| Table of contents |
OSD.BASIC Message Specification
- Class = OSD
- Type = BASIC
This Schema provides a method of displaying text messages to an xPL implementation.
XPL-CMND Structure
OSD.BASIC
{
COMMAND=[CLEAR / WRITE / EXCLUSIVE / RELEASE]
[TEXT=<text to display. each line should be seperated by the \n seperator>]
[ROW=<display row>]
[COLUMN=<display from column>]
[DELAY=<seconds to display>]
}
EXCLUSIVE/RELEASE allow another device to take exclusive control of the osd device. The osd device should ignore all messages from any other source while locked. EXCLUSIVE/RELEASE should be sent on their own only, and be targetted at the osd device. Both should perform a CLEAR.
XPL-TRIG Structure
OSD.BASIC
{
COMMAND=[CLEAR / WRITE]
[TEXT=<text to display. each line should be seperated by the \n seperator>]
[ROW=<display row>]
[COLUMN=<display from column>]
[DELAY=<seconds to display>]
}
A Trigger Message with class OSD.CONFIRM MAY be sent by the application or device to confirm the actual actions taken in displaying a given message. This confirmation message should contain the original details, with the provisions that:
If the Display Device does not support overwriting, and executes a CLEAR each time, the Trigger message should contain COMMAND=CLEAR rather than COMMAND=WRITE
If the Display Device does not support indefinite display, but clears after (for example, 15 seconds) the Trigger message should contain DELAY=15 rather than DELAY=0
XPL-STAT Structure
HBEAT.*
{
(hbeat items)
}
Schema Specific Notes
COMMAND is the only compulsory item.
When COMMAND=CLEAR is used, the display device should execute a "clear screen" operation before displaying the message. It is valid to send a COMMAND=CLEAR without any further text to display.
When COMMAND=WRITE is used, the display device will simply process the TEXT information, possibly overlapping any existing display. Devices are not required to support this mode of operation. When COMMAND=WRITE is used, TEXT is mandatory.
A Value of DELAY=0 should be interpreted by the application as either "maximum possible delay", or as appropriate, "do not clear". Delays are cumulative, that is, text that is placed on screen with a delay of 5 seconds will remain on screen if a subsequent message specifies a further delay.
ROW, COLUMN and DELAY should have default values appropriate to the class of display device within the device or application.
