setContentSize gives poor graphic?

cocos2d-x C++
#1

I want to create sprite with size is relative to the screen.
I.e: Sprite size is equal to screen width * 0.2.

I use setContentSize but it gives ugly and poor graphic.
I’ve read about multiple resolution supports, but it doesn’t work on this case.

setContentSize 512x512 → 32x32 (bad quality)

setContentSize 64x64 → 32x32 (good quality)

Anyway to archive it?

#2

designResolutionSize is for the same purpose, set it, and use Resource in size according to what you’ve setting as resolution.

Sprites are blurred
#3

designResolutionSize works for defined screen resolution only, not for every screen resolution.
screen resolutions on Android devices is countless.

I don’t want to create numerous versions of sprite for each screen resolution.

Or you can tell me the way to do it?