Its called DIgital Textile Printing. And it cannot be done (easily) by just printing your pattern all over the shirt because it will not come out the way you want it. You want the pattern to be consistent and not look like it has any breaks around the shirt. What you do is get fabric that is printed with your design, and then get a tailor or whoever to make your shirts or whatever you want, from scratch using your material. It will get you the results you're looking for.
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