HTMLViewer mailto: and http://

General
1

I’m using HTMLViewer to display some email and web URL’s (from contacts) as hyperlinks but the results seem inconsistent.

Firstly mailto: doesn’t seem to link at all - ie it doesn’t open a new email in Mail.
Secondly http:// is inconsistent. Some sites work with http:// (e.g. Apple), whilst others only work with https:// (eg xojo).

Here’s some simple HTML to illustrate:

<!DOCTYPE html>
<html>
<head>
</head>
<body>
 <a href="mailto:johnny@appleseed.com">johnny</a>
<br>
 <a href="www.xojo.com">xojo</a>
<br>
 <a href="http://www.xojo.com">xojo</a>
<br>
 <a href="https://www.xojo.com">xojo</a>
<br>
 <a href="http://www.apple.com">apple</a>
</body>
</html>

Is this a “feature” ?

2

For mailto URIs you will need to catch them in the CancelLoad event and handle the new email command.
Such as this:

If url.beginswith("mailto:") then
showUrl(url)
return True
End if

As for http:// working in some cases it must be caused by the redirection method used by the server. As to why apple.com works and xojo.com does not, I cannot explain it.

3

If you add the Error event to HTMLViewer you can see that trying to go to http://www.xojo.com the RuntimeException is:

The resource could not be loaded because the App Transport Security policy requires the use of a secure connection.

There is no exception if the url is http://www.apple.com

There is no error and nothing happens if the href is only www.xojo.com

4

Unfortunately the OP didn’t indicate what platform he’s using. Here’s what I do in CancelLoad:

// Called when the content of the HTMLViewer is about to be replaced. If this is due to loading
// an html string into the control, then it seems the URL will be "about:blank". If it happens
// due to the user clicking on a link in the HTMLViewer, we want to show that one. Any links in
// the control will either have no "target" attribute, or it will  have been be changed to "_self".
// This will force all clicked links to trigger this event, which then uses GotoURL() to display
// the linked page in the user's browser, rather than here.
//
// Under Win7 the page loaded from code goes via a temporary file. When an external link is
// clicked, the URL has the normal form, but also another event occurs with the "about:blank" URL.
//
// For macOS, mailto: is handled by an AppleEvent triggered by the GotoURL. For Win/Lin, it is
// handled otherwise, so nothing should be done here.

if  (URL="about:blank" or URL.BeginsWith("file://")=True or URL.BeginsWith("c:\Users\")=True)  then Return False

#if  (TargetMacOS=False)  then
  if  (URL.BeginsWith("mailto:")=True)  then Return True           // The HTMLViewer should ignore this request
#EndIf

system.GotoURL (URL)

Return True

OK I deduce he is on macOS. Then what I have posted will work.

5

The thing to do is to implement all the event handlers for HTMLViewer and see which ones fire under which circumstances. It’s what I did and that gave me the info I needed (along with reading the docs).

See my other post about what to do with mailto:

6

Thanks all. Yes it was OSX.

I didn’t understand the cancel load event before in this context as mailTo doesn’t load into the Viewer.

However, the answers work fine.