Automattic/node-canvas

fontBoundingBox is not implemented

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#1,940 建立於 2021年11月29日

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 (1 留言) (2 反應) (0 負責人)JavaScript (9,524 star) (1,140 fork)batch import
Help wantedText & Fonts

描述

Issue or Feature

Hi! I was expecting to use fontBoundingBox, but as it turns out there's a TODO in code left and it isn't done. I saw some PR's that said it couldn't be done. Could there be some kind of resolution or workaround to experience the same effect as fontBoundingBox?

In the visible image, I would like to get the blue part. (fontBoundingBox) image

Steps to Reproduce

import Canvas from 'canvas';

const canvas = Canvas.createCanvas(10, 10);

const ctx = canvas.getContext('2d')
const measure = ctx.measureText("woohoo!");

console.log(measure.fontBoundingBoxAscent) // undefined :(

Your Environment

  • Version of node-canvas (output of npm list canvas or yarn list canvas): canvas@2.8.0
  • Environment (e.g. node 4.2.0 on Mac OS X 10.8): v16.4.2 on Windows

貢獻者指南

技術棧
javascript
領域
api
議題類型
feature
難度面向新貢獻者的預計實作難度，1 表示很小改動，5 表示專家級工作。
4
預計時間有經驗貢獻者完成調查、實作、測試並準備 pull request 的粗略時間範圍。
over 1 week
活動狀態議題目前的可參與程度：新鮮、活躍、陳舊、阻塞或等待維護者輸入。
stale
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
needs investigation
前置要求
Basic C++ knowledgeUnderstanding of Node.js native addonsFamiliarity with Cairo library
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
20
研究方向
The issue requests the implementation of fontBoundingBox property in the CanvasRenderingContext2D. The TODO is likely in the C++ binding code for the measureText function. Start by examining the current measureText implementation in src/Canvas.cc or similar. Previous PRs attempting this may have discussions about limitations. Investigate the Cairo API for font metrics and how to expose them. The maintainers have not responded, so consider asking for clarification on the desired behavior and any prior attempts.
fontBoundingBox is not implemented · Automattic/node-canvas#1940 | Good First Issue