Add support for read-only parameters

[julianoes]

Description

This parses the readonly flag for a parameter, so that it's clear in the UI when a param can't be set.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Refactoring (no functional changes)
• CI/Build changes
• Other

Testing

• Tested locally
• Added/updated unit tests
• Tested with simulator (SITL)
• Tested with hardware

Platforms Tested

• Linux
• Windows
• macOS
• Android
• iOS

Flight Stacks Tested

• PX4
• ArduPilot

Screenshots

Checklist

• I have read the Contribution Guidelines
• I have read the Code of Conduct
• My code follows the project's coding standards
• I have added tests that prove my fix/feature works
• New and existing unit tests pass locally

Related Issues

Goes together with PX4/PX4-Autopilot#26522.

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By submitting this pull request, I confirm that my contribution is made under the terms of the project's dual license (Apache 2.0 and GPL v3).

[github-actions]

Build Results

Platform Status

Platform	Status	Details
Linux	Passed	View
Windows	Passed	View
MacOS	Failed	View
Android	Passed	View

Some builds failed.

Pre-commit

Check	Status	Details
pre-commit	Failed (non-blocking)	View

Pre-commit hooks: 3 passed, 32 failed, 7 skipped.

Test Results

linux-sanitizers: 65 passed, 0 skipped

linux_gcc_64: 65 passed, 0 skipped

Total: 130 passed, 0 skipped

Artifact Sizes

Artifact	Size
QGroundControl	330.45 MB
QGroundControl-aarch64	177.06 MB
QGroundControl-installer-AMD64	150.86 MB
QGroundControl-installer-AMD64-ARM64	77.09 MB
QGroundControl-installer-ARM64	78.06 MB
QGroundControl-mac	184.52 MB
QGroundControl-windows	184.55 MB
QGroundControl-x86_64	163.16 MB

No baseline available for comparison

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_{Updated: 2026-03-12 10:09:39 UTC • Triggered by: Android}

[julianoes]

Added a commit to display a lock and add a checkbox to filter them out.

[hamishwillee]

That is very cool. I'm slightly surprised it doesn't already exist since ArduPilot support read only params

[julianoes]

I need to check how read only params work in ArduPilot then, so this is compatible.

[hamishwillee]

I need to check how read only params work in ArduPilot then, so this is compatible.

Indeed! Though if they don't have an icon like this then they would probably appreciate one :-)

[julianoes]

@hamishwillee from my research I don't see how AP would be communicating this to QGC. I think we can leave this PR as is.

[hamishwillee]

Cool. I have no more comments. I guess get Don or Holden to look at it now.

[Ryanf55]

FWIW, ArduPilot likes OEM's to use this script.
https://github.com/ArduPilot/ardupilot/blob/master/libraries/AP_Scripting/applets/param-set.lua

[Copilot]

Pull request overview

This PR adds end-to-end support for “read-only” parameter metadata so the Parameter UI can indicate non-editable parameters and optionally hide them from the list.

Changes:

• Parse a new readOnly boolean from parameter metadata JSON into FactMetaData.
• Update the parameter editor dialog to show read-only messaging and prevent editing/saving.
• Add UI affordances: a lock icon in the parameter list and a “Hide read-only” filter wired through ParameterEditorController.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/QmlControls/ParameterEditorDialog.qml	Disables editing for read-only facts, shows read-only messaging/value-only display.
src/QmlControls/ParameterEditorController.h	Adds hideReadOnly property/signal/slot to support filtering.
src/QmlControls/ParameterEditorController.cc	Implements read-only filtering in list build/search and rebuilds lists on toggle.
src/QmlControls/ParameterEditor.qml	Adds “Hide read-only” checkbox and displays a lock icon for read-only facts in the table.
src/FactSystem/FactMetaData.h	Adds JSON key constant for readOnly.
src/FactSystem/FactMetaData.cc	Parses readOnly from JSON metadata.

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[DonLakeFlyer]

This screws up the positioning of the setVolatileValue with the rest of it's code. Also it doesn't follow the pattern and the rest of the value setting. It should do it the same way as the others.

[DonLakeFlyer]

FWIW, ArduPilot likes OEM's to use this script.

For what?

[DonLakeFlyer]

Other question: Did the NCELLS param suddenly become ready only. That is part of Power Setup page as something user should set.

[DonLakeFlyer]

Code review notes:

1. onAccepted still fires for read-only parameters (ParameterEditorDialog.qml)

The dialog uses Dialog.Close for read-only facts, but the onAccepted handler doesn't guard against writes. If Close ever triggers accepted, the handler would attempt to write to a read-only fact. Consider adding an early return:

onAccepted: {
    if (fact.readOnly) return
    ...
}

2. _hideReadOnlyChanged duplicates _buildLists teardown logic (ParameterEditorController.cc)

The _hideReadOnlyChanged method manually clears _currentCategory, _currentGroup, _parameters, _mapCategoryName2Category, and calls _categories.clearAndDeleteContents() — this is the same teardown that _buildLists() already does internally. This duplication is fragile; if _buildLists teardown changes, this code won't stay in sync. Consider extracting a _clearLists() helper, or just calling _buildLists() directly since it already handles the full rebuild.