Re: Phoebus image widget info

["Kasemir, Kay via Tech-talk" <tech-talk at aps.anl.gov>]

Hi:

There's really just the example display, which demos the cursor PVs.

A cursor info PV is updated with the current mouse position in the image and the pixel value at that location.

When the crosshair is active, the position of the crosshair is used instead of the current mouse position, meaning you have to 'click' in the image instead of just moving the mouse around.

The location is reported both in X/Y axis coordinates and as integer offsets within the image.

The value is of type VTable and can be displayed directly in a table widget (useful for test/demo), or used in a script (if you actually want to do something with the data).

While the VTable has more detail, it's somewhat inconvenient for the larger EPICS ecosystem. The Cursor X and Y PVs can be set to plain PVs, which will be updated via channel access. We use that to send the image location that the user clicks to some IOC, which then for example moves motors to position a sample at the clicked location.

-Kay 

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From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Siddons, David via Tech-talk <tech-talk at aps.anl.gov>
Sent: Monday, August 9, 2021 2:43 PM
To: EPICS Tech Talk <tech-talk at aps.anl.gov>
Subject: [EXTERNAL] Phoebus image widget info

 

Is there any documentation for the image widget for Phoebus? In particular, it has three entries relating to a cursor:

Cursor info PV

Cursor X PV

Cursor Y PV

Can anyone tell me how they are supposed to be used?

Pete.