x-fastly-imageopto-overlay

The x-fastly-imageopto-overlay header overlays one image on top of another image.

IMPORTANT: Unlike most IO parameters, overlays must be specified using an HTTP header, rather than via the query string of the client request.

Syntax

x-fastly-imageopto-overlay: {param-list}

{param-list} is a querystring-encoded set of key-value pairs.

Param	Description
`overlay`	Root-relative URL.
`overlay-base64`	Base64 encoded root-relative URL.
`overlay-width`	Width of the overlay image. When specified as a percentage, the width is relative to the output image.
`overlay-height`	Height of the overlay image. When specified as a percentage, the height is relative to the output image.
`overlay-align`	The position of the overlay relative to the image, in the form `{y-align},{x-align}`. For `{y-align}`, choose from `top`, `middle`, and `bottom`. For `{x-align}`, choose from `left`, `center`, and `right`. Defaults to `middle,center`.
`overlay-pad`	Add padding to the edges of the overlay. Takes the same form as `pad`.
`overlay-repeat`	How the overlay should be repeated. Choose from `x`, `y`, or `both`.

Align the overlay to the top of the source image:

sub vcl_recv { ... }

Fastly VCL

set req.http.X-fastly-imageopto-overlay = "overlay=/img/overlay.png&overlay-align=top";

Align the overlay to the bottom-right:

sub vcl_recv { ... }

Fastly VCL

set req.http.X-fastly-imageopto-overlay = "overlay=/img/overlay.png&overlay-align=bottom,right";

Resize the overlay to be 75% the height of the output image, and pad it - on the top and bottom edge by 25px, and on the right and left edge by 50px:

sub vcl_recv { ... }

Fastly VCL

set req.http.X-fastly-imageopto-overlay = "overlay=/img/overlay.png&overlay-height=0.75&overlay-pad=25,50";

Tile an overlay across the source image:

sub vcl_recv { ... }

Fastly VCL

set req.http.X-fastly-imageopto-overlay = "overlay=/img/overlay.png&overlay-repeat=both";