What about when people need to take a screen shot of something sent to them for evidence of a crime committed against them?<p>Also this all hearkens back to the "How do I prevent right clicking on my website with jQuery?" days.
I think the (semi) hidden subtext of both of the applications is the sending of naked pictures or "sexting". I read through the reviews of Snapchat in the app store and it's pretty clear. That may clarify the desire for knowing when a screen cap has been grabbed.
If you're trying to block screenshots, AirPlay mirroring is something else you'll likely want to watch for. It's possible to send a separate feed to the AirPlay display; but not an iOS dev myself so I can't speak to how difficult this is to do.<p>On the Android side there's also DDMS; unsure if this is detectable or not.
Just out of curiosity, has anyone tried having a set of rapidly switching masks to prevent screenshots, so that at any single point of time, all the app can make a screenshot of is a few semi-random (but small) portions of the image? Get it up past 60 frames per second, with something like a noise pattern on the masks, and a screenshot may be pretty indistinguishable, while giving the image only slightly less quality for the end user.<p>Would require quite a bit of tweaking to get just right, but there is clearly a demand
I'm not an iOS user, but what is to stop the user from taking a screenshot and storing it somewhere else? Or posting it to a remote server?<p>Since the image on the screen is in video memory on the device, surely it is impossible to prevent screenshots from being taken?
Would it not be so much easier to simply show images with some steganographic message ("I was displayed in SnapChat") in it, and just check for this rather than checking for "Screenshot-looking" pics?<p>Just sayin'
It seems like these things would be easy to get around by opening the message, disconnecting from the Internet, snapping a screenshot, and installing the app. Sure, a PITA, but digital is forever.
While this may be nice - it's only a partial solution. Anybody can take a photo of screen from device #1 with camera from device #2. Nothing can prevent that.