1 files changed, 249 insertions, 0 deletions
diff --git a/mpdDisplay.go b/mpdDisplay.go
new file mode 100644
index 0000000..93fb552
--- /dev/null
+++ b/mpdDisplay.go
@@ -0,0 +1,249 @@
+// 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 (
+	"math"
+	"time"
+
+	"golang.org/x/text/transform"
+
+	"benjamin.barenblat.name/audiotrond/cfa635"
+)
+
+var (
+	encoder = cfa635.NewEncoder()
+)
+
+func encode(s string) []byte {
+	r, _, err := transform.String(encoder, s)
+	if err != nil {
+		panic(err)
+	}
+	return []byte(r)
+}
+
+func setPlaybackIcon(model *model, lcdState *cfa635.LCDState) {
+	switch model.State {
+	case stopped:
+		lcdState[0][19] = 0xd0
+	case playing:
+		lcdState[0][19] = 0x10
+	case paused:
+		lcdState[0][19] = pauseIconSprite
+	}
+}
+
+func rotate(s []byte, width int, start, now time.Time) []byte {
+	const delay int = 10
+	const rotationRate float64 = 1 / float64(333*time.Millisecond)
+
+	if len(s) <= width {
+		return s
+	}
+
+	ticks := int(float64(now.Sub(start).Nanoseconds()) * rotationRate)
+
+	if len(s) < 2*width {
+		// Just scroll back and forth.
+		period := len(s) - width + delay
+		ticks %= 2 * period
+
+		i := 0
+		if ticks <= delay {
+		} else if ticks <= period {
+			i = ticks - delay
+		} else if ticks <= period+delay {
+			i = len(s) - width
+		} else {
+			i = 2*period - ticks
+		}
+		return s[i : i+width]
+	}
+
+	// Actually rotate.
+	for i := 0; i < 7; i++ {
+		s = append(s, byte(' '))
+	}
+
+	period := len(s) + delay
+	ticks %= period
+
+	i := 0
+	if ticks > delay {
+		i = ticks - delay
+	}
+	return append(s[i:], s[:i]...)[:width]
+}
+
+func setTrackInfo(model *model, now time.Time, lcdState *cfa635.LCDState) {
+	// Cut off the track one character short so we don't overwrite the
+	// playback icon.
+	copy(lcdState[0][:], rotate(encode(model.Track), 19, model.LastTrackInfoUpdate, now))
+	copy(lcdState[1][:], rotate(encode(model.Artist), 20, model.LastTrackInfoUpdate, now))
+	copy(lcdState[2][:], rotate(encode(model.Album), 20, model.LastTrackInfoUpdate, now))
+}
+
+func setTimeElapsed(model *model, lcdState *cfa635.LCDState) int {
+	elapsed := fmtTime(model.Elapsed, model.Duration)
+	copy(lcdState[3][:], elapsed)
+	return len(elapsed)
+}
+
+func setTimeRemaining(model *model, lcdState *cfa635.LCDState) int {
+	remaining := fmtTime(model.Elapsed-model.Duration, model.Duration)
+	copy(lcdState[3][20-len(remaining):], remaining)
+	return len(remaining)
+}
+
+func setProgressBar(model *model, barStart, barEnd int, lcdState *cfa635.LCDState) {
+	fraction := float64(model.Elapsed) / float64(model.Duration)
+
+	// Convert the fraction played to the number of columns that should be
+	// colored in the bar. Each cell has 6 columns; leave one extra column
+	// free at the left of the bar so it doesn't crash into the time
+	// elapsed.
+	c := int(math.Round(fraction * (6*float64(barEnd-barStart) - 1)))
+	if c == 0 {
+		return
+	}
+
+	// There are precomposed block glyphs of widths 1-5 that leave a blank
+	// column at the beginning. Use one of those in the first cell.
+	w := c
+	if w > 5 {
+		w = 5
+	}
+	lcdState[3][barStart] = byte(0xdb - w)
+	c -= w
+	if c == 0 {
+		return
+	}
+
+	// Fill in the full cells in the bar.
+	x := barStart + 1
+	for ; c >= 6; x, c = x+1, c-6 {
+		lcdState[3][x] = progressBarSpriteFull
+	}
+	if c == 0 {
+		return
+	}
+
+	// Fill in the last, partial bar.
+	lcdState[3][x] = byte(progressBarSprite1 - 1 + c)
+}
+
+const (
+	ellipsisSprite = iota
+	pauseIconSprite
+	progressBarSprite1
+	progressBarSprite2
+	progressBarSprite3
+	progressBarSprite4
+	progressBarSprite5
+	progressBarSpriteFull
+)
+
+func initializeMPDDisplay(lcd *cfa635.Module) error {
+	// Load sprites.
+
+	if err := lcd.SetCharacter(ellipsisSprite, &[...]byte{
+		0b00_000000,
+		0b00_000000,
+		0b00_000000,
+		0b00_000000,
+		0b00_000000,
+		0b00_000000,
+		0b00_010101,
+		0b00_000000,
+	}); err != nil {
+		return err
+	}
+
+	if err := lcd.SetCharacter(pauseIconSprite, &[...]byte{
+		0b00_000000,
+		0b00_011011,
+		0b00_011011,
+		0b00_011011,
+		0b00_011011,
+		0b00_011011,
+		0b00_000000,
+		0b00_000000,
+	}); err != nil {
+		return err
+	}
+
+	for w := 1; w <= 6; w++ {
+		r := byte((1<<w - 1) << (6 - w))
+		if err := lcd.SetCharacter(progressBarSprite1-1+w, &[...]byte{
+			r,
+			r,
+			r,
+			r,
+			r,
+			r,
+			r,
+			0b00_000000,
+		}); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func brightnessStep(pm float64, then, now time.Time, old float64) float64 {
+	const brightnessRampRate float64 = 20.0 / float64(500*time.Millisecond)
+
+	dt := float64(now.Sub(then).Nanoseconds())
+	return old + pm*dt*brightnessRampRate
+}
+
+func setBrightness(model *model, now time.Time, old *view) float64 {
+	var z time.Time
+	if old.Mtime == z {
+		return old.DisplayBrightness
+	}
+
+	if model.State == playing || now.Sub(model.LastStateChange).Seconds() < 15 {
+		if old.DisplayBrightness >= 20 {
+			return 20
+		}
+		return brightnessStep(+1, old.Mtime, now, old.DisplayBrightness)
+	} else {
+		if old.DisplayBrightness == 0 {
+			return 0
+		}
+		return math.Max(0, brightnessStep(-1, old.Mtime, now, old.DisplayBrightness))
+	}
+}
+
+func mpdView(model *model, now time.Time, old *view) *view {
+	var new view
+	new.LCD = cfa635.ClearedLCDState()
+	setPlaybackIcon(model, new.LCD)
+	setTrackInfo(model, now, new.LCD)
+	if model.Duration > 0 {
+		barStart := setTimeElapsed(model, new.LCD)
+		barEnd := 20 - setTimeRemaining(model, new.LCD)
+		setProgressBar(model, barStart, barEnd, new.LCD)
+	}
+
+	new.DisplayBrightness = setBrightness(model, now, old)
+
+	new.Mtime = now
+
+	return &new
+}