ui/src/frontend/time_scale.ts

// Copyright (C) 2018 The Android Open Source Project
//
// 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
//
//      http://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.

import {duration, time} from '../base/time';
import {HighPrecisionTime} from '../common/high_precision_time';
import {HighPrecisionTimeSpan} from '../common/high_precision_time_span';

export class TimeScale {
  readonly timeSpan: HighPrecisionTimeSpan;
  readonly pxSpan: PxSpan;
  private readonly timePerPx: number;

  constructor(timespan: HighPrecisionTimeSpan, pxSpan: PxSpan) {
    this.pxSpan = pxSpan;
    this.timeSpan = timespan;
    if (timespan.duration <= 0 || pxSpan.delta <= 0) {
      this.timePerPx = 1;
    } else {
      this.timePerPx = timespan.duration / pxSpan.delta;
    }
  }

  timeToPx(ts: time): number {
    const timeOffset =
      Number(ts - this.timeSpan.start.integral) -
      this.timeSpan.start.fractional;
    return this.pxSpan.start + timeOffset / this.timePerPx;
  }

  hpTimeToPx(time: HighPrecisionTime): number {
    const timeOffset = time.sub(this.timeSpan.start).toNumber();
    return this.pxSpan.start + timeOffset / this.timePerPx;
  }

  // Convert pixels to a high precision time object, which can be further
  // converted to other time formats.
  pxToHpTime(px: number): HighPrecisionTime {
    const timeOffset = (px - this.pxSpan.start) * this.timePerPx;
    return this.timeSpan.start.addNumber(timeOffset);
  }

  durationToPx(dur: duration): number {
    return Number(dur) / this.timePerPx;
  }

  pxToDuration(pxDelta: number): number {
    return pxDelta * this.timePerPx;
  }
}

export class PxSpan {
  static readonly ZERO = new PxSpan(0, 0);

  readonly start: number;
  readonly end: number;

  constructor(start: number, end: number) {
    this.start = start;
    this.end = end;
  }

  get delta(): number {
    return this.end - this.start;
  }
}