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Summary of demonstration.

This is a brief summary of the demonstration of the OTF gridder that was presented at the AIPS++ review.

The demonstration consists of the following glish clients:

• OTF gridder. This is the application that does the gridding of calibrated data. It recognizes the following events
  • grid : start gridding. The input parameters are passed to the gridder client in a glish record.
  • suspend : stop gridding. The client writes out the current image and waits for the next grid event.
  • getImage : write out the current image. The client temporarily suspends gridding in order to write out the current image. Gridding resumes immediately after the image is written.
  The gridder client generates three glish events:
  • progress. This is generated occasionally to indicate the fraction of the data that has been gridded.
  • imageSaved. This indicates that the current image has been saved. It only occurs in response to a getImage event.
  • grid_result. The gridding has finished. The gridder is now waiting for another grid event.
• otfClient. This is a simple glish client that generates the suspend and getImage events from buttons that the user can click on (these events are then passed on to the the gridder client). The otfClient client also recognizes progress events. These are translated into a displayed bar indicating the progress value.
• imager. The image display client. This displays a 2-D AIPS++ Image. It has some simply knowledge of the image coordinates and one can choose and manipulate the colormap. It recognizes the imageFile event, generated in response to an imageSaved or grid_result event, and displays the indicated AIPS++ image (one plane of the image cube is hard-coded as the plane to display). Additionally, one can click on a button (labeled ``spectrum'') and then select a pixel in the image. This generates an xy_plot event.
• plotter. This recognizes the xy_plot events generated by the imager. The value associated with that event indicates the xy pixel selected. From that information, the plotter displays the values of the image cube in the third dimension at the the indicated xy pixel.

The gridder event flow is indicated in the following pseudo-glish code:

	whenever gridder->progress do
	    send otfClient->progress([percent=$value * 100])

	whenever gridder->grid_result, gridder->imageSaved do
	    send imager->ImageFile([name=$value.file, plane=64])

	whenever otfClient->suspend, otfClient->getImage do
	    send gridder->[$name]($value)

	whenever imager->pixel_result do
	    send plotter->xy_plot($value)

The demonstration begins by starting up glish and initializing the four glish clients described above (accomplished by including a glish script).

 	include ``SDGridder.g''

The inputs are retrieved from a mosaic window (although they could also be set from the command line - this was simply one example of some early thoughts on how inputs might be set and passed to an application).

 	inputs := mosaic_inputs(``SDGridder'')

This glish record, inputs, now contains the inputs for the gridder client. It is passed on to the gridder through a glish function which generates a ``grid'' event (after some translation of the inputs record to set the variable types correctly).

SDGridder(inputs)

At this point, the otfClient window appears and the status bar shows zero progress. The gridder reads the data and begins gridding according to the inputs. As the gridding progresses, the status bar in otfClient shows the value associated with the most recent ``progress'' event generated by the gridder.

At some point the user wishes to see an intermediate image (i.e., before all the data have been gridded). The user clicks on the ``Get Image'' button in the otfClient, which generates a ``getImage'' event, which is passed to the gridder. At a time convenient for the gridder, the intermediate image is written to disk and gridding resumes. The gridder generates an ``imageSaved'' event, which is translated to an ``ImageFile'' even which is passed to the imager client. The intermediate image is displayed. The user can switch to ``spectrum'' mode in the imager in order to display the values in the third dimension of the cube at a specific xy pixel.