[wp-trac] [WordPress Trac] #17242: Themes: Allow flexible sizes for custom header uploads

[WordPress Trac]

#17242: Themes: Allow flexible sizes for custom header uploads
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 Reporter:  lancewillett            |       Owner:
     Type:  enhancement             |      Status:  new
 Priority:  normal                  |   Milestone:  3.2
Component:  Themes                  |     Version:
 Severity:  normal                  |  Resolution:
 Keywords:  has-patch dev-feedback  |
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Changes (by lancewillett):

 * keywords:  needs-patch 2nd-opinion => has-patch dev-feedback


Comment:

 I've been working on this for a few days now, changing the crop parameters
 and seeing how things work when you change only the width or height when
 you crop an uploaded image.

 I also experimented with replacing HEADER_IMAGE_WIDTH and
 HEADER_IMAGE_HEIGHT in a few places.

 Attached is a patch with my first pass, it's mostly a proof-of-concept for
 the cropping mechanism changes.

 There are a to main blocker issues with this feature:

 1. Image dimensions are not available if not the default size.

  * Themes with flexible uploaded images have no mechanism to get the
 width/height dimensions of the uploaded image, for use in HTML attributes
 or CSS.
  * Themes that use the same values stored in HEADER_IMAGE_WIDTH and
 HEADER_IMAGE_HEIGHT definitions in other places than the custom header are
 going to have trouble if they allow flexible sizes. For example, if upload
 a smaller header than is defined in the theme — there isn't a way for the
 theme to get its dimensions and apply it to other areas in the theme.
  * In Twenty Eleven you could end up with a short header image (works
 great) but taller featured image headers since the featured image call
 doesn't change to the smaller dimension.

 2. Cropping tool isn't ready for flexibility.

  * To allow correct cropping by one dimension only (when the width or
 height isn't flexible) the existing crop functionality would need a
 rewrite to remove the need for an exact aspect ratio.
  * I found that when one dimension is flexible (and the other not) the
 cropping tool "zooms up" to the uploaded image dimension that you've fixed
 as not flexible. So even if you crop correctly the fixed dimension
 changes.
  * Allowing the 'flexible_header_image_upload' call with ints as arguments
 proved a bit too complex. My patch implements the arguments as boolean
 values, so the flexibility is either on or off. The maximum width or
 height is then taken from HEADER_IMAGE_WIDTH and HEADER_IMAGE_HEIGHT.

 All in all I think this idea is still worth pursuing, but it seems that
 we'd need to first revamp all the cases where HEADER_IMAGE_WIDTH and
 HEADER_IMAGE_HEIGHT are used, and replace them with set and get functions.
 Set to denote the defaults (and any flexibility desired) and get to make
 sure you can return image info anywhere in the theme — not only the source
 path (as {{{get_header_image()}}} does now) but also other image
 attributes.

 If the flexible height is a blocker for Twenty Eleven we should consider
 implementing it in the theme itself — using user input to set the height
 value — and use that dimension to override HEADER_IMAGE_HEIGHT in the
 theme.

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Ticket URL: <http://core.trac.wordpress.org/ticket/17242#comment:15>
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