820 windows phone 7 development internals

Whether you’re an existing Microsoft Silverlight developer wanting to branch out into the mobile space, an existing mobile developer looking to extend your reach across a second or third

Windows® Phone 7

Development Internals

Andrew Whitechapel

Published with the authorization of Microsoft Corporation by:

O’Reilly Media, Inc

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Copyright © 2012 by Andrew Whitechapel

All rights reserved No part of the contents of this book may be reproduced or transmitted in any form or by any means without the written permission of the publisher

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Acquisitions Editor: Russell Jones

Developmental Editor: Russell Jones

Production Editor: Melanie Yarbrough

Editorial Production: Octal Publishing, Inc.

Technical Reviewer: Peter Torr

Copyeditor: Bob Russell

Indexer: WordCo Indexing Services

Cover Design: Twist Creative • Seattle

Cover Composition: Karen Montgomery

Illustrator: Robert Romano

Contents at a Glance

Foreword xvii Introduction xix

PART II APPlICATIon MoDEl

PART III ExTEnDED sERvICEs

PART Iv vERsIon 7.5 EnhAnCEMEnTs

ChAPter 15 Multi-tasking and Fast App Switching 553

Foreword xvii

Introduction xix

PART I BuIlDIng BloCks Chapter 1 vision and Architecture 3 Windows Phone Vision .3

Metro 4

Developer Guidelines 7

Windows Phone Architecture 8

Comparison of Silverlight and XNA 9

Developer Tools 10

Development Cycle 11

The Anatomy of a Basic Windows Phone Application .13

XAP Contents 14

Standard Project Types .15

Themes and Accent Colors 17

Standard Application Images 22

Version 7 vs Version 7.1 24

Summary .27

Chapter 2 uI Core 29 Phone UI Elements 29

Standard UI Elements 29

Visual Tree 32

Screen Layout 38

UserControl vs Custom Control 41

Routed Events 44

Resources 47

Content vs Resource 48

Resource Dictionaries 49

Dependency and Attached Properties 54

Dependency Properties .54

Attached Properties 56

Summary .59

Chapter 3 Controls 61 Standard Controls 61

Platform, SDK, Toolkit 61

SDK Controls: Pivot .63

SDK Controls: Panorama 69

Toolkit Controls .78

Transient Panels 81

Summary .89

Chapter 4 Data Binding and layer Decoupling 91 Life without Data Binding 91

Simple Data Binding and INotifyPropertyChanged .94

Data Binding Collections 98

Data Templates 100

Dynamic Data-Bound Collections 103

Template Resources 105

Type/Value Converters 106

Element Binding 108

Data Validation 110

Separating Concerns .113

Design-Time Data .115

The Model-View ViewModel Pattern 117

The Visual Studio Databound Application Project 124

Summary .133

Chapter 5 Touch uI 135

Logical Touch Gestures .135

Manipulation Events: Single Touch (Tap) .138

Manipulation Events: Single Touch (Flick) 140

Manipulation Events: Multi-Touch 142

Mouse Events 144

FrameReported Events 147

Combining Manipulation and Mouse Events 148

Click vs Mouse/Manipulation Events 150

The Silverlight Toolkit GestureService 150

Pinch and Drag 152

Flick and Tap 153

Problems with the GestureService 154

Behaviors 155

Keyboard Input 159

Orientation .162

The Application Bar .167

Summary .172

PART II APPlICATIon MoDEl Chapter 6 Application Model 175 Lifetime Events and Tombstoning 175

Application Closing 180

Application Deactivated .181

Application Deactivated (the Non-Tombstone Case) .183

Unhandled Exceptions 185

Why Is There No App.Exit? 186

Obscured and Unobscured .186

Launchers/Choosers and Tombstoning 189

User Expectations 189

Page Model 190

Page Creation Order 195

Summary .198

Chapter 7 navigation state and storage 199 Navigation and State 199

Application and Page State 200

Detecting Resurrection 207

Navigation Options .209

Using NavigateUri 209

Pages in Separate Assemblies 210

Fragment and QueryString 211

The NavigationMode Property .214

Rerouting Navigation and URI Mappers 215

Nonlinear Navigation Service .217

Isolated Storage .220

Simple Persistence 221

Persisting the ViewModel 225

Serialization Options 229

Isolated Storage Helpers 237

Summary .241

Chapter 8 Diagnostics and Debugging 243 Visual Studio Debugging 243

Simple Diagnostics 244

Setting Up a Diagnostics Pop-Up Window 244

Fixed Diagnostics Control 249

Post-Release Diagnostics .251

Persisting Logs 253

Configurable Diagnostics 255

Screen Capture 259

Emulator Console Output 261

Debugging Tombstoning and Lock-Screen 263

Debugging MediaPlayer 264

Device and User Information 267

Windows Phone Performance Counters 271

Memory Diagnostics 273

The Device Emulator 278

Emulator vs Device 279

XDE Automation 280

Using the Microsoft Network Monitor 283

Fiddler 285

Silverlight Spy .287

Summary .288

PART III ExTEnDED sERvICEs Chapter 9 Phone services 291 Phone Hardware 291

Launchers and Choosers 293

Photo Extras .297

Accelerometer 301

Reactive Extensions for NET 304

Level Starter Kit .307

Shake 311

Geo-Location 314

Summary .318

Chapter 10 Media services 319 Audio and Video Hardware 319

Audio and Video APIs .320

Media Playback 320

The MediaPlayerLauncher Class 321

The MediaElement Class 321

The MediaStreamSource and ManagedMediaHelpers Classes 323

MediaElement Controls 325

Audio Input and Manipulation 328

The SoundEffect and SoundEffectInstance Classes 329

Audio Input and the Microphone 331

The DynamicSoundEffectInstance Class 339

Music and Videos Hub 343

The FM Tuner 345

Summary .348

Chapter 11 Web and Cloud 349 The WebClient Class 349

WebClient: The DownloadStringAsync Method .349

WebClient: The OpenReadAsync Method 351

The HttpWebRequest Class 353

Web Browser Control 353

Silverlight and Javascript 355

Web Services 358

WCF Data Services 361

The OData Client and XML Data 361

JSON-Formatted Data 369

Bing Maps and Geolocation 372

Using the Map Control 372

Geolocation 374

Bing Maps Web Services 375

Deep Zoom (MultiScaleImage) 378

Windows Azure 383

Windows Azure Web Services 385

Windows Azure Toolkit for Windows Phone 390

bitly 394

Facebook .396

Windows Live 400

SkyDrive 405

Summary .407

Chapter 12 Push Notifications 409

Architecture 409

Push Notification Server .412

Push Notification Client 418

Additional Server Features .423

Batching Intervals 423

XML Payload 424

Response Information 426

Additional Client Features 427

Persistent Client Settings .427

The ErrorOccurred Event 428

User Opt-In/Out 429

Implementing a Push ViewModel 431

The Push Notification Server-Side Helper Library 437

Common Push Notification Service 439

Summary .443

Chapter 13 security 445 Device Security 445

Application Safeguards 446

Application Deployment 447

Managed Code Constraints 449

Chambers and Capabilities 451

Missing Security Features 454

Data Encryption 455

SDL Tools .460

Threat Modeling 461

Static Code Analysis/FxCop 462

Web Service Security 467

Authentication 468

Forms Authentication 468

Basic Authentication 479

SSL 484

Push Notification Security 490

OAuth 1.0 491

OAuth 2.0 493

Securing Web Service IDs 494

Implementing Security for the WebBrowser Control 496

Summary .497

Chapter 14 go to Market 499 Threading 499

Performance .505

UI vs Render Thread, and BitmapCache Mode 505

UI Layout and ListBoxes 512

More UI Performance Tips 513

Non-UI Performance Tips 515

Silverlight Unit Testing Framework .517

Certification and Publication .523

Updates 530

Marketplace Reports 533

Beta Testing 534

Versions 534

Light-Up Features 535

Obfuscation 537

Ads 540

Trial Mode 544

Silverlight Analytics Framework 546

Summary .549

PART Iv vERsIon 7.5 EnhAnCEMEnTs

Fast Application Switching .553

Multi-Tasking 557

Alarms and Reminders 558

Alarms .558

Reminders 561

Background Transfer Service 564

Generic Background Agents 568

Background Audio 578

Background Audio: The Main Application 583

Background Audio: The Background Agent 585

Summary .587

Chapter 16 Enhanced Phone services 589 Sensor APIs 589

Accelerometer .590

Compass .593

Gyroscope 598

Motion APIs 601

Camera Pipeline .606

Augmented Reality 610

The Geo Augmented Reality Toolkit .614

New Photo Extensibility 616

Launcher and Chooser Enhancements 619

The DeviceStatus and DeviceNetworkInformation classes 621

Version 7.1.1 623

Summary .626

Chapter 17 Enhanced Connectivity Features 627

Push, Tile, and Toast Enhancements 627

Local Tiles .628

Pinning Tiles 632

Push Enhancements 638

Sockets 642

TCP Sockets 643

OData Client 650

Search Extensibility 657

App Connect .657

App Instant Answer 664

Summary .665

Chapter 18 Data support 667 Local Database and LINQ-to-SQL 667

Create and Read 669

Update and Delete 675

Schema Updates 677

Associations 681

Isolated Storage Explorer Tool 684

Performance Considerations 692

Database Encryption 695

Encrypting Data and Credentials 697

Contacts and Calendar 699

Sync Framework .703

Service Configuration 705

Database Provisioning 707

Code Generation 707

Summary .710

Chapter 19 Framework Enhancements 711

Navigation Enhancements 711

Frame and Page Navigation 711

Backstack Management 714

UI Enhancements .717

Enhanced Controls 718

The ApplicationBar and SystemTray Classes, and the ProgressIndicator Property .723

The Clipboard API .727

32 Bits per Pixel .728

Background Image Decoding 729

Touch Thread .729

Silverlight 4.0 730

Implicit Styles 730

Command Binding 732

Data-Binding Enhancements 736

Summary .744

Chapter 20 Tooling Enhancements 745 Emulator Improvements .745

Debugger Experience 747

Marketplace Test Kit 749

The Profiler 754

UserVoice Forums 764

Portable Library Tools .765

Async Framework 769

Summary .772

Index 773

So, you’re curious about Windows Phone development? Welcome aboard! Whether you’re an

existing Microsoft Silverlight developer wanting to branch out into the mobile space, an existing

mobile developer looking to extend your reach across a second or third ecosystem, a rising star who’s

ready to create the Next Big Thing and take the world by storm, or maybe just a curious phone user

who wants to know what all the “app” fuss is about, Windows Phone is the platform for you

Getting started with Windows Phone development is free and easy; everything you need to write

apps is just a couple of clicks away You can have your first app up and running in a matter of minutes,

even if you know next to nothing about Windows Phone development or don’t even own a device As

your apps become more ambitious and you encounter more complex development issues, a vibrant

developer community on the web is ready and willing to help you out along the way Mastery of this

platform, with its rich feature set, unique application model, integrated end-to-end experiences, and

burgeoning international marketplace, takes time and effort—and an expertly written guide Luckily

for you, this book is just such a guide

The Windows Phone platform stands on the shoulders of giants—giants such as Silverlight, XNA,

Microsoft Visual Studio, and Microsoft Expression Blend—and as we built the platform, we embraced

the power and familiarity that these existing technologies afforded us; our goal was to introduce new

concepts only when strictly necessary to enable new scenarios, and to re-use existing concepts

every-where else We spent less time re-solving old problems (such as navigation and microphone capture)

and more time tackling new ones so that we could ship a vast array of new phone-specific APIs for

developers to wrap their heads around—cameras, gyroscopes, multi-tasking, phone integration, user

data access, and live tile updates, just to name a few—and Andrew covers all of them (and more!) in

this book

As you’ve probably heard (and seen), Windows Phone ushered in a new design language for

Microsoft, code-named “Metro.” Adhering closely to this design is critical when building user

experi-ences that will delight and engage your customers As you would expect, the Windows Phone

devel-oper tools give you a big helping hand in this department, providing user interface elements and

ap-plication templates that “just work” by default Nevertheless, as the owner of your apap-plication’s overall

experience you are ultimately responsible for ensuring it performs optimally, adhering not just to the

graphic design rules, such as “content over chrome,” but also the fast and fluid interaction model that

your customers will come to expect Throughout this book you’ll find practical examples and

guid-ance that show how to embody the Metro design language in your applications, along with examples

of common pitfalls and how to avoid them—particularly with respect to application performance and

responsiveness, which are key factors in user satisfaction (and hence, app ratings and profitability)

On a more personal note, I was thrilled when Andrew asked me to tech-review this book (although writing this foreword was more than a little daunting!) As an infrastructure guy at heart, I love build-ing platforms and enabling developers to be successful on top of them, but there are only so many people you can reach via blogs or conference speaking sessions I’ve been asked to author books before, but I've never had the time or inclination to do so By piggybacking on Andrew’s hard work with this book, I feel like I’ve made a difference—if only a small one—and that makes me grateful for the opportunity I also learned a lot while reviewing this book, and I know that you will, too.

Peter Torr

Program Manager in the Windows Phone Application Platform team

The smart phone is increasingly important in people’s daily lives It is used for a wide variety of

tasks, both work-related and non-work related People use smart phones to keep up to date

with friends and family, for relaxation, and for entertainment, as well as for viewing documents and

spreadsheets, surfing the Internet, and enriching their lives There is therefore considerable scope

for building smart phone applications Windows Phone is not just another smart phone; rather, it is

positioned as an opportunity for developers to build applications that can make a real difference to

people’s lives The platform has been designed from the ground up to support an all-encompassing,

integrated, and attractive user experience

Windows Phone 7 Development Internals covers the breadth of application development for the

Windows Phone platform, both the major 7 and 7.1/7.5 versions and the minor 7.1.1 version, and

shows how you can build such compelling and useful applications You can build applications for

Windows Phone 7.x by using either the Microsoft Silverlight runtime or the XNA runtime This book

focuses on Silverlight applications The primary development and design tools are Microsoft Visual

Studio and Microsoft Expression Blend Here again, this book focuses on Visual Studio

Each chapter covers a handful of related features For each feature, the book provides one or more

sample applications and walks you through the significant code (C# and XAML) This will help you

to understand the techniques used and also the design and implementation choices that you have

in each case Potential pitfalls are called out, as are scenarios in which you can typically make

per-formance or user experience improvements An underlying theme is to conform not only to the user

interface design guidelines, but also to the notion of a balanced, healthy phone ecosystem

Who should Read This Book

This book is intended to help existing developers understand the core concepts, the significant

pro-grammable feature areas, and the major techniques in Windows Phone development The book is

tai-lored for existing Silverlight developers that want to jump into the exciting world of mobile application

developer with the Windows Phone platform Developers experienced with other mobile platforms

will find this book invaluable in learning the ins and outs of Microsoft’s operating system, but will

likely need additional resources to pick up C# and XAML languages

The Windows Phone 7 release only supports C#, and although support for Visual Basic was

intro-duced with the 7.1 SDK, this book focuses purely on C# and XAML The basic architecture of the

platform is covered in Chapter 1, “Vision and Architecture,” and most chapters go deeply into the

internal behavior of the system This is knowledge that helps to round out your understanding of the

platform, and inform your design decisions, even though, in some cases, the internal details have no

immediate impact on the exposed API

The book assumes that you have a reasonable level of experience of developing in managed code, specifically in C# Basic language constructs are not discussed, nor is basic use of Visual Studio, the project system or the debugger, although more advanced techniques, and phone-specific features are, of course, explained in detail You should also have some knowledge of XAML development, preferably in Silverlight, although Windows Presentation Foundation experience would also be useful background

Although many component-level diagrams are presented as high-level abstractions, there are also many sections that describe the behavior of the feature in question through the use of UML sequence diagrams It helps to have an understanding of sequence diagrams, but it is not essential, as they are fairly self-explanatory

Who should not Read This Book

This book is not intended for use by application designers—if designers are defined as developers who use Expression Blend—although designers might find it useful to understand some of the issues facing developers in the Windows Phone application space The book is also not suitable for XNA developers because it does not cover game development at all

organization of This Book

Windows Phone 7 was first released in October 2010 The first major update, code-named “Mango,” was released in September 2011 The Mango release includes a wide range of enhancements and additional features Note that the user-focused version number for the Mango release (that is, the product version) is version 7.5; however, the developer-focused number is 7.1 (for both the OS version and the SDK version) The reason for this slightly confusing numbering situation is that the Mango release includes improvements across the board—in the operating system, the developer tooling, in the emulator, in the application platform, in Silverlight itself, and also in the server-side experience

of marketplace, and in ingestion All of this is Windows Phone, or Windows Phone 7.5 A developer is normally focused more on the pure technical aspects: the operating system, tooling, and application platform subset of the overall release, and that is technically the 7.1 release (both SDK and OS).This book covers all 7.x versions: the original Windows Phone 7 release, the later Windows Phone 7.1 release, and the minor 7.1.1 release Applications built for version 7 also work without change on 7.1 devices Note that, while there are still about a million version 7 phones in use, it is safe to assume that most of these will be upgraded to 7.1 at some point However, to keep things simple, the first

14 chapters focus on the basic infrastructure, programming model, and the core features that are common to both versions Where there are material differences, these are called out, with references

to the later chapter where the 7.1 behavior is explained in detail Chapter 15, “Multi-Tasking and Fast App Switching,” onward focuses on the features and platform enhancements that are specific

to version 7.1

The 7.1.1 version is a narrowly scoped release intended to support phones with low memory capabilities (256 MB) for specific target markets Most developers—and most applications—will not

be affected by this For the small number that might be affected, the 7.1.1 release provides additional support for performance tuning and an additional marketplace submission option, as discussed in Chapter 16, “Enhanced Phone Services.”

It’s also worth reading Chapter 14, “Go To Market” ahead of time This chapter focuses on the end-game of bringing your application to market, including tuning the design for performance and robustness, and marketplace certification Even before you have a thorough understanding of the architecture and fundamentals, it is instructive to see what you’ll be aiming for

Conventions and Features in This Book

This book presents information by using conventions designed to make the information readable and easy to follow

■

■ In some cases, especially in the early chapters, application code is listed in its entirety More often, only the significant code is listed Wherever code has been omitted for the sake of brev-ity, this is called out in the listing In all cases, you can refer to the sample code that accompa-nies this book for complete listings

■

■ In the XAML listings, attributes that are not relevant to the topic under discussion, and that have

already been explained in previous sections, are omitted This applies, for example, to Grid.Row, Grid.Column, Margin, FontSize, and similarly trivial attributes In this way, you can focus on the

elements and attributes that do actually contribute to the feature at hand, without irrelevant distractions

■

■ A vertical bar between two or more menu items (for example, File | Close), means that you should select the first menu or menu item, then the next, and so on

system Requirements

You can build and run the accompanying sample code, or you can create your own solutions from scratch, following the instructions in the text In either case, you will need the following hardware and software to create the sample applications in this book:

■

■ Either Windows Vista (x86 and x64) with Service Pack 2, all editions except the Starter Edition,

or Windows 7 (x86 and x64), all editions except the Starter Edition If you install the Windows Phone SDK 7.1.1 Update, this also works with the Windows 8 Consumer Preview, although this

is not a supported configuration

■

■ The Windows Phone SDK version 7.0 or 7.1 These are both free downloads that include Visual Studio 2010 Express Edition and all other standard tools, as listed in Chapter 1 If you install the SDK version 7.1, you can then also upgrade this with the SDK version 7.1.1 This is an update to 7.1, not a stand-alone install

Depending on your Windows configuration, you might require Local Administrator rights to install

or configure Visual Studio 2010, and to install or configure features such as Internet Information Services, if not already installed

For the latest requirements, visit the Windows Phone SDK download page at http://www.microsoft com/download/en/details.aspx?id=27570.

Code samples

All of the chapters in this book include multiple sample solutions with which you can interactively try out new material learned in the main text All sample projects can be downloaded from the following page:

http://go.microsoft.com/FWLink/?Linkid=248889

Follow the instructions to download the WP7xDevInternals.zip file

Installing the Code Samples

Follow these steps to install the code samples on your computer so that you can refer to them while learning about the techniques that they demonstrate

1 Unzip the WP7xDevInternals.zip file that you downloaded from the book’s website to any able folder on your local hard disk The sample code expands out to nearly 200 MB, and you will need even more space for the binaries if you choose to build any of the samples

suit-2 If prompted, review the displayed end-user license agreement If you accept the terms, select the accept option, and then click Next

Note If the license agreement doesn’t appear, you can access it from the same webpage

from which you downloaded the WP7xDevInternals.zip file

Using the Code Samples

When you unzip the sample code, this creates a number of subfolders, one for each chapter Within each chapter’s subfolder there are further subfolders In most cases, there is one subfolder per applica-tion (or per version of an application), but in some cases, multiple applications are grouped together; for example, where there is a server-side application as well as a client-side application in the solution

In keeping with the book's structure, the samples for the first 14 chapters were built as version 7 ects, and the remaining samples were built as version 7.1 projects However, you can use the version 7.1 (or 7.1.1) SDK for all the sample projects, for all chapters

proj-All of the samples are complete, fully functioning applications Note, however, that in some cases, you might need to update assembly references, depending on where you install the SDK as well as where you install supplementary libraries and frameworks that don’t ship with the main SDK (for instance the Silverlight toolkit, Live SDK, Azure toolkit, and so on)

For samples that demonstrate the use of some supplementary framework, you will need to load and install that framework so that you can reference its assemblies Also note that, in some cases, this requires a user ID, such as for Bing maps, FaceBook, or Google Analytics, as described in the relevant sections In all cases, you can sign up for the ID without charge as of the time of this writing

The Windows Phone development space is truly inspiring, and the Windows Phone teams at Microsoft are chock-full of smart, helpful people The list of folks who helped me prepare this book is very long I’d particularly like to thank Peter Torr for doing all the heavy lifting in the technical review It’s mainly thanks to Peter that this book isn’t riddled with schoolboy errors In addition, I’d like to thank all the other people who answered my dumb questions, and corrected my various misinterpretations of the internal workings of the platform, especially Tim Kurtzman, Wei Zhang, Jason Fuller, Vij Vasu, Abolade Gbadegesin, Andrew Clinick, Darin Miller, Mark Paley, Jeff Wilcox, Thomas Fennel, Matt Klupchak, Alper Selcuk, Gary Lin, Conrad Chang, Justin Horst, Sai Prasad Patro, Yasser Shaaban, Mike Battista, Jorge Raastroem, and Joao Guberman Raza I’d also like to thank the folks at O’Reilly Media and Mi-crosoft Press who helped to turn my scattered thoughts into polished prose, especially Russell Jones, Devon Musgrave, Melanie Yarbrough, and Bob Russell (at Octal Publishing, Inc.) Finally, none of this would have been possible without the patience and support of Narins Bergstrom

Errata & Book support

We’ve made every effort to ensure the accuracy of this book and its companion content Any rors that have been reported since this book was published are listed on our Microsoft Press site at oreilly.com:

er-http://go.microsoft.com/FWLink/?Linkid=248888

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Part I

Building Blocks

ChAPTER 1 Vision and Architecture 3 ChAPTER 2 UI Core .29 ChAPTER 3 Controls 61 ChAPTER 4 Data Binding and Layer Decoupling .91 ChAPTER 5 Touch UI .135

This part describes the overall vision and architecture of Windows Phone applications, and the basic building blocks that every application requires in order to support minimum functionality

This includes the core user interface features, the various dard controls, touch manipulation, and data-binding

stan-C h A P T E R 1

Vision and Architecture

There are two dimensions to this chapter: an introduction to the vision of the Windows Phone

plat-form and the revolutionary Metro design philosophy, and an introduction to the basic

architec-ture and building blocks of a Windows Phone application The vision is extremely important; it should

inform the way you think about applications, from first concept through design to implementation

and final publication The application platform provides support and guidance, such that it’s quite

difficult to build a truly bad application, but it is definitely possible to build an application that is in

conflict with the system and fails to provide a good user experience (UX) An understanding of the

vision should steer you toward good design choices and help you to identify potential pitfalls, thereby

accelerating your development cycle

Windows Phone vision

“Windows Phone is a software platform that can improve a person’s life.” This is a quote from the

Microsoft User Experience Design Guidelines (kept up-to-date online at http://msdn.microsoft.com/

en-us/library/hh202915(VS.92).aspx) It is a philosophy on which the teams that are responsible for

building the Windows Phone operating system, application platform, and SDK are highly focused

It’s not just marketing-speak, and it’s not just an inspirational motto—it really does speak to the core

vision of the platform

Traditional desktop operating systems such as Windows 7 and Mac OS are used for all sorts of

rea-sons and purposes, but predominantly for work-related activities So applications built for the desktop

(including browser clients for web applications) are typically business-focused (although

buttoned-down PCs are also increasingly being used for social networking applications like Facebook)

Applica-tions for Microsoft Xbox and other game consoles are predominantly geared toward entertainment

The idea behind the Windows Phone UX model is that this is a device that users turn to for

every-thing—for work and play, for keeping in touch with friends and family, for relaxation, games, music

and videos, for research and fact-finding—in short, for enhancing their day-to-day lives As

develop-ers, you have the weighty responsibility of living up to this vision You are encouraged (and extensively

supported through the application platform) to build applications that do improve the user’s life.

A good Windows Phone application is engaging, compelling, and attractive to the user A great

Windows Phone application can make a meaningful contribution to the user’s life The user

interac-tion is well thought out, predictable, and familiar It gives him enjoyment every time he uses it, or it

fulfills some pragmatic need in a simple, unobtrusive manner The application integrates seamlessly

with standard features on the phone, such as email, contacts, photos, and so on It’s a ”team player,” cooperating with the system It’s conservative in its use of CPU, memory, and sensor resources It doesn’t consume battery power in an unbounded way, and it is thoughtful about its use of the user’s data plan The application should have a way to keep itself up-to-date so that its data is always fresh

It can also be location-aware; this way, it can ensure that it is always relevant to the user’s context, and functions in the smart way that user’s expect from a “smart” phone

A good application should also look and feel like it’s a part of the overall phone ecosystem, using the Metro design guidelines in an appropriate way, so that it doesn’t jar the senses or look out of place The same applies to navigation and the way the application behaves when the user switches away from it, and perhaps comes back to it later It should be configurable, so that the user can per-sonalize it, just as he can personalize other parts of the phone experience, such as the Start page, the theme, and accent colors There should be a way for the user to provide feedback to the developer, to report bugs, or to request new features The user should be able to consider the phone as an exten-sion of his personality, configured the way he likes it, and tailoring the set of installed applications to suit his own personal needs and preferences

Metro

Metro is the code name for the design language used in establishing the UX for Windows Phone Metro is modern and clean, light, open, and fast Metro is alive and in motion—hence, the extensive use of page transition animations and the considerable thought that has gone into perfecting the standard animations to provide a visually pleasing experience Consider just one feature: when the user swipes to scroll through a list, the scrolling speed closely matches the force of the swipe gesture

It responds immediately when the user holds a finger on the screen to stop the scrolling If the user drags a list down (or up) to its limits, there’s a visible compression effect, which provides clear feed-back that she’s reached the end of the list When she releases her finger, the compression bounces back in a pleasing and intrinsically recognizable way that makes the phone seem almost organically alive The standard animations have all been designed to provide just the right level of feedback—again, in a pleasing way, without becoming intrusive or distracting

You are encouraged to use the Metro design style for your application Metro covers all aspects

of the user interface (UI), including the use of space, control styles, and typography Content is seen

as an important part of any application; this is in deliberate and emphatic contrast to chrome (that

is, artifacts of the UI that allow the user to manipulate the UI, such as buttons and grab-handles that are presented in addition to the actual content) Other phone platforms focus a lot on chrome—shiny buttons, gradient fills, 3D images, arbitrary custom animations, and so on All these chrome effects might seem entertaining for a brief period, but they soon become a distraction, and they also lead to

a cluttered, inconsistent, confusing UI By contrast, Windows Phone and Metro considers content to

be king, whereas chrome should always be unobtrusive: it should serve its purpose, and then get out

of the user’s way Think about the implementation of the system tray; most of the time, this is invisible

If the user wants to see it, she taps the top of the screen, the tray drops down with a slight bounce, stays around long enough for the user to see the information she needs, and then disappears, leaving

the screen free for the application It also has no shiny, colorful, arbitrarily animated distractions The same applies for the application bar.

The aim is to achieve a UI that looks and feels clean, light, and open Figure 1-1 shows an example

of a panorama-based application in the spirit of Metro: clean lines, no gradient fills, content-driven

FIguRE 1-1 Metro applications should be clean and open

This really represents a major shift in the way you design applications What you might call the

“90s aesthetic” was all about iconography, whereby the chrome took center stage, and the model was hyper-realistic Metro brings a content-focused aesthetic, through which content is represented in its cleanest form, without embellishment or adornment, and without distractions The premise is that the user can get to the information directly, without having to navigate some developer’s view of what is suitable UI decoration Consider, for example, the scrollbar In Metro, this is mostly invisible; the user

scrolls the content, not some shiny scrollbar chrome thumb or widget This is especially important on a

mobile device, given the smaller screen real estate and the use of a touch-based input model

Metro celebrates typography: after all, this is a large part of what the user will see in all tions, so the typography must be true to the Metro principles To embody this principle, the font selected as the standard system font on Windows Phone is Segoe WP (in regular, bold, semi-bold, semi-light and black variants), as shown in Figure 1-2

applica-FIguRE 1-2 Segoe WP is the standard font on Windows Phone.

The FontSize values for the standard theme fonts are listed in Table 1-1.

TABlE 1-1 Standard Theme Font Sizes

Resource name size in Points size in Pixels

■ The Windows Phone Design system—Codename Metro A visual explanation of the

inspiration behind the Windows Phone design system, including the Red Threads principles (Personal, Relevant, Connected)

■

■ Design Templates for Windows Phone 7 A collection of 28 layered Photoshop templates

that help designers to maintain a consistent look and feel across applications

The focus is on building applications that can take part in a holistic UX This extends beyond the visuals to include all aspects of the application Navigation, for example, is deliberately enforced to be very simple, very linear, and predictable The user can quickly become familiar with the standard navi-gation model, and all applications follow this model Thus, the user can quickly become familiar with any new application There are constraints on what your application can do to avoid interfering with this predictability The user must be able to trust the hardware, so all the hardware buttons always behave the same way, and you cannot override this in a damaging way The Start button always goes

to the Start page The Back button always goes back in navigation (both within an application’s pages, and between applications in the backstack) When the user backs up to the beginning of the back-stack, he always ends up at the Start page

Adhering to Metro design principles is not a burden: it actually frees you to concentrate on making your application the best it can be, because you don’t have to spend time on inventing a new design paradigm Instead, you can focus on making your application truly useful, compelling, and delightful, such that it offers a benefit to the user’s daily life Note that Metro is also being applied within Micro-soft for Windows 8 and for Xbox It will be the dominant design aesthetic for the next several years.

Developer Guidelines

If you want to build an ecosystem in which the inhabitants co-exist in harmony to their mutual efit, then there must be rules and guidelines Rules in Windows Phone development are enforced by the operating system, the application platform, and the platform API There are certain programming techniques that might be appropriate in a desktop development environment, but you simply cannot

ben-do them in Winben-dows Phone You cannot currently build a Winben-dows Phone application using native code You also cannot use COM or RPC, or indeed, any kind of inter-process communication Every application is strictly “sandboxed” and has no access to any other application You cannot consume CPU cycles (and battery power) when you’re not running in the foreground However careless you might be in handling exceptions, you cannot bring down the entire system Clearly, these rules have been put in place to optimize the stability of the phone and the overall UX

Then there are guidelines These are recommendations for how your application should look and behave, but they are not explicitly enforced by the phone itself Rather, they are enforced by the mar-ketplace: if you build a bad application, users will quickly uninstall it and give it a bad review You’re not forced to use Metro in your design, but if you don’t, you might end up with an application that clashes with the ecosystem You’re not constrained in how much disk space you use up with applica-tion data, but if you use too much, the user will soon realize your application is making it difficult to run or install other applications You can use more than 90 MB of memory at runtime, but sooner or later the system will run up against a memory cap, and then your application will crash The Windows Phone marketplace publishes a comprehensive set of certification requirements, and the developer has a lot of support (especially in Windows Phone SDK 7.1) in preparing applications for publication However, the marketplace performs only a small set of automated and manual tests; consequently, it

is entirely possible to publish a bad application which then fails at runtime Users typically have very low tolerance for things that crash, so this is very much a self-policing system

In the market today, there is a spectrum of application models from iOS at one end (for which there’s really only one logical device, and applications are severely constrained as to what they can and cannot do), to Android at the other (where there’s a very wide and heterogeneous range of devices, and applications have very wide latitude to do all kinds of things, which might or might not function well, or at all, on every device) Windows Phone sits somewhere in the middle, offering the best of both worlds: there is a small set of supported devices, with a tightly controlled hardware requirements specification to which they must minimally adhere, and an application platform that offers a wide range of features, yet enforces some reasonable constraints in the interests of maintain-ing a consistent UX as well as overall device health

Windows Phone Architecture

Apart from a few applications provided by Microsoft, the device manufacturer, or the service vider, Windows Phone 7 applications are developed in managed code, using either the Windows Phone version of the Microsoft Silverlight runtime or the Windows Phone version of the XNA runtime (or some combination) These are slightly modified, phone-specific versions of the standard Silver-light/XNA libraries The phone application platform includes a set of standard controls and wrap-per classes to the phone services A high-level view of the architecture is shown in Figure 1-3 The underlying operating system is Windows CE, with the Microsoft NET Compact Framework and the Silverlight or XNA runtime layered on top

pro-Silverlight/XNA Application Host Process

Native Application Platform

Operating System Kernel

Install/Update Manager

Window Manager Execution Manager

Managed Runtime

Native Application Runtime

Phone Controls & Services NetCF

Platform Interop Runtime Host Managed Manager Proxy Execution

Silverlight/XNA Runtime

DB

FIguRE 1-3 The Windows Phone application architecture has managed and native layers

The application model exposed to marketplace developers is very robust An important principle is that the core services of the phone must continue to function at all times, regardless of what custom applications might be installed or running

From a UX perspective, this means that the user can rely on the following behavior:

■

■ The user is always able to get back to the Start menu, lock the phone, and turn the phone off She is always able to make and receive calls, navigate to hubs, and so on The phone protects itself mainly by its application isolation/security model

■

■ A new application installs cleanly and cannot break any existing core feature of the phone or any other installed application The same applies to updates The architecture ensures that there can be no versioning conflicts with shared components, because applications cannot install shared components

Comparison of Silverlight and XNA

You can build applications for Windows Phone by using either Silverlight or XNA or a constrained combination of both, as described in Table 1.2

TABlE 1-2 Comparison Between Silverlight and XNA Applications

Primary target app N-tier business applications, tools Games.

Developer

experience XAML-driven, using Microsoft Expression and Microsoft Visual Studio, very similar to Windows

Presentation Foundation (WPF) and desktop Silverlight development.

Visual Studio–code-driven Also similar

to Xbox console and Windows games development.

Typical artifacts Built-in support for controls, data binding, web

services, and text. Models, meshes, sprites, textures.

Execution model Event-driven (via UI controls or external events),

and application-focused. Gaming loop, display-focused.

Graphics Retained mode graphics (application code

up-dates an in-memory model of the graphics, which the OS renders later on), with 2D and limited 3D (PlaneProjection) Cannot use XNA graphics in 7.

Immediate mode graphics (application code causes direct rendering of graphics), with full 3D support.

Audio Focused on simple media playback (music and

video); can use XNA sounds and recording. Multichannel audio, including recording.Screen Standard Silverlight visual tree model, with a

hierarchy of controls. The game always uses the full screen.

Feature silverlight xnA

Controls Rich set of standard controls None.

Data binding Built in to the standard controls None.

Regardless of whether you choose Silverlight or XNA as the primary framework, you can also use some features from the other framework In Windows Phone 7, a Silverlight application can use any

of the XNA classes, except those in Microsoft.Xna.Framework.Games and Microsoft.Xna.Framework Graphics A common scenario is for a Silverlight application to use the advanced audio playback and

recording support in XNA Conversely, an XNA application can use some of the Silverlight features, but is more restricted; it cannot use any of the controls, data, messaging, input, media, browser, navi-gation, or threading features Windows Phone 7.1 introduced significant support for combining the two runtimes in a seamless manner

Developer Tools

The primary reference for Windows Phone platform APIs is MSDN, which is kept up to date online at

http://msdn.microsoft.com/en-us/library/ff402535(VS.92).aspx Another great resource is the AppHub, which you can access at http://create.msdn.com This is a development portal for Windows Phone and

Xbox 360 development, including links to download the core WP7 tools The primary tools are listed

in Table 1-3 Further ancillary tools and early-release frameworks are also mentioned in each chapter

of this book, where appropriate

TABlE 1-3 The Primary Windows Phone Development Tools are available from the AppHub

Windows Phone

Developer Tools This is the 7 version of the tools: you only need these if you want to use the 7 emulator Otherwise, you can use the 7.1 or 7.1.1 SDK for developing both version 7 applications

and version 7.1 applications Available at http://www.microsoft.com/download/en/details.

Windows Phone SDK 7.1 This is the 7.1 version of the tools You can use this to target both versions 7 and 7.1

Available as a free download from http://www.microsoft.com/download/en/details.

Tool Description

Windows Phone SDK 7.1.1

Update An incremental update to the existing Windows Phone SDK 7.1 This update adds sup-port for developing applications that are optimized to run on 256 MB devices It includes

an updated version of the standard (512 MB) emulator, plus a new 256 MB emulator For details, see Chapter 16, “Enhanced Phone Services.” With version 7.1.1 installed, you can

target all versions: 7, 7.1, or 7.1.1 Available for download at http://www.microsoft.com/

Training Kit Hands-on labs for the Windows Phone 7.5 application platform Available at http://www.microsoft.com/download/en/details.aspx?id=28564

Windows Azure Toolkit

for WP7 Visual Studio templates for Windows Phone projects that connect with cloud services run-ning in Windows Azure Available at http://watwp.codeplex.com.

Windows Phone

Developer Guide Patterns & Practices guide to Windows Phone development Available at http://wp7guide.codeplex.com.

Silverlight Media

Framework Includes Windows Phone 7 support for video playback, live/smooth streaming Available at http://smf.codeplex.com.

Note The online MSDN documentation covers version 7.1 If you need to see

documenta-tion that’s specific to version 7, you can download the 7 offline documentadocumenta-tion from

http://www.microsoft.com/download/en/details.aspx?id=20558.

The Windows Phone 7.1 SDK is a complete replacement for the version 7 SDK You cannot run these side by side on the same computer, but you can use the version 7.1 SDK to target both 7 applications and 7.1 applications The one and only reason why you might want to keep a computer with only the version 7 tools on it is because the version 7.1 SDK uses the 7.1 emulator; the version 7.1 emulator will run version 7 applications in backward-compatibility mode on top of the version 7.1 platform Although this has a very high degree of compatibility, you should always run on a real ver-sion 7 device (or emulator) to ensure that your application will work on the version 7 OS Therefore, if you want to be able to test your application on a version 7 emulator, you need to have an installation

of the version 7 tools In all other respects, the version 7.1 tools are preferred

Development Cycle

Developing and publishing applications for Windows Phone is very straightforward, as shown in Figure 1-4

Visual Studio, Expression Blend AppHub Portal

Developer

User

Retail Phone

Emulator

unlocked Phone

Analytics

Review,Feedback

Test, Sign,CertifyTest

1

2

3

Use,Uninstall

Download,install

Update,Revoke

6 5

8

7 4

Payments,Ratings/Reviews,Crash Report

9

Marketplace Catalog

FIguRE 1-4 The develop-publish-feedback cycle is very straightforward

You can download the free tools and get started building applications straight away As part of the development phase, you will typically test first on the emulator that is part of the SDK and then also

on a physical device To deploy unpublished applications to a phone, that phone must be unlocked To do this, you must first register with the AppHub as a developer Each developer account allows you to unlock up to three physical devices These devices will be registered with your AppHub account

developer-When you’re ready to submit your application for publication, there is a simple set of forms to fill out on the AppHub This is a front-end to the Windows Phone marketplace The marketplace inges-tion process will test your application against the certification requirements and then rebuild and sign the final XAP, making it available publicly in the marketplace catalog

Customers can then download and install your application onto their retail phones They can also subsequently update the application (if you publish an update to marketplace), provide a review and feedback, and uninstall/reinstall whenever they choose You can track payments, feedback, and pur-chase analytics in the AppHub portal

The Anatomy of a Basic Windows Phone Application

When you build a Windows Phone application, the output of the build process is a XAP file XAP (pronounced “zap”) is the file extension for a Silverlight-based application package (.xap) This is a zip-format compressed file that contains all your assemblies, your manifest, and any loose image files or other data files that you chose not to embed in your assemblies When the user installs your applica-tion on his phone, the XAP is deployed to an install folder on the filesystem, as shown in Figure 1-5 Each application gets its own install folder The exact location is opaque—there is no supported way

to examine the phone filesystem and no good reason to do so

XAP

XAP Phone Filesystem

In-Memory

Security Sandbox Host Process Application DLLs

MyApp Start Menu

OtherApp App 3

Application Install Folder

Application Isolated Storage Applications Installed

DB

MyApp.dll MyClassLib.dll WMAppManifest.xml

Image & data files

Construct Sandbox,Create Process

4

3 5

FIguRE 1-5 Components from your XAP are loaded into memory at runtime

At install time, the installer service extracts critical metadata from your WMAppManifest.xml and stores it in the phone’s database Information about all installed applications is entered in this data-base Standard parts of the phone UI such as the Start page and the installed application list gather the information they need from this database, including application name, icon, and background tile image Your application manifest includes details of the capabilities that your application requires, and these are used to configure the correct security sandbox for your application This configuration

is also stored in the application database

When the user chooses to launch your application, the system reads the database to construct the security sandbox within which your application will run Then, the platform loads your application assemblies into memory, performs security checks, and instantiates the class that you’ve marked as the entry point to the application Once your application is running, it has implicit access to any of the loose data files that were in the original XAP and deployed at install time to the application’s install folder Any reference in your code to such files is assumed to be relative to the root of the applica-tion’s install folder The application also has exclusive read/write access to its own private isolated storage area on the filesystem This is in a different location than the install folder, both for security reasons and to aid in the application update process

XAP Contents

A Windows Phone XAP is essentially the same as a regular desktop Silverlight XAP—a zip file that contains all the application’s local DLLs, resources, and the AppManifest.xaml, plus an additional file named WMAppManifest.xml The AppManifest.xaml file is a regular Silverlight artifact: it contains a list of “deployment parts” (typically, assemblies local to the application), and the name of the class (and its containing assembly) to be instantiated as the entry point for the application It also contains information about localized resources (if any), and thus the languages that the application supports

<Deployment xmlns="http://schemas.microsoft.com/client/2007/deployment" xmlns:x="http://schemas microsoft.com/winfx/2006/xaml" EntryPointAssembly="WindowsPhoneApplication1" EntryPointType="Win dowsPhoneApplication1.App" RuntimeVersion="3.0.40624.0">

browser, and so on), then you will need the ID_CAP_NETWORKING capability