Layers are positioned by aligning the layer origin (origin=) with the background layer origin at an offset specified by pos=.
If the layer origin is not specified explicitly for an image layer, it is calculated as follows:
- Determine the image anchor. Use anchor= , or, if not specified, catalog::Anchor .
- If the image anchor is defined, apply the layer transforms and extend= to convert it to an origin= value.
- If no image anchor is defined, the layer origin is placed at the center of the layer rectangle (after applying extend= ).