Android tricks – Determine current screen density

Do you know the thing I hate the most about Android? It’s screen fragmentation! On the one hand, having a huge variety of screen sizes is great for the end users. But it’s a complete nightmare for developers! Thus, it’s really hard to create a good looking UI without any problems. There will always be a device with some wired screen size on which your layout will look bad!

There are several different approaches for handling this problem. Sadly, you can’t be 100% sure that there won’t be any UI issues. And if you have to manipulate a View through your Java code, things can get really nasty!

A good practice is to determine the current screen density of the device. We can do that with the following code snippet:

DisplayMetrics metrics = getResources().getDisplayMetrics();
float density = metrics.density;
The density variable holds a float value. It represents the logical density of your device. It’s a factor based on the mdpi baseline.

How is that useful?

I did the following thing several days ago:

My task was to create translation animations for some views. I had a xhdpi phone. Thus, I implemented the UI with values which made the views look great on this particular phone. Of course, they looked terrible on other devices. But that was not a problem.

For example, I knew that I had to translate a view with 200 dp on the X axis to look OK on my current phone. I knew my phone had a xhdpi screen. Thus, to make the UI relatively good for the rest of the devices out there, I had to find the base value for mdpi screens. I used the code from above and divided these 200 dp by the value in the density variable. And found out that the baseline value for mdpi screens was 100 dp.

By having this value, I was able to determine with how many dp I have to translate the view for the current device density. The only thing I had to do was to multiplying it with the value from the code snippet above.

Resources:

http://stackoverflow.com/questions/27590213/android-displaymetrics-densitydpi-returns-zero-on-rooted-devices

Feel free to share, comment & give your opinion on the topic!

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