1 files changed, 130 insertions, 0 deletions
diff --git a/gui/widget/widget.go b/gui/widget/widget.go
new file mode 100644
index 0000000..cbc837e
--- /dev/null
+++ b/gui/widget/widget.go
@@ -0,0 +1,130 @@
+package widget
+
+import (
+	"cmp"
+	"fmt"
+
+	"image"
+	"image/color"
+	"image/draw"
+
+	"volute/gui"
+	"volute/gui/win"
+)
+
+var (
+	FOCUS_COLOR = color.RGBA{179, 217, 255, 255}
+	GREEN       = color.RGBA{51, 102, 0, 255}
+	BLACK       = color.Gray{0}
+	WHITE       = color.Gray{255}
+)
+
+func Label(text string, r image.Rectangle, env gui.Env) {
+	redraw := func(drw draw.Image) image.Rectangle {
+		drawText([]byte(text), drw, r, BLACK, WHITE)
+		return r
+	}
+	env.Draw() <- redraw
+	for event := range env.Events() {
+		switch event := event.(type) {
+		case win.WiFocus:
+			if event.Focused {
+				env.Draw() <- redraw
+			}
+		}
+	}
+	close(env.Draw())
+}
+
+func Input(val chan<- uint, r image.Rectangle, focusChan <-chan bool, env gui.Env) {
+	redraw := func(text []byte, focus bool) func(draw.Image) image.Rectangle {
+		return func(drw draw.Image) image.Rectangle {
+			if focus {
+				drawText(text, drw, r, GREEN, FOCUS_COLOR)
+			} else {
+				drawText(text, drw, r, GREEN, WHITE)
+			}
+			return r
+		}
+	}
+	text := []byte{'0'}
+	focus := false
+
+	env.Draw() <- redraw(text, focus)
+
+	for {
+		select {
+		case focus = <-focusChan:
+			env.Draw() <- redraw(text, focus)
+		case event := <-env.Events():
+			switch event := event.(type) {
+			case win.WiFocus:
+				if event.Focused {
+					env.Draw() <- redraw(text, focus)
+				}
+			case win.KbType:
+				if focus && isDigit(event.Rune) {
+					text = fmt.Appendf(text, "%c", event.Rune)
+					env.Draw() <- redraw(text, focus)
+					val <- atoi(text)
+				}
+			case win.KbDown:
+				if focus && event.Key == win.KeyBackspace && len(text) > 0 {
+					text = text[:len(text)-1]
+					env.Draw() <- redraw(text, focus)
+					val <- atoi(text)
+				}
+			}
+		}
+	}
+	close(env.Draw())
+}
+
+func Output(val <-chan uint, r image.Rectangle, env gui.Env) {
+	redraw := func(n uint) func(draw.Image) image.Rectangle {
+		return func(drw draw.Image) image.Rectangle {
+			drawText([]byte(fmt.Sprint(n)), drw, r, BLACK, WHITE)
+			return r
+		}
+	}
+
+	var n uint = 0
+	env.Draw() <- redraw(n)
+
+Loop:
+	for {
+		select {
+		case n = <-val:
+			env.Draw() <- redraw(n)
+		case event, ok := <-env.Events():
+			if !ok { // channel closed
+				break Loop
+			}
+			if event, ok := event.(win.WiFocus); ok && event.Focused {
+				env.Draw() <- redraw(n)
+			}
+		}
+	}
+	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
+}
+
+func atoi(s []byte) uint {
+	var n uint = 0
+	for _, d := range s {
+		n = n*10 + uint(d-'0')
+	}
+	return n
+}