PeasyPrint 1.8 can print directly from some gphoto-compatible cameras. There is now a Camera button on the row of editing tools. When you click it, your camera's memory card will be mounted at /tmp/camera. You can then load/view/edit/print images just like in previous versions. Clicking the Camera button a second time unmounts the card.
Since your camera's memory is probably not writable from Linux, you will need to use the Copy operation if you want to edit the image. The temporary file is now stored in /tmp. (Previous versions stored the temporary file in the same folder as the original.)
PeasyPrint 1.8 has had VERY LIMITED testing, so I don't know how well the camera mounting procedure will work in general. Please provide feedback. Do NOT test it with a camera full of irreplaceable photos!
More information at the PeasyPrint thread.
Download and install from PeasyPrint thread
Using mTpaint - PeasyPrint can be used to print from mTpaint