jimp-dev/jimp

"print" method on transparent background produces black fringe

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#652 opened on Oct 28, 2018

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 (2 comments) (0 reactions) (0 assignees)JavaScript (13,218 stars) (785 forks)batch import
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Description

Expected Behavior

Printing text on a image with a transparent background should result in text with a transparent fringe.

Current Behavior

Instead of a transparent fringe, the text is drawn with a black fringe.

Possible Fix

In the drawCharacter method of plugin-print, changing:

image.blit(characterPage, x + char.xoffset, y + char.yoffset, char.x, char.y, char.width, char.height);

...to:

image.composite(characterPage.clone().crop(char.x, char.y, char.width, char.height), x + char.xoffset, y + char.yoffset);

...seems to "fix" the fringe. There may be a more efficient way to do it though!

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
JavaScriptNode.jsImage processing basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
Examine the drawCharacter method in the plugin print module (likely in packages/plugin print). Implement the suggested composite approach or a more efficient alternative. Test the fix with images having transparent backgrounds. Ensure existing print functionality still works. Check if there are any related issues or PRs (none linked). Consider the comment on efficiency and optimize if possible.