fixes https://github.com/TryGhost/Team/issues/1652
fixes https://github.com/TryGhost/Ghost/issues/13319
**Image formatting**
Added support for changing the format of images via the `handle-image-sizes` middleware (e.g. format SVG to png, jpeg, webp)
This change was required:
- Not all browsers support SVG favicons, so we need to convert them to PNGs
- We can't fit image resizing and formatting in the `serve-favicon` middleware: we need to store the resized image to avoid resizing on every request. This system was already present in the `handle-image-sizes` middleware.
To format an uploaded image:
- Original URL: https://localhost/blog/content/images/2022/05/giphy.gif
- To resize: https://localhost/blog/content/images/size/w256h256/2022/05/giphy.gif (already supported)
- To resize and format to webp: https://localhost/blog/content/images/size/w256h256/format/webp/2022/05/giphy.gif
- Animations are preserved when converting Gifs to Webp and in reverse, and also when only resizing (https://github.com/TryGhost/Ghost/issues/13319)
**Favicons**
- Custom favicons are no longer served via `/favicon.png` or `/favicon.ico` (only for default favicon), but use their full path
- Added support for uploading more image extensions in Ghost as a favicon: .jpg, .jpeg, .gif, .webp and .svg are now supported (already supported .png and .ico).
- File extensions other than jpg/jpeg, png, or ico will always get transformed to the image/png format to guarantee browser support (webp and svg images are not yet supported as favicons by all browsers).
For all image formats, other than .ico files:
- Allowed to upload images larger than 1000px in width and height, they will get cropped to 256x256px.
- Allowed uploading favicons that are not square. They will get cropped automatically.
- Allowed to upload larger files, up to 20MB (will get served at a lower file size after being resized)
For .svg files:
- The minimum size of 60x60px is no longer required.
For .ico files:
- The file size limit is increased to 200kb (coming from 100kb)
- this is a small part of a bit of cleanup of our test files
- the goal is to make the existing tests clearer with a view to making it easier to write more tests
- this makes the test structure follow the codebase structure more closely
- eventually we will colocate the frontend tests with the frontend code
