A button view attribute is originally a X-Plane command that is submitted after the activation completed, as an additional command. The original intend is to propose a new view after some action to speed up information collection in the cockpit. For example, when the pilot selects APU on the ECAM display, the view attribute specifies a command to change the view and focus on the ECAM display.

To achieve this, the view attribute value is a (single) X-Plane command to execute:

view: x-camera/view/8

This document explains a new expression for the view attribute value to allow for the execution of one or more commands.

This schema has been extended to other definitions that use a command attribute. It is an alternate way to specify a command. Rather that a single string expression:

command: sim/view/map_display_toggle

it is now possible to express an entire block of pseudo code instruction:

# Instruction to display the map if it is not visible.
# The instruction will be hide the map, just show it if not visible.
command:
   command: sim/view/map_display_toggle
   delay: 5
   formula: ${sim/view/map_is_visible} not

Syntax

view:
  - command: command/to/execute
    delay: 2
  - set-dataref: dataref/to/set
    formula: ${dataref/value} 2 +

The new view attribute value is a list of command blocks.

Each command block is a command, an action that will be executed, and a few additional optional parameters.

Command Block

A command block contains a command which can be:

• An X-Plane command,
• An instruction to write a value in a dataref.

In the latter case, the dataref being modified can either be a regular X-Plane dataref, or a Cockpitdecks internal dataref.

Command

command: command/to/execute

Set Dataref

set-dateref: dataref/to/set

If the set dataref does not have any other attribute, the value will be set to the value of the button.

However, it is possible to specify an alternate value to write:

set-dateref: dataref/to/set
formula: ${dataref/value} 2 +

To write another value than the button value, the set-dataref attribute must be accompanied by a formula attribute. The value resulting from the formula computation will be written to the dataref.

Options

The following attributes can complement to above command.

Delay

If specified, a delay is added after the execution of the last command and before the execution of this command.

command: command/to/execute
delay: 5

Command above will be executed 5 seconds after the execution of the activation or 5 seconds after the execution of the previous command.

Condition

A condition attribute is a formula that is executed before he command. If the result of the formula is evaluated to a non null (non zero) value, the command is executed. Otherwise, the command is not executed.

command: command/to/execute
condition: ${some/dataref/to/check} 1 -

If the result of the computation of the formula is non zero, the command will be executed.

Processing

Detection of the new parameter value is easy. Either it is a string representing a command to submit to X-Plane, or it is a list of one or more command blocks. There is no ambiguity.

Usage

The view attribute can be used as a test bed for execution of more than one command in a sequence, a kind of execution of « macro » command, with additional features like conditions and delay of execution.

Example of use:

When executing a command to trigger a status view, you can imagine the following sequence:

1. Regular button: perform the action.
2. View: move the camera to control the effect of the action.
3. Wait a few seconds… (delay).
4. Restore the original view if there was no alarm (this is a condition of execution).

Other sequences can of course be imagined. Literally, the sky is the limit.

This new view attribute value and its development paves the way of a new, more complex, more flexible action definition.