I was looking for the same thing myself! (well, not specifically for Photoshop, but a way to use Google Fonts on my computer)
And I found something...
It's called SkyFonts, and you can download it here: Download Google Fonts - Fonts.com.
More info on skyfonts.com.
(It isn't open-source as far as I know, but the program and the feature to use Google Fonts are both completely free - I use the program myself.
Besides that, it isn't a plugin, but a program. Which has some pros, like that you can also use Google Fonts in other programs than Photoshop)
Instructions below are for Windows (the program is also available for Mac OS X)
- Go to 1
- Click on the big red "Download SkyFonts" button
- Click on either "Download 64-bit SkyFonts" or "Download 32-bit SkyFonts", depending on your system (and if you have a Mac, click on "Download Mac SkyFonts")
You can ignore "Sign in when requested.", you don't actually have to make an account to use Google Fonts, only when you want to use premium Fonts.com fonts (which I assume you won't need)
- Open the downloaded zip file, run the installer (there are no other files in the archive, so you don't have to extract it) and click Yes if prompted by UAC.
- Click "Install" (leave everything that's checked checked), "Next", check "I accept (...)", "Next", "Next", "Install", "Finish".
SkyFonts should automatically start now.
- In the SkyFonts window, click on the list icon at the top-left and click on "Google Fonts". Your web browser should launch (if is doesn't for some reason, go to fonts.com yourself)
- Here you can explore Google Fonts. You can install the 10, 20 and 50 top fonts in one go, or click on a letter to explore fonts beginning with that letter (obviously), or search for a font if you've already got one in mind
- Click on "SkyFonts ▼" next to the desired font(s), select "Add entire family" if necessary and click on the blue "Add" button.
- The text "Google Font added to SkyFonts client" will briefly appear above the "Google Fonts EULA", you'll see a notification above the taskbar, and the font should've appeared in SkyFonts.
- Now, why not head over to Photoshop and see for yourself! (it worked for me, so I don't know why it wouldn't work for you)
IMPORTANT: SkyFonts stores downloaded fonts in the "skyfonts-google" folder in you temp folder ([user folder]\AppData\Local\Temp).
So make a copy of the "skyfonts-google" folder before clearing your Temp folder (either with Windows' built-in "Disk Clean-Up" tool or something like CCleaner) and don't forget to move it back afterwards!
Also, when cleaning your registry, don't forget to uncheck the entries related to the downloaded fonts.