Crestron e-control Database Manager, Руководство пользователя

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Crestron e-control Database Manager SW-DBM
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The Database File Installation & Reference Guide — DOC. 5823
The QueryDescription signal is sent upon arrival at each level, with the caption of
the first list field in the scroller display optionally inserted into the description in
place of a special flag character (a dollar sign).
If the description string is "($ Selection Screen)" then on level 1, the server
sends the string "(Genre Selection Screen)" in the
QueryDescription signal.
On level 2, it resends the signal with "(Artist Selection Screen)", and so on.
The Data
d
signals are used to echo the selections made at each level. Be sure to
define sufficient Data
d
signals to accommodate each level of the query + the number
required to display all the fields listed in dataFields as well.
Navigating Between Levels
Narrowing the Query
As explained above, the user moves to succeeding levels in a successive query by
picking items from the scroller lists.
If defined, the server sends a GoLevelEcho
v
signal to the control system whenever a
transition is made to a new level or when the final record is displayed. In the multi-
page display paradigm, the GoLevelEcho
v
signals are useful for automatically
flipping the pages.
Widening the Query
Returning to a preceding level is easily accomplished using either the UpLevel
signal, or the GoLevel signals. The former redisplays the preceding level’s list; the
latter jumps directly to any preceding level. (Attempts to jump ahead are ignored.)
Special Considerations
Since a single scroller structure is utilized for each level in a successive query, the
multi-page display paradigm suffers from a lack of buffering. That is, on each
succeeding page, the old data is still visible upon arrival. This is serious eyesore
when the column widths differ from query to query. For this reason, the option
“Blank scroller between levels of successive query” in the
Scroller Signal Block
Definition window is provided. Checking this option when using the multi-page
display paradigm blanks the contents of the scroller before flipping the page (as used
in Demo2).
We do not recommend this option for the single-page display paradigm because of
the extra time and network traffic involved. In the single-page paradigm, the scroller
simply appears to refresh when an item is picked (which seems to be acceptable to
most users).
Operating on Database Tables
Several signals are designed to maintain database tables.
Picking a Record
There is one Pick
v
signal associated with each row in the scroller. When the user
touches a row in the scroller, the control system program sends the corresponding
Pick
v
signal to the server. The server knows what scroll page the user is seeing and
opens the indicated record.
How the server responds to the Pick
v
signal is determined first by whether the
scroller is “owned” by any other signal block. If so, the signal block’s code responds
to the touch in its own way.