' `. l: \& E( N: }8 `// ( j1 h5 M! D" u0 q8 ^* P9 X
//One consequence of hardware overlay use is that a screenshot program (for example, 3 @% T/ q4 I% y) t* N
//the one automatically built into Windows that activates when the PrtSc key is pressed) 4 t) _9 Q I ]- D8 Z
//often does not capture the content appearing in the hardware overlay window. Rather, ' x" d9 H) N" `4 o! `2 u( y2 S
//a blank region containing only the special mask color is captured. This is because the ' x) ^' I! y$ W( S) O
//screen capture routine doesn't consider the special video memory regions dedicated to 7 d" s% _8 E! g9 y
//overlays - it simply captures the shared main screen as rendered by the software's graphical + o# p9 k8 s6 d; ~
//subsystem. Some Digital Rights Management schemes use hardware overlay to display 1 m' ]9 y/ _; S6 J" v
//protected content on the screen, taking advantage of this quirk to prevent the copying of 8 H" U5 ~- T' D" E
//protected documents by way of screen capture[citation needed]. Disabling the support for 6 ?# [4 g7 ]9 w7 y" k5 r
//overlays causes the normally overlay using software to fallback to the shared memory, ) u, w* p0 Y- {. r; |//enabling screenshots. . ~1 U6 D0 f$ e+ ~9 w+ Y W" b4 b5 ~2 _% K
//Starting with Windows Vista's enhanced graphics capabilities, the basic concept / a) b* J. k% ^6 O
//of hardware overlays is replaced by full hardware compositing for every application window & V, n# ~2 M9 V1 `! |/ b; m% b
//running on the system, not just movie players or games, through the Desktop Window Manager. S( o. j# ?( U+ C//Mac OS X has been using hardware compositing since Quartz Extreme was introduced in Mac OS X 10.2. ) R7 M- v" ~/ z- J4 M! b. V
//To improve performance, each program draws to its own independent memory buffer instead of to a # p$ t9 J# Z: }9 l `) U% x
//slow graphical subsystem. (In Windows Vista, each hardware overlay is more correctly known as 9 z* ~- ~2 a! Q: G//a Direct3D surface). Then, the system's GPU assembles each of the windows into a single / n; Y; P7 o+ q; o( y. z
//display screen in real time. With enhanced GPUs on the market capable of stunning 3D ' E0 A1 R( x* W4 g" @+ M' |//graphics as a consequence of the video game industry, impressive motion, scaling, / W3 a$ C b: a7 u/ J, D& s
//and lighting effects can be applied to normal 2D windows by the operating system. ; z+ m% ]+ m; H, ^& k2 w; [- n; X% s0 J7 Q' W