feat(sointu): add functions to figure out the stack use and need of a unit

sointu.go

@@ -452,6 +452,34 @@ func (s *Song) ParamHintString(instrIndex, unitIndex int, param string) string {
 	return ""
 }
 
+func (u *Unit) StackChange() int {
+	switch u.Type {
+	case "addp", "mulp", "pop", "out", "outaux", "aux":
+		return -1 - u.Parameters["stereo"]
+	case "envelope", "oscillator", "push", "noise", "receive", "loadnote", "loadval", "in", "compressor":
+		return 1 + u.Parameters["stereo"]
+	case "pan":
+		return 1 - u.Parameters["stereo"]
+	case "speed":
+		return -1
+	case "send":
+		return (-1 - u.Parameters["stereo"]) * u.Parameters["sendpop"]
+	}
+	return 0
+}
+
+func (u *Unit) StackNeed() int {
+	switch u.Type {
+	case "envelope", "oscillator", "noise", "receive", "loadnote", "loadval", "in":
+		return 0
+	case "mulp", "mul", "add", "addp", "xch":
+		return 2 * (1 + u.Parameters["stereo"])
+	case "speed":
+		return 1
+	}
+	return 1 + u.Parameters["stereo"]
+}
+
 func Play(synth Synth, song Song) ([]float32, error) {
 	err := song.Validate()
 	if err != nil {

tracker/instruments.go

@@ -2,6 +2,7 @@ package tracker
 
 import (
 	"image"
+	"strconv"
 
 	"gioui.org/io/pointer"
 	"gioui.org/layout"
@@ -154,15 +155,41 @@ func (t *Tracker) layoutInstrumentEditor(gtx C) D {
 	addUnitBtnStyle.Inset = layout.UniformInset(unit.Dp(4))
 	margin := layout.UniformInset(unit.Dp(2))
 
+	for len(t.StackUse) < len(t.song.Patch.Instruments[t.CurrentInstrument].Units) {
+		t.StackUse = append(t.StackUse, 0)
+	}
+
+	stackHeight := 0
+	for i, u := range t.song.Patch.Instruments[t.CurrentInstrument].Units {
+		stackHeight += u.StackChange()
+		t.StackUse[i] = stackHeight
+	}
+
 	element := func(gtx C, i int) D {
 		gtx.Constraints = layout.Exact(image.Pt(gtx.Px(unit.Dp(120)), gtx.Px(unit.Dp(20))))
 		u := t.song.Patch.Instruments[t.CurrentInstrument].Units[i]
-		labelStyle := LabelStyle{Text: u.Type, ShadeColor: black, Color: white, Font: labelDefaultFont, FontSize: unit.Sp(12)}
-		if labelStyle.Text == "" {
-			labelStyle.Text = "---"
-			labelStyle.Alignment = layout.Center
+		unitNameLabel := LabelStyle{Text: u.Type, ShadeColor: black, Color: white, Font: labelDefaultFont, FontSize: unit.Sp(12)}
+		if unitNameLabel.Text == "" {
+			unitNameLabel.Text = "---"
+			unitNameLabel.Alignment = layout.Center
 		}
-		return labelStyle.Layout(gtx)
+		var stackText string
+		if i < len(t.StackUse) {
+			stackText = strconv.FormatInt(int64(t.StackUse[i]), 10)
+			var prevStackUse int
+			if i > 0 {
+				prevStackUse = t.StackUse[i-1]
+			}
+			if u.StackNeed() > prevStackUse || (i == len(t.StackUse)-1 && t.StackUse[i] > 0) {
+				unitNameLabel.Color = errorColor
+			}
+		}
+		stackLabel := LabelStyle{Text: stackText, ShadeColor: black, Color: mediumEmphasisTextColor, Font: labelDefaultFont, FontSize: unit.Sp(12)}
+
+		return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
+			layout.Flexed(1, unitNameLabel.Layout),
+			layout.Rigid(stackLabel.Layout),
+		)
 	}
 
 	unitList := FilledDragList(t.Theme, t.UnitDragList, len(t.song.Patch.Instruments[t.CurrentInstrument].Units), element, t.SwapUnits)

tracker/theme.go

@@ -109,3 +109,5 @@ var activeLightSurfaceColor = color.NRGBA{R: 45, G: 45, B: 45, A: 255}
 var cursorColor = color.NRGBA{R: 100, G: 140, B: 255, A: 48}
 var selectionColor = color.NRGBA{R: 100, G: 140, B: 255, A: 8}
 var inactiveSelectionColor = color.NRGBA{R: 140, G: 140, B: 140, A: 16}
+
+var errorColor = color.NRGBA{R: 207, G: 102, B: 121, A: 255}

tracker/tracker.go

@@ -76,6 +76,7 @@ type Tracker struct {
 	TopHorizontalSplit    *Split
 	BottomHorizontalSplit *Split
 	VerticalSplit         *Split
+	StackUse              []int
 
 	sequencer    *Sequencer
 	ticked       chan struct{}