Automattic/node-canvas

Right-aligned text with leading/trailing spaces rendered incorrectly

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#333 opened on Oct 1, 2013

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 (9 comments) (1 reaction) (0 assignees)JavaScript (9,524 stars) (1,140 forks)batch import
BugHelp wantedText & Fonts

Description

Using a simple test like this:

ctx.font = '30px Arial';
ctx.textAlign = 'right';
ctx.strokeRect(100, 100, 100, 100);
ctx.fillText('   foobar', 100, 100);

... I'm getting incorrect rendering in latest node-canvas:

leading_spaces_nodecanvas

compare to the same output in Chrome (and FF):

leading_spaces_chrome

There's a similar problem with trailing spaces.

node-canvas:

trailing_spaces_nodecanvas

Chrome (FF):

trailing_spaces_chrome

Contributor guide

Tech stack
javascriptnodejs
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic knowledge of Node Canvas APIUnderstanding of text alignment
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Investigate how the canvas text rendering handles leading and trailing spaces when text alignment is set to 'right'. Look at the C++ source code for text measurement and drawing in src/canvas.cc or similar files. Check the comments for any previous attempts or maintainer hints. Compare the behavior with browser canvas to identify the discrepancy in space handling.