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ENVIAbortable

ENVIAbortable

Use this object class to communicate if an abort is requested. Custom classes can inherit this class if you want to extend the behavior. If you provide an object that implements the ENVIAbortable interface to ENVIStartMessage, then the ENVI user interface progress dialog will have a Cancel option and you can query the ABORT_REQUESTED property on your object to determine if the user cancelled the progress dialog.

Example


This example demonstrates how all of the ENVI API messaging components work together. It simulates an analytic operation and updates its progress in a progress bar and in the IDL console.

PRO ProgressBarAbortExample
  COMPILE_OPT idl2
   
  ; Start the application
  e = ENVI()
   
  ; Get the broadcast channel to send messages to the ENVI system
  Channel = e.GetBroadcastChannel()
   
  ; Create an object that uniquely identifies the message.
  ; Use the ENVIAbortable object to check if progress
  ; was cancelled.
  Abort = ENVIAbortable()
   
  ; Broadcast a start message to the ENVI system
  Start = ENVIStartMessage('Progress Bar Title', Abort)
  Channel.Broadcast, Start
   
  ; Determine the number of steps to calculate
  ; percent complete for progress
  nSteps = 73
   
  ; Initialize progress
  Progress = ENVIProgressMessage('Executing Progress Message', $
    0, Abort)
   
  ; Iterate through the work
  FOR stepIndex=0, nSteps DO BEGIN
    
    ; Calculate progress for the step
    percentProgress = Round(stepIndex* 100.0/nSteps)
    
    ; Update progress percentage and broadcast the progress
    ; message to the ENVI system
    Progress.Percent = percentProgress
    Channel.Broadcast, Progress
   
    ; Check if aborted after sending progress to see if
    ; Abort_Requested was set by any listeners
    IF (Abort.Abort_Requested) THEN BREAK
   
    ; Simulate an analytic
    dataProcess = dist(1000)
   
    ; Print the step to see the abort working
    PRINT, stepIndex
  ENDFOR
   
  ; Broadcast a finish message to the ENVI system
  Finish = ENVIFinishMessage(Abort)
  Channel.Broadcast, Finish
END

Syntax


Result = ENVIAbortable()

Methods


None

Properties


Properties marked as "Set" are those that you can set to specific values. You can also retrieve their current values any time. Properties marked as "Get" are those whose values you can retrieve but not set.

ABORT_REQUESTED (Get, Set)

When the ENVIAbortable class is created, the ABORT_REQUESTED property is set to 0. Set it to 1 to indicate that an abort was requested.

Keywords


ERROR (optional)

Set this keyword to a named variable that will contain any error message issued during execution of this routine. If no error occurs, the ERROR variable will be set to a null string (''). If an error occurs and the routine is a function, then the function result will be undefined.

When this keyword is not set and an error occurs, ENVI returns to the caller and execution halts. In this case, the error message is contained within !ERROR_STATE and can be caught using IDL's CATCH routine. See IDL Help for more information on !ERROR_STATE and CATCH.

See Manage Errors for more information on error handling in ENVI programming.

Version History


ENVI 5.3

Introduced

API Version


3.2

See Also


ENVIBroadcastChannel, ENVIStartMessage, ENVIProgressMessage, ENVIFinishMessage, Messaging



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