/
main.go
158 lines (138 loc) · 3.28 KB
/
main.go
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package main
import (
"bytes"
_ "embed"
"fmt"
"image"
"image/color"
"image/draw"
"image/png"
"io"
"net/http"
"time"
"github.com/NathanBaulch/gifx"
)
var (
//go:embed 7segment.png
ssBytes []byte
ssImage *image.Paletted
ssTransIndex uint8
)
const (
ssDigitWidth = 75
ssColonWidth = 28
)
func main() {
if im, err := png.Decode(bytes.NewReader(ssBytes)); err != nil {
panic(err)
} else {
ssImage = im.(*image.Paletted)
}
found := false
for i, c := range ssImage.Palette {
if _, _, _, a := c.RGBA(); a == 0 {
found = true
ssTransIndex = uint8(i)
}
}
if !found {
if len(ssImage.Palette) == 0xff {
panic("no space for transparent entry in image palette")
}
ssTransIndex = uint8(len(ssImage.Palette))
ssImage.Palette = append(ssImage.Palette, color.Transparent)
}
http.HandleFunc("/time", handleTime)
http.HandleFunc("/stopwatch", handleStopwatch)
http.HandleFunc("/timer", handleTimer)
if err := http.ListenAndServe(":8090", nil); err != nil {
panic(err)
}
}
func handleTime(w http.ResponseWriter, req *http.Request) {
handle(w, req, func() time.Time { return time.Now() })
}
func handleStopwatch(w http.ResponseWriter, req *http.Request) {
start := time.Now()
zero := time.Time{}
handle(w, req, func() time.Time { return zero.Add(time.Now().Sub(start)) })
}
func handleTimer(w http.ResponseWriter, req *http.Request) {
d, err := time.ParseDuration(req.FormValue("d"))
if err != nil {
w.WriteHeader(http.StatusBadRequest)
_, _ = fmt.Fprintln(w, err.Error())
return
}
rem := time.Time{}.Add(d)
handle(w, req, func() time.Time {
t := rem
rem = rem.Add(-time.Second)
return t
})
}
func handle(w http.ResponseWriter, req *http.Request, fn func() time.Time) {
w.Header().Set("content-type", "image/gif")
w.Header().Set("cache-control", "no-store")
rect := image.Rect(0, 0, 6*ssDigitWidth+2*ssColonWidth, ssImage.Rect.Max.Y)
enc := gif.NewEncoder(&flushWriter{w})
if err := enc.WriteHeader(image.Config{Width: rect.Max.X, Height: rect.Max.Y, ColorModel: ssImage.Palette}, 0); err != nil {
panic(err)
}
pm := image.NewPaletted(rect, ssImage.Palette)
ticker := time.NewTicker(time.Second)
var prev []byte
opt := gif.NewOptimizer(ssTransIndex)
loop:
for {
t := fn()
if t.Before(time.Time{}) {
break
}
this := []byte(t.Format("15:04:05"))
x := 0
var crop image.Rectangle
for i, s := range this {
width := ssDigitWidth
if s == ':' {
width = ssColonWidth
}
if len(prev) <= i || prev[i] != s {
r := image.Rect(x, 0, x+width, ssImage.Rect.Max.Y)
draw.Draw(pm, r, ssImage, image.Pt((int(s)-48)*ssDigitWidth, 0), draw.Over)
crop = crop.Union(r)
}
x += width
}
pm, _ := opt.Optimize(pm.SubImage(crop).(*image.Paletted))
if err := enc.WriteFrame(&gif.Frame{Image: pm, DelayTime: time.Second}); err != nil {
panic(err)
}
if err := enc.Flush(); err != nil {
panic(err)
}
select {
case <-req.Context().Done():
break loop
case <-ticker.C:
prev = this
}
}
if err := enc.WriteTrailer(); err != nil {
panic(err)
}
if err := enc.Flush(); err != nil {
panic(err)
}
}
type flushWriter struct {
io.Writer
}
func (w *flushWriter) WriteByte(c byte) error {
_, err := w.Write([]byte{c})
return err
}
func (w *flushWriter) Flush() error {
w.Writer.(http.Flusher).Flush()
return nil
}