Welcome!

IoT User Interface Authors: Dana Gardner, AppDynamics Blog, Liz McMillan, Leon Adato, Elizabeth White

Blog Feed Post

Windows 8 Notifications: Image Handling

In the last post, I discussed the structure of a notification template and the mechanics for providing the various bit of information in that template. As you know, many of the notification templates can include one or more images, and that brings up a host of configuration options that I didn’t have a chance to get into last time. This post will fill in the gaps and provide insight into three main topics:

What image sizes and formats do you need to provide?

Where can the images be hosted?

How do you accommodate different device resolutions and themes?

I’ll close with a quick list of not-so-obvious features and behaviors that will hopefully save you some time as you plan out your strategy for supporting images as part of notifications used within your application.

Images Sizes and Format

There are two overarching constraints for images used within notifications:

  1. Images used in notifications must be in one of three formats: .png, .jpg/.jpeg, or .gif, and the format must match the extension.
  2. Images for notifications must be no larger than 200 KB and 1024 x 1024 in dimension.

Beyond that and depending on the device size and characteristics, images within Windows 8 may be scaled to one of four proportions (80%, 100%, 140% and 180%). Since the notification image formats supported are all raster formats (versus vector-based) you cannot rely on the scaling to result in clear, crisp imagery, so it’s recommended that you provide artwork to accommodate all four scaling factors.

The table below (which is adapted from the App images topic on MSDN) shows most of the sizes [see note] needed for tile and toast notifications as well as the (optional) badge logo for the start screen. Only those images highlighted in red (100% size for logo and small logo) are required and must be supplied in the app manifest (as .jpg/jpeg or .png formats [see note]). Other sizes are optional and if not provided will be generated by scaling the default 100% image.

appxmanifest Image Name
(where used)
80% [see note] 100% 140% 180%
Logo
(default square tile)
120x120 150x150 210x210 270x270
Small logo
(tile under semantic zoom,
tile and toast branding)
[see note]
24x24 30x30 42x42 54x54
Wide logo
(default wide tile)
248x120 310x150 434x210 558x270
Badge Logo [see note]
(Lock screen)
  24x24 33x33 43x43
Tip: Use the Visual Studio 2012 simulator to check out the appearance of your images under various scaling factors (and contrast modes [see note]).

Image Locations

Images used for notifications can be stored in one of three places:

  • within the app package, using the ms-appx:/// prefix to a directory in your deployed application (this is the default).
  • within local storage, using the ms-appdata:///local prefix to a directory within local storage. Note that images in temporary and roaming application data storage cannot be used.
  • on the web, using an http or https URI that serves up image content (this requires that the application declare Internet client capability in its manifest).

Within the template XML you can specify the entire image URI or use paths relative to the baseUri value specified within the template.  The baseUri can be set for either the visual (tile | toast) tag or the binding tag (tile | toast), with the latter overriding the former when provided.

App Package Images

Here, for example, is a code snippet from the App tiles and badges sample showing the use of an image within the local application package:

var tileXml = Windows.UI.Notifications.TileUpdateManager.getTemplateContent(
        Windows.UI.Notifications.TileTemplateType.tileWideImageAndText01);

// get the text attributes for this template and fill them in
var tileTextAttributes = tileXml.getElementsByTagName("text");
tileTextAttributes[0].appendChild(tileXml.createTextNode(
      "This tile notification uses ms-appx images"));

// get the image attributes for this template and fill them in
var tileImageAttributes = tileXml.getElementsByTagName("image");
tileImageAttributes[0].setAttribute("src", "ms-appx:///images/redWide.png");

Local Storage Images

The code for accessing an image in local storage is very similar, differing only by the addressing scheme:

tileImageAttributes[0].setAttribute("src", "ms-appdata:///local/images/redWide.png");

Here the image is located in a subdirectory called images at the location returned by ApplicationData.localFolder; when I ran an excursion of the sample app using this access mechanism, the image was served from:

C:\Users\joneil\AppData\Local\Packages\Microsoft.SDKSamples.Tiles.JS_8wekyb3d8bbwe\
    
LocalState\images\redWide.png

Images in the Cloud

One option to consider when architecting your application is leveraging the cloud for external resources that your application uses. If you place images and other content on the web or in the cloud, you’ve decoupled those resources from your application, and by doing so you can freshen the look and feel of your application without publishing a new version of your application or requiring the end users to get an update.

Windows Azure, Microsoft’s public cloud offering, can be an incredibly convenient and cost effective way to manage the images you’re using for your notifications. The easiest way to serve image content from Windows Azure is via blob storage which provides highly scalable and highly available storage of unstructured data at one of eight Windows Azure data centers worldwide. A Content Delivery Network (currently comprising 24 nodes) is also available to improve performance and user experience for end-users who aren’t located near a data center.

Keep in mind there are some caveats when using cloud or web hosted images:
  1. The most obvious is that if the machine lacks network connectivity, the image won't be available and the notification will not be sent.
  2. Web images are cached, so an update to the image in the cloud may not be immediately reflected on the client. If the cache is full, images will be removed in a policy opaque to the developer. Additionally the system will clear the cache when
    1. The application is uninstalled, or
    2. The user clears personal information from all of her application tiles (via the Settings flyout on the Start screen).

    The system will comply with caching and expiration headers in the HTTP response. Those headers are not configurable in Windows Azure storage alone, but a web service can be configured and hosted on Windows Azure to support this.

  3. The cloud isn't free! While there are no-cost options (like the 90-day trial and MSDN subscriptions), you ultimately may end up paying for the storage and the transactions (HTTP GET requests) that are made by your application. The complete pricing details are available at the Azure pricing page, but it’s very likely you'll be able to support a popular Windows 8 application for dollars if not pennies a month.

Handling Scaling and Contrast Themes

The elephant in the room thus far in this post is that all the samples I’ve shown above refer to a single image of some unknown size, and I appear to have ignored the advice to provide four different image sizes (80%, 100%, 140% and 180%) scale to provide the best user experience!

It turns out that there’s a bit of magic happening behind the scenes to make managing the combination of image sizes and contrast mode (don’t forget there’s are high-contrast white and high-contrast black options too!). The amount of ‘magic’ depends on the image source, so I’ll cover them independently below.

App Package Images

When you provide images as part of your application package, a naming convention can be leveraged which enables you to specify one base image name (say in the notification template image src attribute) yet the system automatically selects a file with a modified name based on the current scale factor and contrast mode.

For instance, while the code sample above refers to redWide.png, the application can deliver a slew of versions that vary by scale factor, contrast mode, culture (e.g., en-US versus zh-CN), and several other resource qualifiers.

A file named redWide.scale-140.png, if available, would be used in the samples above – in lieu of scaling the default image – whenever there was a request for redWide.png and the current scale required was 140%. Your code doesn’t need to do a thing!

If you had a special version of the tile just for those in French locales, you could name that image, redWide.lang-FR-fr_scale-140.png. (Note the lang prefix to the BCP-47 language identifier)

Likewise, redWide.scale-180_contrast-black.png would be used when the contrast mode is black and an image scaled to 180% is needed. By the way, redWide.contrast-black_scale-180.png works too!

You can also arrange the images in subdirectories, to provide a myriad of customization options. Take, for example, the following directory structure.

   1:  /ProjectFolder
   2:      /images
   3:          welcome.scale-80.png
   4:          welcome.scale-100.png
   5:          welcome.scale-140.png
   6:          /contrast-black
   7:              welcome.scale-80.png
   8:              welcome.scale-100.png
   9:              welcome.scale-140.png
  10:          /contrast-white
  11:              welcome.scale-80.png
  12:              welcome.scale-100.png
  13:              welcome.scale-140.png
  14:          /ja-JP
  15:              welcome.scale-80.png
  16:              welcome.scale-100.png
  17:              welcome.scale-140.png
  18:              /contrast-black
  19:                  welcome.scale-80.png
  20:                  welcome.scale-100.png
  21:                  welcome.scale-140.png
  22:              /contrast-white
  23:                  welcome.scale-80.png
  24:                  welcome.scale-100.png
  25:                  welcome.scale-140.png

If the application were run on a US based system, but the user selected a black high contrast theme, a reference for welcome.png for a tile notification on a typical laptop would pick the variant on Line 8.  Someone running the applications with his locale set to Japan on a high-resolution device would see the image file associated with Line 17.

Local Images

Unfortunately, none of the conventions supported for app package images are supported when using local images (the ms-appdata:///local namespace), but you could implement similar semantics programmatically using the following Windows APIs:

Attribute Windows Class or Property Values
Resolution DisplayProperties.resolutionScale Scale100Percent
Scale140Percent
Scale180Percent
Language ApplicationLanguage.languages a list of BCP-47 codes corresponding to the applications supported languages (see ���How to manage language and region” for details)
Contrast Scheme [see note] AccessibilitySettings.highContrast

AccessibilitySettings.highContrastScheme
true | false

”High Contrast White”
”High Contrast Black”
”High Contrast #1”
”High Contrast #2”
Home Region GlobalizationPreferences.homeGeographicRegion BCP-47 subtag code corresponding to user’s Region preference in Control Panel

Images in the Cloud

Both the tile schema and the toast schema include an optional attribute called addImageQuery, on the visual, binding, and image elements (the value set on the deepest element overriding those above it). When addImageQuery is set to true, HTTP/HTTPS requests made for images will have a query string appended consisting of the following three name value pairs:

Attribute Query String Name Query String Value
Resolution ms-scale 80, 100, 140 or 180
Language ms-lang BCP-47 code
Contrast Scheme [see note] ms-contrast standard
black
white

Here for instance is an HTTP request made for the redWide.png tile:

GET http://win8apps.blob.core.windows.net/images/redWide.png?ms-scale=100
&ms-contrast=standard&ms-lang=en-US HTTP/1.1 Accept: */* Accept-Encoding: identity, peerdist Range: bytes=0-2419 User-Agent: Microsoft BITS/7.6 X-P2P-PeerDist: Version=1.1 X-P2P-PeerDistEx: MinContentInformation=1.0, MaxContentInformation=2.0 Connection: Keep-Alive Host: win8apps.blob.core.windows.net

The good news is that you don’t have to figure out which variant of an image is being requested – that information is available in the query parameters; the bad news is that you have to build your own web service to inspect those parameters and serve up the correct image in response. You can’t just use the blob storage mechanism shown above, because those query parameters aren't automatically interpreted by Windows Azure blob storage, but you can still use Windows Azure with a little bit of code (PHP, ASP.NET, Node.js, or essentially any implementation of a web service that will run on Windows).


A Recap of the Not-So-Obvious

  • 80% images are used on tiles for some combinations of screen size and resolution.
  • Size specifications haven’t been published for images that appear on toast or that do not fill the entire tile, such as the template samples below. In most cases, these will be photographic images which scale fairly well (using the Fant algorithm internally). You could measure the sizes empirically, but if you create images that work for 180% scale they should also scale down well for the other three factors.
ToastImageAndText02 example   TileWideImageCollection example
  • Default images (those declared in your app manifest) must be .png or .jpg/.jpeg format, but you can use .gif in your toast and tile notification templates.
  • If an image is of the wrong format or not available (such as a image hosted on the Web when the client is not connected), the notification will not be sent.
  • The branding element is taken from the small logo in your manifest. For tiles it appears in the bottom left and for toast in the bottom right. In the tile schema you can use text, logo, or no branding; in the toast schema, the branding attribute is not used and you will always see the logo.
  • The badge logo must be monochromatic.
  • if you don’t supply multiple images to accommodate scaling, try to create images with dimensions that are a multiple of 5 as they won’t experience pixel shifting during scaling.
  • The Visual Studio simulator is an awesome way to test out tile behavior under different resolutions and contrast modes, but be aware, you’ll have to restart your debug session in the simulator if your change in resolution results in loading a different version of the image.
  • PC Settings > Ease of Access (accessible via the Settings charm) includes a switch to toggle High Contrast mode; however, since there are four high contrast modes, you’ll need to use the desktop Control Panel option to pick one.  Once you’ve selected the contrast mode there, PC Settings > Ease of Access will use that High Contrast mode when you toggle the option.Ease of Access settings for High Contrast (click for larger view)
  • Windows supports four high contrast modes (White, Black, #1, and #2), and these map to four overlapping resource types: standard, high, black, and white as follows:
    Contrast Setting in Control Panel Applicable Resource Qualifiers ms-contrast Query Parameter Value
    High Contrast White contrast-high and contrast-white white
    High Contrast Black contrast-high and contrast-black black
    High Contrast #1 contrast-high and contrast-black black
    High Contrast #2 contrast-high and contrast-black black
    none contrast-standard standard

Read the original blog entry...

More Stories By Jim O'Neil

Jim is a Technology Evangelist for Microsoft who covers the Northeast District, namely, New England and upstate New York. He is focused on engaging with the development community in the area through user groups, code camps, BarCamps, Microsoft-sponsored events, etc., and just in general serve as ambassador for Microsoft. Since 2009, Jim has been focusing on software development scenarios using cloud computing and Windows Azure. You can follow Jim on Twitter at @jimoneil

@CloudExpo Stories
SYS-CON Events announced today that Peak 10, Inc., a national IT infrastructure and cloud services provider, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Peak 10 provides reliable, tailored data center and network services, cloud and managed services. Its solutions are designed to scale and adapt to customers’ changing business needs, enabling them to lower costs, improve performance and focus inter...
You think you know what’s in your data. But do you? Most organizations are now aware of the business intelligence represented by their data. Data science stands to take this to a level you never thought of – literally. The techniques of data science, when used with the capabilities of Big Data technologies, can make connections you had not yet imagined, helping you discover new insights and ask new questions of your data. In his session at @ThingsExpo, Sarbjit Sarkaria, data science team lead ...
So, you bought into the current machine learning craze and went on to collect millions/billions of records from this promising new data source. Now, what do you do with them? Too often, the abundance of data quickly turns into an abundance of problems. How do you extract that "magic essence" from your data without falling into the common pitfalls? In her session at @ThingsExpo, Natalia Ponomareva, Software Engineer at Google, will provide tips on how to be successful in large scale machine lear...
If there is anything we have learned by now, is that every business paves their own unique path for releasing software- every pipeline, implementation and practices are a bit different, and DevOps comes in all shapes and sizes. Software delivery practices are often comprised of set of several complementing (or even competing) methodologies – such as leveraging Agile, DevOps and even a mix of ITIL, to create the combination that’s most suitable for your organization and that maximize your busines...
Struggling to keep up with increasing application demand? Learn how Platform as a Service (PaaS) can streamline application development processes and make resource management easy.
Whether your IoT service is connecting cars, homes, appliances, wearable, cameras or other devices, one question hangs in the balance – how do you actually make money from this service? The ability to turn your IoT service into profit requires the ability to create a monetization strategy that is flexible, scalable and working for you in real-time. It must be a transparent, smoothly implemented strategy that all stakeholders – from customers to the board – will be able to understand and comprehe...
See storage differently! Storage performance problems have only gotten worse and harder to solve as applications have become largely virtualized and moved to a cloud-based infrastructure. Storage performance in a virtualized environment is not just about IOPS, it is about how well that potential performance is guaranteed to individual VMs for these apps as the number of VMs keep going up real time. In his session at 18th Cloud Expo, Dhiraj Sehgal, in product and marketing at Tintri, will discu...
Machine Learning helps make complex systems more efficient. By applying advanced Machine Learning techniques such as Cognitive Fingerprinting, wind project operators can utilize these tools to learn from collected data, detect regular patterns, and optimize their own operations. In his session at 18th Cloud Expo, Stuart Gillen, Director of Business Development at SparkCognition, will discuss how research has demonstrated the value of Machine Learning in delivering next generation analytics to im...
Up until last year, enterprises that were looking into cloud services usually undertook a long-term pilot with one of the large cloud providers, running test and dev workloads in the cloud. With cloud’s transition to mainstream adoption in 2015, and with enterprises migrating more and more workloads into the cloud and in between public and private environments, the single-provider approach must be revisited. In his session at 18th Cloud Expo, Yoav Mor, multi-cloud solution evangelist at Cloudy...
There is an ever-growing explosion of new devices that are connected to the Internet using “cloud” solutions. This rapid growth is creating a massive new demand for efficient access to data. And it’s not just about connecting to that data anymore. This new demand is bringing new issues and challenges and it is important for companies to scale for the coming growth. And with that scaling comes the need for greater security, gathering and data analysis, storage, connectivity and, of course, the...
This is not a small hotel event. It is also not a big vendor party where politicians and entertainers are more important than real content. This is Cloud Expo, the world's longest-running conference and exhibition focused on Cloud Computing and all that it entails. If you want serious presentations and valuable insight about Cloud Computing for three straight days, then register now for Cloud Expo.
Redis is not only the fastest database, but it has become the most popular among the new wave of applications running in containers. Redis speeds up just about every data interaction between your users or operational systems. In his session at 18th Cloud Expo, Dave Nielsen, Developer Relations at Redis Labs, will shares the functions and data structures used to solve everyday use cases that are driving Redis' popularity.
SYS-CON Events announced today that Stratoscale, the software company developing the next generation data center operating system, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Stratoscale is revolutionizing the data center with a zero-to-cloud-in-minutes solution. With Stratoscale’s hardware-agnostic, Software Defined Data Center (SDDC) solution to store everything, run anything and scale everywhere...
Many private cloud projects were built to deliver self-service access to development and test resources. While those clouds delivered faster access to resources, they lacked visibility, control and security needed for production deployments. In their session at 18th Cloud Expo, Steve Anderson, Product Manager at BMC Software, and Rick Lefort, Principal Technical Marketing Consultant at BMC Software, will discuss how a cloud designed for production operations not only helps accelerate developer...
Angular 2 is a complete re-write of the popular framework AngularJS. Programming in Angular 2 is greatly simplified – now it's a component-based well-performing framework. This immersive one-day workshop at 18th Cloud Expo, led by Yakov Fain, a Java Champion and a co-founder of the IT consultancy Farata Systems and the product company SuranceBay, will provide you with everything you wanted to know about Angular 2.
SYS-CON Events announced today that Enzu, a leading provider of cloud hosting solutions, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Enzu’s mission is to be the leading provider of enterprise cloud solutions worldwide. Enzu enables online businesses to use its IT infrastructure to their competitive advantage. By offering a suite of proven hosting and management services, Enzu wants companies to foc...
Peak 10, Inc., has announced the implementation of IT service management, a business process alignment initiative based on the widely adopted Information Technology Infrastructure Library (ITIL) framework. The implementation of IT service management enhances Peak 10’s current service-minded approach to IT delivery by propelling the company to deliver higher levels of personalized and prompt service. The majority of Peak 10’s operations employees have been trained and certified in the ITIL frame...
SYS-CON Events announced today that Men & Mice, the leading global provider of DNS, DHCP and IP address management overlay solutions, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. The Men & Mice Suite overlay solution is already known for its powerful application in heterogeneous operating environments, enabling enterprises to scale without fuss. Building on a solid range of diverse platform support,...
You deployed your app with the Bluemix PaaS and it's gaining some serious traction, so it's time to make some tweaks. Did you design your application in a way that it can scale in the cloud? Were you even thinking about the cloud when you built the app? If not, chances are your app is going to break. Check out this webcast to learn various techniques for designing applications that will scale successfully in Bluemix, for the confidence you need to take your apps to the next level and beyond.
Increasing IoT connectivity is forcing enterprises to find elegant solutions to organize and visualize all incoming data from these connected devices with re-configurable dashboard widgets to effectively allow rapid decision-making for everything from immediate actions in tactical situations to strategic analysis and reporting. In his session at 18th Cloud Expo, Shikhir Singh, Senior Developer Relations Manager at Sencha, will discuss how to create HTML5 dashboards that interact with IoT devic...