Laravel Dusk Draw on Canvas Element

I am trying to make a Laravel Dusk test to sign a canvas elememt (jSignature plugin)

But can seem to get it working. this is my current code:

    $this->browse(function (Browser $browser) {
        $browser->visit('/form')

            # Sign
            ->click('#input-13')
            ->pause(3000)
            ->mouseover('.jSignature')
            ->click('.jSignature')
            ->moveByOffset(100,100)
    });

Any ideas how?