CODEWITHSUNDEEP
androidandroid-layout
Lara
Lara

Reputation: 172

drawable folders - What resolutions do I need

All images I use in my app are located in one folder -> drawable-hdpi. I use them as backgrounds for my buttons, for my layouts and for some imageViews. These images have all different sizes from 50x50px to 900x900px.

I calculate the size of my buttons and other controls (in pixels) depending on the screen size (in pixels).

Pseudo-code:

 screenWidth = getScreenWidthInPixels();
 screenHeight = getScreenHeightInPixels();

 myButtons.setHeight(screenHeight * 0.1); //buttonHeight = 10 % of screenHeight
 ......
 ...
 ..

I want the quality of my images (button backgrounds, imageviews, layout backgrounds, ...) to be good on all devices. There are now 5 different drawable folders. As far as I know I can now put the same images I already have in my drawable-hdpi folder in the other four drawable folders but with different resolutions. What I'm trying to figuring out right now is what resolution I have to pick for what folder. And like I said, my images have resolutions right now from 50x50px to 900x900px.

Upvotes: 2

Views: 1047

Answers (2)

Phantômaxx
Phantômaxx

Reputation: 38098

These are the resolutions in dpi:

ldpi:    120 dpi  
mdpi:    160 dpi  
hdpi:    240 dpi  
xhdpi:   320 dpi  
xxhdpi:  480 dpi  
xxxhdpi: 640 dpi

You have to calculate the dimensions in pixels basing on the resulution:

Scale factor:

ldpi:    0.75  
mdpi:    1.0  
hdpi:    1.5  
xhdpi:   2.0  
xxhdpi:  3.0  
xxxhdpi: 4.0

You COULD have all the images in the xxxhdpi folder and let Android scale them down... but not always you'd get nice results (Android scaling DOWN is good, but not as good as pre-sized images).
Nowadays I guess that an xxhdpi resolution is enough, but tomorrow...
It would be scaled UP on an xxxhdpi screen, with not-so-good results (visible pixellation).

A solution would be using svg graphics (which is a vectorial standard based on xml), but you'd need an external library (there are several open source / free - you choose the one which fits best) to render them in a standard control.

Upvotes: 3

S.M_Emamian
S.M_Emamian

Reputation: 17383

if you have an icom with 100*100 px in the mdpi then :

(3:4:6:8)

mdpi (4) = 100*100 px (default image)

hdpi (6) = (100*6)/4 = 150*150 px

xhdpi (8) = (100*8)/4 = 200*200 px or (150*8)/6 = 200*200

Upvotes: 0

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