Windows Phone 7 tips and tricks

This week the final versions of the Windows Phone Developer Tools and Silverlight for Windows Phone Toolkit were released.

Some things are different at Silverlight Windows Phone 7 applications and so the hints of Jeff Wilcox (great guy, which I met at my current Windows Phone 7 project at German Telekom) will be helpful for the ugly starting phase of developing complex Windows phone 7 applications. Jeff is now at vacation and so his Microsoft fellow Tim Heuer published his hints here: Windows Phone 7 Developer Tips and Tricks

Tips and Tricks of Jeff Wilcox for developing Windows Phone 7 applications:

• Panorama looks nice, but Pivot will offer faster start time.
• You can also set a Background image to a Pivot. You won't get the parallax effect, but it is another option.
• Be aware of how many pano and pivot items you do have. Memory expands quick when you have a lot of views and images!
• Even if you have a 30k compressed JPEG image, at runtime that becomes an uncompressed surface that may take several MBs of memory
• Pivot and Panorama can have UI element headers and titles, too, but you'll need to apply your own styling (fonts and sizes)
• Beware that UI elements larger than 2000x2000 pixels that are bitmap cached clip on Windows Phone 7. We know it isn't perfect, but beware k?
• Setting SelectedIndex before the items are set on a Pivot causes an exception. Wrap in a try/catch or wait for loaded (sorry!)
• A slideshow app in 5 minutes: Pivot with null Header and Title and item headers. Beware memory use though.
• A lot of people try building 'wizard' screens with panorama & pivot control. Please don't do this! Thx, the "UX gods"
• Layout is a killer. But like death, you eventually have to pay it for everything.
• So consider delay loading controls and screens. A Panorama with a billion items will take forever to load due to layout.
• If you're not using PerformanceProgressBar, I'll send @JustinAngel after you ProgressBar for Windows Phone 7
• If your app rocks and starts really quick *on a device* consider not using a splash screen
• It's true. Your 6-core machine running the wp7 emulator is NOT indicative of device (single core!) performance. Beware!
• We've talked perf before... Content over Resources for images means fast startup time http://bit.ly/9DhVbd
• If you're using Panorama, a Resource background will load immediately compared to Content
• Remember that for ingestion to the marketplace, your apps need to consume under 90MB of memory
• However on devices with > 256MB, its cool to use more *in those cases
• long deviceTotalMemory = (long)DeviceExtendedProperties.GetValue("DeviceTotalMemory");
• long applicationCurrentMemoryUsage = (long)DeviceExtendedProperties.GetValue("ApplicationCurrentMemoryUsage");
• long applicationPeakMemoryUsage = (long)DeviceExtendedProperties.GetValue("ApplicationPeakMemoryUsage")
• Your compositor thread should rock out around 60fps all the time please. #wp7dev perf counters: http://bit.ly/busJIi
• If your UI thread gets pegged, your compositor thread will suffer... remember your BackgroundWorker kids!
• Unfortunately the "Analytics" type from desktop Silverlight is not on the phone today, so you can't measure CPU in a regular app
• Having a single DispatcherTimer in your app can affect your battery life regardless of interval. Chose wisely
• You can set the Foreground property on Pivot to set the title and header text color
• Using a map control inside a Panorama or Pivot is not recommended for a number of UX and technical reasons. Navigate to a subpage.
• Please use text styles and never hardcode sizes or default fonts.
• The panorama/pivot items expect most their contents to have a 12px margin left/right for UX reasons. The default styles have this.
• So if you have something in a pano/pivot item with 0 margin & padding, your UX will be funky
• Fill rate is super important. Keep it under 2.5 please
• What is fill rate? 1.00 means one screen of pixels being rendered every frame.
• Check your apps for extra, un-needed background colors on pages, controls, etc.. They impact perf.
• That sexy "tilt" effect? Use Peter's behavior http://bit.ly/90Z1yR and/or check out the MSDN docs
• DataTemplates with a bunch of StackPanels and Grids? Try to simplify to a Grid with the right col/rows instead for perf wins.
• Unit testing in a quick and dirty way is possible on the Windows Phone thx to the sl unit test fx. http://bit.ly/a0DWah
• Only use Dispatcher.BeginInvoke when you must. Look at SmartDispatcher (ps old code sry) http://bit.ly/axHh36
• For a "wide" Panorama item, set the item's Orientation to "Horizontal"
• Play with the cache and redraw vis. settings to see what's being cached in your app http://bit.ly/busJIi
• Things in a list/scroll viewer are often automatically bitmap cached by Silverlight for Windows Phone runtime
• If you have a progress bar with IsIndeterminate="True" in your app, even if its hidden those storyboards are costly! Set to False!
• We did work on Windows Phone 7 to move more networking to the background thread - hope it helps
• When a Panorama loads, all its items go through a render pass. For pivot, it is done incrementally for neighboring items.
• When making web requests, see if the service lets you scope down the fields that are returned for quicker perf (and JSON over XML!)
• If you navigate to a subpage, the old page will stick around - so complex pano/pivot pgs stay in memory unless you're proactive
• The "app deployment tool" installed with the dev tools lets you run others apps in emulator/device without needing source
• We optimize for loading some things from isolated storage. Images from an isostore stream may load faster than a MemoryStream
• If your source files have "Black" or "White", you might be doing it wrong. PhoneForegroundBrush, PhoneBackgroundBrush instead!
• If your control's dep. property has a change handler, animating that prop. will always happen on the UI thread (no gpu accel.)
• Animating Opacity on a CacheMode="BitmapCache" element = compositor thread (GPU!)
• In the RTM tools, scroll viewers all have the "bounce" effect automatically
• If you ignore the phone's theme (and go all light bg, like the mail app), your scrollbars must be retemplated or you won't see them!
• Although data binding is not evil, an observable col. with a complex data temp. and 200k items is evil.
• The web browser control won't let you NavigateToString until it has loaded.
• If you have an app with a lot of different web browser controls, think about consolidating to one, so it only has to load once.
• Panorama is designed to be a starting place. Think whitespace. Not tons of data
• Free performance win: when you use Panorama the way the UX guidelines recommend, it is faster! http://bit.ly/9zTxtU
• Those theme xamls for #wp7? Yeah they are in %ProgramFiles%\Microsoft SDKs\Windows Phone\v7.0\Design\
• Resist the urge to Panorama every app.  It is a sweet UX thing when used right…but not just because.
• Resist the urge to iPhone gradient your apps. Think outside the box! Also it avoids color banding...

Other useful links are:

• Jeff on Hanselminutes talking about Windows Phone 7 application performance
• Creating High Performance Silverlight for Windows Phone Applications (whitepaper)
• Shane Guillet on optimizing Windows Phone Silverlight Applications (video)