[wp-trac] [WordPress Trac] #30062: Add Hooks to Image Editor UI

[WordPress Trac]

#30062: Add Hooks to Image Editor UI
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 Reporter:  ericmann             |       Owner:
     Type:  enhancement          |      Status:  new
 Priority:  normal               |   Milestone:  Awaiting Review
Component:  Media                |     Version:  4.0
 Severity:  normal               |  Resolution:
 Keywords:  has-patch has-tests  |     Focuses:  ui, administration
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Changes (by ericmann):

 * keywords:  has-patch has-tests reporter-feedback => has-patch has-tests


Comment:

 Wanted to take a second to provide some overview for reviewers.

 In short, every image edit group in the right rail of the image editor is
 now registered by way of a callback. These callbacks can be registered
 with a simple API:

 - `add_imgedit_group()` - Registers and loads a specific callback
 - `register_imgedit_group()` - Registers a callback
 - `remove_imgedit_group()` - Unloads a specific callback but leaves it
 registered
 - `unregister_imgedit_group()` - Unregisters a callback
 - `get_imgedit_groups()` - Gets an array/list of all loaded image edit
 groups

 Core will now register four default image groups:
 1. Scale Image
 1. Restore Image
 1. Apply to
 1. Crop Image

 (These are the same groups registered pre-patch in the same order.
 Registering them as discrete elements here allows developers to filter and
 reorder/remove where necessary.)

 In addition, several new hooks are defined so developers (themes/plugins)
 can hook in wherever needed. Whenever an image edit group is added/removed
 or registered/unregistered we trigger an action call passing the unique
 name of the edit group.

 The `get_imgedit_groups()` function internally calls a filter, passing the
 array of all loaded image groups. This allows developers to dynamically
 filter which groups show up or don't show up based on whatever conditions
 they need.

 Internally, the image edit groups are stored in a global array
 (`$_imgedit_groups`) in two buckets - > registered and loaded.  Registered
 edit groups are available for use, but must be loaded (by calling
 `add_imgedit_group()`) in order to appear in the UI. This allows plugin
 editors to specify callbacks and register edit groups, but leave the
 decision to load them up to theme developers instead.

 The `wp_image_editor()` function remains largely unchanged, but instead of
 building out its own markup for each existing image edit group (see the
 numbered list above) it merely calls a `foreach` across the array returned
 by `get_imgedit_groups()`. This means, by default, WordPress will still
 iterate over the four default groups - developers can, however, inject as
 many additional groups as needed into the markup by either
 adding/registering a new group through the API or filtering
 `imgedit_groups` to manually specify the groups they want printed and
 their order.

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Ticket URL: <https://core.trac.wordpress.org/ticket/30062#comment:5>
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