Files
gio/widget/material/slider.go
T
Gordon Klaus 22aa00f476 widget/material: add Float.Invert
Setting Float.Invert=true not only inverts the order of values (which was already easily done by swapping min and max), it also draws the widget inverted so that the track is darkened on the opposite side from usual.

This patch also fixes a bug wherein a vertical slider was drawn inverted by default.

Signed-off-by: Gordon Klaus <gordon.klaus@gmail.com>
2023-01-27 21:04:01 -06:00

112 lines
2.7 KiB
Go

// SPDX-License-Identifier: Unlicense OR MIT
package material
import (
"image"
"image/color"
"gioui.org/internal/f32color"
"gioui.org/layout"
"gioui.org/op"
"gioui.org/op/clip"
"gioui.org/op/paint"
"gioui.org/unit"
"gioui.org/widget"
)
// Slider is for selecting a value in a range.
func Slider(th *Theme, float *widget.Float, min, max float32) SliderStyle {
return SliderStyle{
Min: min,
Max: max,
Color: th.Palette.ContrastBg,
Float: float,
FingerSize: th.FingerSize,
}
}
type SliderStyle struct {
Min, Max float32
Color color.NRGBA
Float *widget.Float
FingerSize unit.Dp
}
func (s SliderStyle) Layout(gtx layout.Context) layout.Dimensions {
thumbRadius := gtx.Dp(6)
trackWidth := gtx.Dp(2)
axis := s.Float.Axis
// Keep a minimum length so that the track is always visible.
minLength := thumbRadius + 3*thumbRadius + thumbRadius
// Try to expand to finger size, but only if the constraints
// allow for it.
touchSizePx := min(gtx.Dp(s.FingerSize), axis.Convert(gtx.Constraints.Max).Y)
sizeMain := max(axis.Convert(gtx.Constraints.Min).X, minLength)
sizeCross := max(2*thumbRadius, touchSizePx)
size := axis.Convert(image.Pt(sizeMain, sizeCross))
o := axis.Convert(image.Pt(thumbRadius, 0))
trans := op.Offset(o).Push(gtx.Ops)
gtx.Constraints.Min = axis.Convert(image.Pt(sizeMain-2*thumbRadius, sizeCross))
s.Float.Layout(gtx, thumbRadius, s.Min, s.Max)
gtx.Constraints.Min = gtx.Constraints.Min.Add(axis.Convert(image.Pt(0, sizeCross)))
thumbPos := thumbRadius + int(s.Float.Pos())
trans.Pop()
color := s.Color
if gtx.Queue == nil {
color = f32color.Disabled(color)
}
rect := func(minx, miny, maxx, maxy int) image.Rectangle {
r := image.Rect(minx, miny, maxx, maxy)
if s.Float.Invert != (axis == layout.Vertical) {
r.Max.X, r.Min.X = sizeMain-r.Min.X, sizeMain-r.Max.X
}
r.Min = axis.Convert(r.Min)
r.Max = axis.Convert(r.Max)
return r
}
// Draw track before thumb.
track := rect(
thumbRadius, sizeCross/2-trackWidth/2,
thumbPos, sizeCross/2+trackWidth/2,
)
paint.FillShape(gtx.Ops, color, clip.Rect(track).Op())
// Draw track after thumb.
track = rect(
thumbPos, axis.Convert(track.Min).Y,
sizeMain-thumbRadius, axis.Convert(track.Max).Y,
)
paint.FillShape(gtx.Ops, f32color.MulAlpha(color, 96), clip.Rect(track).Op())
// Draw thumb.
pt := image.Pt(thumbPos, sizeCross/2)
thumb := rect(
pt.X-thumbRadius, pt.Y-thumbRadius,
pt.X+thumbRadius, pt.Y+thumbRadius,
)
paint.FillShape(gtx.Ops, color, clip.Ellipse(thumb).Op(gtx.Ops))
return layout.Dimensions{Size: size}
}
func max(a, b int) int {
if a > b {
return a
}
return b
}
func min(a, b int) int {
if a < b {
return a
}
return b
}