Progress

Overview

Progress derives from native System.Windows.Controls.ProgressBar (NaviusProgress), reusing its PART_Track/PART_Indicator template parts and built-in IRangeValueProvider automation. It is a non-interactive, read-only display: an out-of-range Value flips the bar to indeterminate rather than clamping, and NaviusProgressValue/NaviusProgressLabel are companion text parts wired by reference rather than nested content.

Usage

xmlns:navius="clr-namespace:Navius.Wpf.Primitives.Controls;assembly=Navius.Wpf.Primitives"

<StackPanel>
    <navius:NaviusProgressLabel x:Name="UploadLabel" Text="Upload progress" />
    <navius:NaviusProgress x:Name="Upload"
                            Value="42"
                            Maximum="100"
                            AutomationProperties.LabeledBy="{Binding ElementName=UploadLabel}" />
    <navius:NaviusProgressValue Source="{Binding ElementName=Upload}" />
</StackPanel>

Properties

Property	Type	Default	From	Description
Value	double	0.0	NaviusProgress (overrides RangeBase)	Current value. Negative or > Maximum flips IsIndeterminate to true via a CoerceValueCallback override instead of clamping into range (“validate, don’t clamp”). NaN/Infinity are rejected outright by RangeBase’s own inherited validation before this coercion runs.
Maximum	double	100.0	NaviusProgress (overrides RangeBase)	A value <= 0 falls back to 100.
IsIndeterminate	bool	false	ProgressBar	Native property; set directly or coerced to true by an out-of-range Value.
GetValueLabel	Func<double, double, string?>?	null	NaviusProgress	Builds the value text (value, maximum) for a determinate value. Defaults to the rounded percentage. Never invoked while indeterminate.
IsComplete	bool	false	NaviusProgress	Read-only. True when determinate and Value >= Maximum.
IsProgressing	bool	computed	NaviusProgress	Read-only, not a DP. True when determinate and Value < Maximum (!IsIndeterminate && !IsComplete).
Source	NaviusProgress?	null	NaviusProgressValue	The progress instance whose formatted value text this element renders.
TextOverride	string?	null	NaviusProgressValue	When set, overrides the default rounded-percentage text.

Methods

Method	Description
FormatValueText()	Returns the formatted value text: null while indeterminate, otherwise GetValueLabel or the default rounded percentage.

Events

Event	Signature	Fires when
StateChanged	RoutedEventHandler	Value, Maximum, or IsIndeterminate changes; consumed by NaviusProgressValue to refresh its text.

UIA mechanism

NaviusProgressAutomationPeer (derives ProgressBarAutomationPeer) overrides GetItemStatusCore() to return FormatValueText(), since the base peer has no first-class value-text slot. AutomationControlType stays the inherited ProgressBar value, and the native IRangeValueProvider (min/max/current) continues to work unmodified. The unit suite covers the coercion rule (Value_AboveMaximum_BecomesIndeterminateWithoutClamping, Value_Negative_BecomesIndeterminate, Value_ReenteringValidRange_ClearsIndeterminate), the NaN/Infinity rejection (Value_NaN_IsRejectedByNativeValidation), the Maximum <= 0 fallback, and the automation peer’s ItemStatus text.

Web deltas

• “Validate, don’t clamp” is preserved via a CoerceValueCallback override on Value rather than a clamp, deliberately replacing RangeBase’s default clamp-to-range coercion.
• NaN/Infinity are not reachable at all: RangeBase.ValueProperty’s own inherited ValidateValueCallback rejects them with an ArgumentException before NaviusProgress’s coercion ever runs; only negative/> Maximum values are portable to the “becomes indeterminate” path.
• GetValueLabel is Func<double, double, string?>? (a non-nullable value parameter) rather than the web contract’s Func<double?, double, string?>?, since there is no nullable-value state to pass through at this layer.
• aria-labelledby/HasLabel push-based registration is replaced by the native WPF idiom: a consumer sets AutomationProperties.LabeledBy on the NaviusProgress, pointing at a NaviusProgressLabel, rather than a label registering itself with a cascaded context.
• NaviusProgressValue is a companion element wired via an explicit Source property (not nested content or a visual-tree ancestor lookup), since ProgressBar has no content model to nest a value part inside.
• Known residual (M6 audit): while IsIndeterminate is true, the inherited ProgressBarAutomationPeer still surfaces a RangeValue.Value to UIA, whereas the web contract omits aria-valuenow entirely in the indeterminate state. This is not claimed as fixed anywhere in the implementation notes, so it is a genuine unfixed parity gap in the UIA surface, not a false claim.

Captures

The Progress Gallery page rendered at the pinned commit, in each theme.