i'd like to get a full understanding of dpi and images.
I notice that titanium has folders - hdpi, ldpi etc etc, and i'd like to know:
what is the point of this?
When i make an image - say, an all white background - does it matter what size i make it, or what dpi i make it? Or both?
And if i want an image that is for a device that is, say, 320 * 480, how big should i make the image? And what resolution should i set this image for? And now that i want this image used in all different devices, what do i do? Do i resize the image? Do i add resolution to it? Also, is it better to downgrade or upgrade an image's resolution?
I guess what I am asking for is either a really thorough explanation of what i need to do to make an all-sizes consistent app from an image point of view.
It is a deep subject - not something that can be full explained here. If you are looking for graphics sizes / resolutions to tell your graphics guy what sizes you need for each folder, I blogged a little about it last week. This isn't a complete explaination, but with this and the link Anthony provided, it might be enough for you to get on the right track.
We don't just make this stuff up, there are folders for different devices and densities because that is how Android deals with their many form factors. If you want a thorough explanation on this, the best place to start is usually the Android Docs for Supporting Multiple Screens
To have a full understanding of the subject (as you mentioned yourself). You must understand all the implications of supporting multiple screen densities. Since there are so many devices and many resolutions, your design have to take this into consideration when creating images and other resources.
The most comprehensive explanation on this subject can be fount on the Android Developer Website. While the explanation covers Android native development, the same principles apply here with Titanium.
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