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 query string-encoded set of key-value pairs.
Sub-parameters
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 . |
Examples
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";