Quoting Rob Antonishen <rob.antonishen@xxxxxxxxx>: > I am writing a c plugin to scale a layer. (This is much as an > exercise for me as anything). > > I have looked at a few examples and they handle things differently.... > > - Create a new image with a new layer the new size The only reason I can conceive why this might be desirable is if the image is Indexed (and RGB scaling is desired); and then you must decide how the rescaled layer is to be re-converted back to Indexed. > - Create a new layer in the existing image just above the input layer I'm not much of a fan of scripts/plug-ins which merely combine two operations into one. Running a "dup-scale" command is hardly a sufficient improvement to duplicating the layer and scaling the duplicate. (The exception to this being if a user wishes to assign a keyboard shortcut to that single command, but this is most dependent upon the use case and is best left to customized, one-off scripts.) > - Create a new layer in the existing image just above the input layer > and delete the input layer Under normal scenarios, this produces the result I should expect, effectively scaling the layer; however, it raises some implementation and behavioral issues should the active layer be in the floated state. Furthermore, this approach has the unfortunate side effect of changing the layer's ID (and less importantly, its tattoo). A filter should avoid changing a layer's ID *if possible* as this facilitates other scripts/plug-ins being able to use the filter and in some cases permits. > - Initialize the input pixel region then change the input layer's size > and push the output pixel region into the resized input layer > > - change the image canvass to match the resized layer? This seems to me the approach that should be pursued as it would appear to work with floated layers and doesn't unnecessarily modify the layer's ID. Quoting Rob Antonishen <rob.antonishen@xxxxxxxxx>: > The "built-in" scaling options are: ... > Layer->Scale Layer which scales the active layer only but does not > change the image canvas size or scale the associated layer mask (is > that a reasonable behavior?). "Layer->Scale Layer" (in the Menus) indeed scales the associated layermask. Currently, I believe all PDB layer transformations also likewise operate upon the associated layermask (this was not always the case). > - should an action like scaling scale all layers, masks, channels > and paths of an image if it is the image menu (otherwise in the layer > menu)? (I'm leaning towards yes) Yes. Commands in the Image Menu should operate on the image as a whole. > - should an action like scaling a layer also scale an associated > layer mask? (yes?) It has been my experience that having a layermask with different dimensions then the layer with which it's associated can lead to catastrophic problems in GIMP. I would highly advise that directly after changing the dimensions of a layer, its layermask's dimensions be adjusted to match. _______________________________________________ Gimp-developer mailing list Gimp-developer@xxxxxxxxxxxxxxxxxxxxxx https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
