Why does paint.net crop parts of layers that are dragged outside the canvas?

[Guest]

If you select and move part of a layer outside the edge of the canvas and then clear the selection, the part of the layer that moved beyond the boundaries of the canvas is cropped and does not return when moving the layer back within the boundaries of the canvas. Why is this and are there any plans to change how this works?

[midora]

Because all layers share the same position and size.

If you apply something to a layer it will be cropped to the layer borders.

Changing this behavior would impact a lot of things including the file format of .pdn files.

[MJW]

The layer is the area within the image boundaries, not something that extends in all directions outside it. As long as the region is selected PDN can maintain a separate copy, which can be moved around outside the edge. Once you clear the selection, you've committed the selection move, so only the area within the image boundary remains. I have no say about it, but I very much doubt if that will ever change.

 

EDIT: I don't actually know whether, when moving a selection, PDN makes a copy of the selection, or whether it maintains some structure that points at the selected pixels in the original image. In either case (or some other I haven't considered), once the selection is cleared, the previously-selected pixels are copied to their new positions, which must be within the image boundary.

Edited August 12, 2015 by MJW

[Rick Brewster]

Nothing exists outside of the canvas. Some tools hold objects in their own buffers and allow you to move them in and out of the canvas without cropping until you move onto the next action, but this is not a property of the canvas or layers.

 

Layers are always the same size as the image. They can't be moved. It might only appear that you're "moving a layer" because you've moved around the pixels inside of it.

[Rick Brewster]

MJW, to answer your question about whether paint.net copies the selection: internally, no. It (rather, the Move Selected Pixels tool) actually does some very complicated stuff to ensure that copying the internal buffers isn't needed. The only time things have to be "copied around" is when you finish/commit and move on to the next thing.

[MJW]

Thanks, Rick. I sort of suspected that was the case, and that my original comment was incorrect in that respect.