Having trouble getting my head around UI Graphics android

Question

At the moment I have just targeted my UI graphics for the hdpi resolutions for android and this works flawlessly, the graphics are designed with 3 resolutions in mind with only the background image being altered really. Problem is the plan was to use the same images for hdpi (480x800 and 480x854) and as well as mdpi (320x480). But when I test it for mdpi with the images in both the -hdpi and copied into -mdpi it doesn't scale them down, do I have to resize all the images and have them duplicated for the mdpi screens?

Sorry if this is not very eloquent it is the first time I have done any UI design for android and still don't understand it properly.

Answer 1

Android should correctly use the right image when you use R.drawable and your images are in drawable-hdpi, drawable-mdpi etc. Since that is what I think you've described as what you've done, it hints that maybe you've hardcoded a size? Are you using ImageView and set a size for them? If so, did you do it in Java code or in XML? If in Java code the values would be in pixels, so 50px on mdpi screens will look larger than on hdpi screens. If you used XML did you again set a size with px? If so, you should use dp.