android - Why is BitmapFactory.decodeResource() slower when I put the images in the drawable folder? -

i've noticed while checking decoding times of resource images, bitmapfactory.decoderesource() function 3-6 times slower, when move resource image drawable folder.

question:

does know why happens? images scaled if in drawable folder? possible prevent without storing copy of image in each folder?

details:

i used following code check decoding times of image.

for(int = 0; < 5; i++){     long time = system.currenttimemillis();     bitmapfactory.decoderesource(getresources(),r.drawable.welcome_01);     log.i(tag, "time: " + (system.currenttimemillis() - time)); } 

bitmap size: 774 x 1280

device: nexus 6 (which uses drawable-xxxhdpi folder if resource available)

test results:

if image in drawable folder these decoding times:

08-03 09:18:01.072: i/mainactivity(26242): time: 298 08-03 09:18:01.352: i/mainactivity(26242): time: 280 08-03 09:18:01.656: i/mainactivity(26242): time: 304 08-03 09:18:01.929: i/mainactivity(26242): time: 272 08-03 09:18:02.263: i/mainactivity(26242): time: 334 

if in drawable-xxxhdpi folder these results:

08-03 09:19:49.733: i/mainactivity(26456): time: 54 08-03 09:19:49.786: i/mainactivity(26456): time: 53 08-03 09:19:49.841: i/mainactivity(26456): time: 54 08-03 09:19:49.905: i/mainactivity(26456): time: 64 08-03 09:19:49.966: i/mainactivity(26456): time: 61 

i found solution problem.

it might else.

solution:

putting image drawable-nodpi folder prevents image scaled.

additional infos:

in every other folder images scaled in case, in drawable folder.

i've checked bitmap sizes after decoding resource inside different folders.

original size 774x1280

drawable folder: bitmap: 2709x4480 drawable-ldpi :  bitmap: 3612x5973 drawable-mdpi: bitmap: 2709x4480 drawable-hdpi:  bitmap: 1806x2987 drawable-xhdpi:  bitmap: 1355x2240 drawable-xxhdpi: bitmap: 903x1493 drawable-xxxhdpi: bitmap: 677x1120 drawable-nodpi:  bitmap: 774x1280 

thanks joey chong found official answer problem. on android developers page can read following lines:

if resources not available in correct density, system loads default resources , scales them or down needed match current screen's density. system assumes default resources (those directory without configuration qualifiers) designed baseline screen density (mdpi), unless loaded density-specific resource directory. pre-scaling is, thus, system when resizing bitmap appropriate size current screen density.

in short - if don't provide density, android handles them mdpi.