draw - graphics device

bind '#d' /dev

/dev/draw/new
/dev/draw/<n>/ctl
/dev/draw/<n>/data
/dev/draw/<n>/refresh

Description

The draw device serves a two-level file system providing an interface to the graphics facilities of the system; the Limbo Draw module (see Limbo Draw Module in Chapter 11) accesses the device to implement its functions.

The operation of the draw device is transparent to users of the Draw module (see Limbo Draw Module in Chapter 11).

Each client of the device connects by opening /dev/draw/new and reading back seven decimal numbers in the standard 12-character format. The seven values are:

The connection number, n
The image id of the display image (always zero)
The ldepth of the display image
Four values (min.x, min.y, max.x, and max.y) that define the display image.

The client can then open the directory /dev/draw/<n>/ (where n is the connection number) to access the ctl, data, and refresh files associated with the connection.


ctl	The ctl file accepts no messages; its only purpose is to return the initialization information.
data	The data file accepts messages corresponding to procedures in the Draw module, such as: n Allocate a window or image n Draw on the image. n Paint text Such messages generate data to be returned to the client which can be recovered by reading the data file. See also Limbo Draw Module in Chapter 11.
refresh (read-only)	As windows owned by the client are uncovered, they may not be refreshed by the server. For example, they could have refresh functions associated with them. In this case, the client is notified by a message refresh file reporting what needs to be repainted by the client. The message has five decimal integers formatted as in the ctl message: n The image id of the window. n Four decimal values (min.x, min.y, max.x, and max.y) that define the display image in need of refreshment.

draw - graphics device

Description

See Also