feat: support high-Contrast Color Mode Toggle for Low-Vision Users

[jooyoungseo]

Feature Request:

Description
We would like to implement a high-contrast color mode to enhance accessibility for low-vision users. This mode can be toggled on and off using a single key binding.

Proposed Solution

• Toggle Key: Pressing the 'C' key will enable or disable the high-contrast mode.
• High-Contrast Mode Settings:
  • Background Color: Black
  • Plot Color: White
  • Highlight Color: Light Green for any selected elements.
• Multicolor Plots: In plots with multiple colors (e.g., multi-class plots), all plot elements will be displayed in white, ignoring the original colors.
• Aesthetic Consistency: The background will remain black, and all plot markers will be white, with light green highlights for selected items.

Benefits
This feature will improve usability for low-vision users by providing a clear and high-contrast visual mode that can be easily toggled on and off.

[ellvix]

H for help
C for contrast
L C for captions

[ellvix]

Feature creep time!

• Implement a 3 color level thing to be used for stuff like heatmap and stacked. Make it variable and in settings so users can choose the number of levels they can see. One end will be black, other end white, scale in between. This means colors for things like heatmap will be redone.
• Add more than just the current B/W setting; add color settings for the usual colorblind set: b/w, red/green, blue, simple grayscale, custom. Custom will be a set of colors (min 4) picked in settings, and used as colors are needed. IE, for bar, just use 3 (background, foreground, highlight); for stacked use 5 (background, 3 foreground, highlight), etc. Good luck on heatmap lol, maybe just do the same level gradient with the first 2 colors as above?

[ellvix]

Still todo:

• Settings: actual toggle, # levels, color picker for each level
• Announcement: "High contrast mode enabled" in text and aria live
• Correct trigger key, need to use C key which has a conflict
• If there's time: convert transparency HEXA to HEX to increase support

[ellvix]

PR #406 addresses:

• Settings (#levels, color picker (though just light and dark)
• Announcement
• Trigger is Shift C, as I couldn't figure out the conflict
• HEXA support
• Pattern fill for charts like stacked which will surely end up with bars of the same color that should be distinct.

[ellvix]

Trigger being shift + c may have to stay as is. There's a known issue with key scoping, in that the 'all' scope is always active and running different scopes doesn't actually work: jaywcjlove/hotkeys-js#429

Workaround is to manually remove keys and add new keys when switching scope.