I haven't tested it, only had a quick look at the code and looks good. Also like the idea of displaying it in the app

Great idea @sgiehl - I put couple comments, otherwise good to merge

Re; bitcoin, alternatively you could just show the bitcoin address and users could copy paste it to send money to?

@mattab I've changed the bitcoin stuff. I've updated the screenshot in the PR description above.
Do you have suggestions to improve the text? Otherwise guess we could merge!

Bitcoin could be specified in one of two ways:

• a URL to a bitcoin processor/landing page ( two examples: https://bitpay.com/775767/donate -> Bitcoin processor page, http://legoutdulibre.com/bitcoin -> custom landing page)
• Bitcoin URI ( bitcoin:1xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx )

It is against best practices to reuse a single address but possible (and may be used for any of many valid reasons). Bitcoin payment processors take care of generating a new address, forwarding/converting payments, etc.

When clicking a Bitcoin URI it will open the local Bitcoin app for payment if one is installed (for example Electrum).

I can test this if/when implemented.

@MagicFab Plugin developers can set exactly one bitcoin address per plugin, so we need to use that one.
I don't have an account at bitpay.com, but I guess it's mostly like coinbase.com. Problem with that is, we do not want to include external javascripts. So I guess using the bitcoin uri might be the best solution for now.

@sgiehl ok, using a single Bitcoin address is fine.

Adding the possibility to have a direct URL link to self-shoted pages or to service like Bitpay does not require Javascript, however. It's a direct link, just like the current Paypal / Flatter links.

@MagicFab not sure if I got you wrong, that would require to let the user define the full URL to their bitcoin donation page. Guess it should be possible to check if the value is a full url or a bitcoin address and handle the link according to that.

@mattab what do you think about that?

@sgiehl sounds good to me if bitcoin can be either a bitcoin address, or a URL to a custom bitcoin donate page. btw let's also mention this possibility in the dev guide in http://developer.piwik.org/guides/distributing-your-plugin#prepare-your-plugin

@mattab ok. do we have any validation checks on the marketplace for the value of the donation fields?

Good point! I just found this code:

            if (empty($donate['bitcoin'])
                || !ctype_xdigit($donate['bitcoin'])
                || strlen($donate['bitcoin']) < 10
                || strlen($donate['bitcoin']) > 100) {
                $donate['bitcoin'] = null;
            }

so URLs will not work in the bitcoin field!

Could you get in touch with Thomas to discuss/have this changed?

Hm... on the other hand I'm not sure if it would really be good to link to a custom URL. That would allow users to inject "bad" links in piwik and the marketplace. Maybe it would be better to whitelist some urls (domains), but I don't know which services might be good to whitelist

@mattab: I'd suggest to leave it as it is for now. Maintaining kind of a whitelist for serious bitcoin donation service does not really seem to be a good option.. So guess we can merge, if the wording is fine for you.

Nice change!