Intermediate image sizing, new thumbnails

[tellyworth]

This improves the new image sizing features and implements new thumbnails.

Instead of a single thumbnail, images can now have multiple intermediate sizes. By default there's a Thumbnail size and a Medium size. These are generated at upload time and stored in the image metadata as a new array element 'sizes'. There's a hook so plugins can include additional sizes.

The new thumbnail size is 150x150, cropped to a square. The new design calls for 75x75 square thumbs; I decided on 150x150 because it's closer to the old size or 128x96, but can be scaled in the browser to half size without ugly artefacts.

get_attachment_thumb_url() and get_attachment_icon_src() will return the new thumbnail if it exists, and fall back to the old one if it does not.

[tellyworth]

For best results apply the bugfix in #6073 first.

[matt]

Fixed in [7135].

[andy]

image_downsize: Do not return attachment file URL as thumbnail if not an image

[andy]

[7135] broke Media Library icons, returning the attachment file URL for as a thumbnail for non-images

[ryan]

(In [7137]) Image sizing fix from andy. fixes #6074

[KirkM]

Replying to tellyworth:

This improves the new image sizing features and implements new thumbnails.

Instead of a single thumbnail, images can now have multiple intermediate sizes. By default there's a Thumbnail size and a Medium size. These are generated at upload time and stored in the image metadata as a new array element 'sizes'. There's a hook so plugins can include additional sizes.

The new thumbnail size is 150x150, cropped to a square. The new design calls for 75x75 square thumbs; I decided on 150x150 because it's closer to the old size or 128x96, but can be scaled in the browser to half size without ugly artefacts.

get_attachment_thumb_url() and get_attachment_icon_src() will return the new thumbnail if it exists, and fall back to the old one if it does not.

Just took a look at the latest (03/03/08) 2.5 build. This above fix wouldn't have affected the "Media Library" at all would it? I just happened to notice that now all the thumbnail images in the Image Library are now appearing at what looks like their original size (rather huge). In yesterdays build (03/02/08) the thumbnails in the "Media Library" were fine.