dev.flush: Hold or Flush Output on an On-Screen Graphics Device.

Description

This gives a way to hold/flush output on certain on-screen devices, and is ignored by other devices.

Usage

dev.hold(level = 1L)
dev.flush(level = 1L)

Arguments

level

Integer >= 0. The amount by which to change the hold level. Negative values will be silently replaced by zero.

Value

The current level after the change, invisibly. This is 0 on devices where hold levels are not supported.

Details

Devices which implement this maintain a stack of hold levels: calling dev.hold increases the level and dev.flush decreases it. Calling dev.hold when the hold level is zero increases the hold level and inhibits graphics display. When calling dev.flush clears all pending holds the screen display is refreshed and normal operation is resumed.

This is implemented for the cairo-based X11 types with buffering. When the hold level is positive the ‘watch’ cursor is set on the device's window.

It is available on the quartz device on OS X.

This is implemented for the windows device with buffering selected (the default). When the hold level is positive the ‘busy’ cursor is set on the device's window.