gui: a /dev/draw layer in go, with no cgo and no devdraw

9fans.net/go/draw builds for plan9 but shells out to plan9port's
devdraw, which 9front does not have. This talks to /dev/draw itself:
the protocol is file i/o, so a pure-go client is a few hundred lines
under an already-complete idea.

draw/keyboard.go opens /dev/cons and turns the console raw, as
libdraw's initkeyboard does. Without it rio keeps its line editor on
the window and paints what you type over the drawing.

draw/snarf.go writes /dev/snarf, which is what every other program on
the system means by copy.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

1 files changed, 66 insertions, 0 deletions

diff --git a/gui/cmd/text/main.go b/gui/cmd/text/main.go
new file mode 100644
index 0000000..f1e2a9f
--- /dev/null
+++ b/gui/cmd/text/main.go
@@ -0,0 +1,66 @@
+// text: prove the font layer draws glyphs on the raw screen.
+package main
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	"9front/gui/draw"
+)
+
+const fontpath = "/lib/font/bit/lucidasans/unicode.8.font"
+
+func main() {
+	if err := run(); err != nil {
+		fmt.Fprintf(os.Stderr, "text: %v\n", err)
+		os.Exit(1)
+	}
+}
+
+func run() error {
+	d, err := draw.Init("/dev")
+	if err != nil {
+		return err
+	}
+	defer d.Close()
+	scr := d.Screen
+	r := scr.Rect()
+
+	f, err := d.OpenFont(fontpath)
+	if err != nil {
+		return err
+	}
+	fmt.Fprintf(os.Stderr, "text: font h=%d ascent=%d\n", f.Height, f.Ascent)
+
+	// acme's palette: a 25% mix over white, per allocimagemix.
+	bg, err := d.Color(0xFFFFEAFF)
+	if err != nil {
+		return err
+	}
+	ink, err := d.Color(0x000000FF)
+	if err != nil {
+		return err
+	}
+	rule, err := d.Color(0x99994CFF)
+	if err != nil {
+		return err
+	}
+
+	draw.Draw(scr, r, bg, nil, draw.ZP)
+	y := r.Min.Y + 20
+	for _, s := range []string{
+		"Go on Plan 9: glyphs from /lib/font/bit, no libdraw.",
+		"ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz",
+		"0123456789  !@#$%^&*()-=[]{};'\\:\"|,./<>?",
+		"width(\"hello\") = " + fmt.Sprint(f.Width("hello")) + " px",
+		time.Now().Format("Mon 2 Jan 2006 15:04:05"),
+	} {
+		f.String(scr, draw.Point{X: r.Min.X + 20, Y: y}, ink, s)
+		y += int32(f.Height) + 6
+	}
+	draw.Draw(scr, draw.Rect(r.Min.X+20, y+8, r.Min.X+520, y+9), rule, nil, draw.ZP)
+	d.Flush()
+	time.Sleep(90 * time.Second)
+	return nil
+}