Welcome!

Containers Expo Blog Authors: Elizabeth White, Pat Romanski, Liz McMillan, Amit Gupta, Mark Leake

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

@ThingsExpo Stories
Amazon is pursuing new markets and disrupting industries at an incredible pace. Almost every industry seems to be in its crosshairs. Companies and industries that once thought they were safe are now worried about being “Amazoned.”. The new watch word should be “Be afraid. Be very afraid.” In his session 21st Cloud Expo, Chris Kocher, a co-founder of Grey Heron, will address questions such as: What new areas is Amazon disrupting? How are they doing this? Where are they likely to go? What are th...
SYS-CON Events announced today that IBM has been named “Diamond Sponsor” of SYS-CON's 21st Cloud Expo, which will take place on October 31 through November 2nd 2017 at the Santa Clara Convention Center in Santa Clara, California.
Infoblox delivers Actionable Network Intelligence to enterprise, government, and service provider customers around the world. They are the industry leader in DNS, DHCP, and IP address management, the category known as DDI. We empower thousands of organizations to control and secure their networks from the core-enabling them to increase efficiency and visibility, improve customer service, and meet compliance requirements.
Join IBM November 1 at 21st Cloud Expo at the Santa Clara Convention Center in Santa Clara, CA, and learn how IBM Watson can bring cognitive services and AI to intelligent, unmanned systems. Cognitive analysis impacts today’s systems with unparalleled ability that were previously available only to manned, back-end operations. Thanks to cloud processing, IBM Watson can bring cognitive services and AI to intelligent, unmanned systems. Imagine a robot vacuum that becomes your personal assistant tha...
SYS-CON Events announced today that IBM has been named “Diamond Sponsor” of SYS-CON's 21st Cloud Expo, which will take place on October 31 through November 2nd 2017 at the Santa Clara Convention Center in Santa Clara, California.
In his Opening Keynote at 21st Cloud Expo, John Considine, General Manager of IBM Cloud Infrastructure, will lead you through the exciting evolution of the cloud. He'll look at this major disruption from the perspective of technology, business models, and what this means for enterprises of all sizes. John Considine is General Manager of Cloud Infrastructure Services at IBM. In that role he is responsible for leading IBM’s public cloud infrastructure including strategy, development, and offering ...
SYS-CON Events announced today that N3N will exhibit at SYS-CON's @ThingsExpo, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. N3N’s solutions increase the effectiveness of operations and control centers, increase the value of IoT investments, and facilitate real-time operational decision making. N3N enables operations teams with a four dimensional digital “big board” that consolidates real-time live video feeds alongside IoT sensor data a...
In a recent survey, Sumo Logic surveyed 1,500 customers who employ cloud services such as Amazon Web Services (AWS), Microsoft Azure, and Google Cloud Platform (GCP). According to the survey, a quarter of the respondents have already deployed Docker containers and nearly as many (23 percent) are employing the AWS Lambda serverless computing framework. It’s clear: serverless is here to stay. The adoption does come with some needed changes, within both application development and operations. Tha...
With major technology companies and startups seriously embracing Cloud strategies, now is the perfect time to attend 21st Cloud Expo October 31 - November 2, 2017, at the Santa Clara Convention Center, CA, and June 12-14, 2018, at the Javits Center in New York City, NY, and learn what is going on, contribute to the discussions, and ensure that your enterprise is on the right path to Digital Transformation.
SYS-CON Events announced today that Avere Systems, a leading provider of enterprise storage for the hybrid cloud, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Avere delivers a more modern architectural approach to storage that doesn't require the overprovisioning of storage capacity to achieve performance, overspending on expensive storage media for inactive data or the overbui...
Digital transformation is changing the face of business. The IDC predicts that enterprises will commit to a massive new scale of digital transformation, to stake out leadership positions in the "digital transformation economy." Accordingly, attendees at the upcoming Cloud Expo | @ThingsExpo at the Santa Clara Convention Center in Santa Clara, CA, Oct 31-Nov 2, will find fresh new content in a new track called Enterprise Cloud & Digital Transformation.
Most technology leaders, contemporary and from the hardware era, are reshaping their businesses to do software. They hope to capture value from emerging technologies such as IoT, SDN, and AI. Ultimately, irrespective of the vertical, it is about deriving value from independent software applications participating in an ecosystem as one comprehensive solution. In his session at @ThingsExpo, Kausik Sridhar, founder and CTO of Pulzze Systems, will discuss how given the magnitude of today's applicati...
Smart cities have the potential to change our lives at so many levels for citizens: less pollution, reduced parking obstacles, better health, education and more energy savings. Real-time data streaming and the Internet of Things (IoT) possess the power to turn this vision into a reality. However, most organizations today are building their data infrastructure to focus solely on addressing immediate business needs vs. a platform capable of quickly adapting emerging technologies to address future ...
SYS-CON Events announced today that NetApp has been named “Bronze Sponsor” of SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. NetApp is the data authority for hybrid cloud. NetApp provides a full range of hybrid cloud data services that simplify management of applications and data across cloud and on-premises environments to accelerate digital transformation. Together with their partners, NetApp emp...
As popularity of the smart home is growing and continues to go mainstream, technological factors play a greater role. The IoT protocol houses the interoperability battery consumption, security, and configuration of a smart home device, and it can be difficult for companies to choose the right kind for their product. For both DIY and professionally installed smart homes, developers need to consider each of these elements for their product to be successful in the market and current smart homes.
Widespread fragmentation is stalling the growth of the IIoT and making it difficult for partners to work together. The number of software platforms, apps, hardware and connectivity standards is creating paralysis among businesses that are afraid of being locked into a solution. EdgeX Foundry is unifying the community around a common IoT edge framework and an ecosystem of interoperable components.
Join IBM November 1 at 21st Cloud Expo at the Santa Clara Convention Center in Santa Clara, CA, and learn how IBM Watson can bring cognitive services and AI to intelligent, unmanned systems. Cognitive analysis impacts today’s systems with unparalleled ability that were previously available only to manned, back-end operations. Thanks to cloud processing, IBM Watson can bring cognitive services and AI to intelligent, unmanned systems. Imagine a robot vacuum that becomes your personal assistant th...
SYS-CON Events announced today that Avere Systems, a leading provider of hybrid cloud enablement solutions, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Avere Systems was created by file systems experts determined to reinvent storage by changing the way enterprises thought about and bought storage resources. With decades of experience behind the company’s founders, Avere got its ...
SYS-CON Events announced today that Golden Gate University will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Since 1901, non-profit Golden Gate University (GGU) has been helping adults achieve their professional goals by providing high quality, practice-based undergraduate and graduate educational programs in law, taxation, business and related professions. Many of its courses are taug...
SYS-CON Events announced today that SIGMA Corporation will exhibit at the Japan External Trade Organization (JETRO) Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. uLaser flow inspection device from the Japanese top share to Global Standard! Then, make the best use of data to flip to next page. For more information, visit http://www.sigma-k.co.jp/en/.