an overview of how assistive technologies work. Presented as a guest lecture in University of Toronto Faculty of Information's INF 2187H: Introduction to Inclusive Design course.



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    Architectures for Inclusive Design Architectures for Inclusive Design Presentation Transcript

    • Architectures for Inclusive Design Colin Clark, Fluid Project Technical Lead Adaptive Technology Resource Centre
    • Things we’ll talk about • Priorities for software • What is software architecture? • Object oriented programming • Model View Controller • Case study: the Web • How do assistive technologies work? • Rethinking the role-based paradigm • Techniques for open architecture
    • Who am I? Who are you?
    • Fluid... http://fluidproject.org • Is an open source community of - Designers - Developers - Accessibility experts • Helps other open communities • Consists of universities, museums and individuals
    • What We Do • Offer design advice and resources • Contribute to other communities: - jQuery UI - Dojo - W3C Accessibility • Build Infusion, our JavaScript application framework • Build Kettle, our JavaScript server-side infrastructure
    • Software priorities
    • Some questions... 1. What’s the most important thing on your computer? 2. What’s your favourite piece of software? 3. Why do you use software?
    • Content is king • Your stuff. • The things you do with your stuff. Software architectures need to be focussed on enabling creativity and contribution, for everyone.
    • Software shouldn’t suck • Good software... • Doesn’t crash • Doesn’t eat your data • Helps you accomplish your goals • Is fast enough to keep up with you • Can grow over time with your needs
    • Architecture
    • What is architecture? • Concerned with the shape of software • Defines the structure and APIs of a system • Highly abstract: recognition of patterns • Best done iteratively, not all up front
    • Architecture is hard • Code is hard to understand and maintain • Goals of a good architecture: • Enable growth • Allow for outside extension • Manage dependencies
    • Architectural tendencies • Loose coupling • Shallow dependency hierarchies • Interoperability & semantics • Less code
    • Object Orientation
    • Goals of OO • Define a system in real-world terms • Hide away the guts of an implementation • Create small, useful modules • Enable reusability
    • Three Pillars of OO 1. Inheritance 2. Encapsulation 3. Polymorphism
    • Inheritance • A way of structuring dependencies and reusing code • Defines the identity of an object (is a) • Mammals, Felines, Cats and Lions • Vehicles, Cars, and Trucks • Fruit, Apples, Oranges • Lost of other contrived examples...
    • Inheritance AbstractMap Method Method Method Data Method IdentityHashMap HashMap Method Method Method Method Method Method Data Data Method Method PrinterStateReasons LinkedHashMap Method Method Method Method Method Method Data Data Method Method
    • Encapsulation • Hide away the internals of an object • Define a contract through methods • Traditionally, data is considered opaque
    • Encapsulated Object Method Method Method Data Method
    • Polymorphism • The ability for different objects to respond to the same method in different ways • Interface vs. implementation
    • Crumbling Pillars • Inheritance is brittle and ineffective • Composition (has a) works better • Encapsulation can lead to overzealousness: • Cuts off access to useful information • Assumes custom structures are better than plain old, interoperable standards
    • Model View Controller
    • Model View Controller • Model is the application data and associated behaviour • View presents the model and drives the interaction logic • Controller is glue, mediating access between model and view
    • Traditional MVC Model n atio oti c State Query State Change ge N n Cha View Selection View Controller User Gestures
    • The Problem with Controllers • Controllers are the least defined part of the equation • What’s “glue?” • Always referred to as the non-reusable part • MVC has been warped over the decades
    • Controllers and Frameworks • Orginally, in Smalltalk, the Controller managed the low-level event loop for an application • In Web apps, they’re usually responsible for parsing requests and dispatching • These are both things that high-level frameworks do for us now • E.g. The event loop in a Web browser
    • Model View (controller) Model Change Noti cation State Query State Change View Framework
    • The Web
    • Architecture of the Web • Separation of structure from presentation • Declarative • Stateless • Interoperable
    • Structure vs. Presentation <ul class="fl-list-menu"> .fl-list-menu li { <li> padding:0; <a href="#">Link Text</a> } </li> .fl-list-menu li a {   <li> display:block; <a href="#">Link Text</a> padding: 12px 0px 12px 12px; </li> text-decoration: none;   <li> font-weight: bold; <a href="#">Link Text</a> outline: none; </li> } </ul>
    • Declarative Programming Declarative programming is a programming paradigm that expresses the logic of a computation without describing its control flow
    • Declarative Programming what not how
    • Compare & Contrast
    • Compare & Contrast Scroller
    • Imperative if (!highlighted) { ctx.globalAlpha = 0.3; } else { // Draw the scroll track rectangle. var clientLength = this._getClientLength(); ctx.fillStyle = theme.scrollTrackFillStyle; ctx.fillRect(NIB_PADDING + 0.5, 0.5, clientLength - 2*NIB_PADDING, thickness - 1); ctx.strokeStyle = theme.scrollTrackStrokeStyle; ctx.strokeRect(NIB_PADDING + 0.5, 0.5, clientLength - 2*NIB_PADDING, thickness - 1); } var buildHandlePath = function() { ctx.beginPath(); ctx.arc(handleDistance + halfThickness + 0.5, // x halfThickness, // y halfThickness - 0.5, Math.PI / 2, 3 * Math.PI / 2, false); ctx.arc(handleDistance + handleLength - halfThickness - 0.5, // x halfThickness, // y halfThickness - 0.5, 3 * Math.PI / 2, Math.PI / 2, false); ctx.lineTo(handleDistance + halfThickness + 0.5, thickness - 0.5); ctx.closePath(); }; buildHandlePath(); // Paint the interior of the handle path. var gradient = ctx.createLinearGradient(handleDistance, 0, handleDistance, thickness); gradient.addColorStop(0, theme.scrollBarFillGradientTopStart.replace(/%a/, alpha)); gradient.addColorStop(0.4, theme.scrollBarFillGradientTopStop.replace(/%a/, alpha)); gradient.addColorStop(0.41, theme.scrollBarFillStyle.replace(/%a/, alpha)); gradient.addColorStop(0.8, theme.scrollBarFillGradientBottomStart.replace(/%a/, alpha)); gradient.addColorStop(1, theme.scrollBarFillGradientBottomStop.replace(/%a/, alpha)); ctx.fillStyle = gradient; ctx.fill();
    • Declarative .fl-thumbnailContainer { position: absolute; top: 0pt; <form class="fl-thumbnailContainer"> left: 0pt; ... bottom: 0pt; </form> overflow: auto; width: 185px; z-index: 100; }
    • Statelessness “The Web is broken. It can’t remember me between requests”
    • Statelessness • The Web is stateless for a reason: it scales • State is visible, not encapsulated http://build.fluidproject.org:8095/engage/artifacts/view.html? accessNumber=M2000.38.97&db=mccord&lang=en
    • Interoperable • Web formats are: • Plain text • Declarative • Openly published and standardized • This means they are adaptable and extensible
    • How assistive technologies work
    • Assistive Technologies • Present and control the user interface in different ways • Not just screen readers! • Use built-in operating system APIs to understand the user interface Screen readers Screen magnifiers On-screen keyboards
    • OS AT APIs • A channel for UI introspection • What’s on screen? • How are things labelled, organized, etc.? • What states are things in? • UI Roles, states, properties
    • The Role-Based Model • Just about every API works the same way • Give each UI widget a name • e.g. slider, tabs, dialog, button, text field • Names imply behaviour • For AT users, names define interactions
    • View Hierarchies
    • Accessibility Inspector
    • Like getting a flood of data through a straw...
    • Hearing it in action
    • Web Accessibility
    • Opaque Markup // These are tabs. How would you know? <ol> <li><a href=”#cats”>Cats</a></li> <li><a href=”#dogs”>Dogs</a></li> <li><a href=”#gators”>Gators</a></li> </ol> <div> <div id=”cats”>Cats meow.</div> <div id=”dogs”>Dogs bark.</div> <div id=”gators”>Gators bite.</div> </div>
    • Opaque Markup: Tabs
    • ARIA • Accessible Rich Internet Applications • W3C specification in the works • Fills the semantic gaps in HTML • Roles, states, and properties • Live regions
    • Roles, States, Properties • Roles describe widgets not present in HTML 4 • slider, menubar, tab, dialog • Properties describe characteristics: • draggable, hasPopup, required • States describe what’s happening: • busy, disabled, selected, hidden
    • Using ARIA // Now *these* are Tabs! <ol id=”animalTabs” role=”tablist” tabindex=”0”> <!-- Individual Tabs shouldn’t be focusable --> <!-- We’ll focus them with JavaScript instead --> <li role=”tab”><a href=”#” tabindex=”-1”>Cats</a></li> <li role=”tab”><a href=”#” tabindex=”-1”>Dogs</a></li> <li role=”tab”><a href=”#” tabindex=”-1”>Gators</a></li> </ol> <div id=”panels”> <div role=”tabpanel” aria-labelledby=”cats”>Cats meow.</div> <div role=”tabpanel” aria-labelledby=”dogs”>Dogs bark.</div> <div role=”tabpanel” aria-labelledby=”gators”>Gators bite.</div> </div>
    • Adding ARIA in Code // Identify the container as a list of tabs. tabContainer.attr("role", "tablist"); // Give each tab the "tab" role. tabs.attr("role", "tab"); // Give each panel the appropriate role, panels.attr("role", "tabpanel"); panels.each(function (idx, panel) { var tabForPanel = that.tabs.eq(idx); // Relate the panel to the tab that labels it. $(panel).attr("aria-labelledby", tabForPanel[0].id); });
    • The Problem with Roles Roles are driven by 1980’s era desktop widgets
    • The Problem with Roles The Web is driving hybrid UIs
    • The Problem with Roles ... even on the desktop
    • Analyzing User Interfaces
    • Inline Edit Roles Button?
    • Inline Edit Roles Text Field?
    • Inline Edit Roles Button? Text Field?
    • Inline Edit Behaviours Read-only Activatable Editable Undoable
    • Open Architecture
    • Open applications • Transparent models • Event-driven • Loosely-coupled and separable • Case study: Fluid Infusion
    • Transparent Models • Break open data encapsulation • Publicly share models in standard formats • Allows others to see into your application’s data and state
    • Events • Interesting moments in the life of your app • e.g. onSave, onSelect, onOpen, etc. • Use events to wire up app, and talk to the world • Key feature: notifying people about changes in your model
    • Data Change Events Change Request Guard Observer Guard Observer Guard Observer Apply Change Method Method Data Method Method Method Data Method Method Method Data Method
    • Accessible Architectures • Interoperable apps are accessible apps • Your application state is content, too • Extensible: allow for alternatives • Personalisable
    • Slate FSS Themes Mist High Contrast
    • UI Options & FSS
    • UI Options: High Contrast Theme
    • Subcomponents • Provides loose coupling between parts (IoC) • Look up dependencies by name, and the framework will instantiate them for you • Users can implement their own version or configure alternatives
    • Subcomponents Illustrated
    • Uploader Dialog Box
    • Uploader File Queue
    • Uploader File Row
    • Uploader Progress Bar
    • Where does this lead us? • Today, ATs just describe what’s visible • Imagine alternative representations • Knowledge of structure, data, actions • Completely different UI optimized for the user?
    • Accessible architectures are... • Introspective • Declarative programming • Transparent models • Describe behaviour, roles, and state • Adaptable • Declarative programming • Loose coupling & inversion of control • Separation of structure and presentation
    • Questions?