A grid-based visualization of musical notes over time, as seen in digital audio workstations (DAWs). Each note is represented as a horizontal rectangle positioned by pitch (y-axis) and time (x-axis), with bar length indicating note duration and color indicating velocity (dynamics). The background alternates between white and dark rows to mirror piano keyboard layout, with vertical grid lines marking beats and measures.
# anyplot.ai
# piano-roll-midi: MIDI Piano Roll Visualization
# Library: makie 0.22.10 | Julia 1.11.9
# Quality: 89/100 | Created: 2026-06-03
using CairoMakie
using Colors
using Random
Random.seed!(42)
# Theme tokens
const THEME = get(ENV, "ANYPLOT_THEME", "light")
const PAGE_BG = THEME == "light" ? colorant"#FAF8F1" : colorant"#1A1A17"
const ELEVATED_BG = THEME == "light" ? colorant"#FFFDF6" : colorant"#242420"
const INK = THEME == "light" ? colorant"#1A1A17" : colorant"#F0EFE8"
const INK_SOFT = THEME == "light" ? colorant"#4A4A44" : colorant"#B8B7B0"
# Imprint sequential colormap: green (#009E73) → blue (#4467A3), lookup inverted so blue=soft
const VEL_CMAP = cgrad([colorant"#009E73", colorant"#4467A3"])
const NOTE_NAMES = ["C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B"]
# Piano keyboard row backgrounds
const WHITE_KEY_BG = THEME == "light" ? RGBAf(0.980, 0.973, 0.945, 1.0) : RGBAf(0.130, 0.130, 0.112, 1.0)
const BLACK_KEY_BG = THEME == "light" ? RGBAf(0.900, 0.891, 0.858, 1.0) : RGBAf(0.082, 0.082, 0.070, 1.0)
# Data: C major generative phrase over 4 measures (4/4, 16 beats total)
# Each tuple: (pitch, start, duration, velocity)
notes_raw = [
# Measure 1 — ascending melody
(60, 0.0, 0.5, 68), # C4
(62, 0.5, 0.5, 74), # D4
(64, 1.0, 0.5, 80), # E4
(67, 1.5, 0.5, 86), # G4
(69, 2.0, 1.0, 92), # A4
(67, 3.0, 0.5, 80), # G4
(65, 3.5, 0.5, 74), # F4
# Measure 1 — chord accompaniment
(48, 0.0, 2.0, 52), # C3
(52, 0.0, 2.0, 48), # E3
(55, 0.0, 2.0, 48), # G3
(53, 2.0, 2.0, 52), # F3
(57, 2.0, 2.0, 48), # A3
(60, 2.0, 2.0, 48), # C4 chord
# Measure 2 — rising to climax
(64, 4.0, 0.5, 84), # E4
(65, 4.5, 0.5, 80), # F4
(67, 5.0, 1.0, 96), # G4
(69, 6.0, 0.5, 88), # A4
(71, 6.5, 0.5, 92), # B4
(72, 7.0, 1.0, 102), # C5 peak
# Measure 2 — chord accompaniment
(55, 4.0, 2.0, 54), # G3
(59, 4.0, 2.0, 48), # B3
(62, 4.0, 2.0, 48), # D4
(50, 6.0, 2.0, 54), # D3
(53, 6.0, 2.0, 48), # F3
(57, 6.0, 2.0, 48), # A3
# Measure 3 — descending return
(71, 8.0, 0.5, 90), # B4
(69, 8.5, 0.5, 84), # A4
(67, 9.0, 0.5, 78), # G4
(65, 9.5, 0.5, 74), # F4
(64, 10.0, 1.0, 82), # E4
(62, 11.0, 0.5, 72), # D4
(60, 11.5, 0.5, 68), # C4
# Measure 3 — chord accompaniment
(48, 8.0, 2.0, 52), # C3
(52, 8.0, 2.0, 48), # E3
(55, 8.0, 2.0, 48), # G3
(50, 10.0, 2.0, 52), # D3
(53, 10.0, 2.0, 48), # F3
(57, 10.0, 2.0, 48), # A3
# Measure 4 — resolution
(67, 12.0, 0.5, 78), # G4
(65, 12.5, 0.5, 74), # F4
(64, 13.0, 1.0, 84), # E4
(62, 14.0, 0.5, 70), # D4
(60, 14.5, 1.5, 92), # C4 final
# Measure 4 — final tonic chord
(48, 12.0, 4.0, 58), # C3
(52, 12.0, 4.0, 54), # E3
(55, 12.0, 4.0, 54), # G3
(60, 12.0, 4.0, 50), # C4
]
pitches = [n[1] for n in notes_raw]
starts = Float32[n[2] for n in notes_raw]
durations = Float32[n[3] for n in notes_raw]
velocities = [n[4] for n in notes_raw]
pitch_min = minimum(pitches) - 1 # 47
pitch_max = maximum(pitches) + 1 # 73
total_beats = 16.0f0
# Plot
fig = Figure(
size = (1600, 900),
fontsize = 13,
backgroundcolor = PAGE_BG,
)
ax = Axis(
fig[1, 1];
title = "piano-roll-midi · julia · makie · anyplot.ai",
titlesize = 20,
titlecolor = INK,
xlabel = "Time (beats)",
ylabel = "Pitch",
xlabelsize = 14,
ylabelsize = 14,
xlabelcolor = INK,
ylabelcolor = INK,
xticklabelsize = 12,
yticklabelsize = 11,
xticklabelcolor = INK_SOFT,
yticklabelcolor = INK_SOFT,
xtickcolor = INK_SOFT,
ytickcolor = INK_SOFT,
backgroundcolor = PAGE_BG,
topspinevisible = false,
rightspinevisible = false,
leftspinecolor = INK_SOFT,
bottomspinecolor = INK_SOFT,
xgridvisible = false,
ygridvisible = false,
)
# Background rows: alternate white/black key shading
for pitch in pitch_min:pitch_max
bg = mod(pitch, 12) in (1, 3, 6, 8, 10) ? BLACK_KEY_BG : WHITE_KEY_BG
poly!(ax, Rect2f(0.0f0, pitch - 0.5f0, total_beats, 1.0f0); color = bg)
end
# Vertical beat grid lines
for beat in 0:Int(total_beats)
is_measure = mod(beat, 4) == 0
lw = is_measure ? 1.8f0 : 0.7f0
alpha = is_measure ? 0.40f0 : 0.18f0
vlines!(ax, Float32(beat);
color = RGBAf(INK.r, INK.g, INK.b, alpha),
linewidth = lw,
)
end
# Note rectangles, colored by velocity
note_rects = [Rect2f(starts[i], pitches[i] - 0.42f0, durations[i] - 0.04f0, 0.84f0)
for i in eachindex(notes_raw)]
note_colors = [get(VEL_CMAP, 1.0 - velocities[i] / 127.0) for i in eachindex(notes_raw)]
poly!(ax, note_rects;
color = note_colors,
strokecolor = RGBAf(INK.r, INK.g, INK.b, 0.55f0),
strokewidth = 0.7f0,
)
# Y-axis ticks: show names for white-key pitches only (avoid crowding)
white_pitches = [p for p in pitch_min:pitch_max if !(mod(p, 12) in (1, 3, 6, 8, 10))]
ax.yticks = (white_pitches, [string(NOTE_NAMES[mod(p, 12) + 1], div(p, 12) - 1) for p in white_pitches])
# X-axis ticks: beats 0, 4, 8, 12, 16
ax.xticks = (0:4:16, string.(0:4:16))
# Measure number labels at the top of each measure
for m in 1:4
x_pos = (m - 1) * 4.0f0 + 0.12f0
text!(ax, x_pos, Float32(pitch_max) + 0.3f0;
text = "Meas. $m",
fontsize = 11,
color = INK_SOFT,
align = (:left, :center),
)
end
xlims!(ax, -0.3f0, total_beats + 0.3f0)
ylims!(ax, pitch_min - 0.5f0, pitch_max + 0.8f0)
# Velocity colorbar
Colorbar(fig[1, 2];
colormap = reverse(VEL_CMAP),
limits = (0.0, 127.0),
label = "Velocity",
labelsize = 13,
labelcolor = INK,
ticksize = 5,
tickcolor = INK_SOFT,
ticklabelsize = 11,
ticklabelcolor = INK_SOFT,
ticks = [0, 32, 64, 96, 127],
width = 18,
topspinecolor = INK_SOFT,
bottomspinecolor = INK_SOFT,
leftspinecolor = INK_SOFT,
rightspinecolor = INK_SOFT,
)
colsize!(fig.layout, 1, Relative(0.93))
save(joinpath(@__DIR__, "plot-$(THEME).png"), fig; px_per_unit = 2)
Runnable source as JSON, for any HTTP client: https://api.anyplot.ai/specs/piano-roll-midi/makie/code. Any spec id and library id listed in llms-full.txt fit the same URL shape; every URL below is complete and callable.
{
"spec_id": "piano-roll-midi",
"language": "julia",
"library": "makie",
"page": "https://anyplot.ai/piano-roll-midi/julia/makie",
"hub": "https://anyplot.ai/piano-roll-midi",
"code_json": "https://api.anyplot.ai/specs/piano-roll-midi/makie/code",
"spec_json": "https://api.anyplot.ai/specs/piano-roll-midi",
"render_light_png": "https://storage.googleapis.com/anyplot-images/plots/piano-roll-midi/julia/makie/plot-light.png",
"render_dark_png": "https://storage.googleapis.com/anyplot-images/plots/piano-roll-midi/julia/makie/plot-dark.png",
"quality_score": 89.0,
"license": "MIT",
"guide": "https://anyplot.ai/llms.txt"
}Part of MIDI Piano Roll Visualization on anyplot.ai.