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Designing For Android

For designers, Android is the elephant in the room when it comes to app design. As much as designers would like to think it’s an iOS1 world in which all anyones cares about are iPhones, iPads and the App Store, nobody can ignore that Android currently has the majority of smartphone market share2 and that it is being used on everything from tablets to e-readers. In short, the Google Android platform is quickly becoming ubiquitous, and brands are starting to notice.

But let’s face it. Android’s multiple devices and form factors make it feel like designing for it is an uphill battle. And its cryptic documentation3 is hardly a starting point for designing and producing great apps. Surf the Web for resources on Android design and you’ll find little there to guide you.

If all this feels discouraging (and if it’s the reason you’re not designing apps for Android), you’re not alone. Fortunately, Android is beginning to address the issues with multiple devices and screen sizes, and device makers are slowly arriving at standards that will eventually reduce complexity.

This article will help designers become familiar with what they need to know to get started with Android and to deliver the right assets to the development team. The topics we’ll cover are:

  • Demystifying Android screen densities,
  • Learning the fundamentals of Android design via design patterns,
  • Design assets your developer needs,
  • How to get screenshots,
  • What Android 3 is about, and what’s on the horizon.

Android Smartphones And Display Sizes Link

When starting any digital design project, understanding the hardware first is a good idea. For iOS apps, that would be the iPhone and iPod Touch. Android, meanwhile, spans dozens of devices and makers. Where to begin?

The old baseline for screens supported for Android smartphone devices was the T-Mobile G1, the first commercially available Android-powered device which has an HVGA screen measuring 320 x 480 pixels.

HVGA4 stands for “half-size video graphics array” (or half-size VGA) and is the standard display size for today’s smartphones. The iPhone 3GS, 3G and 2G use the same configuration.

Screenshot5
T-Mobile G1, the first commercially available Android device and the baseline for Android screen specifications.

To keep things simple, Android breaks down physical screen sizes (measured as the screen’s diagonal length from the top-left corner to bottom-right corner) into four general sizes: small, normal, large and xlarge.

Screenshot6
Two common Android screen sizes. (Image from Google I/O 2010)

320 × 480 is considered a “normal” screen size by Android. As for “xlarge,” think tablets. However, the most popular Android smartphones7 today have WVGA (i.e. wide VGA) 800+ × 480-pixel HD displays. So, what’s “normal” is quickly changing. For now, we’ll say that most Android smartphones have large screens.

Screenshot8
Diagram of various screen configurations available from emulator skins in the Android SDK. (Image: Android Developers website)

The variety of display sizes can be challenging for designers who are trying to create one-size-fits-all layouts. I’ve found the best approach is to design one set of layouts for 320 x 533 physical pixels and then introduce custom layouts for the other screen sizes.

While this creates more work for both the designer and developer, the larger physical screen size on bigger devices such as the Motorola Droid and HTC Evo might require changes to the baseline layouts that make better use of the extra real estate.

What You Need to Know About Screen Densities Link

Screen sizes are only half the picture! Developers don’t refer to a screen’s resolution, but rather its density. Here’s how Android defines the terms in its Developers Guide9:

  • Resolution
    The total number of physical pixels on a screen.
  • Screen density
    The quantity of pixels within a physical area of the screen, usually referred to as DPI (dots per inch).
  • Density-independent pixel (DP)
    This is a virtual pixel unit that you would use when defining a layout’s UI in order to express the layout’s dimensions or position in a density-independent way. The density-independent pixel is equivalent to one physical pixel on a 160 DPI screen, which is the baseline density assumed by the system of a “medium”-density screen. At runtime, the system transparently handles any scaling of the DP units as necessary, based on the actual density of the screen in use. The conversion of DP units to screen pixels is simple: pixels = DP * (DPI / 160). For example, on a 240 DPI screen, 1 DP equals 1.5 physical pixels. Always use DP units when defining your application’s UI to ensure that the UI displays properly on screens with different densities.

It’s a bit confusing, but this is what you need to know: Like screen sizes, Android divides screen densities into four basic densities: ldpi (low), mdpi (medium), hdpi (high), and xhdpi (extra high). This is important because you’ll need to deliver all graphical assets (bitmaps) in sets of different densities. At the very least, you’ll need to deliver mdpi and hdpi sets for any smartphone apps.

What this means is all bitmap graphics need to be scaled up or down from your baseline (320 x 533) screen layouts (note: there is also a way for parsing SVG files10 that provides a way to scale vector art on different screens sizes and densities without loss of image quality).

The bitmap requirement is similar to preparing graphics for print vs. the Web. If you have any experience with print production, you’ll know that a 72 PPI image will look very pixelated and blurry when scaled up and printed. Instead, you would need to redo the image as a vector image or use a high-resolution photo and then set the file’s resolution at around 300 PPI in order to print it without any loss of image quality. Screen density for Android works similar, except that we’re not changing the file’s resolution, only the image’s size (i.e. standard 72 PPI is fine).

Let’s say you took a bitmap icon measuring 100 × 100 pixels from one of the screens of your baseline designs (remember the “baseline” is a layout set at 320 × 480). Placing this same 100 × 100 icon on a device with an lDPI screen would make the icon appear big and blurry. Likewise, placing it on a device with an hDPI screen would make it appear too small (due to the device having more dots per inch than the mDPI screen).

Screenshot11
An application without density support. (Image: Android Developers website)

To adjust for the different device screen densities, we need to follow a 3:4:6:8 scaling ratio between the four density sizes. (For the iPhone, it’s easy: it’s just a 2:1 ratio between the iPhone 4 and 3GS.) Using our ratios and some simple math, we can create four different versions of our bitmap to hand off to our developer for production:

  • 75 × 75 for low-density screens (i.e. ×0.75);
  • 100 × 100 for medium-density screens (our baseline);
  • 150 × 150 for high-density screens (×1.5);
  • 200 × 200 for extra high-density screens (×2.0). (We’re concerned with only lDPI, mDPI and hDPI for Android smartphone apps.)

Screenshot12
The final graphic assets would appear like this using the four different screen densities.

After you’ve produced all of your graphics, you could organize your graphics library as follows:

Screenshot13
The suggested organization and labeling of asset folders and files. In preparing our star graphic, all file prefixes could be preceded by the name ic_star, without changing the names of the respective densities.

You might be confused about what PPI (pixels per inch) to set your deliverables at. Just leave them at the standard 72 PPI, and scale the images accordingly.

Using Android Design Patterns Link

Clients often ask whether they can use their iPhone app design for Android. If you’re looking for shortcuts, building an app for mobile Web browsers using something like Webkit14 and HTML5 is perhaps a better choice. But to produce a native Android app, the answer is no. Why? Because Android’s UI conventions are different from iPhone’s.

The big difference is the “Back” key, for navigating to previous pages. The Back key on Android devices is fixed and always available to the user, regardless of the app. It’s either a physical part of the device or digitally fixed to the bottom of the screen, independent of any app, as in the recently released Android 3.0 for tablets (more on this later).

Screenshot15
The hard “Back” key on a smartphone running Android 2.0.

The presence of a Back key outside of the app itself leaves space for other elements at the top of the screen, such as a logo, title or menu. While this navigational convention differs greatly from that of iOS, there are still other differentiators that Android calls “design patterns.” According to Android, a design pattern is a “general solution to a recurring problem.” Below are the main Android design patterns that were introduced with version 2.0.

Dashboard Link

This pattern solves the problem of having to navigate to several layers within an app. It provides a launch pad solution for rich apps such as Facebook, LinkedIn and Evernote.

Screenshot16
The dashboard design pattern, as used by Facebook and LinkedIn.

Action Bar Link

The action bar is one of Android’s most important design patterns and differentiators. It works very similar to a conventional website’s banner, with the logo or title typically on the left and the navigation items on the right. The action bar’s design is flexible and allows for hovering menus and expanding search boxes. It’s generally used as a global feature rather than a contextual one.

Screenshot17
The action bar design pattern as used by Twitter.

This gives the user a simple way to search by category, and it provides search suggestions.

Screenshot18
The search bar design pattern as used in the Google Search app.

Quick Actions Link

This design pattern is similar to iOS’ pop-up behavior that gives the user additional contextual actions. For example, tapping a photo in an app might trigger a quick action bar that allows the user to share the photo.

Screenshot19
The quick action design pattern as used by Twitter.

Companion Widget Link

Widgets20 allow an app to display notifications on the user’s launch screen. Unlike push notifications in iOS, which behave as temporary modal dialogs, companion widgets remain on the launch screen. (Tip: to select a widget for your Android device, simply tap and hold any empty space on one of the launch screens.)

Screenshot21
Companion widgets by Engadget, New York Times and Pandora.

Using established design patterns is important for keeping the experience intuitive and familiar for your users. Users don’t want an iPhone experience on their Android device any more than a Mac user wants a Microsoft experience in their Mac OS environment. Understanding design patterns is the first step to learning to speak Android and designing an optimal experience for its users. Your developers will also thank you!

Android Design Deliverables Link

OK, so you’ve designed your Android app and are ready to make it a reality. What do you need to hand off to the developer? Here’s a quick list of deliverables:

  1. Annotated wireframes of the user experience based on the baseline large screen size of 320 x 533 physical pixels. Include any additional screens for instances where a larger or smaller (320 x 480) screen size requires a modified layout or a landscape version is required.
  2. Visual design mockups of key screens for WVGA large size (320 x 533) screens (based on a WVGA 800 x 480 hdpi physical pixel screen size) in addition to any custom layouts needed for other screen sizes.
  3. Specifications for spacing, font22 sizes and colors, and an indication of any bitmaps.
  4. A graphics library with lDPI, mDPI and hDPI versions of all bitmaps saved as transparent PNG files.
  5. Density-specific app icons, including the app’s launch icon, as transparent PNG files. Android already provides excellent tips for designers23 on this topic, along with some downloads, including graphic PSD templates and other goodies.

How To Take Screenshots Link

Your product manager has just asked for screenshots of the developer’s build. The developer is busy and can’t get them to you until tomorrow. What do you do?! As of this writing, Android has no built-in way to take screenshots (bummer, I know). The only way is to just deal with it, and that means pretending to be a developer for a while and downloading some really scary software. Let’s get started!

The following software must be downloaded:

  1. All USB drivers for your Android device,
  2. Android software development kit24 (SDK),
  3. Java SE SDK25

Then, on your computer:

  1. Extract the USB drivers to a folder on your desktop,
  2. Extract the Android SDK to a folder on your desktop,
  3. Install the Java SE SDK.

On your Android device:

  1. Open “Settings” (you’ll find it in the apps menu),
  2. Tap on “Applications,”
  3. Tap on “Development,”
  4. Check the box for “USB debugging.”

Screenshot26

Now, for the fun part:

  1. Connect your Android device to your computer via USB. Windows users: allow Windows to install all drivers. One of the drivers may not be found and will require you to go to the Window’s Device Manager under the Control Panel. There, you can locate the device (having a yellow warning icon next to it) and right-click on it.
  2. Choose to “update/install” the driver for your device.
  3. Go to your desktop. Open the Android SDK folder and select SDK Setup.exe.
  4. Allow it to automatically refresh its list of the operating system SDKs that are available, and select to install all packages.
  5. Once finished, exit the application.
  6. Go back to the opened Android SDK folder on your desktop, and open the “Tools” folder.
  7. Click on the file ddms to open the Dalvik Debug Monitor.
  8. Select your device from the “Name” pane.
  9. In the application’s top menu, open the “Device” menu, and choose “Screen capture…” A Device Screen Capture window will open, and you should see the launch screen of your Android device.

Screenshot27
The Dalvik Debut Monitor.

To navigate:

  1. Grab your Android device and navigate to any page. Go back to your computer and select “Refresh” in the Device Screen Capture window. The current screen from your Android device should appear.
  2. If you’re on a Mac, you can just do the old Shift + Command + 4 trick to take a screenshot. In Windows, you can copy and paste it into one of the Windows media applications.

About Android Tablets Link

At CES 2011, companies rained down Android tablets28, with an array of screen sizes. However, after a quick review of the most popular ones29, we can conclude that the two important screen sizes to focus on in terms of physical pixels are 1280 × 800 and 800 × 480.

With the Android 3.0 Honeycomb release, Google provided device makers with an Android UI made for tablets. Gone is the hard “Back” button, replaced by an anchored software-generated navigation and system status bar at the bottom of the screen.

Screenshot30
The anchored navigation and system bar in Android 3.0.

Android 3.0 got a visual refresh, while incorporating all of the design patterns introduced in Android 2.0. One of the major differences with 3.0 is the Action Bar which has been updated to include tabs, drop-down menus or breadcrumbs. The action bar can also change its appearance to show contextual actions when the user selects single or multiple elements on a screen.

Screenshot31
The new action bar with tabs, introduced in Android 3.0.

Another new feature added to the Android framework with 3.0 is a mechanism called “fragments32.” A fragment is a self-contained component in a layout that can change size and position depending on the screen’s orientation and size. This further addresses the problem of designing for multiple form factors by giving designers and developers a way to make their screen layout components elastic and stackable, depending on the screen limitations of the app. Screen components can be stretched, stacked, expanded and collapsed, and revealed and hidden.

Screenshot33
Diagram showing examples of how fragments can be used.

The next Android release, scrumptiously dubbed Ice Cream Sandwich34, promises to bring this functionality to Android smartphones as well, giving designers and developers the option to build an app using a one-size-fits-all strategy. This could be a paradigm shift for designers and developers, who will need to learn to think of app design in terms of puzzle pieces that can be stretched, stacked, expanded or hidden to fit the form factor. In short, this will allow one Android OS to run anywhere (with infinite possibilities!).

A Word of Advice Link

Do get your hands on an Android phone and tablet, and spend some time downloading apps and exploring their interfaces. In order to design for Android, you have to immerse yourself in the environment and know it intimately. This might sound obvious, but it’s always surprising to hear when even the product manager doesn’t have an Android device.

Screenshot35

Online Resources Link

Here are some links to online resources I’ve found especially useful:

Presentations Link

Videos Link

Blogs Link

Product Reviews Link

Android Developers Link

Other Link

(al) (il) (kw)

Footnotes Link

  1. 1 http://en.wikipedia.org/wiki/IOS_%28Apple%29
  2. 2 http://www.pcworld.com/article/226339/android_market_share_growth_accelerating_nielsen_finds.html
  3. 3 http://developer.android.com/guide/practices/ui_guidelines/index.html
  4. 4 http://en.wikipedia.org/wiki/Quarter_Video_Graphics_Array#QVGA_.28320.C3.97240.29
  5. 5 https://www.smashingmagazine.com/wp-content/uploads/2011/06/t-mobile-g1.jpg
  6. 6 https://www.smashingmagazine.com/wp-content/uploads/2011/06/screen-sizes.gif
  7. 7 http://developer.android.com/resources/dashboard/screens.html
  8. 8 https://www.smashingmagazine.com/wp-content/uploads/2011/06/table.png
  9. 9 http://developer.android.com/guide/practices/screens_support.html
  10. 10 http://code.google.com/p/svg-android/
  11. 11 https://www.smashingmagazine.com/wp-content/uploads/2011/06/density-test-bad.png
  12. 12 https://www.smashingmagazine.com/wp-content/uploads/2011/06/icon-sizes.jpg
  13. 13 https://www.smashingmagazine.com/wp-content/uploads/2011/06/folders.gif
  14. 14 http://en.wikipedia.org/wiki/WebKit
  15. 15 https://www.smashingmagazine.com/wp-content/uploads/2011/06/back-key.jpg
  16. 16 https://www.smashingmagazine.com/wp-content/uploads/2011/06/pattern-dashboard.jpg
  17. 17 https://www.smashingmagazine.com/wp-content/uploads/2011/06/pattern-action-bar.jpg
  18. 18 https://www.smashingmagazine.com/wp-content/uploads/2011/06/pattern-search-bar.jpg
  19. 19 https://www.smashingmagazine.com/wp-content/uploads/2011/06/pattern-quick-actions.jpg
  20. 20 http://www.businessinsider.com/best-android-widgets-2011-4
  21. 21 https://www.smashingmagazine.com/wp-content/uploads/2011/06/pattern-widgets.jpg
  22. 22 http://www.droidfonts.com/home/androidsdk/
  23. 23 http://developer.android.com/guide/practices/ui_guidelines/icon_design.html
  24. 24 http://developer.android.com/sdk/index.html
  25. 25 http://www.oracle.com/technetwork/java/javase/downloads/index.html
  26. 26 https://www.smashingmagazine.com/wp-content/uploads/2011/06/settings.jpg
  27. 27 https://www.smashingmagazine.com/wp-content/uploads/2011/06/dalvik-screen.png
  28. 28 http://www.engadget.com/features/tablets-at-ces-2011/
  29. 29 http://reviews.cnet.com/best-tablets/best-5-android-tablets
  30. 30 https://www.smashingmagazine.com/wp-content/uploads/2011/06/system-bar.jpg
  31. 31 https://www.smashingmagazine.com/wp-content/uploads/2011/06/new-action-bar.jpg
  32. 32 http://android-developers.blogspot.com/2011/02/android-30-fragments-api.html
  33. 33 https://www.smashingmagazine.com/wp-content/uploads/2011/06/fragments.gif
  34. 34 http://gizmodo.com/5800358/what-is-androids-ice-cream-sandwich
  35. 35 https://www.smashingmagazine.com/wp-content/uploads/2011/06/android-ice-cream-sandwich.jpg
  36. 36 https://docs.google.com/fileview?id=0B9Lrx2XbHPV6NTBiYTA5OGMtYmEwNi00Yzc3LWIxNWUtZWYwZGZlZGViZWMz&hl=zh_CN
  37. 37 http://www.slideshare.net/AndroidDev/android-ui-design-tips
  38. 38 http://www.youtube.com/watch?v=WGIU2JX1U5Y&feature=player_embedded#at=3469
  39. 39 http://anidea.com/technology/designer%E2%80%99s-guide-to-supporting-multiple-android-device-screens/
  40. 40 http://www.androidpatterns.com/
  41. 41 http://www.androidpatterns.com/
  42. 42 http://reviews.cnet.com/best-android-phones/
  43. 43 http://reviews.cnet.com/best-tablets/best-5-android-tablets
  44. 44 http://developer.android.com/guide/practices/screens_support.html
  45. 45 http://developer.android.com/guide/practices/ui_guidelines/icon_design.html
  46. 46 http://speckyboy.com/2010/05/10/android-app-developers-gui-kits-icons-fonts-and-tools/
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Born and raised in Silicon Valley, Daniel McKenzie is a digital product designer helping startups and companies strategize and design products that matter. He also likes to write and tweet (@danielmckenzie) on various design and innovation topics.

  1. 1

    Not everyone is willing to void their warranty to just take a screenshot.

    14
  2. 2

    But Great article anyway !

    0
  3. 3

    jenni has her head in the clouds

    June 30, 2011 7:52 am

    The hardest thing I’ve been having problems with is finding current Android GUIs. Most of the ones out there are 1-2 years old. Anyone have any leads?

    1
  4. 4

    Your method is not the only way to take a screenshot.

    You can easily root your device and download one of many apps from the Market that capture screenshots.

    Much simpler.

    0
  5. 5

    Great article. One pointer: the `ddms` program will run fine on OS X with Java installed–there’s no need to have a Windows virtual machine.

    1
  6. 6

    “nobody can ignore that Android currently has the majority of smartphone market share and that it is being used on everything from tablets to e-readers.”

    Not really. You have to check the network traffic to have a good overview about the OS Market share. And iOS devices are still ahead today.

    Android is used on a LOT of low end devices that can not even support applications, especially in emerging country.

    Google is not showing any numbers about smartphone / tablet usage and speaks only about activations because they know this.

    Well we know about tablet usage: it’s ridiculous.

    -13
  7. 7

    Mikko Ohtamaa

    June 30, 2011 6:27 am

    Samsung Android models have internal, much easier, screenshotting facilities:

    http://blog.mfabrik.com/2011/02/27/taking-a-screenshot-on-samsung-galaxy-s-and-other-samsung-android-devices/

    No need to install SDK.

    1
  8. 8

    Dan McKenzie

    June 30, 2011 6:42 am

    Good point. The only reason I specified Windows is because most Android devices only have drivers for Windows :(

    1
  9. 9

    Wow, wrong on so many fundamental levels.

    1. There never was an Android device incapable of running apps, same as iOS.
    2. Why would network traffic be an indicator of market share? Market share is the only indicator for market share. And network traffic is no indicator of how well your app would sell either.
    3. You will never get real numbers from anyone about usage. With the Android Market, we as developers/designers at least see how well competing applications sell, which you can’t on iOS.

    You’re right on tablet usage, it is miniscule at the moment. It might be a market to get into; then again, it might be a dead end.

    8
  10. 10

    Dan, I develop solely on a mac with a host of 10+ Android devices for testing. You don’t need drivers on the Mac (or Linux for that part), it uses the built-in standard serial port driver. It should work with every device.
    With Windows, you need drivers.

    3
  11. 11

    Valid point. I’d wish Google would add screenshot capability to the platform. On another note, a lot of newer devices can create screenshots (LG, Samsung) by pressing Volume Down + Menu at the same time, so no need to root them.

    Oh and btw: great article, thanks.

    0
  12. 12

    Dan McKenzie

    June 30, 2011 6:57 am

    Great. Thanks for the tip!

    0
  13. 13

    Rooting your device doesn’t make you void your warranty: you can unroot your device with one click-tap. Unlock the bootloader is another story.

    2
  14. 14

    Great article! If you are new to Android i ld recommend to use ACRA or http://www.bugsense.com to uncaught exceptions

    0
  15. 15

    We’re in the same boat jenni. I always end having to recreate my own components.

    0
  16. 16

    Feel free to share them and maybe the next person won’t be in the same boat :)

    1
  17. 17

    To take a screenshot fom an Android device, just press the home button and the devices on/off button simultaneously, and the screen will be saved to your gallery. Then for example mail that to yourself.

    1
  18. 18

    Great.. now if someone could just figure out how to actually make money… wishing Android owners were as willing to spend money as iOS ones. I don’t know that it’s ever going to improve.

    2
  19. 19

    Unfortunately, I have yet to find a screenshot app that doesnt involve either shaking the device or pulling down the notifcation tray. 10 points to anyone that either makes one or finds one.

    0
  20. 20

    I would love to spend money on apps, but nothing I actually want is available on Android :( It always says “Android version coming soon”. I don’t look for things very often as a result, only when I have a specific need. Just my experience.

    1

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