getDimension()/getDimensionPixelSize() - mutliplier issue

Question

So I have android 2.3.5 device which is NORMAL/HDPI. I have a dimens.xml in my project:

...
    20sp         


        

Answer 1

Method getDimension() converts dp or sp values into pixels based on current screen density. This is very useful as you don't have to do it on your own, when you want to set in Java width or text size (they accepts only pixels).

But if you need original sp or dp you could do "reverse engineering".

Step 1. Check current scale ratio (based on screen density):

float scaleRatio = getResources().getDisplayMetrics().density;

Step 2. Get dimension from dimens.xml

float dimenPix = getResources().getDimension(R.dimen.your_dimen_name);

Step 3. Do some math

float dimenOrginal = dimenPix/scaleRatio;

Remarks:

• usually you need int for dimension methods (like setWidth()), so you have to convert float result to int for instance using Math.round()
• more accurate result when rounding to int you could get using such formula (dimenPix-0.5f)/scaleRatio
• in case of sp you could take also into account user preferences about text scale

Read more about dimensions in Android: http://android4beginners.com/2013/07/appendix-c-everything-about-sizes-and-dimensions-in-android/