annotate src/app/visualisations/FeatureUtilities.ts @ 349:bf038a51f7e3

Restore some of the feature related logic from waveform.component into a utilities module. Introduce some additional types for representing reshaped features. A work in progress.

/**
 * Created by lucast on 24/05/2017.
 */

import {FeatureList} from 'piper/Feature';
import {OutputDescriptor, toSeconds} from 'piper';
import {
  MatrixFeature,
  SimpleResponse,
  TracksFeature,
  VectorFeature
} from 'piper/HigherLevelUtilities';


export type NoteLikeUnit = 'midi' | 'hz' ;
export interface Note {
  time: number;
  duration: number;
  pitch: number;
  velocity?: number;
}

export function getCanonicalNoteLikeUnit(unit: string): NoteLikeUnit | null {
  const canonicalUnits: NoteLikeUnit[] = ['midi', 'hz'];
  return canonicalUnits.find(canonicalUnit => {
    return unit.toLowerCase().indexOf(canonicalUnit) >= 0;
  });
}

export function mapFeaturesToNotes(featureData: FeatureList,
                                   descriptor: OutputDescriptor): Note[] {
  const canonicalUnit = getCanonicalNoteLikeUnit(descriptor.configured.unit);
  const isHz = canonicalUnit === 'hz';
  return featureData.map(feature => ({
    time: toSeconds(feature.timestamp),
    duration: toSeconds(feature.duration),
    pitch: isHz ?
      frequencyToMidiNote(feature.featureValues[0]) : feature.featureValues[0]
  }));
}

export function frequencyToMidiNote(frequency: number,
                                    concertA: number = 440.0): number {
  return 69 + 12 * Math.log2(frequency / concertA);
}

export function* createColourGenerator(colours) {
  let index = 0;
  const nColours = colours.length;
  while (true) {
    yield colours[index = ++index % nColours];
  }
}

export const defaultColourGenerator = createColourGenerator([
  '#0868ac', // "sapphire blue", our waveform / header colour
  '#c33c54', // "brick red"
  '#17bebb', // "tiffany blue"
  '#001021', // "rich black"
  '#fa8334', // "mango tango"
  '#034748' // "deep jungle green"
]);

// TODO this might belong somewhere else, or perhaps the stuff above ^^ does

export interface Instant {
  time: number;
  label: string;
}

type CollectedShape = 'vector' | 'matrix' | 'tracks';

// TODO regions
type ShapeDeducedFromList = 'instants' | 'notes';
export type HigherLevelFeatureShape = CollectedShape | ShapeDeducedFromList;

export type ShapedFeatureData = VectorFeature
  | MatrixFeature
  | TracksFeature
  | Note[]
  | Instant[];

// These needn't be classes (could just be interfaces), just experimenting
export abstract class ShapedFeature<Shape extends HigherLevelFeatureShape,
  Data extends ShapedFeatureData> {
  shape: Shape;
  collected: Data;
}

export class Vector extends ShapedFeature<'vector', VectorFeature> {}
export class Matrix extends ShapedFeature<'matrix', MatrixFeature> {}
export class Tracks extends ShapedFeature<'tracks', TracksFeature> {}
export class Notes extends ShapedFeature<'notes', Note[]> {}
export class Instants extends ShapedFeature<'instants', Instant[]> {}
export type KnownShapedFeature = Vector
  | Matrix
  | Tracks
  | Notes
  | Instants;

function hasKnownShapeOtherThanList(shape: string): shape is CollectedShape {
  return ['vector', 'matrix', 'tracks'].includes(shape);
}

const throwShapeError = () => { throw new Error('No shape could be deduced'); };
function deduceHigherLevelFeatureShape(response: SimpleResponse)
: HigherLevelFeatureShape {
  const collection = response.features;
  const descriptor = response.outputDescriptor;
  if (hasKnownShapeOtherThanList(collection.shape)) {
    return collection.shape;
  }


  // TODO it's a shame that the types in piper don't make this easy for the
  // compiler to deduce
  if (collection.shape !== 'list' && collection.collected instanceof Array) {
    throwShapeError();
  }

  const featureData = collection.collected as FeatureList;
  const hasDuration = descriptor.configured.hasDuration;
  const binCount = descriptor.configured.binCount;
  const isMarker = !hasDuration
    && binCount === 0
    && featureData[0].featureValues == null;

  const isMaybeNote = getCanonicalNoteLikeUnit(descriptor.configured.unit)
    && [1, 2].find(nBins => nBins === binCount);

  // TODO any need to be directly inspecting features?
  const isRegionLike = hasDuration && featureData[0].timestamp != null;

  const isNote = isMaybeNote && isRegionLike;
  if (isMarker) {
    return 'instants';
  }
  if (isNote) {
    return 'notes';
  }
  throwShapeError();
}

export function toKnownShape(response: SimpleResponse): KnownShapedFeature {
  const deducedShape = deduceHigherLevelFeatureShape(response);
  switch (deducedShape) {
    case 'vector':
      return response.features as Vector;
    case 'matrix':
      return response.features as Matrix;
    case 'notes':
      return {
        shape: deducedShape,
        collected: mapFeaturesToNotes(
          response.features.collected as FeatureList,
          response.outputDescriptor
        )
      };
    case 'instants':
      const featureData = response.features.collected as FeatureList;
      return {
        shape: deducedShape,
        collected: featureData.map(feature => ({
          time: toSeconds(feature.timestamp),
          label: feature.label
        }))
      };
  }
  throwShapeError();
}