Document ISafeFormatAvatar (#130)

Resolves #129

Co-authored-by: Matthias Schmidt <gravatronics@live.com>

diff --git a/docs/migration/wsc53/php.md b/docs/migration/wsc53/php.md
index 0bedceb0f5f1a589ed9986e4a36b3972449ebb4a..d9b5c110d661545757d04a4a212b38f7ce36d468 100644 (file)
--- a/docs/migration/wsc53/php.md
+++ b/docs/migration/wsc53/php.md
@@ -99,3 +99,10 @@ With WoltLab Suite 5.4, it will no longer be part of any indices, allowing more
 If you need to filter the contents of `wcf1_tag_to_object` by language, you should perform an `INNER JOIN wcf1_tag tag ON tag.tagID = tag_to_object.tagID` and filter on `wcf1_tag.languageID`.
 
 See [WoltLab/WCF#3904](https://github.com/WoltLab/WCF/pull/3904) for details.
+
+## Avatars
+
+The `ISafeFormatAvatar` interface was added to properly support fallback image types for use in emails.
+If your custom `IUserAvatar` implementation supports image types without broad support (i.e. anything other than PNG, JPEG, and GIF), then you should implement the `ISafeFormatAvatar` interface to return a fallback PNG, JPEG, or GIF image.
+
+See [WoltLab/WCF#4001](https://github.com/WoltLab/WCF/pull/4001) for details.