865518 - Add support for GetImageContainer to ClippedImage

Status: RESOLVED WONTFIX

(Core :: Graphics: ImageLib, defect)

Description

[Seth Fowler [:seth] [:s2h]]

For performance reasons it might be worthwhile to support ClippedImage::GetImageContainer. However, there are some stumbling blocks:

- Invalidating the ImageContainer is tricky.
- If we use the cached image produced internally by ClippedImage::GetFrame to populate the ImageContainer, we only get an ImageContainer when ClippedImage has to tile or otherwise produce a temporary surface for some reason. It's not clear that this is what we want, but if we produce an ImageContainer all the time, it seems that we may as well also produce a cached surface all the time, and part of the point of ClippedImage was to avoid creating an extra surface when it isn't needed!

For these reasons I've avoided implementing this so far. I'm not entirely sure that this bug shouldn't end up being WONTFIX. It's also possible that these issues point to fundamental problems with the GetImageContainer API as it currently exists.

Comment 1

[Seth Fowler [:seth] [:s2h]]

Attachment: (WIP Patch) - Implement GetImageContainer for ClippedImages.

Here's a work-in-progress version of the patch. We'd need to address the concerns above to turn this into something worth using.

Comment 2

[Seth Fowler [:seth] [:s2h]]

Attachment: (WIP Patch) - Implement GetImageContainer for ClippedImages.

Rebase.

Comment 3

[Seth Fowler [:seth] [:s2h]]

Attachment: (WIP Patch) - Implement GetImageContainer for ClippedImages.

Recording my final local version of this patch here.

Comment 4

[Seth Fowler [:seth] [:s2h]]

After experimenting with this in bug 859377 I did not see significant performance improvements. I don't think this is worth the added complexity. WONTFIX'ing for now; things may change in the future.