Introducing DP
DP = Density Independent pixelsAlso called DIP
•Introduced to declare and create UIs that are screen size/resolution independent.•Helps to ensure interfaces work well across devices of different aspect ratio/ screen density etc.•In Android, refrain from using px for width/distance and other measurements. Always use DP.
Concept of DPsresolution = number of pixels available in the display
density = how many pixels appear within a constant area of the display, dots per inch = dpi
size = amount of physical space available for displaying an interface, screen's diagonal, inch
density-independent pixel = virtual pixel that is independent of the screen density, dp
Concept of DPs
With device independence
Without device independence
Concept of DPs
Density or dpi = Physical Size / ResolutionBaseline density in Android = 160
DIP or DP = Resolution / ( density / 160 )
A little about Density
Galaxy Nexus Nexus 7
4.65” 7”
720x1280 800x1280
316 dpi 216 dpi
Notes1. Higher density/ dpi = more data, more clarity.2. Two devices with same/similar resolution need not have same
physical size and vice versa.
Screen sizes & Density buckets
*Only a guideline
Designing for phones and tablets
Handling different sizes
Explicitly declare in the manifest which screen sizes your application supports
Handling different sizes
Provide different layouts for different screen sizes
Handling different sizes
Provide different bitmap drawables for different screen densities
Handling different sizes
Use qualifiers effectively<resources_name>-<qualifier>
Handling different sizes
Some recommendations from Google
Tip Preview all screens via IDE
Handling different sizes
Using 9-patch images helps you scale a graphic without distortion.Use 9 patch images for BG of Buttons, EditText etc
9-patch tool comes as a part of the Android SDK
Some resourceshttp://developer.android.com/guide/practices/screens_support.html
http://developer.android.com/design/index.html
http://blog.edwinevans.me/?p=131
http://blogs.captechconsulting.com/blog/steven-byle/understanding-density-independence-android
http://stefan222devel.blogspot.com/2012/10/android-screen-densities-sizes.html
http://developer.android.com/tools/help/draw9patch.html
