whatwg/html

Small clarity improvements to canvas transform methods

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#2848 opened on Jul 19, 2017

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clarificationgood first issuetopic: canvas

Description

While in the area for #2845, I noticed the following small tweaks that we could make to improve that section of the spec:

  • Replace "abort these steps" with "return" everywhere. (The latter is a more modern convention, per Infra.)
  • Link "multiplying" in the definition of transform(a, b, c, d, e, f) to https://drafts.fxtf.org/geometry/#matrix-multiply
  • Re-do setTransform(a, b, c, d, e, f) steps 2-3 to reset the current transformation matrix to the appropriate matrix (a c e / b d f / 0 0 1), instead of resetting the matrix to the identity matrix then invoking the transform() method. It's bad practice to invoke methods from other methods.

This is a good first bug :)

Contributor guide

Tech stack
htmlcssjavascript
Domain
documentation
Issue type
documentation
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
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
understanding of HTML specification stylebasic knowledge of canvas transformations
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
80
Research direction
The issue requests three small changes to the canvas transformations section of the HTML spec (https://html.spec.whatwg.org/#transformations). First, replace 'abort these steps' with 'return' throughout, following the Infra spec convention (https://infra.spec.whatwg.org/). Second, add a link to 'multiplying' in the definition of transform(a, b, c, d, e, f) pointing to https://drafts.fxtf.org/geometry/#matrix multiply. Third, rewrite setTransform(a, b, c, d, e, f) steps 2-3 to directly reset the transformation matrix instead of invoking transform(). Check the spec source (likely in the whatwg/html repository) to locate the relevant text and make these edits. The issue has some strike throughs indicating partial completion, so verify which items remain.