[dynamic] Use dvipng instead of ImageMagick

2 files changed, 6 insertions, 8 deletions

diff --git a/haunt/README.md b/haunt/README.md
index 6aff7c3..a20189a 100644
--- a/haunt/README.md
+++ b/haunt/README.md
@@ -83,7 +83,7 @@ Before running the API server, the following databases will need to be created:
 - GNU Guile `>= 2.2.7`
 - `guile-gcrypt >= 0.3.0`
 - `guile-json >= 4.7.2`
-- `imagemagick`
+- `latex` and `dvipng`
 - PostgreSQL `>= 14.0`
 
 [squee](https://notabug.org/cwebber/guile-squee/) is currently vendored at `haunt/squee.scm`.
diff --git a/haunt/jakob/dynamic/captcha.scm b/haunt/jakob/dynamic/captcha.scm
index b71bb23..d8b3d56 100644
--- a/haunt/jakob/dynamic/captcha.scm
+++ b/haunt/jakob/dynamic/captcha.scm
@@ -203,13 +203,11 @@ internally-defined `time-to-live-seconds'."
 \\end{varwidth}
 \\end{document}
 " src)))
-    (unless (eqv? 0 (status:exit-val (system "pdflatex formula.tex")))
-      (error "Cannot generate PDF" #f))
-    (let* ((port (open-input-pipe "convert -density 300 formula.pdf -quality 90 png:-"))
-           (data (get-bytevector-all port)))
-      (unless (eqv? 0 (status:exit-val (close-pipe port)))
-          (error "Cannot generate PNG" #f))
-      data)))
+    (unless (eqv? 0 (status:exit-val (system "latex formula.tex")))
+      (error "Cannot generate DVI" #f))
+    (unless (eqv? 0 (status:exit-val (system "dvipng -D 300 formula.dvi")))
+      (error "Cannot generate PNG" #f))
+    (call-with-input-file "formula1.png" get-bytevector-all)))
 
 (define (new-captcha!)
   (let* ((lower-bound (random 10))