1// Copyright (C) 2024 The Android Open Source Project 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// http://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14 15import {BigintMath} from '../../base/bigint_math'; 16import {HighPrecisionTimeSpan} from '../../base/high_precision_time_span'; 17import {duration} from '../../base/time'; 18 19/** 20 * Work out an appropriate "resolution" for a given time span stretched over a 21 * given number of pixels. 22 * 23 * The returned value will be rounded down to the nearest power of 2, and will 24 * always be >= 1. 25 * 26 * @param timeSpan The span of time to represent. 27 * @param widthPx How many pixels we have to represent the time span. 28 * @returns The resultant resolution. 29 */ 30export function calculateResolution( 31 timeSpan: HighPrecisionTimeSpan, 32 widthPx: number, 33): duration { 34 // Work out how much time corresponds to one pixel 35 const timePerPixel = Number(timeSpan.duration) / widthPx; 36 37 // Round down to the nearest power of 2, noting that the smallest value this 38 // function can return is 1 39 return BigintMath.bitFloor(BigInt(Math.floor(timePerPixel))); 40} 41