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Merged
riknoll merged 2 commits into from
Apr 7, 2026
Merged

port over melody parsing from pxt-microbit #11252

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9dbfbc3
port over melody parsing from pxt-microbit
riknoll Apr 6, 2026
7458d08
Merge branch 'master' into dev/riknoll/microbit-improve-melody-parsing
riknoll Apr 7, 2026
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169 changes: 146 additions & 23 deletions pxtblocks/fields/field_melodySandbox.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -297,14 +297,35 @@ export class FieldCustomMelody<U extends FieldCustomOptions> extends FieldMatrix
let oldValue: string = value;
try {
value = value.slice(1, -1); // remove the boundary quotes
value = value.trim(); // remove boundary white space
this.createMelodyIfDoesntExist();
let notes: string[] = value.split(" ");
const reader = new MelodyStringReader(value, true);

const notes: string[] = [];
const validNotes = [48, 50, 52, 53, 55, 57, 59, 60];

while (reader.hasNextNote()) {
reader.readNote();
if (reader.currentDuration !== 4) throw new Error(lf("Only quarter notes are supported"));

if (reader.currentNote === REST) {
notes.push("-");
continue;
}

const absoluteNote = reader.currentOctave * 12 + reader.currentNote;

notes.forEach(n => {
if (!this.isValidNote(n)) throw new Error(lf("Invalid note '{0}'. Notes can be C D E F G A B C5", n));
});
if (!validNotes.includes(absoluteNote)) {
throw new Error(lf("Invalid note '{0}'. Notes can be C D E F G A B C5", absoluteNote));
}

const noteName = pxtmelody.rowToNote(7 - validNotes.indexOf(absoluteNote));
notes.push(noteName);
}

if (notes.length > this.numMatrixCols) {
throw new Error(lf("Too many notes. Maximum is {0}", this.numMatrixCols));
}

this.createMelodyIfDoesntExist();
this.melody.resetMelody();

for (let j = 0; j < notes.length; j++) {
Expand All @@ -314,27 +335,13 @@ export class FieldCustomMelody<U extends FieldCustomOptions> extends FieldMatrix
}
}
this.updateFieldLabel();
} catch (e) {
}
catch (e) {
pxt.log(e)
this.invalidString = oldValue;
}
}

private isValidNote(note: string): boolean {
switch (note) {
case "C":
case "D":
case "E":
case "F":
case "G":
case "A":
case "B":
case "C5":
case "-": return true;
}
return false;
}

// The width of the preview on the block itself
protected getPreviewWidth(): number {
this.updateSize_();
Expand Down Expand Up @@ -569,7 +576,7 @@ export class FieldCustomMelody<U extends FieldCustomOptions> extends FieldMatrix
if (pxt.BrowserUtils.isEdge()) FieldCustomMelody.VIEWBOX_WIDTH += 37;
FieldCustomMelody.VIEWBOX_HEIGHT = (FieldCustomMelody.CELL_WIDTH + FieldCustomMelody.CELL_VERTICAL_MARGIN) * this.numMatrixRows + FieldCustomMelody.CELL_VERTICAL_MARGIN;
this.matrixSvg = pxsim.svg.parseString(`<svg xmlns="http://www.w3.org/2000/svg" class="melody-grid-div blocklyMatrix" role="grid" viewBox="0 0 ${FieldCustomMelody.VIEWBOX_WIDTH} ${FieldCustomMelody.VIEWBOX_HEIGHT}" tabindex="0" />`);
this.matrixSvg.ariaLabel = lf("Melody grid");
this.matrixSvg.ariaLabel = lf("Melody grid");

this.createMatrixDisplay({
cellWidth: FieldCustomMelody.CELL_WIDTH,
Expand Down Expand Up @@ -944,3 +951,119 @@ function getPlaceholderColor(row: number): string {
}
return "#DCDCDC";
}

const offsetLookup = [0x09, 0x0b, 0x00, 0x02, 0x04, 0x05, 0x07];
const REST = -0xffff;

// copied from pxt-microbit/libs/core/music.ts
class MelodyStringReader {
currentOctave: number;
currentNote: number;
currentDuration: number;
melodyStringIndex: number;

constructor(public melody: string, public resetOctave: boolean) {
this.melodyStringIndex = 0;
this.currentOctave = 4;
this.currentDuration = 4;
this.currentNote = REST;
}

readNote() {
this.eatWhitespace();
if (this.resetOctave) {
this.currentOctave = 4;
}
let note: number = undefined;
let modifier = 0;

while (this.melodyStringIndex < this.melody.length) {
const c = this.melody.charCodeAt(this.melodyStringIndex++);
if (c == 32 /* space */) {
break;
}

else if (c === 35 /* # */) {
modifier++;
}
else if (c === 45 /* - */ || c === 114 /* r */ || c === 82 /* R */) {
if (note !== undefined) {
this.melodyStringIndex--;
break;
}
note = -1;
}
else if (c === 98 /* b */) {
if (note === undefined) {
note = 11;
}
else {
modifier--;
}
}
else if (c >= 48 && c <= 57) {
// number
if (note === undefined) {
// invalid if we haven't seen a note yet, ignore the number
continue;
}
else {
this.melodyStringIndex--;
this.currentOctave = this.readNumber();
}
}
else if (c >= 65 && c <= 71) {
// A-G
if (note !== undefined) {
this.melodyStringIndex--;
break;
}
note = offsetLookup[c - 65];
}
else if (c >= 97 && c <= 103) {
// a-g
if (note !== undefined) {
this.melodyStringIndex--;
break;
}
note = offsetLookup[c - 97];
}
else if (c === 58 /* : */) {
this.currentDuration = Math.max(1, this.readNumber());
break;
}
}

if (note === undefined || note < 0) {
// invalid note, treat as rest
this.currentNote = REST;
}
else {
this.currentNote = note + modifier;
}

this.eatWhitespace();
}

readNumber() {
let result = 0;
while (this.melodyStringIndex < this.melody.length) {
const c = this.melody.charCodeAt(this.melodyStringIndex);
if (c < 48 || c > 57) break;
result = result * 10 + (c - 48);
this.melodyStringIndex++;
}
return result;
}

eatWhitespace() {
while (this.melodyStringIndex < this.melody.length && this.melody.charAt(this.melodyStringIndex) == " ") {
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@srietkerk srietkerk Apr 7, 2026

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Same question in the other PR about if this should be a === or not.

this.melodyStringIndex++;
}
}

hasNextNote(): boolean {
this.eatWhitespace();
return this.melodyStringIndex < this.melody.length;
}
}
2 changes: 1 addition & 1 deletion pxtlib/melody-editor/melodyArray.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -143,7 +143,7 @@ namespace pxtmelody {

export function noteToRow(note: string): number {
let rowNum: number = -1;
switch (note) {
switch (note.toUpperCase()) {
case "C5": rowNum = 0; break;
case "B": rowNum = 1; break;
case "A": rowNum = 2; break;
Expand Down
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