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-rw-r--r--AGENTS.md24
-rw-r--r--CHANGELOG.org6
-rw-r--r--README.org11
-rw-r--r--justfile25
-rw-r--r--kitty-graphics.el73
5 files changed, 124 insertions, 15 deletions
diff --git a/AGENTS.md b/AGENTS.md
index ccd185f..bfd618b 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -244,7 +244,11 @@ Key design differences from images:
## Known Issues & Planned Work
- **Fixed**: Overlays remain visible when org headings are collapsed (#1)
-- **Limitation**: Does not work inside tmux (neither Kitty passthrough nor Sixel) (#2)
+- **Partial**: tmux support (#2) -- Sixel works inside tmux >= 3.4 (native
+ rendering, foot/Konsole/etc as outer terminal); guarded by
+ `kitty-gfx-tmux-allow-sixel'. Known caveat: images may persist after
+ scrolling because tmux's cell buffer is not pixel-aware (upstream limit).
+ Kitty graphics passthrough is still unimplemented -- tracked separately.
- **Limitation**: Each mode needs explicit `:around` advice integration
- **Limitation**: GIF files are not supported (multi-frame conversion issues,
no animation support in terminal)
@@ -265,10 +269,20 @@ Key design differences from images:
- **Required**: Emacs >= 27.1, a supported terminal (Kitty/WezTerm/Ghostty
for Kitty backend; foot/Konsole/xterm/mlterm/mintty for Sixel)
-- **Required for Sixel**: a Sixel encoder on PATH -- `img2sixel`
- (libsixel, recommended) or ImageMagick (`magick`/`convert`).
- Override via `kitty-gfx-sixel-encoder-program'; bound by
- `kitty-gfx-sixel-encoder-timeout' (default 5s).
+- **Required for Sixel**: a Sixel encoder on `PATH`.
+ - **Strongly recommended**: `img2sixel` from libsixel (~2.2x smaller
+ payload, ~10x faster than ImageMagick on the same input). Critical
+ inside tmux, where every refresh re-emits the full DCS payload --
+ using ImageMagick there leads to visible flicker.
+ - **Fallback**: ImageMagick 7 (`magick`) or 6 (`convert`). Works,
+ just slower.
+ - Auto-detect order: `img2sixel` > `magick` > `convert`. Override
+ via `kitty-gfx-sixel-encoder-program' (nil = auto, string = pin).
+ - With **no** encoder on `PATH`, the Sixel backend silently produces
+ no output and logs `no encoder found` (set `kitty-gfx-debug' to
+ surface this). Always verify with `just sixel-encoder' before
+ diagnosing rendering bugs.
+ - Bounded by `kitty-gfx-sixel-encoder-timeout' (default 5s).
- **Optional for Kitty**: ImageMagick for non-PNG formats and pixel-accurate sizing
- **Optional for typst preview**: `typst` CLI on PATH (used by
`kitty-gfx-typst-preview`)
diff --git a/CHANGELOG.org b/CHANGELOG.org
index 837968e..82e8c5b 100644
--- a/CHANGELOG.org
+++ b/CHANGELOG.org
@@ -51,9 +51,11 @@ I will keep on improving this feature. I think it is actually great eyecandy, an
**** tmux support
-tmux support is next. It already supports sixel, so the sixel backend will work there out of the box.
+The Sixel side is now unlocked: starting in =0.5.0=, =kitty-graphics= no longer hard-disables the Sixel backend when =$TMUX= is set. tmux 3.4 (released 2024-02-13) ships native Sixel rendering, so running Emacs inside =tmux new-session= under foot/Konsole/mintty/mlterm/WezTerm just works. The detector probes =tmux -V= once per session and only engages on tmux >= 3.4. A new option =kitty-gfx-tmux-allow-sixel= (default =t=) lets you opt out if your tmux build lacks =--enable-sixel=.
-There is also an in-progress branch adding [[https://github.com/tmux/tmux/tree/ta/kitty-img][kitty image protocol support to tmux]]. If you already use Kitty directly, though, I would stick with it. The kitty protocol gives you stateful image management, truecolor rendering, and a smoother overall experience.
+Caveat: tmux's cell buffer is not pixel-aware, so images may stick to their old position after scrolling until the affected cells are overwritten. That is an upstream tmux limitation, not something this package can fix.
+
+The Kitty graphics protocol still does not work inside tmux because we do not yet wrap APC sequences with the =\ePtmux;...\e\\= passthrough envelope. There is also an in-progress branch adding [[https://github.com/tmux/tmux/tree/ta/kitty-img][native Kitty image protocol support to tmux]]. Until either lands, if you already use Kitty directly I would stick with it -- the Kitty protocol gives you stateful image management, truecolor rendering, and a smoother overall experience.
**** Package renaming?
diff --git a/README.org b/README.org
index eb0ab62..258dde0 100644
--- a/README.org
+++ b/README.org
@@ -47,7 +47,11 @@ Integrations are provided for:
- A supported terminal:
- *Kitty backend*: [[https://sw.kovidgoyal.net/kitty/][Kitty]] >= 0.20.0, WezTerm, or Ghostty
- *Sixel backend*: foot, Konsole, xterm (with ~+sixel~), mlterm, mintty, VS Code Terminal, and others with Sixel support
-- ImageMagick (~magick~ / ~convert~ / ~identify~) --- required for Sixel, and for non-PNG formats on Kitty
+- A Sixel encoder on ~PATH~ --- /required/ for the Sixel backend.
+ - *Strongly recommended*: ~img2sixel~ from [[https://github.com/saitoha/libsixel][libsixel]] (Nix: ~nixpkgs#libsixel~). Roughly =2.2x= smaller payloads and =~10x= faster than ImageMagick, which matters a lot in tmux where every refresh re-emits the full DCS payload.
+ - *Fallback*: ImageMagick 7 (~magick~) or 6 (~convert~). Works, but slower; on long sessions and in tmux you may notice flicker on redraw.
+ - Override the auto-detect order via ~kitty-gfx-sixel-encoder-program~. If neither is on ~PATH~ the Sixel backend logs ~no encoder found~ and silently produces no image, so make sure one is installed before launching Emacs.
+- ImageMagick (~magick~ / ~identify~) --- still needed for non-PNG formats on the Kitty backend (JPEG/WebP/SVG/TIFF/BMP -> PNG conversion) and for the dimension probe
- For LaTeX preview: a TeX distribution with ~dvipng~ (e.g. ~texlive~)
- For doc-view: ~ghostscript~ (for PDF), ~dvipng~ (for DVI) --- same tools as GUI Emacs
- Launch Emacs with ~TERM=xterm-256color~ (Emacs often can't find the ~xterm-kitty~ terminfo)
@@ -143,10 +147,11 @@ TIFF, BMP) are converted to PNG via ImageMagick before transmission.
* Known Limitations
-- No tmux support (neither Kitty passthrough nor Sixel)
+- Partial tmux support: Sixel works inside tmux >= 3.4 (native sixel rendering, foot/Konsole/mintty/mlterm/WezTerm as outer terminal); set ~kitty-gfx-tmux-allow-sixel~ to ~nil~ to opt out. Images may stick to old positions after scrolling because tmux's cell buffer is not pixel-aware (upstream tmux limitation). Kitty graphics passthrough inside tmux is still unimplemented
- Animated GIFs display only the first frame
- Sixel is limited to 256 colors (vs truecolor on Kitty) and is stateless --- images are re-emitted on every scroll, which may be slower on large images
-- Without ImageMagick, only PNG files work on the Kitty backend; the Sixel backend requires ImageMagick unconditionally
+- The Sixel backend needs a Sixel encoder on ~PATH~. ~img2sixel~ (libsixel) is strongly recommended; ~magick~ / ~convert~ work as fallback but are noticeably slower. With no encoder on ~PATH~, the backend silently produces no output and only logs ~no encoder found~ to ~/tmp/kitty-gfx.log~ when ~kitty-gfx-debug~ is non-nil
+- Without ImageMagick, only PNG files work on the Kitty backend
- Doc-view page may briefly flash at wrong position before centering on initial load
* License
diff --git a/justfile b/justfile
index 22fe756..306290e 100644
--- a/justfile
+++ b/justfile
@@ -141,10 +141,33 @@ test-sixel-image encoder="":
@echo ">> Run inside foot, Konsole, mintty, mlterm, or WezTerm."
TERM={{TERM_}} {{EMACS}} -nw -Q -l {{SRC}} \
--eval "(setq kitty-gfx-debug t kitty-gfx-preferred-protocol 'sixel)" \
- $(if [ -n "{{encoder}}" ]; then echo "--eval (setq\\ kitty-gfx-sixel-encoder-program\\ \"{{encoder}}\")"; fi) \
+ --eval '(when (> (length "{{encoder}}") 0) (setq kitty-gfx-sixel-encoder-program "{{encoder}}"))' \
--eval "(kitty-graphics-mode 1)" \
tests/test-image.png
+# Open test-image.png inside tmux with sixel backend forced.
+# Outer terminal must be sixel-capable (foot, Konsole, mintty, mlterm, WezTerm).
+# Requires tmux >= 3.4 built with --enable-sixel.
+# When already inside tmux, runs emacs directly (no nesting).
+test-sixel-tmux encoder="":
+ #!/usr/bin/env bash
+ set -eu
+ if [ -n "${TMUX:-}" ]; then
+ echo ">> Already inside tmux -- running emacs directly in this pane."
+ exec env TERM={{TERM_}} {{EMACS}} -nw -Q -l {{SRC}} \
+ --eval '(setq kitty-gfx-debug t kitty-gfx-preferred-protocol (quote sixel))' \
+ --eval '(when (> (length "{{encoder}}") 0) (setq kitty-gfx-sixel-encoder-program "{{encoder}}"))' \
+ --eval '(kitty-graphics-mode 1)' \
+ tests/test-image.png
+ else
+ echo ">> Outer terminal must be sixel-capable; spawning fresh tmux session."
+ exec tmux new-session -As kgfx-sixel-test \
+ "TERM={{TERM_}} {{EMACS}} -nw -Q -l {{SRC}} \
+ --eval '(setq kitty-gfx-debug t kitty-gfx-preferred-protocol (quote sixel))' \
+ --eval '(when (> (length \"{{encoder}}\") 0) (setq kitty-gfx-sixel-encoder-program \"{{encoder}}\"))' \
+ --eval '(kitty-graphics-mode 1)' tests/test-image.png"
+ fi
+
# --- Logs -------------------------------------------------------------------
# Tail the kitty-gfx debug log (set kitty-gfx-debug to t to populate)
diff --git a/kitty-graphics.el b/kitty-graphics.el
index 640454b..adfe6b7 100644
--- a/kitty-graphics.el
+++ b/kitty-graphics.el
@@ -207,6 +207,17 @@ will otherwise block Emacs."
:type '(choice (const :tag "No timeout" nil) number)
:group 'kitty-graphics)
+(defcustom kitty-gfx-tmux-allow-sixel t
+ "When non-nil, allow the Sixel backend to engage inside tmux >= 3.4.
+tmux 3.4 (released 2024-02-13) ships native Sixel rendering, so this
+package no longer hard-disables Sixel under tmux. Set to nil if your
+tmux is built without `--enable-sixel' or if you prefer to avoid the
+upstream scroll artifact: tmux's cell buffer is not pixel-aware, so
+images may persist after scrolling until the affected cells are
+overwritten."
+ :type 'boolean
+ :group 'kitty-graphics)
+
(defcustom kitty-gfx-heading-scales '((1 . 2.0) (2 . 1.5) (3 . 1.2))
"Alist mapping org heading level to visual scale factor.
Headings at levels not listed use scale 1.0 (normal size).
@@ -588,19 +599,60 @@ OV is the overlay (unused by Kitty backend but part of the interface)."
(defvar kitty-gfx--sixel-cache (make-hash-table :test 'equal)
"Maps (file . dims-string) to temp sixel file paths.")
+(defvar kitty-gfx--tmux-version-cache 'unset
+ "Cached `kitty-gfx--tmux-version' result.
+Sentinel `unset' means the probe has not run yet; nil means tmux was
+absent or its version could not be parsed; otherwise a list (MAJOR MINOR).")
+
+(defun kitty-gfx--tmux-version ()
+ "Return tmux version as (MAJOR MINOR) integers, or nil when unavailable.
+Memoised in `kitty-gfx--tmux-version-cache'."
+ (when (eq kitty-gfx--tmux-version-cache 'unset)
+ (setq kitty-gfx--tmux-version-cache
+ (when (executable-find "tmux")
+ (with-temp-buffer
+ (when (zerop (ignore-errors
+ (call-process "tmux" nil t nil "-V")))
+ (goto-char (point-min))
+ (when (re-search-forward
+ "tmux\\(?:[[:space:]]+next-\\)?[[:space:]]+\\([0-9]+\\)\\.\\([0-9]+\\)"
+ nil t)
+ (list (string-to-number (match-string 1))
+ (string-to-number (match-string 2)))))))))
+ kitty-gfx--tmux-version-cache)
+
+(defun kitty-gfx--tmux-sixel-supported-p ()
+ "Return non-nil when running under tmux >= 3.4 with Sixel allowed.
+Returns nil outside tmux, nil when `kitty-gfx-tmux-allow-sixel' is off,
+nil when tmux's version cannot be determined, and nil for tmux < 3.4."
+ (and (getenv "TMUX")
+ kitty-gfx-tmux-allow-sixel
+ (let ((ver (kitty-gfx--tmux-version)))
+ (and ver
+ (or (> (car ver) 3)
+ (and (= (car ver) 3) (>= (cadr ver) 4)))))))
+
(defun kitty-gfx--sixel-detect ()
- "Return non-nil if the terminal likely supports Sixel protocol."
+ "Return non-nil if the terminal likely supports Sixel protocol.
+Inside tmux, requires tmux >= 3.4 (native Sixel rendering, 2024-02-13)
+and `kitty-gfx-tmux-allow-sixel'. Older tmux versions still disable
+Sixel because they drop the DCS payload."
(let* ((term (getenv "TERM"))
(term-prog (getenv "TERM_PROGRAM"))
(in-tmux (getenv "TMUX"))
+ (tmux-ver (and in-tmux (kitty-gfx--tmux-version)))
+ (tmux-ok (kitty-gfx--tmux-sixel-supported-p))
(supported (and term
- (not in-tmux) ; Sixel doesn't work in tmux
+ (or (not in-tmux) tmux-ok)
(or (string-match-p "xterm\\|vt[0-9]\\|foot\\|contour" term)
(member term-prog '("foot" "Konsole" "mintty" "mlterm"
"contour" "WezTerm")))
t)))
- (kitty-gfx--log "sixel-detect: %s (TERM=%s TERM_PROGRAM=%s TMUX=%s)"
- supported term term-prog (if in-tmux "yes" "no"))
+ (kitty-gfx--log
+ "sixel-detect: %s (TERM=%s TERM_PROGRAM=%s TMUX=%s tmux-ver=%s tmux-ok=%s)"
+ supported term term-prog (if in-tmux "yes" "no")
+ (if tmux-ver (format "%d.%d" (car tmux-ver) (cadr tmux-ver)) "n/a")
+ (if tmux-ok "yes" "no"))
supported))
(defun kitty-gfx--sixel-cache-path (file cols rows)
@@ -2114,6 +2166,19 @@ The buffer should be writable (caller handles `inhibit-read-only')."
(kitty-gfx--query-text-sizing-support))
(kitty-gfx--install-hooks)
(kitty-gfx--install-integrations)
+ ;; Sixel backend silently drops images when no encoder is on
+ ;; PATH. Warn loudly so users notice before they wonder why
+ ;; nothing renders.
+ (when (and (eq kitty-gfx--active-backend 'sixel)
+ (not (kitty-gfx--sixel-resolve-encoder)))
+ (kitty-gfx--log "mode: WARNING no Sixel encoder on PATH")
+ (display-warning
+ 'kitty-graphics
+ "Sixel backend active but no encoder on PATH.
+Install `img2sixel' (libsixel; strongly recommended) or
+ImageMagick (`magick'/`convert'). Without an encoder, no images
+will render even though detection reports Sixel as supported."
+ :warning))
(kitty-gfx--log "mode: enabled (backend=%s cell=%dx%d text-sizing=%s)"
kitty-gfx--active-backend
kitty-gfx--cell-pixel-width kitty-gfx--cell-pixel-height