Commit initial version

src/image.go

@@ -0,0 +1,93 @@
+package main
+
+import (
+	"image"
+	"image/color"
+	"io"
+	"io/ioutil"
+	"log"
+	"net"
+	"time"
+)
+
+const (
+	LedpanelWidth  = 120
+	LedpanelHeight = 48
+)
+
+func Listen() (chan image.Image, chan error) {
+	errs := make(chan error, 1)
+	out := make(chan image.Image, 1)
+	out <- bitvisImage{}
+	go func() {
+		defer close(errs)
+		defer close(out)
+		service, err := net.Listen("tcp", ":1338")
+		if err != nil {
+			errs <- err
+			return
+		}
+		for {
+			conn, err := service.Accept()
+			if err != nil {
+				errs <- err
+				return
+			}
+			go func() {
+				if err := handleConnection(conn, out); err != nil {
+					log.Printf("Error handling connection: %v", err)
+				}
+			}()
+		}
+	}()
+	return out, errs
+}
+
+func handleConnection(conn net.Conn, out chan<- image.Image) error {
+	for {
+		if err := conn.SetReadDeadline(time.Now().Add(time.Second * 4)); err != nil {
+			return err
+		}
+
+		var boundary [1]byte
+		if _, err := io.ReadFull(conn, boundary[:]); err != nil {
+			return err
+		}
+		if boundary[0] != ':' {
+			continue
+		}
+		io.CopyN(ioutil.Discard, conn, 2)
+
+		var img bitvisImage
+		if _, err := io.ReadFull(conn, img[:]); err != nil {
+			return err
+		}
+		select {
+		case out <- img:
+		default:
+		}
+	}
+}
+
+type bitvisImage [LedpanelWidth * LedpanelHeight / 4]uint8
+
+func (img bitvisImage) ColorModel() color.Model {
+	return color.RGBAModel
+}
+
+func (img bitvisImage) Bounds() image.Rectangle {
+	return image.Rectangle{
+		Min: image.Point{X: 0, Y: 0},
+		Max: image.Point{X: LedpanelWidth, Y: LedpanelHeight},
+	}
+}
+
+func (img bitvisImage) At(x, y int) color.Color {
+	return bitvisColor(img[y*LedpanelWidth/4+x/4] >> ((3 - uint(x)%4) * 2))
+}
+
+type bitvisColor uint8
+
+func (c bitvisColor) RGBA() (r, g, b, a uint32) {
+	return uint32(c&2>>1) * 0xffff, uint32(c&1) * 0xffff, 0, 0xffff
+}