ui/src/frontend/flamegraph.ts - third_party/perfetto - Git at Google

 // 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 {searchSegment} from '../base/binary_search';
 import {cropText} from '../common/canvas_utils';

 import {CallsiteInfo} from './globals';

 interface Node {
   width: number;
   x: number;
   nextXForChildren: number;
   size: number;
 }

 interface CallsiteInfoWidth {
   callsite: CallsiteInfo;
   width: number;
 }

 const NODE_HEIGHT_DEFAULT = 15;

 export const HEAP_PROFILE_COLOR = 'hsl(224, 45%, 70%)';
 export const HEAP_PROFILE_HOVERED_COLOR = 'hsl(224, 45%, 55%)';

 export function findRootSize(data: CallsiteInfo[]) {
   let totalSize = 0;
   let i = 0;
   while (i < data.length && data[i].depth === 0) {
     totalSize += data[i].totalSize;
     i++;
   }
   return totalSize;
 }

 export class Flamegraph {
   private isThumbnail = false;
   private flamegraphData: CallsiteInfo[];
   private maxDepth = -1;
   private totalSize = -1;
   private textSize = 12;
   // Key for the map is depth followed by x coordinate - `depth;x`
   private graphData: Map<string, CallsiteInfoWidth> = new Map();
   private xStartsPerDepth: Map<number, number[]> = new Map();

   private hoveredX = -1;
   private hoveredY = -1;
   private hoveredCallsite?: CallsiteInfo;
   private clickedCallsite?: CallsiteInfo;

   constructor(flamegraphData: CallsiteInfo[]) {
     this.flamegraphData = flamegraphData;
     this.findMaxDepth();
   }

   private findMaxDepth() {
     this.maxDepth = Math.max(...this.flamegraphData.map(value => value.depth));
   }

   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;
   }

   generateColor(name: string, isGreyedOut = false): string {
     if (this.isThumbnail) {
       return HEAP_PROFILE_COLOR;
     }
     if (isGreyedOut) {
       return '#d9d9d9';
     }
     if (name === 'unknown' || name === 'root') {
       return '#c0c0c0';
     }
     const hue = this.hash(name);
     return `hsl(${hue}, 50%, 65%)`;
   }

   /**
    * Caller will have to call draw method ater updating data to have updated
    * graph.
    */
   updateDataIfChanged(
       flamegraphData: CallsiteInfo[], clickedCallsite?: CallsiteInfo) {
     if (this.flamegraphData === flamegraphData) {
       return;
     }
     this.flamegraphData = flamegraphData;
     this.clickedCallsite = clickedCallsite;
     this.findMaxDepth();
     // Finding total size of roots.
     this.totalSize = findRootSize(flamegraphData);
   }

   draw(
       ctx: CanvasRenderingContext2D, width: number, height: number, x = 0,
       y = 0, unit = 'B') {
     // TODO(tneda): Instead of pesimistic approach improve displaying text.
     const name = '____MMMMMMQQwwZZZZZZzzzzzznnnnnnwwwwwwWWWWWqq$$mmmmmm__';
     const charWidth = ctx.measureText(name).width / name.length;
     const nodeHeight = this.getNodeHeight();

     if (this.flamegraphData === undefined) {
       return;
     }
     // For each node, we use this map to get information about it's parent
     // (total size of it, width and where it starts in graph) so we can
     // calculate it's own position in graph.
     const nodesMap = new Map<number, Node>();
     let currentY = y;
     nodesMap.set(-1, {width, nextXForChildren: x, size: this.totalSize, x});

     // Initialize data needed for click/hover behaivior.
     this.graphData = new Map();
     this.xStartsPerDepth = new Map();

     // Draw root node.
     ctx.fillStyle = this.generateColor('root', false);
     ctx.fillRect(x, currentY, width, nodeHeight);
     ctx.font = `${this.textSize}px Google Sans`;
     const text = cropText(
         `root: ${
             this.displaySize(
                 this.totalSize, unit, unit === 'B' ? 1024 : 1000)}`,
         charWidth,
         width - 2);
     ctx.fillStyle = 'black';
     ctx.fillText(text, x + 5, currentY + nodeHeight - 4);
     currentY += nodeHeight;


     for (let i = 0; i < this.flamegraphData.length; i++) {
       if (currentY > height) {
         break;
       }
       const value = this.flamegraphData[i];
       const parentNode = nodesMap.get(value.parentId);
       if (parentNode === undefined) {
         continue;
       }

       const isClicked = !this.isThumbnail && this.clickedCallsite !== undefined;
       const isFullWidth =
           isClicked && value.depth <= this.clickedCallsite!.depth;
       const isGreyedOut =
           isClicked && value.depth < this.clickedCallsite!.depth;

       const parent = value.parentId;
       const parentSize = parent === -1 ? this.totalSize : parentNode.size;
       // Calculate node's width based on its proportion in parent.
       const width =
           (isFullWidth ? 1 : value.totalSize / parentSize) * parentNode.width;

       const currentX = parentNode.nextXForChildren;
       currentY = nodeHeight * (value.depth + 1);

       // Draw node.
       const name = this.getCallsiteName(value);
       ctx.fillStyle = this.generateColor(name, isGreyedOut);
       ctx.fillRect(currentX, currentY, width, nodeHeight);

       // Set current node's data in map for children to use.
       nodesMap.set(value.id, {
         width,
         nextXForChildren: currentX,
         size: value.totalSize,
         x: currentX
       });
       // Update next x coordinate in parent.
       nodesMap.set(value.parentId, {
         width: parentNode.width,
         nextXForChildren: currentX + width,
         size: parentNode.size,
         x: parentNode.x
       });

       // Thumbnail mode doesn't have name on nodes and click/hover behaviour.
       if (this.isThumbnail) {
         continue;
       }

       // Draw name.
       ctx.font = `${this.textSize}px Google Sans`;
       const text = cropText(name, charWidth, width - 2);
       ctx.fillStyle = 'black';
       ctx.fillText(text, currentX + 5, currentY + nodeHeight - 4);

       // Draw border around node.
       ctx.strokeStyle = 'white';
       ctx.beginPath();
       ctx.moveTo(currentX, currentY);
       ctx.lineTo(currentX, currentY + nodeHeight);
       ctx.lineTo(currentX + width, currentY + nodeHeight);
       ctx.lineTo(currentX + width, currentY);
       ctx.moveTo(currentX, currentY);
       ctx.lineWidth = 1;
       ctx.closePath();
       ctx.stroke();

       // Add this node for recognizing in click/hover.
       // Map graphData contains one callsite which is on that depth and X
       // start. Map xStartsPerDepth for each depth contains all X start
       // coordinates that callsites on that level have.
       this.graphData.set(
           `${value.depth};${currentX}`, {callsite: value, width});
       const xStarts = this.xStartsPerDepth.get(value.depth);
       if (xStarts === undefined) {
         this.xStartsPerDepth.set(value.depth, [currentX]);
       } else {
         xStarts.push(currentX);
       }
     }

     if (this.hoveredX > -1 && this.hoveredY > -1 && this.hoveredCallsite) {
       // Draw the tooltip.
       const lines: string[] = [];
       let lineSplitter: LineSplitter;
       const nameText = this.getCallsiteName(this.hoveredCallsite);
       lineSplitter =
           splitIfTooBig(nameText, width, ctx.measureText(nameText).width);
       const nameTextWidth = lineSplitter.lineWidth;
       lines.push(...lineSplitter.lines);

       const mappingText = this.hoveredCallsite.mapping;
       lineSplitter =
           splitIfTooBig(mappingText, width, ctx.measureText(mappingText).width);
       const mappingTextWidth = lineSplitter.lineWidth;
       lines.push(...lineSplitter.lines);

       const percentage = this.hoveredCallsite.totalSize / this.totalSize * 100;
       const totalSizeText = `total: ${
           this.displaySize(
               this.hoveredCallsite.totalSize,
               unit,
               unit === 'B' ? 1024 : 1000)} (${percentage.toFixed(2)}%)`;
       lineSplitter = splitIfTooBig(
           totalSizeText, width, ctx.measureText(totalSizeText).width);
       const totalSizeTextWidth = lineSplitter.lineWidth;
       lines.push(...lineSplitter.lines);

       let selfSizeWidth = 0;
       if (this.hoveredCallsite.selfSize > 0) {
         const selfSizeText = `self: ${
             this.displaySize(
                 this.hoveredCallsite.selfSize,
                 unit,
                 unit === 'B' ? 1024 : 1000)} (${percentage.toFixed(2)}%)`;
         lineSplitter = splitIfTooBig(
             selfSizeText, width, ctx.measureText(selfSizeText).width);
         selfSizeWidth = lineSplitter.lineWidth;
         lines.push(...lineSplitter.lines);
       }

       const rectWidth = Math.max(
                             nameTextWidth,
                             mappingTextWidth,
                             totalSizeTextWidth,
                             selfSizeWidth) +
           16;
       const rectXStart = this.hoveredX + 8 + rectWidth > width ?
           width - rectWidth - 8 :
           this.hoveredX + 8;
       const rectHeight = nodeHeight * (lines.length + 1);
       const rectYStart = this.hoveredY + 4 + rectHeight > height ?
           height - rectHeight - 8 :
           this.hoveredY + 4;

       ctx.font = '12px Google Sans';
       ctx.fillStyle = 'rgba(255, 255, 255, 0.9)';
       ctx.fillRect(rectXStart, rectYStart, rectWidth, rectHeight);
       ctx.fillStyle = 'hsl(200, 50%, 40%)';
       ctx.textAlign = 'left';
       for (let i = 0; i < lines.length; i++) {
         const line = lines[i];
         ctx.fillText(line, rectXStart + 4, rectYStart + (i + 1) * 18);
       }
     }
   }

   private getCallsiteName(value: CallsiteInfo): string {
     return value.name === undefined || value.name === '' ? 'unknown' :
                                                            value.name;
   }

   private displaySize(totalSize: number, unit: string, step = 1024): string {
     if (unit === '') return totalSize.toLocaleString();
     if (totalSize === 0) return `0 ${unit}`;
     const units = [
       ['', 0],
       ['K', step],
       ['M', Math.pow(step, 2)],
       ['G', Math.pow(step, 3)]
     ];
     let unitsIndex = Math.trunc(Math.log(totalSize) / Math.log(step));
     unitsIndex = unitsIndex > units.length - 1 ? units.length - 1 : unitsIndex;
     return `${(totalSize / +units[unitsIndex][1]).toLocaleString()} ${
         units[unitsIndex][0]}${unit}`;
   }

   onMouseMove({x, y}: {x: number, y: number}) {
     this.hoveredX = x;
     this.hoveredY = y;
     this.hoveredCallsite = this.findSelectedCallsite(x, y);
     const isCallsiteSelected = this.hoveredCallsite !== undefined;
     if (!isCallsiteSelected) {
       this.onMouseOut();
     }
     return isCallsiteSelected;
   }

   onMouseOut() {
     this.hoveredX = -1;
     this.hoveredY = -1;
     this.hoveredCallsite = undefined;
   }

   // Returns id of clicked callsite if any.
   onMouseClick({x, y}: {x: number, y: number}): number {
     if (this.isThumbnail) {
       return -1;
     }
     const clickedCallsite = this.findSelectedCallsite(x, y);
     return clickedCallsite === undefined ? -1 : clickedCallsite.id;
   }

   private findSelectedCallsite(x: number, y: number): CallsiteInfo|undefined {
     const depth = Math.trunc(y / this.getNodeHeight()) - 1;  // at 0 is root
     if (depth >= 0 && this.xStartsPerDepth.has(depth)) {
       const startX = this.searchSmallest(this.xStartsPerDepth.get(depth)!, x);
       const result = this.graphData.get(`${depth};${startX}`);
       if (result !== undefined) {
         const width = result.width;
         return startX + width >= x ? result.callsite : undefined;
       }
     }
     return undefined;
   }

   searchSmallest(haystack: number[], needle: number): number {
     haystack = haystack.sort((n1, n2) => n1 - n2);
     const [left, ] = searchSegment(haystack, needle);
     return left === -1 ? -1 : haystack[left];
   }

   getHeight(): number {
     return this.flamegraphData.length === 0 ?
         0 :
         (this.maxDepth + 2) * this.getNodeHeight();
   }

   getNodeHeight() {
     return this.isThumbnail ? 1 : NODE_HEIGHT_DEFAULT;
   }

   enableThumbnail(isThumbnail: boolean) {
     this.isThumbnail = isThumbnail;
   }
 }

 export interface LineSplitter {
   lineWidth: number;
   lines: string[];
 }

 export function splitIfTooBig(
     line: string, width: number, lineWidth: number): LineSplitter {
   if (line === '') return {lineWidth, lines: []};
   const lines: string[] = [];
   const charWidth = lineWidth / line.length;
   const maxWidth = width - 32;
   const maxLineLen = Math.trunc(maxWidth / charWidth);
   while (line.length > 0) {
     lines.push(line.slice(0, maxLineLen));
     line = line.slice(maxLineLen);
   }
   lineWidth = Math.min(maxWidth, lineWidth);
   return {lineWidth, lines};
 }
	// 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 {searchSegment} from '../base/binary_search';
	import {cropText} from '../common/canvas_utils';

	import {CallsiteInfo} from './globals';

	interface Node {
	width: number;
	x: number;
	nextXForChildren: number;
	size: number;
	}

	interface CallsiteInfoWidth {
	callsite: CallsiteInfo;
	width: number;
	}

	const NODE_HEIGHT_DEFAULT = 15;

	export const HEAP_PROFILE_COLOR = 'hsl(224, 45%, 70%)';
	export const HEAP_PROFILE_HOVERED_COLOR = 'hsl(224, 45%, 55%)';

	export function findRootSize(data: CallsiteInfo[]) {
	let totalSize = 0;
	let i = 0;
	while (i < data.length && data[i].depth === 0) {
	totalSize += data[i].totalSize;
	i++;
	}
	return totalSize;
	}

	export class Flamegraph {
	private isThumbnail = false;
	private flamegraphData: CallsiteInfo[];
	private maxDepth = -1;
	private totalSize = -1;
	private textSize = 12;
	// Key for the map is depth followed by x coordinate - `depth;x`
	private graphData: Map<string, CallsiteInfoWidth> = new Map();
	private xStartsPerDepth: Map<number, number[]> = new Map();

	private hoveredX = -1;
	private hoveredY = -1;
	private hoveredCallsite?: CallsiteInfo;
	private clickedCallsite?: CallsiteInfo;

	constructor(flamegraphData: CallsiteInfo[]) {
	this.flamegraphData = flamegraphData;
	this.findMaxDepth();
	}

	private findMaxDepth() {
	this.maxDepth = Math.max(...this.flamegraphData.map(value => value.depth));
	}

	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;
	}

	generateColor(name: string, isGreyedOut = false): string {
	if (this.isThumbnail) {
	return HEAP_PROFILE_COLOR;
	}
	if (isGreyedOut) {
	return '#d9d9d9';
	}
	if (name === 'unknown' \|\| name === 'root') {
	return '#c0c0c0';
	}
	const hue = this.hash(name);
	return `hsl(${hue}, 50%, 65%)`;
	}

	/**
	* Caller will have to call draw method ater updating data to have updated
	* graph.
	*/
	updateDataIfChanged(
	flamegraphData: CallsiteInfo[], clickedCallsite?: CallsiteInfo) {
	if (this.flamegraphData === flamegraphData) {
	return;
	}
	this.flamegraphData = flamegraphData;
	this.clickedCallsite = clickedCallsite;
	this.findMaxDepth();
	// Finding total size of roots.
	this.totalSize = findRootSize(flamegraphData);
	}

	draw(
	ctx: CanvasRenderingContext2D, width: number, height: number, x = 0,
	y = 0, unit = 'B') {
	// TODO(tneda): Instead of pesimistic approach improve displaying text.
	const name = '____MMMMMMQQwwZZZZZZzzzzzznnnnnnwwwwwwWWWWWqq$$mmmmmm__';
	const charWidth = ctx.measureText(name).width / name.length;
	const nodeHeight = this.getNodeHeight();

	if (this.flamegraphData === undefined) {
	return;
	}
	// For each node, we use this map to get information about it's parent
	// (total size of it, width and where it starts in graph) so we can
	// calculate it's own position in graph.
	const nodesMap = new Map<number, Node>();
	let currentY = y;
	nodesMap.set(-1, {width, nextXForChildren: x, size: this.totalSize, x});

	// Initialize data needed for click/hover behaivior.
	this.graphData = new Map();
	this.xStartsPerDepth = new Map();

	// Draw root node.
	ctx.fillStyle = this.generateColor('root', false);
	ctx.fillRect(x, currentY, width, nodeHeight);
	ctx.font = `${this.textSize}px Google Sans`;
	const text = cropText(
	`root: ${
	this.displaySize(
	this.totalSize, unit, unit === 'B' ? 1024 : 1000)}`,
	charWidth,
	width - 2);
	ctx.fillStyle = 'black';
	ctx.fillText(text, x + 5, currentY + nodeHeight - 4);
	currentY += nodeHeight;


	for (let i = 0; i < this.flamegraphData.length; i++) {
	if (currentY > height) {
	break;
	}
	const value = this.flamegraphData[i];
	const parentNode = nodesMap.get(value.parentId);
	if (parentNode === undefined) {
	continue;
	}

	const isClicked = !this.isThumbnail && this.clickedCallsite !== undefined;
	const isFullWidth =
	isClicked && value.depth <= this.clickedCallsite!.depth;
	const isGreyedOut =
	isClicked && value.depth < this.clickedCallsite!.depth;

	const parent = value.parentId;
	const parentSize = parent === -1 ? this.totalSize : parentNode.size;
	// Calculate node's width based on its proportion in parent.
	const width =
	(isFullWidth ? 1 : value.totalSize / parentSize) * parentNode.width;

	const currentX = parentNode.nextXForChildren;
	currentY = nodeHeight * (value.depth + 1);

	// Draw node.
	const name = this.getCallsiteName(value);
	ctx.fillStyle = this.generateColor(name, isGreyedOut);
	ctx.fillRect(currentX, currentY, width, nodeHeight);

	// Set current node's data in map for children to use.
	nodesMap.set(value.id, {
	width,
	nextXForChildren: currentX,
	size: value.totalSize,
	x: currentX
	});
	// Update next x coordinate in parent.
	nodesMap.set(value.parentId, {
	width: parentNode.width,
	nextXForChildren: currentX + width,
	size: parentNode.size,
	x: parentNode.x
	});

	// Thumbnail mode doesn't have name on nodes and click/hover behaviour.
	if (this.isThumbnail) {
	continue;
	}

	// Draw name.
	ctx.font = `${this.textSize}px Google Sans`;
	const text = cropText(name, charWidth, width - 2);
	ctx.fillStyle = 'black';
	ctx.fillText(text, currentX + 5, currentY + nodeHeight - 4);

	// Draw border around node.
	ctx.strokeStyle = 'white';
	ctx.beginPath();
	ctx.moveTo(currentX, currentY);
	ctx.lineTo(currentX, currentY + nodeHeight);
	ctx.lineTo(currentX + width, currentY + nodeHeight);
	ctx.lineTo(currentX + width, currentY);
	ctx.moveTo(currentX, currentY);
	ctx.lineWidth = 1;
	ctx.closePath();
	ctx.stroke();

	// Add this node for recognizing in click/hover.
	// Map graphData contains one callsite which is on that depth and X
	// start. Map xStartsPerDepth for each depth contains all X start
	// coordinates that callsites on that level have.
	this.graphData.set(
	`${value.depth};${currentX}`, {callsite: value, width});
	const xStarts = this.xStartsPerDepth.get(value.depth);
	if (xStarts === undefined) {
	this.xStartsPerDepth.set(value.depth, [currentX]);
	} else {
	xStarts.push(currentX);
	}
	}

	if (this.hoveredX > -1 && this.hoveredY > -1 && this.hoveredCallsite) {
	// Draw the tooltip.
	const lines: string[] = [];
	let lineSplitter: LineSplitter;
	const nameText = this.getCallsiteName(this.hoveredCallsite);
	lineSplitter =
	splitIfTooBig(nameText, width, ctx.measureText(nameText).width);
	const nameTextWidth = lineSplitter.lineWidth;
	lines.push(...lineSplitter.lines);

	const mappingText = this.hoveredCallsite.mapping;
	lineSplitter =
	splitIfTooBig(mappingText, width, ctx.measureText(mappingText).width);
	const mappingTextWidth = lineSplitter.lineWidth;
	lines.push(...lineSplitter.lines);

	const percentage = this.hoveredCallsite.totalSize / this.totalSize * 100;
	const totalSizeText = `total: ${
	this.displaySize(
	this.hoveredCallsite.totalSize,
	unit,
	unit === 'B' ? 1024 : 1000)} (${percentage.toFixed(2)}%)`;
	lineSplitter = splitIfTooBig(
	totalSizeText, width, ctx.measureText(totalSizeText).width);
	const totalSizeTextWidth = lineSplitter.lineWidth;
	lines.push(...lineSplitter.lines);

	let selfSizeWidth = 0;
	if (this.hoveredCallsite.selfSize > 0) {
	const selfSizeText = `self: ${
	this.displaySize(
	this.hoveredCallsite.selfSize,
	unit,
	unit === 'B' ? 1024 : 1000)} (${percentage.toFixed(2)}%)`;
	lineSplitter = splitIfTooBig(
	selfSizeText, width, ctx.measureText(selfSizeText).width);
	selfSizeWidth = lineSplitter.lineWidth;
	lines.push(...lineSplitter.lines);
	}

	const rectWidth = Math.max(
	nameTextWidth,
	mappingTextWidth,
	totalSizeTextWidth,
	selfSizeWidth) +
	16;
	const rectXStart = this.hoveredX + 8 + rectWidth > width ?
	width - rectWidth - 8 :
	this.hoveredX + 8;
	const rectHeight = nodeHeight * (lines.length + 1);
	const rectYStart = this.hoveredY + 4 + rectHeight > height ?
	height - rectHeight - 8 :
	this.hoveredY + 4;

	ctx.font = '12px Google Sans';
	ctx.fillStyle = 'rgba(255, 255, 255, 0.9)';
	ctx.fillRect(rectXStart, rectYStart, rectWidth, rectHeight);
	ctx.fillStyle = 'hsl(200, 50%, 40%)';
	ctx.textAlign = 'left';
	for (let i = 0; i < lines.length; i++) {
	const line = lines[i];
	ctx.fillText(line, rectXStart + 4, rectYStart + (i + 1) * 18);
	}
	}
	}

	private getCallsiteName(value: CallsiteInfo): string {
	return value.name === undefined \|\| value.name === '' ? 'unknown' :
	value.name;
	}

	private displaySize(totalSize: number, unit: string, step = 1024): string {
	if (unit === '') return totalSize.toLocaleString();
	if (totalSize === 0) return `0 ${unit}`;
	const units = [
	['', 0],
	['K', step],
	['M', Math.pow(step, 2)],
	['G', Math.pow(step, 3)]
	];
	let unitsIndex = Math.trunc(Math.log(totalSize) / Math.log(step));
	unitsIndex = unitsIndex > units.length - 1 ? units.length - 1 : unitsIndex;
	return `${(totalSize / +units[unitsIndex][1]).toLocaleString()} ${
	units[unitsIndex][0]}${unit}`;
	}

	onMouseMove({x, y}: {x: number, y: number}) {
	this.hoveredX = x;
	this.hoveredY = y;
	this.hoveredCallsite = this.findSelectedCallsite(x, y);
	const isCallsiteSelected = this.hoveredCallsite !== undefined;
	if (!isCallsiteSelected) {
	this.onMouseOut();
	}
	return isCallsiteSelected;
	}

	onMouseOut() {
	this.hoveredX = -1;
	this.hoveredY = -1;
	this.hoveredCallsite = undefined;
	}

	// Returns id of clicked callsite if any.
	onMouseClick({x, y}: {x: number, y: number}): number {
	if (this.isThumbnail) {
	return -1;
	}
	const clickedCallsite = this.findSelectedCallsite(x, y);
	return clickedCallsite === undefined ? -1 : clickedCallsite.id;
	}

	private findSelectedCallsite(x: number, y: number): CallsiteInfo\|undefined {
	const depth = Math.trunc(y / this.getNodeHeight()) - 1; // at 0 is root
	if (depth >= 0 && this.xStartsPerDepth.has(depth)) {
	const startX = this.searchSmallest(this.xStartsPerDepth.get(depth)!, x);
	const result = this.graphData.get(`${depth};${startX}`);
	if (result !== undefined) {
	const width = result.width;
	return startX + width >= x ? result.callsite : undefined;
	}
	}
	return undefined;
	}

	searchSmallest(haystack: number[], needle: number): number {
	haystack = haystack.sort((n1, n2) => n1 - n2);
	const [left, ] = searchSegment(haystack, needle);
	return left === -1 ? -1 : haystack[left];
	}

	getHeight(): number {
	return this.flamegraphData.length === 0 ?
	0 :
	(this.maxDepth + 2) * this.getNodeHeight();
	}

	getNodeHeight() {
	return this.isThumbnail ? 1 : NODE_HEIGHT_DEFAULT;
	}

	enableThumbnail(isThumbnail: boolean) {
	this.isThumbnail = isThumbnail;
	}
	}

	export interface LineSplitter {
	lineWidth: number;
	lines: string[];
	}

	export function splitIfTooBig(
	line: string, width: number, lineWidth: number): LineSplitter {
	if (line === '') return {lineWidth, lines: []};
	const lines: string[] = [];
	const charWidth = lineWidth / line.length;
	const maxWidth = width - 32;
	const maxLineLen = Math.trunc(maxWidth / charWidth);
	while (line.length > 0) {
	lines.push(line.slice(0, maxLineLen));
	line = line.slice(maxLineLen);
	}
	lineWidth = Math.min(maxWidth, lineWidth);
	return {lineWidth, lines};
	}