From 7bd9dbecdcbaaf7441cee57362f950d1409b3f9a Mon Sep 17 00:00:00 2001
From: Christophe Dervieux <christophe.dervieux@gmail.com>
Date: Tue, 24 Feb 2026 14:13:18 +0100
Subject: [PATCH] Revealjs writer: default scrollProgress to 'auto'.

RevealJS defaults scrollProgress to 'auto', but the writer was
setting it to true.  Use lookupMeta to distinguish between
MetaBool True, MetaBool False, and unset (defaulting to 'auto').
The template uses a helper variable scrollProgressAuto since
pandoc templates cannot distinguish a MetaString "auto" from
MetaBool True in a single variable.
---
 data/templates/default.revealjs    |  6 +++++
 src/Text/Pandoc/Writers/HTML.hs    |  6 ++++-
 test/command/11486.md              | 40 ++++++++++++++++++++++++++++++
 test/command/11486/scroll.revealjs |  7 ++++++
 4 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/data/templates/default.revealjs b/data/templates/default.revealjs
index 95fe80cc5..0fc4464f1 100644
--- a/data/templates/default.revealjs
+++ b/data/templates/default.revealjs
@@ -243,7 +243,13 @@ $if(view)$
         // Enable scroll view
         view: '$view/nowrap$',
         // see https://revealjs.com/scroll-view/#scrollbar
+$if(scrollProgressAuto)$
+        scrollProgress: 'auto',
+$elseif(scrollProgress)$
         scrollProgress: $scrollProgress$,
+$else$
+        scrollProgress: false,
+$endif$
         // see https://revealjs.com/scroll-view/#url-activation
         scrollActivationWidth: $scrollActivationWidth$,
         // see https://revealjs.com/scroll-view/#scroll-snapping
diff --git a/src/Text/Pandoc/Writers/HTML.hs b/src/Text/Pandoc/Writers/HTML.hs
index 026d6ed4c..944794107 100644
--- a/src/Text/Pandoc/Writers/HTML.hs
+++ b/src/Text/Pandoc/Writers/HTML.hs
@@ -434,7 +434,11 @@ pandocToHtml opts (Pandoc meta blocks) = do
                          defField "backgroundTransition" ("fade" :: Doc Text) .
                          defField "viewDistance" ("3" :: Doc Text) .
                          defField "mobileViewDistance" ("2" :: Doc Text) .
-                         defField "scrollProgress" True .
+                         (case lookupMeta "scrollProgress" meta of
+                            Just (MetaBool False) -> id
+                            Just (MetaBool True)  ->
+                              defField "scrollProgress" True
+                            _  -> defField "scrollProgressAuto" True) .
                          defField "scrollActivationWidth" ("0" :: Doc Text) .
                          defField "scrollSnap" ("mandatory" :: Doc Text) .
                          defField "scrollLayout" ("full" :: Doc Text) .
diff --git a/test/command/11486.md b/test/command/11486.md
index 60edb50fd..4496586b7 100644
--- a/test/command/11486.md
+++ b/test/command/11486.md
@@ -6,6 +6,7 @@ view: scroll
 ^D
         scrollActivationWidth: 0,
         scrollSnap: 'mandatory',
+        scrollProgress: 'auto',
 ```
 
 ```
@@ -17,6 +18,7 @@ scrollSnap: false
 ^D
         scrollActivationWidth: 0,
         scrollSnap: false,
+        scrollProgress: 'auto',
 ```
 
 ```
@@ -28,6 +30,7 @@ scrollSnap: proximity
 ^D
         scrollActivationWidth: 0,
         scrollSnap: 'proximity',
+        scrollProgress: 'auto',
 ```
 
 ```
@@ -39,4 +42,41 @@ scrollActivationWidth: 500
 ^D
         scrollActivationWidth: 500,
         scrollSnap: 'mandatory',
+        scrollProgress: 'auto',
+```
+
+```
+% pandoc -t revealjs --template=command/11486/scroll.revealjs
+---
+view: scroll
+scrollProgress: true
+---
+^D
+        scrollActivationWidth: 0,
+        scrollSnap: 'mandatory',
+        scrollProgress: true,
+```
+
+```
+% pandoc -t revealjs --template=command/11486/scroll.revealjs
+---
+view: scroll
+scrollProgress: false
+---
+^D
+        scrollActivationWidth: 0,
+        scrollSnap: 'mandatory',
+        scrollProgress: false,
+```
+
+```
+% pandoc -t revealjs --template=command/11486/scroll.revealjs
+---
+view: scroll
+scrollProgress: auto
+---
+^D
+        scrollActivationWidth: 0,
+        scrollSnap: 'mandatory',
+        scrollProgress: 'auto',
 ```
diff --git a/test/command/11486/scroll.revealjs b/test/command/11486/scroll.revealjs
index edffebe5b..5d4296cbf 100644
--- a/test/command/11486/scroll.revealjs
+++ b/test/command/11486/scroll.revealjs
@@ -5,4 +5,11 @@ $if(scrollSnap)$
 $else$
         scrollSnap: false,
 $endif$
+$if(scrollProgressAuto)$
+        scrollProgress: 'auto',
+$elseif(scrollProgress)$
+        scrollProgress: $scrollProgress$,
+$else$
+        scrollProgress: false,
+$endif$
 $endif$