| // Copyright (C) 2024 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 {BigintMath} from '../base/bigint_math'; |
| import {duration} from '../base/time'; |
| import {HighPrecisionTimeSpan} from '../base/high_precision_time_span'; |
| |
| /** |
| * Work out an appropriate "resolution" for a given time span stretched over a |
| * given number of pixels. |
| * |
| * The returned value will be rounded down to the nearest power of 2, and will |
| * always be >= 1. |
| * |
| * @param timeSpan The span of time to represent. |
| * @param widthPx How many pixels we have to represent the time span. |
| * @returns The resultant resolution. |
| */ |
| export function calculateResolution( |
| timeSpan: HighPrecisionTimeSpan, |
| widthPx: number, |
| ): duration { |
| // Work out how much time corresponds to one pixel |
| const timePerPixel = Number(timeSpan.duration) / widthPx; |
| |
| // Round down to the nearest power of 2, noting that the smallest value this |
| // function can return is 1 |
| return BigintMath.bitFloor(BigInt(Math.floor(timePerPixel))); |
| } |
