| *dev_theme.txt* Nvim |
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| NVIM REFERENCE MANUAL |
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| Nvim colorscheme guidelines *dev-theme* |
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| Style guidelines for developing Nvim's default colorscheme. |
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| License: CC-By 3.0 https://creativecommons.org/licenses/by/3.0/ |
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| Type |gO| to see the table of contents. |
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| ============================================================================== |
| Design |
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| - Be "Neovim branded", i.e. have mostly "green-blue" feel plus one or two |
| colors reserved for very occasional user attention. |
| - Be oriented for 'termguicolors' (true colors) while being extra minimal for |
| 'notermguicolors' (16 colors) as fallback. |
| - Be accessible, i.e. have high enough contrast ratio (as defined in |
| https://www.w3.org/TR/2008/REC-WCAG20-20081211/#contrast-ratiodef). |
| This means to have value at least 7 for |hl-Normal| and 4.5 for some common |
| cases (|hl-Visual|, `Comment` with set 'cursorline', colored syntax, `Diff*`, |
| |hl-Search|). |
| - Be suitable for dark and light backgrounds via exchange of dark and light |
| palettes. |
| - Be usable, i.e. provide enough visual feedback for common objects. |
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| ============================================================================== |
| Palettes |
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| - There are two separate palettes: dark and light. They all contain the same |
| set of colors exported as `NvimDark*` and `NvimLight*` colors respectively. |
| - The dark palette is used for background in the dark color scheme and for |
| foreground in the light color scheme; and vice versa. This introduces |
| recognizable visual system without too standing out. |
| - Actual computation of palettes should be done in a perceptually uniform |
| color space. Oklch is a good choice. |
| - Each palette has the following colors (descriptions are for dark background; |
| reverse for light one): |
| - Four shades of colored "cold" greys for general UI. |
| - Dark ones (from darkest to lightest) are reserved as background for |
| |hl-NormalFloat| (considered as "black"), |hl-Normal| (background), |
| |hl-CursorLine|, |hl-Visual|. |
| - Light ones (also from darkest to lightest) are reserved for |
| `Comment`, |hl-StatusLine|/|hl-TabLine|, |hl-Normal| (foreground), |
| and color considered as "white". |
| - Six colors to provide enough terminal colors: red, yellow, green, cyan, |
| blue, magenta. |
| They should have (reasonably) similar lightness and chroma to make them |
| visually coherent. Lightness should be as equal to the palette's basic grey |
| (which is used for |hl-Normal|) as possible. They should have (reasonably) |
| different hues to make them visually separable. |
| - For 16 colors: |
| - Greys are not used and are replaced with the foreground and background |
| colors of the terminal emulator. |
| - Non-grey colors fall back to terminal colors as ordered in ANSI codes |
| (https://en.wikipedia.org/wiki/ANSI_escape_code#3-bit_and_4-bit), |
| that is red (1, 9), green (2, 10), yellow (3, 11), blue (4, 12), |
| magenta (5, 13), cyan (6, 14). |
| To increase contrast, colors 1-6 are used for light background and 9-14 |
| for dark background. |
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| ============================================================================== |
| Highlight groups |
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| Use: |
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| - Grey shades for general UI according to their design. |
| - Bold text for keywords (`Statement` highlight group). This is an important |
| choice to increase accessibility for people with color deficiencies, as it |
| doesn't rely on actual color. |
| - Green for strings, |hl-DiffAdd| (as background), |hl-DiagnosticOk|, and some |
| minor text UI elements. |
| - Cyan as main syntax color, i.e. for function usage (`Function` highlight |
| group), |hl-DiffText|, |hl-DiagnosticInfo|, and some minor text UI elements. |
| - Red to generally mean high user attention, i.e. errors; in particular for |
| |hl-ErrorMsg|, |hl-DiffDelete|, |hl-DiagnosticError|. |
| - Yellow very sparingly to mean mild user attention, i.e. warnings. That is, |
| |hl-DiagnosticWarn| and |hl-WarningMsg|. |
| - Blue very sparingly as |hl-DiagnosticHint| and some additional important |
| syntax group (like `Identifier`). |
| - Magenta very carefully (if at all). |
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| In case of 16 colors: |
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| - Rely on the assumption "Background color can be used as background; other |
| colors can be used as foreground". This means that in any |
| foreground/background combination there should be background and one |
| non-background color. |
| - Use 0 (black) or 15 (bright white) as foreground for non-grey background, |
| depending on whether normal background is light or dark. |
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| vim:tw=78:ts=8:et:ft=help:norl: |
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