Lock Screen Background

[kwatt29]

Hey All,

I'm running a 10.11.3 machine and I'm seeing odd Lock Window behavior.

What I'm trying to accomplish: A custom background image that displays at the FileVault Screen, Login Window, and the lock screen.

For the first two screens, I've been able to successfully change the image to what I want by editing the com.apple.desktop.admin.png under /Library/Caches.

For the lock screen I had to dig to /System/Library/Frameworks/AppKit.framework/Versions/C/Resources/NSTexturedFullScreenBackgroundColor.png and change it to the desired photo. I had to disable SIP to do so.

What is odd: When I lock the machine I get a screenshot of my desktop with a gray film layer on top. If i get the window to re render (I connect an external monitor) while the machine is still locked I get my desired photo like the FileVault and LoginWindow screen.

Looking at console during a screen lock (see attached) I notice that WindowServer generates the desktop screenshot and puts it as the Lock Screen. Is there a way to stop this from happening? Is this why my image is not displaying till a re render happens? Should there be a sleep image for WillPowerOffWithImages / where are those images stored?

Or better yet, is there a better way to handle putting a custom Image on the Lock Screen, FileVault, and Window Login?

Thanks for any information!

[Bongardino]

@kwatt29

Did you have any luck with this one? I'm looking for a similar fix since I cant get policy banners to display on the lock screen until a user has already logged

[kwatt29]

@Bongardino I've somewhat given up on trying to get the lock screen to not take a screenshot of the desktop.. I actually didn't need to edit the /System/Library/Frameworks/AppKit.Framework/Versions/C/Resources/NSTexturedFullScreenBackgroundColor.png for the lock screen to change the picture on a re-render too.

I'm putting a Login Window Banner on the Lock screen using this command:
sudo defaults write /Library/Preferences/com.apple.loginwindow LoginwindowText "Your Login Text Here"

I put that script into a policy that runs at login.

You could also get create an extension Attribute to look for your Text:
sudo defaults read /Library/Preferences/com.apple.loginwindow LoginwindowText | grep LoginwindowText | cut -c 23-468

I used the cut -c command to remove everything expect the text i was looking for. You'd want to set up some variables to set what the text should be and what the users text is.