fb

util/fb/fb.go

@@ -0,0 +1,61 @@
+package fb
+
+import (
+	"bufio"
+	"fmt"
+	"image"
+	"image/color"
+	"os"
+)
+
+func Resolution() (w int, h int) {
+	resFile, err := os.Open("/sys/class/graphics/fb0/virtual_size")
+	if err != nil {
+		panic(err)
+	}
+
+	r := bufio.NewReader(resFile)
+	s, err := r.ReadString('\n')
+	if err != nil {
+		panic(err)
+	}
+	fmt.Sscanf(s, "%d,%d", &w, &h)
+	return
+}
+
+var devfb *os.File
+var width, height = Resolution()
+
+func init() {
+	var err error
+	devfb, err = os.OpenFile("/dev/fb0", os.O_WRONLY, os.ModePerm)
+	if err != nil {
+		panic(err)
+	}
+}
+
+func Bytes(c color.Color) []byte {
+	r, g, b, a := c.RGBA()
+	return []byte{byte(b), byte(g), byte(r), byte(a)}
+}
+
+func Draw(img image.Image) error {
+	buf := bufio.NewWriterSize(devfb, 1<<16)
+	for h := 0; h < height; h++ {
+		for w := 0; w < width; w++ {
+			_, err := buf.Write(Bytes(img.At(w, h)))
+			if err != nil {
+				return err
+			}
+		}
+	}
+	err := buf.Flush()
+	if err != nil {
+		return err
+	}
+	_, err := devfb.Seek(0,0)
+	if err != nil {
+		return err
+	}
+	return nil
+}