Basic, read-only audiotrondHEADmain

Audiotrond exists and properly displays music being played through MPD.
The display includes title, artist, album, and progress bar, and text
scrolls if too long to fit on the screen. Backlight support exists; the
display backlight fades smoothly on and off when the music starts and
stops. After being stopped for a little while, audiotrond switches to a
clock. Currently, audiotrond lacks user interaction support, so it keeps
the keypad backlight off.

1 files changed, 270 insertions, 0 deletions

diff --git a/audiotrond.go b/audiotrond.go
new file mode 100644
index 0000000..f59a4db
--- /dev/null
+++ b/audiotrond.go
@@ -0,0 +1,270 @@
+// Copyright 2022 Benjamin Barenblat
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not
+// use this file except in compliance with the License. You may obtain a copy of
+// the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations under
+// the License.
+
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"os/signal"
+	"time"
+
+	"benjamin.barenblat.name/audiotrond/cfa635"
+	"github.com/fhs/gompd/v2/mpd"
+	"github.com/tarm/serial"
+)
+
+func putWrapped(lcd *cfa635.Module, col, row int, data []byte) error {
+	for row < 4 && len(data) > 0 {
+		if err := lcd.Put(col, row, data); err != nil {
+			return err
+		}
+		if len(data) <= 20-col {
+			data = nil
+		} else {
+			data = data[20-col:]
+		}
+		col = 0
+		row++
+	}
+	return nil
+}
+
+func update[T comparable](dst *T, src T, mtime *time.Time, now time.Time) {
+	if *dst == src {
+		return
+	}
+	*dst = src
+	*mtime = now
+}
+
+type playbackState byte
+
+const (
+	_ playbackState = 1 + iota
+	stopped
+	playing
+	paused
+)
+
+type foreground byte
+
+const (
+	_ foreground = iota
+	mpdForeground
+	clockForeground
+)
+
+type model struct {
+	State           playbackState
+	LastStateChange time.Time
+
+	Duration time.Duration
+	Elapsed  time.Duration
+
+	Track               string
+	Artist              string
+	Album               string
+	LastTrackInfoUpdate time.Time
+
+	Foreground foreground
+}
+
+func connectToCFA635() *cfa635.Module {
+	s, err := serial.OpenPort(&serial.Config{Name: "/dev/lcd", Baud: 115200})
+	if err != nil {
+		panic(err)
+	}
+	m := cfa635.Connect(s)
+
+	go func() {
+		for r := m.ReadReport(); r != nil; r = m.ReadReport() {
+			log.Println("report:", r)
+		}
+	}()
+
+	return m
+}
+
+func reportPanicOrClear(lcd *cfa635.Module) {
+	if v := recover(); v != nil {
+		putWrapped(lcd, 0, 0, encode(fmt.Sprint("panic: ", v)))
+		panic(v)
+	}
+	lcd.Clear()
+}
+
+func poll(mpd *mpd.Client, now time.Time, model *model) error {
+	cmds := mpd.BeginCommandList()
+	statusP := cmds.Status()
+	currentP := cmds.CurrentSong()
+	if err := cmds.End(); err != nil {
+		return err
+	}
+
+	status, err := statusP.Value()
+	if err != nil {
+		return err
+	}
+
+	switch status["state"] {
+	case "stop":
+		update(&model.State, stopped, &model.LastStateChange, now)
+	case "play":
+		update(&model.State, playing, &model.LastStateChange, now)
+	case "pause":
+		update(&model.State, paused, &model.LastStateChange, now)
+	}
+
+	if status["duration"] == "" {
+		model.Duration = 0
+		model.Elapsed = 0
+	} else {
+		if model.Duration, err = time.ParseDuration(status["duration"] + "s"); err != nil {
+			panic(err)
+		}
+		if model.Elapsed, err = time.ParseDuration(status["elapsed"] + "s"); err != nil {
+			panic(err)
+		}
+	}
+
+	current, err := currentP.Value()
+	if err != nil {
+		return err
+	}
+
+	update(&model.Track, current["Title"], &model.LastTrackInfoUpdate, now)
+	update(&model.Artist, current["Artist"], &model.LastTrackInfoUpdate, now)
+	update(&model.Album, current["Album"], &model.LastTrackInfoUpdate, now)
+	return nil
+}
+
+func ellipsize(src []byte, ellipsis byte, dst []byte) {
+	if len(src) <= len(dst) {
+		copy(dst, src)
+	} else {
+		dots := len(dst) - 1
+		copy(dst, src[:dots])
+		dst[dots] = ellipsis
+	}
+}
+
+func fmtTime(t, max time.Duration) string {
+	f := func(neg string, h, m, s int) string {
+		_ = h
+		return fmt.Sprintf("%s%d:%02d", neg, m, s)
+	}
+	if max/time.Hour > 0 {
+		f = func(neg string, h, m, s int) string {
+			return fmt.Sprintf("%s%d:%02d:%02d", neg, h, m, s)
+		}
+	} else if int(max/time.Minute)%60 >= 10 {
+		f = func(neg string, h, m, s int) string {
+			_ = h
+			return fmt.Sprintf("%s%02d:%02d", neg, m, s)
+		}
+	}
+
+	var neg string
+	if t < 0 {
+		t *= -1
+		neg = "-"
+	}
+	return f(neg, int(t/time.Hour), int(t/time.Minute)%60, int(t/time.Second)%60)
+}
+
+func main() {
+	lcd := connectToCFA635()
+	defer reportPanicOrClear(lcd)
+	defer lcd.SetBacklight(0, 0)
+	if err := lcd.SetLED(0, false, 0); err != nil {
+		panic(err)
+	}
+	if err := lcd.SetLED(0, true, 0); err != nil {
+		panic(err)
+	}
+
+	if err := lcd.Clear(); err != nil {
+		panic(err)
+	}
+
+	mpd, err := mpd.Dial("unix", "/run/mpd/socket")
+	if err != nil {
+		panic(err)
+	}
+
+	var model model
+
+	view1 := new(view)
+	view1.LCD = cfa635.ClearedLCDState()
+	view1.Mtime = time.Now()
+
+	// Create an idle timer and put it in a drained state so the event loop
+	// can set it.
+	idle := time.NewTimer(0)
+	<-idle.C
+
+	sigterm := make(chan os.Signal, 1)
+	signal.Notify(sigterm, os.Interrupt)
+
+EventLoop:
+	for {
+		now := time.Now()
+
+		if err := poll(mpd, now, &model); err != nil {
+			panic(err)
+		}
+
+		var foreground2 foreground
+		if model.State == playing || now.Sub(model.LastStateChange).Seconds() < 17 {
+			foreground2 = mpdForeground
+		} else {
+			foreground2 = clockForeground
+		}
+
+		if foreground2 != model.Foreground {
+			switch foreground2 {
+			case mpdForeground:
+				if err := initializeMPDDisplay(lcd); err != nil {
+					panic(err)
+				}
+			case clockForeground:
+				if err := initializeClockDisplay(lcd); err != nil {
+					panic(err)
+				}
+			}
+		}
+		model.Foreground = foreground2
+
+		var view2 *view
+		switch model.Foreground {
+		case mpdForeground:
+			view2 = mpdView(&model, now, view1)
+		case clockForeground:
+			view2 = clockView(now)
+		}
+		if err := updateView(lcd, view1, view2); err != nil {
+			panic(err)
+		}
+		view1 = view2
+
+		idle.Reset(10 * time.Millisecond)
+		select {
+		case <-sigterm:
+			break EventLoop
+		case <-idle.C:
+		}
+	}
+}