I'm trying to figure out how to prevent users of my app from snapping a screenshot of any of my app's windows. I'm mainly concerned with users automating screenshots using /usr/sbin/screencapture with cron. At first I thought there was no way to prevent it but then I discovered that there are some apps that are doing something that causes the screenshot to be all black or the color of the desktop. If I could pull that off I would be golden. I've seen other posts that touch on the subject but nothing that actually works in my situation. I'm running catalina. Any and all insights would be greatly appreciated.
Use NSWindowSharingNone of sharingType property on NSWindow
setSharingType: specifies whether the window content can be read
and/or written from another process. The default sharing type is
NSWindowSharingReadOnly, which means other processes can read the
window content (eg. for window capture) but cannot modify it. If you
set your window sharing type to NSWindowSharingNone, so that the
content cannot be captured, your window will also not be able to
participate in a number of system services, so this setting should be
used with caution. If you set your window sharing type to
NSWindowSharingReadWrite, other processes can both read and modify the
window content.
#property NSWindowSharingType sharingType API_AVAILABLE(macos(10.5));
Related
Imagine I save my window's position in my preferences file. Now, the user moves the window to a second monitor, then quits my app. Then he disconnects the second monitor and launches my app again.
Now my app wants to restore the window's saved location. But if it blindly restores the old window coordinates, the window will be off-screen.
I used to use ConstrainWindowToScreen for my Carbon app, but now that I'm porting it to Cocoa, I can not find an equivalent for this.
The docs suggest that, somehow, Cocoa would automatically prevent this from happening. While that might be the case when the monitors change while the window is open, in my case where I've stored the window location myself and restore them when I re-open the window at launch, this isn't going to work. I need to invoke Cocoa's magic functionality on demand, but how?
(Note: I am aware that I could iterate over all available screens, but that's quite a pain to write myself if I want to get this foolproof. Still, if you can present a complete C or ObjC function that solve it this way, that'd be appreciated, too.)
See the "Managing Window Frames in User Defaults" section in the NSWindow Class Reference. Those methods ensure that a window will be placed entirely on screen.
If you want to save and restore the window location yourself (as a string), use -stringWithSavedFrame and -setFrameFromString:.
Use -saveFrameUsingName: and -setFrameUsingName to have NSWindow save and restore its frame in the user defaults, given a window name.
I agree with Darren's suggestion to use the built-in mechanism for restoring window positions. Really, it's as easy as setting a window's frame autosave name in IB (or with -setFrameAutosaveName:).
That said, if a window has a title bar, then all of the methods which order it onto the screen (e.g. -orderFront: or -makeKeyAndOrderFront:) will automatically reposition it to make sure at least the title bar and a significant chunk of the window is on the screen. It's honestly difficult to get a titled window to be theoretically visible but actually off-screen.
I am trying to make an interactive desktop application that replaces the wallpaper image. It sounds like it is not possible to have an NSWindow at that level with events. According to all of the documentation I can find, a window needs to be at level -598 in order to allow views to accept such events, but the desktop level is -1000. Is there a way to get past this limitation (if there even is a limitation) with a light-weight API?
Solved. I am so embarrassed!
I printed the value of kCGDesktopWindowLevel and it turned out to be -2147483623. When I set the level of the window to -1000 it started to work perfectly.
I want to observe any window on OSX if it is moved. I don't own the windows so i can't get to it directly so I think I have to use the Accessibility APIs. I found a solution for the current active Application here: How can my app detect a change to another app's window? but I can't figure out how I have to modify this that it works for any window which is open. I hope anybody could give me a hint in which direction I have to look.
As I mentioned in the comments, people usually only want to detect window-move events on focused windows. (As unfocused windows seldom move.) If you want to detect application switches, you can poke into this sample project by Apple that shows how to update iChat status with the frontmost application’s name. And as you said, there’s already a solution for an active window.
We have a Linux based system that does not use a Window manager. When we start certain applications (for instance Firefox) from a terminal window (e.g. Firefox &) we find that no matter what we do, we can't get the application to display full screen.
If we run xrandr, it shows the default resolution is 1280x1024, but when we try to maximize Firefox (by pressing F11) the application is only sized to 1203x650.
Another application that seems to have the same problem is the evince PDF reader.
Our application is not configured to run a window manager (and we don't want to add one), so I'm wondering if there is something else that we can do to get these applications to render full screen.
Thanks...
Although you don't want to use a window manager, you might need to use a window manager.
I haven't dug into the X server sources around this, so I can't definitively say X requires a window manager to run properly. But as somebody who writes X client code, and hacks the X server, on minimalist embedded devices with small screens, low CPU power and no GPU... let's just say, all the major players in that space use one, and have good reasons for it.
If you want to avoid chewing up a lot of disk space, RAM or CPU power doing window management, you should check out matchbox. It's a low-footprint window manager designed to meet those criteria, and it's what many folks in that minimalist embedded space are using. My employer uses it on cell phones, configured so that only one app at a time is visible to the user, and the foreground app takes up the whole screen with no window borders. But you can use it other ways, too - Nokia uses it for their Maemo-based network tablets.
You could use xwit(1) to forcibly resize and place the windows. But as as far as I know, X11 in itself does not have the concept of a "maximized" window; the very idea is only added by most window managers and/or applications (like Firefox).
Does passing the "-geometry=1280x1024+0+0" option to Firefox help?
Oh, also... if you don't explicitly set a window manager, you might be unexpectedly falling back to the default X11 window manager. If you're not absolutely positive there's no window manager, you should check into this possibility.
In a fairly graphics intsensive application the requirements state that it should default to full screen mode even though the application is running under Windows. I know many games do this but I find it annoying. The default IMO should be to open in a window rather than full screen mode. I am proposing the first time the user runs the application they should select the default behavior. Am I wrong?
I think the annoyance-factor depends a lot on what the application tries to do.
If it is some utility that I might start while working in 5 different applications and it forces its fullscreen-ness on my, then I'd get highly annoyed.
If it is a specialized application that helps me with the entire workflow of a given task (so that I never or rarely need any other apps open at the same time), then fullscreen might actually be a valid default.
Whatever you do, just make sure that toggling the startup behaviour is very discoverable. Because no matter which way you'll go, some of your users will disagree with your decision. And for them it should be very easy to change to their prefered way.
I would follow the requirement the first time the application is launched. I would also provide a simple way to switch from full screen to windowed, for instance by pressing ESC (and another way to go back to full screen). Then I would store the mode when quitting the application and restore this mode at next launch.
Before doing the opposite of what your requirements say, I'd have the requirements changed.
However, what about giving the user the choice at install time?
The window at first-start-up should default to the optimal size for the largest proportion of users. For a graphics-intensive full-featured app, that may very well be full screen.
As for individual user preferences for window size, it seems to me most users won’t know if they want full screen or not until after they’ve started to use the app and see how much screen space they need and how much they use the window in conjunction with other windows. Asking them which size they want at install or first-start-up could thus be annoying and even confusing. It’s better to put such a setting under Options/Preferences.
Perhaps the best thing to do is save the window status on exit. Users who like it non-maximized thus only have to non-maximize it (and size it) once and then forget about it. The only consideration is to have some way to reset the window to the default (e.g., Window > Standard Size menu item) for novice users who accidentally resize or reposition the window to something bizarre and don’t know how to get it back. Alternatively, you could have a Window > Keep Sizes and Positions menu item for users to explicitly save the window status across sessions.
Go back to the requirements writers and ask them if they have considered non-traditional monitor setups, such as:
30" or larger monitor. Do you really want your app hogging up all the screen real-estate?
Multiple monitors. Which monitor will you run on? Can the user move your app from one monitor to another? Can your app span more than one monitor?
Virtual desktops. Can the user move your app from one desktop to another? Can they switch desktops while your app is running? Can your app span more than one desktop?
Such setups are increasingly common, especially large monitors. IMO, full-screen mode (the default for many older Windows apps) is becoming less and less useful.
The problem with presenting the user with the option of initially selecting fullscreen / vs windows is that they haven't used the software yet. How can they make a decision on which is better for them, without experience?
I would run the app in whichever mode provided the best user experience and then offer an option to change it both in the Preferences and though a hint while starting up the application for the 2nd time.