I recently noticed that when aligning masked images, the original un-masked image's dimensions are used. When using clipped images, the newly clipped dimensions are used instead, but not immediately. When an image is clipped, the size of it's selection box stays the size of the full image for a bit. The way I've forced this to update is by centering (or any other form of alignment) it over another object. After the first alignment, the selection boxes dimension update to reflect the clipped image. Then one more centering is required to make use of these new dimensions.

This seems like a relatively minor bug, but I thought I'd post here to solicit some of your reactions to this. I wasn't really expecting this difference between masked and clipped images, but am glad to have stumbled on a way of aligning my clipped images based on its dimensions after clipping.

LiquidAsh wrote:when aligning masked images, the original un-masked image's dimensions are used. When using clipped images, the newly clipped dimensions are used instead

AFAIK that's based on the difference of the two operations as defined in the SVG specification: basically, a masked object is defined by the original image (and included areas where the applied mask results in transparent pixels), whereas for a clipped object, the visibility is limited to the area inside the clip-path (defined by its geometry).
You will also notice how it changes (reverts) when switching to the geometric bounding box (see 'Preferences > Tools > Bounding Box to use').

LiquidAsh wrote:the newly clipped dimensions are used instead, but not immediately. (…)

The current selection needs to be refreshed to reflect the modified dimensions of the visual bounding box?

Which version of Inkscape are you using, stable or trunk?

Experiencing it with Inkscape 0.48 + devel r10744... so trunk (I think).

LiquidAsh wrote:Experiencing it with Inkscape 0.48 + devel r10744... so trunk (I think).

Yes, that's "trunk", though not really current (latest revision is at r10915).

Visual bounding box not immediately updating after applying the clip does not occur in stable (0.48.2), and is probably related to the current state of visual bounding box caching in trunk (work in progress): see this mail on the mailing list (inskcape-devel) (here a related observance when changing the filter effects region) and the thread itself for a discussion about issues with the calculation of the visual bbox, continued here.

Nudging the clipped image with the arrow keys (e.g. a tick up and back down again) quickly triggers an update of the visual bounding box. Likely to get addressed before 0.49 is released, but feel free to file a bug report about it (please confirm the issue with the latest available build before reporting).

Thanks ~suv.