From 8ca12b2a0f11ad124c828a79c8edb0f828b15ffc Mon Sep 17 00:00:00 2001
From: Carlos Scheidegger <carlos.scheidegger@rstudio.com>
Date: Mon, 19 May 2025 10:54:54 -0400
Subject: [PATCH 1/2] beamer - convert PanelLayouts to column div structure
 (#12775)

---
 news/changelog-1.8.md                     |  4 +++
 src/resources/filters/common/layout.lua   |  3 --
 src/resources/filters/common/validate.lua |  4 +--
 src/resources/filters/layout/latex.lua    | 36 +++++++++++++++++++++--
 4 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/news/changelog-1.8.md b/news/changelog-1.8.md
index 8d8b3e2065..98c02ea195 100644
--- a/news/changelog-1.8.md
+++ b/news/changelog-1.8.md
@@ -30,6 +30,10 @@ All changes included in 1.8:
 - ([#12554](https://github.com/quarto-dev/quarto-cli/pull/12554)): CSS properties `font-weight` and `font-style` are translated to Typst `text` properties.
 - ([#12739](https://github.com/quarto-dev/quarto-cli/pull/12739)): Remove unused variable `heading-background-color` and `heading-decoration` from Typst's templates. They are leftover from previous change, and not part of Brand.yml schema for typography of headings.
 
+### `beamer`
+
+- ([#12775](https://github.com/quarto-dev/quarto-cli/issues/12775)): Convert Quarto-native layouts (divs with `layout` syntax) to Beamer columns, equivalent to using the Pandoc-native syntax of div with `columns` and `column` classes.
+
 ## Projects
 
 ### `website`
diff --git a/src/resources/filters/common/layout.lua b/src/resources/filters/common/layout.lua
index c50e5561f0..3931c34d07 100644
--- a/src/resources/filters/common/layout.lua
+++ b/src/resources/filters/common/layout.lua
@@ -11,12 +11,9 @@ function layout_align_attribute(el_with_attr, default)
   return validatedAlign(el_with_attr.attributes[kLayoutAlign], default)
 end
 
--- now unused. Remove?
--- luacov: disable
 function layout_valign_attribute(el_with_attr, default)
   return validatedVAlign(el_with_attr.attributes[kLayoutVAlign] or default)
 end
--- luacov: enable
 
 function attr_has_layout_attributes(attr)
   local attribs = tkeys(attr.attributes)
diff --git a/src/resources/filters/common/validate.lua b/src/resources/filters/common/validate.lua
index 7e6cfab681..ef4fd9c527 100644
--- a/src/resources/filters/common/validate.lua
+++ b/src/resources/filters/common/validate.lua
@@ -1,14 +1,14 @@
 -- validate.lua
 -- Copyright (C) 2020-2022 Posit Software, PBC
 
-kAlignments = pandoc.List({ "center", "left", "right" })
-kVAlignments = pandoc.List({"top", "center", "bottom"})
 
 function validatedAlign(align, default)
+  local kAlignments = pandoc.List({ "center", "left", "right" })
   return validateInList(align, kAlignments, "alignment", default)
 end
 
 function validatedVAlign(vAlign)
+  local kVAlignments = pandoc.List({"top", "top-baseline", "center", "bottom"})
   return validateInList(vAlign, kVAlignments, "vertical alignment", "top")
 end
 
diff --git a/src/resources/filters/layout/latex.lua b/src/resources/filters/layout/latex.lua
index 6660e70a44..e5bce66ba4 100644
--- a/src/resources/filters/layout/latex.lua
+++ b/src/resources/filters/layout/latex.lua
@@ -4,7 +4,7 @@ kSideCaptionEnv = 'sidecaption'
 
 _quarto.ast.add_renderer("PanelLayout", function(_)
   return _quarto.format.isLatexOutput()
-end, function(layout)
+end, function (layout)
   local rendered_panel = latexPanel(layout)
   local preamble = layout.preamble
   if preamble == nil then
@@ -18,9 +18,41 @@ end, function(layout)
   return result
 end)
 
+_quarto.ast.add_renderer("PanelLayout", function(_)
+  return _quarto.format.isBeamerOutput()
+end, function(panel)
+  local result = pandoc.Blocks({})
+  if panel.preamble then
+    panel_insert_preamble(result, panel.preamble)
+  end
+
+  for i, row in ipairs(panel.layout) do
+    local beamer_cols = pandoc.Div({}, pandoc.Attr("", { "columns" }))
+    for j, cell in ipairs(row) do
+      local attrs = {}
+      local align = nil
+      -- NB: column "align" in beamer is "valign" in our layouts
+      if cell.attributes["valign"] then
+        align = cell.attributes["valign"]
+      end
+      if cell.attributes["width"] then
+        attrs.width = cell.attributes["width"]
+      end
+      if align then
+        attrs.align = align
+      end
+      local beamer_col = pandoc.Div({}, pandoc.Attr(cell.identifier, { "column" }, attrs))
+      beamer_col.content:extend(cell.content)
+      beamer_cols.content:insert(beamer_col)
+    end
+    result:insert(beamer_cols)
+  end
+
+  return result
+end)
+
 -- function latexPanel(divEl, layout, caption)
 function latexPanel(layout)
-  
   -- begin container
   local env, pos = latexPanelEnv(layout)
   local panel_node, panel = quarto.LatexEnvironment({

From 4ef2c65a27a9f9df13877e8545ae14c14d86b061 Mon Sep 17 00:00:00 2001
From: Carlos Scheidegger <carlos.scheidegger@rstudio.com>
Date: Mon, 19 May 2025 10:56:46 -0400
Subject: [PATCH 2/2] regression test

---
 tests/docs/smoke-all/2025/05/19/issue-12775.qmd | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 tests/docs/smoke-all/2025/05/19/issue-12775.qmd

diff --git a/tests/docs/smoke-all/2025/05/19/issue-12775.qmd b/tests/docs/smoke-all/2025/05/19/issue-12775.qmd
new file mode 100644
index 0000000000..4dfd33f99c
--- /dev/null
+++ b/tests/docs/smoke-all/2025/05/19/issue-12775.qmd
@@ -0,0 +1,17 @@
+---
+title: "title"
+date: last-modified
+format: beamer
+---
+
+## slide
+
+::::::{layout="[48, 48]"}
+:::{#first-column valign="bottom"}
+hallo
+:::
+:::{#second-column valign="top-baseline"}
+### a block title
+du
+:::
+::::::