Maybe "defaults" is not the correct word to describe what I am trying to accomplish. The parameter values that pop up when you first drop the block down onto a flowgraph aren't
necessarily important. But once the user double clicks the block to open the properties dialog, I want them to be able to select from a drop down menu list of presets that will auto-fill the rest of the parameters according to which option was selected.
Note that I would like the user to still be able to change the values that were "auto-filled" previously, so they can enter a setup that deviates slightly from the preset without having to enter all of the parameters manually.
I can add all of the necessary info in the xml file. I just don't know how to set the parameters to the proper values based on the selected option. It seems like there should be some mechanism to do it because I can hide or show parameters based on the selected
options (conditional statements seem to work inside of <hide> tags), so there must be some callback mechanism in place. But no way to change the values of the parameters based on a selected option?
Mark
From: Marcus D. Leech address@hidden
Sent: Monday, June 20, 2016 3:49 PM
To: Mark Arlinghaus; address@hidden
Subject: Re: [Discuss-gnuradio] Load Preset parameters in block
On 06/20/2016 03:17 PM, Mark Arlinghaus wrote:
Hi Marcus,
Thank you for your quick response. Sorry I wasn't clear. I'm actually talking about GRC construction. Once the code is running the parameters won't need to be changed. If we need to change the parameters, stopping the flowgraph is acceptable. It's
really just meant to make the block slightly easier/faster to set up by the user. I'm hoping that this makes the solution simpler!?
Mark
Defaults for block parameters in GRC are defined in the .xml description of the block, but there's no way to override what ever is in
the .xml when you first instantiate a block in GRC.
On 06/20/2016 02:15 PM, Mark Arlinghaus wrote:
Hello,
Is there a way to load preset default parameters in a block. For example, I have a channel model block that takes several parameters, such as the doppler spread, path delays, path gains, doppler spectrum, etc., and I want to have presets that will auto-populate
the parameters in the GRC block for pre-defined channel models. I can make a drop-down menu that has the pre-defined channel models, but I don't know how to change the values that populate in the other parameters. I would like to do this using the xml file.
Is there a way to put a conditional parameter in the <value> tags that would depend on the setting in the drop down menu (It seems conditionals can be used in the <hide> and <import> tags, but not inside the <value> tags)? Is there a way to do it using the
<opt> tags? Is there a list of valid options and what they do anywhere? It seems the <opt> val:XXX <\opt> tags might do it, but I can't seem to get any of them to work.
Although I could pass in a preset parameter to the C++ function and simply override everything coming from the GUI, I'd rather have it populate the parameters in the block, but still let them be changed. This way, if someone wanted to load the settings for
a "Channel X" preset, except with a different Doppler spread, it could be done easily.
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It's not clear whether you're talking about *runtime* or during GRC construction.
For runtime, I'd write a little Python module that contains a function for each parameter:
setter_function(configfilename, command-line-parameter, widget-control-value)
You then have logic in the function to determine the priority of what gets returned:
config-->command-line-->widget-control-value
I've done that in the past.
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