"Clone in Windows" button - how it works?

Question

I am curious to how the button works. Can you explain how when I click the "Clone in Windows" button it knows to open a local application(GitHub) on my machine.

Answer 1

Look at this patch of GitExtension: it register that action in HKCR

  <Component Id="Protocol.github_windows" Guid="*">
    <RegistryKey Key="github-windows" Root="HKCR">
      <RegistryValue Value="URL: Github for Windows Protocol" Type="string" />
      <RegistryValue Name="URL Protocol" Value="" Type="string" />
    </RegistryKey>
    <RegistryKey Key="github-windows\DefaultIcon" Root="HKCR">
      <RegistryValue Value="[INSTALLDIR]GitExtensions.exe" Type="string" />
    </RegistryKey>
    <RegistryKey Root="HKCR" Key="github-windows\shell"/>
    <RegistryKey Root="HKCR" Key="github-windows\shell\open"/>
    <RegistryKey Root="HKCR" Key="github-windows\shell\open\command">
      <RegistryValue Value="&quot;[INSTALLDIR]GitExtensions.exe&quot; %1" Type="string" />
    </RegistryKey>
  </Component>

And it adds:

if (args[1].StartsWith("git://"))
{
    args = new string[]{args[0], "clone", args[1]};
}
if (args[1].StartsWith("github-windows://openRepo/"))
{
     args = new string[]{args[0], "clone", args[1].Replace("github-windows://openRepo/", "")};
}

GitHub for Windows would go for a similar approach.