问题
I'm creating an Android application. The main activity layout will have a background image that will wrap with the whole screen. What resolution should I use to create the background image? What about DPI? I need it to be compatible with all devices (for example the HTC Sensation screen's resolution is 540 × 960 pixels).
回答1:
The best way for you is to start reading this article, it contains the best practices for supporting multiple screen sizes and densities.
EDIT:
I use the following directories to store the drawables for maximum size and density optimization:
Small screens support
- drawable-small-hdpi
- drawable-small-ldpi
Normal screen support
- drawable-normal-mdpi
- drawable-normal-hdpi
Large screens support
- drawable-large-mdpi
Tablet screen support
- drawable-xlarge-mdpi
Of course not every time this solution is the best, aqs's solution is more common used. You can follow this site to track which screen sizes and density's are most used and decide which of the screens worth support for your application. And of course you can read about the Providing Alternative Resources to understand better what are your options.
回答2:
You should read Supporting multiple screens. You must define dpi on your emulator. 240 is hdpi, 160 is mdpi and below that are usually ldpi.
Extract from Android Developer Guide link above:
320dp: a typical phone screen (240x320 ldpi, 320x480 mdpi, 480x800 hdpi, etc).
480dp: a tweener tablet like the Streak (480x800 mdpi).
600dp: a 7” tablet (600x1024 mdpi).
720dp: a 10” tablet (720x1280 mdpi, 800x1280 mdpi, etc).
回答3:
IMHO answer of @Cata is a bit misleading because of mixing screen size and screen density for providing graphics.
I think the best practice is to distinguish this two things by providing:
different size images (PNGs) for different densitiesanddifferent layouts for different generalized screen sizes.
By doing so developer can reduce number of different images to 4 categories (ldpi, mdpi, hdpi, xhdpi) if he wants to support all currently existing densities. Of course XML layouts files for different (small, normal, large, xlarge) screen sizes are necessary if we support them but it is much easier to make/edit/correct/adjust xml files than PNGs.
A bit more details and explanation u can find in my previous answer about this topic on this link.
Hope u find this answer useful. Cheers.
来源：https://stackoverflow.com/questions/8956408/how-can-i-create-android-images-with-good-resolution