Files
gio-patched/widget/material/theme.go
T
Elias Naur 3af01a3f43 layout: change Widget to take explicit Context and return explicit Dimensions
Change the definition of Widget from the implicit

        type Widget func()

to the explicit functional

        type Widget func(gtx layout.Context) layout.Dimensions

The advantages are numerous:

- Clearer connection between the incoming context and the output dimensions.
- Returning the Dimensions are impossible to omit.
- Contexts passed by value, so its fields can be exported
and freely mutated by the program.

The only disadvantage is the longer function literals and the many "returns".
What tipped the scales in favour of the explicit Widget variant is that type
aliases can dramatically shorten the literals:

	type (
		C = layout.Context
		D = layout.Dimensions
	)

	widget := func(gtx C) D {
		...
	}

Note that the aliases are not part of the Gio API and it is up to each user
whether they want to use them.

Finally the Go proposal for lightweight function literals,
https://github.com/golang/go/issues/21498, may remove the disadvantage
completely in future.

Context becomes a plain struct with only public fields, and its Reset is
replaced by a NewContext convenience constructor.

Signed-off-by: Elias Naur <mail@eliasnaur.com>
2020-05-23 22:28:49 +02:00

76 lines
1.7 KiB
Go

// SPDX-License-Identifier: Unlicense OR MIT
package material
import (
"image/color"
"gioui.org/f32"
"gioui.org/font"
"gioui.org/layout"
"gioui.org/op/paint"
"gioui.org/text"
"gioui.org/unit"
"gioui.org/widget"
"golang.org/x/exp/shiny/materialdesign/icons"
)
type Theme struct {
Shaper text.Shaper
Color struct {
Primary color.RGBA
Text color.RGBA
Hint color.RGBA
InvText color.RGBA
}
TextSize unit.Value
checkBoxCheckedIcon *widget.Icon
checkBoxUncheckedIcon *widget.Icon
radioCheckedIcon *widget.Icon
radioUncheckedIcon *widget.Icon
}
func NewTheme() *Theme {
t := &Theme{
Shaper: font.Default(),
}
t.Color.Primary = rgb(0x3f51b5)
t.Color.Text = rgb(0x000000)
t.Color.Hint = rgb(0xbbbbbb)
t.Color.InvText = rgb(0xffffff)
t.TextSize = unit.Sp(16)
t.checkBoxCheckedIcon = mustIcon(widget.NewIcon(icons.ToggleCheckBox))
t.checkBoxUncheckedIcon = mustIcon(widget.NewIcon(icons.ToggleCheckBoxOutlineBlank))
t.radioCheckedIcon = mustIcon(widget.NewIcon(icons.ToggleRadioButtonChecked))
t.radioUncheckedIcon = mustIcon(widget.NewIcon(icons.ToggleRadioButtonUnchecked))
return t
}
func mustIcon(ic *widget.Icon, err error) *widget.Icon {
if err != nil {
panic(err)
}
return ic
}
func rgb(c uint32) color.RGBA {
return argb(0xff000000 | c)
}
func argb(c uint32) color.RGBA {
return color.RGBA{A: uint8(c >> 24), R: uint8(c >> 16), G: uint8(c >> 8), B: uint8(c)}
}
func fill(gtx layout.Context, col color.RGBA) layout.Dimensions {
cs := gtx.Constraints
d := cs.Min
dr := f32.Rectangle{
Max: f32.Point{X: float32(d.X), Y: float32(d.Y)},
}
paint.ColorOp{Color: col}.Add(gtx.Ops)
paint.PaintOp{Rect: dr}.Add(gtx.Ops)
return layout.Dimensions{Size: d}
}