Fix PlantUML image rendering failure with UTF-8 diagrams in Previm #229
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Previm’s PlantUML encoder failed to generate valid URLs when diagrams contained non-ASCII (UTF-8) characters or comment lines starting with `' ---`. The custom encode64 implementation produced incorrect PlantUML-encoded data, causing the PlantUML server to return 404 IMAGE NOT FOUND errors. Additionally, `' ---` lines were sometimes misinterpreted as Markdown horizontal rules, resulting in truncated UML text. This patch replaces the encoder with the official PlantUML encode.js implementation (encode6bit / append3bytes / encode64), ensuring correct UTF-8 handling and compliant URL generation. It also normalizes problematic `' ---` comment lines to avoid Markdown tokenizer conflicts. As a result, diagrams containing Japanese text and inline comments now render correctly in Previm.
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Previm’s PlantUML encoder failed to generate valid URLs when diagrams contained non-ASCII (UTF-8) characters or comment lines starting with
' ---. The custom encode64 implementation produced incorrect PlantUML-encoded data, causing the PlantUML server to return 404 IMAGE NOT FOUND errors. Additionally,' ---lines were sometimes misinterpreted as Markdown horizontal rules, resulting in truncated UML text.This patch replaces the encoder with the official PlantUML encode.js implementation (encode6bit / append3bytes / encode64), ensuring correct UTF-8 handling and compliant URL generation. It also normalizes problematic
' ---comment lines to avoid Markdown tokenizer conflicts.As a result, diagrams containing Japanese text and inline comments now render correctly in Previm.