+
+ The hacks themselves use utils/grabclient.c to invoke the
+ "xscreensaver-getimage" program as a sub-process.
+
+ On "real" X11 systems:
+
+ "driver/xscreensaver-getimage" runs the code in this file to grab
+ the X11 root window image as a Pixmap.
+
+ On MacOS systems running X11, which nobody does any more:
+
+ "driver/xscreensaver-getimage" runs the Perl script
+ "driver/xscreensaver-getimage-desktop", which in turn runs the MacOS
+ program "/usr/sbin/screencapture" to get the Mac desktop image as a
+ PNG file.
+
+ On MacOS systems running the native Cocoa build, or on iOS or Android
+ systems:
+
+ "driver/xscreensaver-getimage" is not used. Instead, each saver's
+ "utils/grabclient.c" links against "OSX/grabclient-osx.m",
+ "OSX/grabclient-ios.m" or "jwxyz/jwxyz-android.c" to grab
+ screenshots directly without invoking a sub-process to do it.
+
+ See the comment at the top of utils/grabclient.c for a more detailed
+ explanation.