1 files changed, 65 insertions, 0 deletions
diff --git a/gui/widget/widget.go b/gui/widget/widget.go
new file mode 100644
index 0000000..913809b
--- /dev/null
+++ b/gui/widget/widget.go
@@ -0,0 +1,65 @@
+package widget
+
+import (
+	"cmp"
+	"fmt"
+
+	"image"
+	"image/draw"
+
+	"volute/gui"
+	"volute/gui/win"
+)
+
+func Input(env gui.Env, r image.Rectangle, val chan<- float64) {
+	redraw := func(text []byte) func(draw.Image) image.Rectangle {
+		return func(drw draw.Image) image.Rectangle {
+			drawText(text, drw, r)
+			return r
+		}
+	}
+	text := []byte{'0'}
+	focus := false
+
+	env.Draw() <- redraw(text)
+
+	for event := range env.Events() {
+		switch event := event.(type) {
+		case win.WiFocus:
+			if event.Focused {
+				env.Draw() <- redraw(text)
+			}
+		case win.MoDown:
+			if event.Point.In(r) {
+				focus = true
+			}
+		case win.KbType:
+			if !focus ||
+				(!isDigit(event.Rune) && event.Rune != '.') ||
+				(event.Rune == '.' && contains(text, '.')) {
+				continue
+			}
+			text = fmt.Appendf(text, "%c", event.Rune)
+			env.Draw() <- redraw(text)
+		case win.KbDown:
+			if event.Key == win.KeyBackspace && len(text) > 0 {
+				text = text[:len(text)-1]
+				env.Draw() <- redraw(text)
+			}
+		}
+	}
+	close(env.Draw())
+}
+
+func isDigit(r rune) bool {
+	return '0' <= r && r <= '9'
+}
+
+func contains[T cmp.Ordered](slc []T, v T) bool {
+	for i := range slc {
+		if slc[i] == v {
+			return true
+		}
+	}
+	return false
+}