A growing list of frequently asked questions.
Why does Doka throw a CORS error when processing the image?
The most likely cause of these issues is an incorrectly configured CORS policy on a remote server. A resource is deemed remote when it has a different domain, subdomain, protocol, or port as the local server.
Some examples of cross-origin requests:
https://my-site.com -> https://your-site.com https://my-site.com -> https://sub.my-site.com https://my-site.com -> http://my-site.com https://my-site.com -> http://my-site.com:1234
We can determine if the CORS policy is configured incorrectly by looking at the network tab of our browser developer tools and inspecting the request. If the
Access-Control response headers are turned CORS is configured.
Below we can see the results of loading a test image from the PQINA webserver:
Request Headers Url: https://pqina.nl/doka/cors/test.jpg Method: GET Response Headers Access-Control-Allow-Methods: GET Access-Control-Allow-Origin: * Content-Type: image/jpeg
A wildcard means that the file can be accessed from everywhere, it’s best to set a specific origin.
If a specific origin is set (so no wildcard), we need to make sure the image is correctly cached as well. To do this we need to set the
Vary header to
Origin, see CORS and caching on MDN.
More information on setting a CORS policy:
If for some reason the remote CORS policy can’t be changed we can proxy the image request through the local server. In that situation we send the URL of the remote image to our local server, our local server then requests the remote image and returns the result to the front-end.
Can I change the language?
The text used on each element can be changed with label properties. These properties should allow for enough flexibility to cover any internationalisation / i18n requirement.
Does Doka correct EXIF orientation information?
Doka will automatically correct the orientation of images when the
outputCorrectImageExifOrientation is set to
true (this is the default).
On export Doka will strip the EXIF header, to keep the header, please set
Can I limit the output size of the image?
You can set the maximum size of the output image using the
outputHeight properties. By default these properties describe the max size of the output image, if the crop is smaller the output image will be smaller.
To upscale the image to fit the defined output size, set