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javascripthtml5-canvasopenlayershtml2canvas

Clean tainted canvas

Is it possible to clean a tainted canvas?

I have an Openlayers map where user can add layer with CORS restriction. I can't bypass the cors by my proxy config and crossOrigin='anonymus' is not an option.

What I need, it's to be able to remove the "bad" layer and let the user produces the map image.

So I try to:

  • Remove the layer who can't be printed
  • Try to sync the map
  • Try to print

But I always get the cors error. How can I make my map great again without refreshing the browser?

Solution

  • No there is no way to clean a tainted canvas.
    Once tainted, it will remain tainted for its whole life.

    Not only this, but also drawing this canvas on a second canvas will taint that second canvas too. Even if that canvas has been completely cleared.

    So, the only way for you, is to start again from a new canvas element, and to filter out the bad layers before they are drawn.