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ProgressBar

widget.ProgressBar renders a horizontal progress indicator for values between 0.0 and 1.0. It is a display-only widget with no interactive key bindings.

Basic usage​

pb := widget.NewProgressBar()
pb.SetValue(0.65)   // 65%

Percentage label​

By default the percentage label is shown at the left edge. Use WithPercentage to control both visibility and position:

// Left (default) — " 65% ██████░░░░"
pb := widget.NewProgressBar().WithPercentage(true)

// Centre — "███ 65% ░░░░"
pb := widget.NewProgressBar().WithPercentage(true, oat.AnchorCenter)

// Right — "██████░░░░ 65%"
pb := widget.NewProgressBar().WithPercentage(true, oat.AnchorRight)

// Hidden
pb := widget.NewProgressBar().WithPercentage(false)

The anchor parameter is optional — omit it to get oat.AnchorLeft by default.

AnchorLayout
oat.AnchorLeft (default)Label precedes the bar: " 65% ██░░░░"
oat.AnchorCenterLabel stamped into the midpoint: "██ 65% ░░"
oat.AnchorRightLabel appended after the bar: "████░░ 65%"
note

WithShowPercent(bool) still works as a deprecated shorthand but does not let you set the anchor. Prefer WithPercentage.

Builder options​

MethodDescription
WithPercentage(show bool, anchor ...oat.Anchor)Control label visibility and position (default true, AnchorLeft)
WithStyle(s latte.Style)Override the display style (colour, background)
WithID(id string)Set a stable identifier for Canvas.GetValue(id)
WithFillChar(r rune)Rune used for the filled portion (default █)
WithEmptyChar(r rune)Rune used for the empty portion (default ░)
WithShowPercent(show bool)Deprecated — use WithPercentage instead

Custom fill characters​

pb := widget.NewProgressBar().
    WithFillChar('=').
    WithEmptyChar('-').
    WithPercentage(true, oat.AnchorRight)
// Renders as:  ======---- 60%

Per-item colour​

After theme application you can override the fill colour per-item using WithStyle:

pb := widget.NewProgressBar().
    WithStyle(latte.Style{FG: latte.ColorRed})

SetStyle is still available as a deprecated alias for WithStyle when you need to mutate the style after construction (e.g. in a list renderer).

In a flex layout​

ProgressBar grows to fill available horizontal space when given a flex weight:

row := layout.NewHBox()
row.AddChild(widget.NewText("Progress: "))
row.AddFlexChild(pb, 1)
row.AddChild(widget.NewText(" 4/10"))

Reading the value​

v := pb.Progress() // float64, 0.0–1.0

ProgressBar also implements oat.ValueGetter: Canvas.GetValue(id) returns the current value as a float64.

Updating from a goroutine​

SetValue is safe to call from any goroutine. Use widget.NotificationManager (via oat.WithNotificationManager) to trigger a re-render:

notifs := widget.NewNotificationManager()
app := oat.NewCanvas(
    oat.WithBody(body),
    oat.WithNotificationManager(notifs),
)

go func() {
    for i := 0; i <= 100; i++ {
        pb.SetValue(float64(i) / 100.0)
        notifs.Push("", widget.NotificationKindInfo, time.Millisecond) // triggers re-render
        time.Sleep(50 * time.Millisecond)
    }
}()