Chart.js v4 support

Bugfix

• CanvasGradient fallback. #73

Features

• Add support for predefined color schemes: chartjs-plugin-colorschemes
• Add support for Google Image Charts QR code format
• Add support for emoji fonts

Bugfixes

• Fix a crash when graph doesn't have datasets
• Fix a bug where outlabeledDoughnuts would not support charts with doughnutlabels plugin
• Set Google Image Charts pixel ratio to 1.0 (true size)
• Handle and log failed Google Image Charts

Misc

• Add X-quickchart-error header which is populated on error
• Add built-in chart padding plugin
• Add width and height maximums

Minor fix to Docker image

Many features and bugfixes, including

• Support for Google Image Charts-style URLs
• Support for doughtnut labels, violin, box plot, and graphviz visualizations
• Built-in functions for helping with gradient fills and patterns
• Allow custom chart plugins
• much more

• Upgrade Chart.js to 2.9.3 (from 2.7.3)
• Fix a bug where some chart POST options would not be parsed correctly
• Improve Javascript sandboxing
• Improvements to logging
• Add timeouts and error handling to telemetry
• Add test suite

Add the ability to record usage stats, as well as the ENABLE_TELEMETRY_WRITE and DISABLE_TELEMETRY flags.

First tagged release!

Features/Additions

• PDF rendering
• base64 encoding support of chart configs
• Health check endpoints
• Ability to store charts as short URLs (via Cloudflare KV)
• Configurable rate limiting
• API keys to bypass rate limiting
• Monit config example
• Load testing example

Bugfixes

• Add a global request timeout to prevent server from locking up under heavy load
• Fix an issue where sparklines could have pixels cut off using automatic scaling
• Fix an issue causing certain chart configs to be misinterpreted due to vm2 bug (#19)