theme/material: add the material theme

Signed-off-by: Elias Naur <mail@eliasnaur.com>

widget/material/editor.go

@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package material
+
+import (
+	"image/color"
+
+	"gioui.org/layout"
+	"gioui.org/op"
+	"gioui.org/op/paint"
+	"gioui.org/text"
+	"gioui.org/unit"
+	"gioui.org/widget"
+)
+
+type Editor struct {
+	Font text.Font
+	// Color is the text color.
+	Color color.RGBA
+	// Hint contains the text displayed when the editor is empty.
+	Hint string
+	// HintColor is the color of hint text.
+	HintColor color.RGBA
+
+	shaper *text.Shaper
+}
+
+func (t *Theme) Editor(hint string) Editor {
+	return Editor{
+		Font: text.Font{
+			Size: unit.Sp(16),
+		},
+		Color:     t.Color.Text,
+		shaper:    t.Shaper,
+		Hint:      hint,
+		HintColor: t.Color.Hint,
+	}
+}
+
+func (e Editor) Layout(gtx *layout.Context, editor *widget.Editor) {
+	var stack op.StackOp
+	stack.Push(gtx.Ops)
+	var macro op.MacroOp
+	macro.Record(gtx.Ops)
+	paint.ColorOp{Color: e.HintColor}.Add(gtx.Ops)
+	tl := widget.Label{Alignment: editor.Alignment}
+	tl.Layout(gtx, e.shaper, e.Font, e.Hint)
+	macro.Stop()
+	if w := gtx.Dimensions.Size.X; gtx.Constraints.Width.Min < w {
+		gtx.Constraints.Width.Min = w
+	}
+	if h := gtx.Dimensions.Size.Y; gtx.Constraints.Height.Min < h {
+		gtx.Constraints.Height.Min = h
+	}
+	editor.Layout(gtx, e.shaper, e.Font)
+	if editor.Len() > 0 {
+		paint.ColorOp{Color: e.Color}.Add(gtx.Ops)
+		editor.PaintText(gtx)
+	} else {
+		macro.Add(gtx.Ops)
+	}
+	paint.ColorOp{Color: e.Color}.Add(gtx.Ops)
+	editor.PaintCaret(gtx)
+	stack.Pop()
+}