Initialize Fact QVariant as invalid

[rubenp02]

Initialize Fact QVariant as invalid

Description

Adjusted the default Fact _rawValue from 0 to QVariant::Invalid and updated _variantToString to return placeholders for Facts that haven't received a value yet. This makes it possible to distinguish them from those that are legitimately 0 (or the equivalent for their type). It also avoids starting every Fact's QVariant lifecycle as an integer, which is incorrect in most cases.

Related code that set initial values for a few VehicleFactGroup Facts (Hobbs meter, altitude above terrain, flight distance & time) has been updated or removed for consistency.

Note: While I believe these changes are in the right direction, and an improvement over the old code, they may be incomplete (I've only focused on testing the VehicleFactGroup) and there's a decent chance of unforseen bugs. Anything that relied on default facts being integer 0 is now broken.

Telemetry bar before/after

The following screenshots use these telemetry bar settings, that include all Facts from the VehicleFactGroup:

Click to show telemetry bar settings used

[TelemetryBarUserSettings-1]
version=1
fontSize=2
rowCount=4
columns\1\rows\1\text=Roll
columns\1\rows\1\showUnits=true
columns\1\rows\1\icon=
columns\1\rows\1\rangeType=0
columns\1\rows\1\factGroupName=Vehicle
columns\1\rows\1\factName=Roll
columns\1\rows\size=4
columns\2\rows\1\text=Pitch
columns\2\rows\1\showUnits=true
columns\2\rows\1\icon=
columns\2\rows\1\rangeType=0
columns\2\rows\1\factGroupName=Vehicle
columns\2\rows\1\factName=Pitch
columns\2\rows\size=4
columns\3\rows\1\text=Heading
columns\3\rows\1\showUnits=true
columns\3\rows\1\icon=
columns\3\rows\1\rangeType=0
columns\3\rows\1\factGroupName=Vehicle
columns\3\rows\1\factName=Heading
columns\3\rows\size=4
columns\4\rows\1\text=Roll Rate
columns\4\rows\1\showUnits=true
columns\4\rows\1\icon=
columns\4\rows\1\rangeType=0
columns\4\rows\1\factGroupName=Vehicle
columns\4\rows\1\factName=RollRate
columns\4\rows\size=4
columns\size=8
columns\1\rows\2\text=
columns\1\rows\2\showUnits=true
columns\1\rows\2\icon=
columns\1\rows\2\rangeType=0
columns\1\rows\2\factGroupName=Vehicle
columns\1\rows\2\factName=AirSpeedSetpoint
columns\1\rows\3\text=
columns\1\rows\3\showUnits=true
columns\1\rows\3\icon=
columns\1\rows\3\rangeType=0
columns\1\rows\3\factGroupName=Vehicle
columns\1\rows\3\factName=RangeFinderDist
columns\1\rows\4\text=Heading to Home
columns\1\rows\4\showUnits=true
columns\2\rows\2\text=Climb Rate
columns\1\rows\4\icon=
columns\2\rows\2\showUnits=true
columns\1\rows\4\rangeType=0
columns\2\rows\2\icon=
columns\1\rows\4\factGroupName=Vehicle
columns\2\rows\2\rangeType=0
columns\1\rows\4\factName=HeadingToHome
columns\2\rows\2\factGroupName=Vehicle
columns\2\rows\2\factName=ClimbRate
columns\2\rows\3\text=Flight Distance
columns\2\rows\3\showUnits=true
columns\3\rows\2\text=Alt (Rel)
columns\2\rows\3\icon=
columns\3\rows\2\showUnits=true
columns\2\rows\3\rangeType=0
columns\3\rows\2\icon=
columns\2\rows\3\factGroupName=Vehicle
columns\3\rows\2\rangeType=0
columns\2\rows\3\factName=FlightDistance
columns\3\rows\2\factGroupName=Vehicle
columns\3\rows\2\factName=AltitudeRelative
columns\2\rows\4\text=Heading from Home
columns\2\rows\4\showUnits=true
columns\2\rows\4\icon=
columns\4\rows\2\text=Alt (AMSL)
columns\2\rows\4\rangeType=0
columns\4\rows\2\showUnits=true
columns\2\rows\4\factGroupName=Vehicle
columns\4\rows\2\icon=
columns\2\rows\4\factName=HeadingFromHome
columns\4\rows\2\rangeType=0
columns\4\rows\2\factGroupName=Vehicle
columns\3\rows\3\text=Flight Time
columns\4\rows\2\factName=AltitudeAMSL
columns\3\rows\3\showUnits=true
columns\3\rows\3\icon=
columns\3\rows\3\rangeType=0
columns\3\rows\3\factGroupName=Vehicle
columns\3\rows\3\factName=FlightTime
columns\3\rows\4\text=Heading from GCS
columns\3\rows\4\showUnits=true
columns\4\rows\3\text=Distance to Home
columns\3\rows\4\icon=
columns\4\rows\3\showUnits=true
columns\3\rows\4\rangeType=0
columns\4\rows\3\icon=
columns\3\rows\4\factGroupName=Vehicle
columns\4\rows\3\rangeType=0
columns\3\rows\4\factName=HeadingFromGCS
columns\4\rows\3\factGroupName=Vehicle
columns\4\rows\3\factName=DistanceToHome
columns\4\rows\4\text=Distance to GCS
columns\4\rows\4\showUnits=true
columns\4\rows\4\icon=
columns\4\rows\4\rangeType=0
columns\4\rows\4\factGroupName=Vehicle
columns\4\rows\4\factName=DistanceToGCS
columns\5\rows\1\text=Pitch Rate
columns\5\rows\1\showUnits=true
columns\5\rows\1\icon=
columns\5\rows\1\rangeType=0
columns\5\rows\1\factGroupName=Vehicle
columns\5\rows\1\factName=PitchRate
columns\5\rows\2\text=Alt (Above Terrain)
columns\5\rows\2\showUnits=true
columns\5\rows\2\icon=
columns\5\rows\2\rangeType=0
columns\5\rows\2\factGroupName=Vehicle
columns\5\rows\2\factName=AltitudeAboveTerr
columns\5\rows\3\text=Time to Home
columns\5\rows\3\showUnits=true
columns\5\rows\3\icon=
columns\5\rows\3\rangeType=0
columns\5\rows\3\factGroupName=Vehicle
columns\5\rows\3\factName=TimeToHome
columns\5\rows\4\text=Hobbs Meter
columns\5\rows\4\showUnits=true
columns\5\rows\4\icon=
columns\5\rows\4\rangeType=0
columns\5\rows\4\factGroupName=Vehicle
columns\5\rows\4\factName=Hobbs
columns\5\rows\size=4
columns\6\rows\1\text=Yaw Rate
columns\6\rows\1\showUnits=true
columns\6\rows\1\icon=
columns\6\rows\1\rangeType=0
columns\6\rows\1\factGroupName=Vehicle
columns\6\rows\1\factName=YawRate
columns\6\rows\2\text=
columns\6\rows\2\showUnits=true
columns\6\rows\2\icon=
columns\6\rows\2\rangeType=0
columns\6\rows\2\factGroupName=Vehicle
columns\6\rows\2\factName=AltitudeTuning
columns\6\rows\3\text=Mission Item Index
columns\6\rows\3\showUnits=true
columns\6\rows\3\icon=
columns\6\rows\3\rangeType=0
columns\6\rows\3\factGroupName=Vehicle
columns\6\rows\3\factName=MissionItemIndex
columns\6\rows\4\text=Throttle %
columns\6\rows\4\showUnits=true
columns\6\rows\4\icon=
columns\6\rows\4\rangeType=0
columns\6\rows\4\factGroupName=Vehicle
columns\6\rows\4\factName=ThrottlePct
columns\6\rows\size=4
columns\7\rows\1\text=Ground Speed
columns\7\rows\1\showUnits=true
columns\7\rows\1\icon=
columns\7\rows\1\rangeType=0
columns\7\rows\1\factGroupName=Vehicle
columns\7\rows\1\factName=GroundSpeed
columns\7\rows\2\text=
columns\7\rows\2\showUnits=true
columns\7\rows\2\icon=
columns\7\rows\2\rangeType=0
columns\7\rows\2\factGroupName=Vehicle
columns\7\rows\2\factName=AltitudeTuningSetpoint
columns\7\rows\3\text=Next WP Heading
columns\7\rows\3\showUnits=true
columns\7\rows\3\icon=
columns\7\rows\3\rangeType=0
columns\7\rows\3\factGroupName=Vehicle
columns\7\rows\3\factName=HeadingToNextWP
columns\7\rows\4\text=Imu temperature
columns\7\rows\4\showUnits=true
columns\7\rows\4\icon=
columns\7\rows\4\rangeType=0
columns\7\rows\4\factGroupName=Vehicle
columns\7\rows\4\factName=ImuTemp
columns\7\rows\size=4
columns\8\rows\1\text=Air Speed
columns\8\rows\1\showUnits=true
columns\8\rows\1\icon=
columns\8\rows\1\rangeType=0
columns\8\rows\1\factGroupName=Vehicle
columns\8\rows\1\factName=AirSpeed
columns\8\rows\2\text=
columns\8\rows\2\showUnits=true
columns\8\rows\2\icon=
columns\8\rows\2\rangeType=0
columns\8\rows\2\factGroupName=Vehicle
columns\8\rows\2\factName=XTrackError
columns\8\rows\3\text=Next WP distance
columns\8\rows\3\showUnits=true
columns\8\rows\3\icon=
columns\8\rows\3\rangeType=0
columns\8\rows\3\factGroupName=Vehicle
columns\8\rows\3\factName=DistanceToNextWP
columns\8\rows\4\text=Alt (Rel)
columns\8\rows\4\showUnits=true
columns\8\rows\4\icon=
columns\8\rows\4\rangeType=0
columns\8\rows\4\factGroupName=Vehicle
columns\8\rows\4\factName=AltitudeRelative
columns\8\rows\size=4

Before:

After:

Checklist:

• Review Contribution Guidelines.
• Review Code of Conduct.
• I have tested my changes. (I have tested them, just not 100% thoroughly considering the implications this change might have)

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[rubenp02]

Looking forward to Copilot thrashing this

[Copilot]

Pull Request Overview

This PR improves the Fact system's initialization by using invalid QVariant instead of defaulting to integer 0, making it possible to distinguish uninitialized Facts from those with legitimate zero values. This change also corrects the QVariant lifecycle, avoiding the incorrect initial state where all Facts started as integers.

Key Changes:

• Changed Fact's default _rawValue from integer 0 to QVariant::Invalid
• Added invalid QVariant handling in _variantToString with type-appropriate placeholders
• Updated Hobbs meter placeholder from "0000:00:00" to "----:--:--" for consistency

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/FactSystem/Fact.h	Changed default _rawValue initialization from 0 to invalid QVariant with clarifying comment
src/FactSystem/Fact.cc	Added invalid QVariant check in _variantToString returning type-appropriate placeholders ("--.--" for floats/doubles, "--:--:--" for elapsed time, "-" for others)
src/Vehicle/FactGroups/VehicleFactGroup.cc	Updated Hobbs meter placeholder string from "0000:00:00" to "----:--:--" to indicate uninitialized state
src/Vehicle/Vehicle.cc	Removed redundant initializations for altitude above terrain (NaN), flight distance (0), and flight time (0) that are now handled by invalid QVariant default or explicit initialization when needed

[rubenp02]

I've pushed a small improvement: the number of decimal places is now taken into account for the placeholder String generation, which is also now centralized. For consistency, I've also changed a couple places in the QML where placeholder strings were hardcoded just in case the corresponding Facts weren't available at all (which is a bit unrealistic given that they're just loaded from JSON, but whatever). Here's how it's looking now:

After after:

[Copilot]

Pull Request Overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated no new comments.

[rubenp02]

All done. I changed all instances of what previously was a single dash for a double dash, including a couple you didn't mention for consistency. I think a triple dash might be better, but it's easy enough to change in the future.

[DonLakeFlyer]

Thanks Ruben

All good now