generate high resolution images for printing as well as viewing on iPhone

[aheirich]

I have an app in which I impose text on top of a user-supplied image. Normally I display the result on the iPhone screen. This display is low resolution, 480x320.

I also want to send the result (by email) so that it can be printed. The printed format should be much higher resolution than the on-screen format, for example 300 dpi. So the problems I am facing are: make the image higher resolution, and generate the text at higher resolution.

If I use Quartz to draw on top of a PNG is there an easy way to make it generate a high resolution result? Is there another approach to generating low- and high-resolution imagery that doesn't require writing two versions of the code?

[paymaster]

(I'm a newbie myself, other feel free to correct me)

Create a context - CGBitmapContextCreate
You decide how big it is- it can exceed the iphone screen dimensions.
Draw your image and text into that context. (You will likely need to scale your font programatically to match the resolution your are drawing into.)

You can turn it into a new high res image to display with [UIImage imageWithCGImage:]. This is the image to save/email.

If it is less than 1024 pixels in any dimension, you can add it to a 480x320 imageView and have the view automatically scale to fit. If it is too large, you will need to scale it on your own.