Custom editors

One option, eight views

A buffer has a kind of editor over it, and :set editor <kind> picks which. There is no new mode, no separate application and no second copy of the data: the window keeps its buffer and changes what it draws, the normal keymap keeps dispatching, and everything the keys do is written back into the file the buffer came from.

colour is spelled either way. Bare :set editor answers with the one that is up — editor=tileset — and a name that is not on the list is refused with the list: not an editor: hex (want tileset, normalmap, curve, color, gradient, bischema, bidata or image). A kind asked for on a buffer that cannot take it says so instead of doing nothing — no image here on text, no curve under the cursor on a line with no numbers in it.

Nothing here is a trap. : still opens the ex line, Ctrl-W still moves between windows, and :w still writes the file the buffer came from — not a picture of it. Getting out is one key: Esc takes the grid off a tileset, and closes the curve, colour, gradient and normal map tools the way :q does, putting the cursor back in the window you came from. The property view is the one that wants the option spelled out, :set editor text. Either way the edits are already in the buffer, on the buffer’s own history, so u afterwards undoes what you did inside.

The rest of this lesson is the picture itself, because image is what tileset and normalmap are drawn on top of.

Opening one

bi atlas.png, or :e atlas.png from anywhere. The picture is drawn in the window where a terminal speaks the kitty graphics protocol; where it does not, the file opens as the text it always was. Nothing is scaled to fit: a sheet wider than the pane is cropped, and the motions below are how you look at the rest of it.

tiles.png A picture in a window 1 / 5 play

1. start bi tiles.png draws the sheet — 256×256, an eight-by-eight grid of 32-pixel dungeon tiles. The status row carries its size where row:col would be.
2. 1 :zoom 3Enter Three times, nearest-neighbour — every pixel is a block, and the zoom joins the size in the status row.
3. 2 :zoom 9Enter Nine times is bigger than the pane, so the picture is cropped — never shrunk to fit.
4. 3 jjjjll hjkl scroll the crop by a text row’s worth at a time.
5. 4 :zoom 0Enter :zoom 0 is back to 1x.

The status row carries the size where row:col would be — 256×256 — and the zoom after it once it is not 1x.

There is no image keymap to learn or rebind: the window dispatches through the normal keymap, and the handful of keys that mean something to a picture are re-read as pixels. Keys that have nothing to do — i, v, /, s — do nothing.

Zoom

:zoom          says what it is: zoom=2x
:zoom 0        back to 1x
:zoom +        double            :zoom -     halve
:zoom 5        five times        :zoom 0.1   a tenth

A number, not 5x. It is clamped between 0.05 and 32, and scaling is nearest-neighbour, because a filter that blends is a filter that ruins a 16-pixel tile. Zoom belongs to the image, like its scroll: :vs clones it, Ctrl-^ brings it back, :bd throws it away.

Whole-image operations

:tool image grayscale
:tool image invert
:tool image flip x                        or y
:tool image blur 2.5                      sigma, in pixels
:tool image resize 64,64                  pixels — the tileset resizes in tiles
:tool image resize 64,64 --alg lanczos    nearest (default) | bilinear | lanczos
:tool image crop 0,0,32,32                x, y, width, height
:tool image conv jpg                      png | jpg | webp | bmp
:tool image conv jpg --quality 80         1..100, jpg only; 90 unless said

Pairs and quads take commas, never 64x64. resize defaults to nearest for the same reason zoom does; --alg lanczos is there for a photograph. A crop that runs past the edge is refused rather than clipped — 0,0,64,64 runs past 50×40 — and on a window with no picture every one of these says no image here.

tiles.png Whole-image operations 1 / 5 play

1. start The dungeon sheet at 3x.
2. 1 :tool image grayscaleEnter Every channel equal, in one undo step.
3. 2 :tool image invertEnter Inverted on top of that.
4. 3 uu u twice: the colours come back. Each operation was its own step.
5. 4 :tool image conv jpgEnter conv touches no pixels — it sets what :w writes and re-points the extension.

Each operation is one undo step, on the image’s own history, so u after a grayscale brings the colours back. The before and after pixels are both kept, so undo is a copy rather than a recomputation — which matters for blur, which is not reversible by arithmetic.

What :w writes

conv changes no pixels. It sets the format the image is written in and re-points the path’s extension to match, so :w on atlas.png after conv jpg writes atlas.jpg and says so. PNG, JPEG, WebP and BMP can be written; anything else is refused by name — cannot write gif (png, jpg, webp, bmp) — rather than written as PNG under a lying extension. JPEG has no alpha, so --rgb is implied there; WebP is written lossless and ignores --quality with a note.

The format is also set by the name: opening decides it, and :w other.webp re-types the picture the way :w other.rs re-types a buffer.

The file name placeholders work here too, which is what makes a companion file one command:

:w %:r.small.%:e      atlas.png  →  atlas.small.png
:w $dir/atlas.jpg     beside it, under another name

Reloading

:e on a picture means what it means on a buffer: the file as it is on disk now, refused on a dirty picture until you say :e!. The reload is one undo step, so what :e! discarded is one u away, and the crop, the zoom, the grid and the format all survive it. A file that no longer decodes changes nothing and says why.

Next: the tileset, which is the same picture with a grid over it.