Documentation
¶
Overview ¶
Package slider provides a draggable slider widget for selecting a value from a continuous or discrete range.
Construction uses functional options for immutable configuration, while fluent methods handle mutable styling:
s := slider.New(
slider.Min(0),
slider.Max(100),
slider.Value(50),
slider.OnChange(handleChange),
).Padding(8)
Visual Style ¶
The visual rendering is provided by a Painter implementation. Each design system (Material 3, Fluent, Cupertino) supplies its own painter to render sliders in the appropriate visual style.
If no painter is set, DefaultPainter is used, which draws a minimal slider suitable for testing and prototyping.
Orientation ¶
Two orientations are available:
- Horizontal (default) -- thumb moves left-to-right
- Vertical -- thumb moves bottom-to-top
Value Range ¶
The slider operates within [Min, Max] bounds. If Step is set to a value greater than zero, the value snaps to the nearest step. When Step is zero, the slider is continuous.
Marks ¶
Optional Mark values can annotate specific positions on the track (e.g. tick marks or labeled positions). Marks are purely visual and do not constrain the slider value.
Interaction ¶
Sliders respond to:
- Mouse click on the track to jump to a value
- Mouse drag on the thumb to continuously adjust the value
- Keyboard: Left/Down to decrease, Right/Up to increase, Home for minimum, End for maximum, Page Up/Down for larger steps
Disabled sliders ignore all interaction and are drawn with a dimmed appearance.
Signal Binding ¶
Slider properties can be bound to reactive signals from the state package. When a signal value changes, the slider automatically reflects the new state.
- ValueSignal -- TWO-WAY binding: reads value from signal AND writes back on change
- DisabledSignal -- one-way binding for the disabled state
Example:
volume := state.NewSignal[float32](50)
s := slider.New(
slider.Min(0),
slider.Max(100),
slider.ValueSignal(volume),
slider.OnChange(func(v float32) {
fmt.Printf("volume: %.0f\n", v)
}),
)
Focus ¶
Sliders implement widget.Focusable and participate in tab navigation. A focus ring is drawn around the thumb when the slider has keyboard focus.
Index ¶
- type DefaultPainter
- type Mark
- type Option
- func A11yHint(hint string) Option
- func Disabled(d bool) Option
- func DisabledFn(fn func() bool) Option
- func DisabledReadonlySignal(sig state.ReadonlySignal[bool]) Option
- func DisabledSignal(sig state.Signal[bool]) Option
- func Marks(m []Mark) Option
- func Max(v float32) Option
- func Min(v float32) Option
- func OnChange(fn func(float32)) Option
- func OrientationOpt(o Orientation) Option
- func PainterOpt(p Painter) Option
- func Step(v float32) Option
- func Value(v float32) Option
- func ValueFn(fn func() float32) Option
- func ValueReadonlySignal(sig state.ReadonlySignal[float32]) Option
- func ValueSignal(sig state.Signal[float32]) Option
- type Orientation
- type PaintState
- type Painter
- type SliderColorScheme
- type Widget
- func (w *Widget) Children() []widget.Widget
- func (w *Widget) Draw(ctx widget.Context, canvas widget.Canvas)
- func (w *Widget) Event(ctx widget.Context, e event.Event) bool
- func (w *Widget) IsFocusable() bool
- func (w *Widget) Layout(_ widget.Context, constraints geometry.Constraints) geometry.Size
- func (w *Widget) Mount(ctx widget.Context)
- func (w *Widget) Padding(v float32) *Widget
- func (w *Widget) Unmount()
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type DefaultPainter ¶
type DefaultPainter struct{}
DefaultPainter provides a minimal fallback painter with no design system styling. It draws a simple slider -- useful for testing and as a base reference.
func (DefaultPainter) PaintSlider ¶
func (p DefaultPainter) PaintSlider(canvas widget.Canvas, ps PaintState)
PaintSlider renders a minimal slider with gray track, blue active segment, and a white thumb circle with border. If state.ColorScheme is non-zero, its colors are used instead of built-in defaults.
type Mark ¶
type Mark struct {
// Value is the position on the slider where the mark appears.
Value float32
// Label is the optional text label displayed near the mark.
// If empty, only a tick mark is drawn.
Label string
}
Mark represents a labeled position on the slider track. Marks are purely visual annotations; they do not constrain the slider value.
type Option ¶
type Option func(*config)
Option configures a slider during construction.
func Disabled ¶
Disabled sets the slider's disabled state. A disabled slider does not respond to user input and is drawn with a dimmed appearance.
func DisabledFn ¶
DisabledFn sets a dynamic function that is evaluated to determine whether the slider is disabled. When set, this takes precedence over the static value but not over a signal set via DisabledSignal.
func DisabledReadonlySignal ¶
func DisabledReadonlySignal(sig state.ReadonlySignal[bool]) Option
DisabledReadonlySignal binds the slider's disabled state to a read-only signal. This is useful for computed signals created via state.NewComputed. When set, this takes highest precedence over all other disabled sources.
func DisabledSignal ¶
DisabledSignal binds the slider's disabled state to a reactive signal. When set, the signal value takes precedence over both DisabledFn and Disabled but not over DisabledReadonlySignal.
func OnChange ¶
OnChange sets the callback invoked when the slider value changes. The callback receives the new value.
func OrientationOpt ¶
func OrientationOpt(o Orientation) Option
OrientationOpt sets the slider's orientation.
func PainterOpt ¶
PainterOpt sets the painter used to render the slider. Each design system provides its own painter. If not set, DefaultPainter is used.
func Step ¶
Step sets the step increment. When step > 0, the value snaps to the nearest multiple of step within [min, max]. When step is 0 (default), the slider is continuous.
func ValueFn ¶
ValueFn sets a dynamic value function that is evaluated on each draw. When set, this takes precedence over the static value but not over a signal set via ValueSignal.
func ValueReadonlySignal ¶
func ValueReadonlySignal(sig state.ReadonlySignal[float32]) Option
ValueReadonlySignal binds the slider's value to a read-only signal. This is useful for computed signals created via state.NewComputed. When set, this takes highest precedence over all other value sources.
func ValueSignal ¶
ValueSignal binds the slider's value to a reactive signal. This is a TWO-WAY binding: the widget reads the value from the signal, and when the user drags the thumb, the new value is written back to the signal. When set, the signal value takes precedence over both ValueFn and Value but not over ValueReadonlySignal.
type Orientation ¶
type Orientation uint8
Orientation controls the direction of the slider track.
const ( // Horizontal renders the slider with the thumb moving left to right. // This is the default orientation. Horizontal Orientation = iota // Vertical renders the slider with the thumb moving bottom to top. Vertical )
Orientation constants.
func (Orientation) String ¶
func (o Orientation) String() string
String returns a human-readable name for the orientation.
type PaintState ¶
type PaintState struct {
Value float32 // current value (within [Min, Max])
Min float32 // minimum value
Max float32 // maximum value
Progress float32 // normalized 0..1 progress
Hovered bool // mouse is over the slider
Dragging bool // thumb is being dragged
Focused bool // slider has keyboard focus
Disabled bool // slider is disabled
Bounds geometry.Rect // total widget bounds
Orientation Orientation // horizontal or vertical
Marks []Mark // optional tick marks
ColorScheme SliderColorScheme // theme-derived colors
}
PaintState provides the current slider state to the painter.
type Painter ¶
type Painter interface {
PaintSlider(canvas widget.Canvas, state PaintState)
}
Painter draws the visual representation of a slider. Each design system (Material 3, Fluent, Cupertino) provides its own Painter implementation to render the slider in its visual style.
If no Painter is set, the slider uses DefaultPainter.
type SliderColorScheme ¶
type SliderColorScheme struct {
ActiveTrack widget.Color // active (filled) portion of the track
InactiveTrack widget.Color // inactive (empty) portion of the track
Thumb widget.Color // thumb circle fill
ThumbBorder widget.Color // thumb circle border
FocusRing widget.Color // focus indicator color
DisabledTrack widget.Color // track color when disabled
DisabledThumb widget.Color // thumb color when disabled
MarkColor widget.Color // tick mark color
}
SliderColorScheme provides theme-derived colors for slider painting. Zero value means the painter should use its built-in defaults.
type Widget ¶
type Widget struct {
widget.WidgetBase
// contains filtered or unexported fields
}
Widget implements a draggable slider for selecting a value from a range.
A slider is created with New using functional options:
s := slider.New(
slider.Min(0),
slider.Max(100),
slider.Value(50),
slider.OnChange(handleChange),
)
Fluent styling methods may be chained after construction:
s.Padding(8)
func New ¶
New creates a new slider Widget with the given options.
The returned widget is visible, enabled, and focusable by default. The default range is [0, 100] with Horizontal orientation.
func (*Widget) IsFocusable ¶
IsFocusable reports whether the slider can currently receive focus. A slider is focusable when it is visible, enabled, and not disabled.
func (*Widget) Mount ¶
Mount creates signal bindings for push-based invalidation. Implements widget.Lifecycle.
func (*Widget) Padding ¶
Padding sets the padding around the slider. Returns the widget for method chaining.
func (*Widget) Unmount ¶
func (w *Widget) Unmount()
Unmount is called when the slider is removed from the widget tree. Implements widget.Lifecycle.
Source Files