ui/src/tracks/chrome_slices/frontend.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 {cropText} from '../../common/canvas_utils';
import {TrackState} from '../../common/state';
import {checkerboardExcept} from '../../frontend/checkerboard';
import {globals} from '../../frontend/globals';
import {Track} from '../../frontend/track';
import {trackRegistry} from '../../frontend/track_registry';

import {Config, Data, SLICE_TRACK_KIND} from './common';

const SLICE_HEIGHT = 20;
const TRACK_PADDING = 5;

function hash(s: string): number {
  let hash = 0x811c9dc5 & 0xfffffff;
  for (let i = 0; i < s.length; i++) {
    hash ^= s.charCodeAt(i);
    hash = (hash * 16777619) & 0xffffffff;
  }
  return hash & 0xff;
}

class ChromeSliceTrack extends Track<Config, Data> {
  static readonly kind = SLICE_TRACK_KIND;
  static create(trackState: TrackState): ChromeSliceTrack {
    return new ChromeSliceTrack(trackState);
  }

  private hoveredTitleId = -1;

  constructor(trackState: TrackState) {
    super(trackState);
  }

  renderCanvas(ctx: CanvasRenderingContext2D): void {
    // TODO: fonts and colors should come from the CSS and not hardcoded here.

    const {timeScale, visibleWindowTime} = globals.frontendLocalState;
    const data = this.data();

    // If there aren't enough cached slices data in |data| request more to
    // the controller.
    const inRange = data !== undefined &&
        (visibleWindowTime.start >= data.start &&
         visibleWindowTime.end <= data.end);
    if (!inRange || data === undefined ||
        data.resolution > globals.getCurResolution()) {
      globals.requestTrackData(this.trackState.id);
      if (data === undefined) return;  // Can't possibly draw anything.
    }

    // If the cached trace slices don't fully cover the visible time range,
    // show a gray rectangle with a "Loading..." label.
    checkerboardExcept(
        ctx,
        timeScale.timeToPx(visibleWindowTime.start),
        timeScale.timeToPx(visibleWindowTime.end),
        timeScale.timeToPx(data.start),
        timeScale.timeToPx(data.end), );

    ctx.font = '12px Google Sans';
    ctx.textAlign = 'center';

    // measuretext is expensive so we only use it once.
    const charWidth = ctx.measureText('ACBDLqsdfg').width / 10;
    const pxEnd = timeScale.timeToPx(visibleWindowTime.end);

    for (let i = 0; i < data.starts.length; i++) {
      const tStart = data.starts[i];
      const tEnd = data.ends[i];
      const depth = data.depths[i];
      const cat = data.strings[data.categories[i]];
      const titleId = data.titles[i];
      const title = data.strings[titleId];
      if (tEnd <= visibleWindowTime.start || tStart >= visibleWindowTime.end) {
        continue;
      }
      const rectXStart = Math.max(timeScale.timeToPx(tStart), 0);
      const rectXEnd = Math.min(timeScale.timeToPx(tEnd), pxEnd);
      const rectWidth = rectXEnd - rectXStart;
      const rectYStart = TRACK_PADDING + depth * SLICE_HEIGHT;

      const hovered = titleId === this.hoveredTitleId;
      const hue = hash(cat);
      const saturation = Math.min(20 + depth * 10, 70);
      ctx.fillStyle = `hsl(${hue}, ${saturation}%, ${hovered ? 30 : 65}%)`;
      ctx.fillRect(rectXStart, rectYStart, rectWidth, SLICE_HEIGHT);

      ctx.fillStyle = 'white';
      const displayText = cropText(title, charWidth, rectWidth);
      const rectXCenter = rectXStart + rectWidth / 2;
      ctx.textBaseline = "middle";
      ctx.fillText(displayText, rectXCenter, rectYStart + SLICE_HEIGHT / 2);
    }
  }

  onMouseMove({x, y}: {x: number, y: number}) {
    const data = this.data();
    this.hoveredTitleId = -1;
    if (data === undefined) return;
    const {timeScale} = globals.frontendLocalState;
    if (y < TRACK_PADDING) return;
    const t = timeScale.pxToTime(x);
    const depth = Math.floor(y / SLICE_HEIGHT);
    for (let i = 0; i < data.starts.length; i++) {
      const tStart = data.starts[i];
      const tEnd = data.ends[i];
      const titleId = data.titles[i];
      if (tStart <= t && t <= tEnd && depth === data.depths[i]) {
        this.hoveredTitleId = titleId;
        break;
      }
    }
  }

  onMouseOut() {
    this.hoveredTitleId = -1;
  }

  getHeight() {
    return SLICE_HEIGHT * (this.config.maxDepth + 1) + 2 * TRACK_PADDING;
  }
}

trackRegistry.register(ChromeSliceTrack);