snowie2000/mactype

ClipBox problem with combining characters

Open

#282 opened on May 27, 2017

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 (33 comments) (0 reactions) (1 assignee)C++ (9,178 stars) (446 forks)batch import
bugfuture versionhelp wanted

Description

The character is clipped if it is decorated by a combining character. Here is an example with IPA diacritics in Firefox (font: Segoe UI, backend: cairo):

example

Tried ClipBoxFix = 1, it doesn't work. I think this is caused by the combining character. Since its clipbox is smaller than the decorated character's, part of the decorated character is clipped.

Contributor guide

Tech stack
cpp
Domain
frontend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
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
Font rendering basicsC++ debuggingWindows APIMacType architecture
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
Investigate the ClipBoxFix mechanism and its interaction with combining characters. Look at the font rendering code, particularly in the cairo backend, to understand how clip boxes are computed. Review existing comments and any work by the assignee (if any). Consider testing with different fonts and backends to isolate the issue.