Compositing window manager
[1][2] Compositing managers may perform additional processing on buffered windows, applying 2D and 3D animated effects such as blending, fading, scaling, rotation, duplication, bending and contortion, shuffling, blurring, redirecting applications, and translating windows into one of a number of displays and virtual desktops.
Computer graphics technology allows for visual effects to be rendered in real time such as drop shadows, live previews, and complex animation.
Window managers are broadly categorised by their strategy for causing that newly revealed area to be displayed to the user.
With a stacking manager, the repainting process can become corrupted when a program that is slow, unresponsive or buggy does not respond to messages in a timely manner.
[9] On March 24, 2001, Mac OS X v10.0 became the first mainstream operating system to feature software-based 3D compositing and effects, provided by its Quartz component.
With the release of Mac OS X v10.2 and Quartz Extreme, the job of compositing could move to dedicated graphics hardware.
[2][10] In 2003 Sun Microsystems demonstrated an ambitious 3D graphics system called Project Looking Glass to layer on top of its Swing toolkit.
Although Apple threatened to sue Sun for breach of intellectual-property rights, other window managers have implemented some of the functionality in Looking Glass.
By 2006 development was discontinued by Sun, whose primary business was transitioning from graphically oriented Unix workstations to selling enterprise mainframes.
[12] Severe delays in the development of Longhorn caused Microsoft not to debut its 3D-compositing window-manager until the release of Windows Vista in January 2007.
Compositing window manager software communicates with graphics hardware via programming interfaces such as OpenGL or Direct3D.
Under X11, the ability to do full 3D-accelerated compositing required fundamental changes to the window system protocol in order to use hardware acceleration.
[18] In 2012, Compiz was included in Ubuntu Linux, and was enabled automatically when supported hardware and drivers were available and the user had not selected 2D Mode.
The Granular Linux live CD distribution includes Looking Glass as an optional window manager.
In the aftermath of it being discontinued, some of its features, such as cover switching and thumbnail live previews, have found their way onto other window managers.
As such, their window managers have mostly planar rendering capabilities that include composite layering, alpha blending, gradients, high resolution and multiple desktops ("screens") that can partially clip one another.
Few commercial applications took advantage of alpha blending; freeware programs were among the first to experiment with it, albeit through optional settings.
Other systems with similar functionality (Microsoft Windows, Compiz, KWin, third-party applications) are referred to as Exposé clones.
Mac OS X 10.7 combines several other compositing features developed by Apple—such as Exposé, Dashboard, and Spaces—into a larger program called Mission Control.
On macOS, "widgets" (single-purpose applets) such as a clock, note pad, and calculator can appear by pressing a hotkey.
Some systems like the Classic Mac OS avoided this issue with ZoomRects, animating the windows outline "zooming" toward its final position.
[citation needed] Visual transitions provide context and help distinguish the causal relationships of GUI elements.
especially helpful for elderly or visually impaired users who notice changes to the screen more slowly and with less clarity.
The short delay necessary to display a visual transition may give the user enough time to make a conscious decision, and avoid such mistakes.
