feat(image): configurable templates for math expressions. Closes #1338

lua/snacks/image/doc.lua

@@ -41,13 +41,11 @@ M.transforms = {
     if not img.content then
       return
     end
-    local fg = Snacks.util.color("SnacksImageMath") or "#000000"
+    img.content = Snacks.picker.util.tpl(Snacks.image.config.math.typst.tpl, {
-    img.content = ([[
+      color = Snacks.util.color("SnacksImageMath") or "#000000",
-#set page(width: auto, height: auto, margin: (x: 2pt, y: 2pt))
+      header = M.get_header(ctx.buf),
-#show math.equation.where(block: false): set text(top-edge: "bounds", bottom-edge: "bounds")
+      content = img.content,
-#set text(size: 12pt, fill: rgb("%s"))
+    }, { indent = true, prefix = "$" })
-%s
-%s]]):format(fg, M.get_header(ctx.buf), img.content)
   end,
   latex = function(img, ctx)
     if not img.content then
@@ -62,7 +60,7 @@ M.transforms = {
       content = ("\\[%s\\]"):format(content)
     end
     local packages = { "xcolor" }
-    vim.list_extend(packages, Snacks.image.config.convert.math.packages)
+    vim.list_extend(packages, Snacks.image.config.math.latex.packages)
     for _, line in ipairs(vim.api.nvim_buf_get_lines(ctx.buf, 0, -1, false)) do
       if line:find("\\usepackage") then
         for _, p in ipairs(vim.split(line:match("{(.-)}") or "", ",%s*")) do
@@ -73,17 +71,13 @@ M.transforms = {
       end
     end
     table.sort(packages)
-    local fs = Snacks.image.config.convert.math.font_size or "large"
+    img.content = Snacks.picker.util.tpl(Snacks.image.config.math.latex.tpl, {
-    img.content = ([[
+      font_size = Snacks.image.config.math.latex.font_size or "large",
-\documentclass[preview,border=2pt,varwidth,12pt]{standalone}
+      packages = table.concat(packages, ", "),
-\usepackage{%s}
+      header = M.get_header(ctx.buf),
-\begin{document}
+      color = fg:upper():sub(2),
-%s
+      content = content,
-{ \%s \selectfont
+    }, { indent = true, prefix = "$" })
-  \color[HTML]{%s}
-%s}
-\end{document}
-    ]]):format(table.concat(packages, ", "), M.get_header(ctx.buf), fs, fg:upper():sub(2), content)
   end,
 }
 
@@ -233,7 +227,7 @@ function M._img(ctx)
   if img.src then
     img.src = M.resolve(ctx.buf, img.src)
   end
-  if not Snacks.image.config.doc.math and img.ext and img.ext:find("math") then
+  if not Snacks.image.config.math.enabled and img.ext and img.ext:find("math") then
     return
   end
   if img.content and not img.src then

lua/snacks/image/init.lua

@@ -68,7 +68,6 @@ local defaults = {
     -- enable image viewer for documents
     -- a treesitter parser must be available for the enabled languages.
     enabled = true,
-    math = true, -- enable math expression rendering
     -- render the image inline in the buffer
     -- if your env doesn't support unicode placeholders, this will be disabled
     -- takes precedence over `opts.float` on supported terminals
@@ -105,12 +104,6 @@ local defaults = {
   ---@class snacks.image.convert.Config
   convert = {
     notify = true, -- show a notification on error
-    math = {
-      font_size = "Large", -- see https://www.sascha-frank.com/latex-font-size.html
-      -- for latex documents, the doc packages are included automatically,
-      -- but you can add more packages here. Useful for markdown documents.
-      packages = { "amsmath", "amssymb", "amsfonts", "amscd", "mathtools" },
-    },
     ---@type snacks.image.args
     mermaid = function()
       local theme = vim.o.background == "light" and "neutral" or "dark"
@@ -124,6 +117,36 @@ local defaults = {
       pdf = { "-density", 192, "{src}[0]", "-background", "white", "-alpha", "remove", "-trim" },
     },
   },
+  math = {
+    enabled = true, -- enable math expression rendering
+    -- in the templates below, `${header}` comes from any section in your document,
+    -- between a start/end header comment. Comment syntax is language-specific.
+    -- * start comment: `// snacks: header start`
+    -- * end comment:   `// snacks: header end`
+    typst = {
+      tpl = [[
+        #set page(width: auto, height: auto, margin: (x: 2pt, y: 2pt))
+        #show math.equation.where(block: false): set text(top-edge: "bounds", bottom-edge: "bounds")
+        #set text(size: 12pt, fill: rgb("${color}"))
+        ${header}
+        ${content}]],
+    },
+    latex = {
+      font_size = "Large", -- see https://www.sascha-frank.com/latex-font-size.html
+      -- for latex documents, the doc packages are included automatically,
+      -- but you can add more packages here. Useful for markdown documents.
+      packages = { "amsmath", "amssymb", "amsfonts", "amscd", "mathtools" },
+      tpl = [[
+        \documentclass[preview,border=2pt,varwidth,12pt]{standalone}
+        \usepackage{${packages}}
+        \begin{document}
+        ${header}
+        { \${font_size} \selectfont
+          \color[HTML]{${color}}
+        ${content}}
+        \end{document}]],
+    },
+  },
 }
 M.config = Snacks.config.get("image", defaults)
 

lua/snacks/picker/util/init.lua

@@ -172,13 +172,15 @@ end
 
 ---@param str string
 ---@param data table<string, string>
-function M.tpl(str, data)
+---@param opts? {prefix?: string, indent?: boolean, offset?: number[]}
-  return (
+function M.tpl(str, data, opts)
+  opts = opts or {}
+  local ret = (
     str:gsub(
-      "(%b{})",
+      "(" .. vim.pesc(opts.prefix or "") .. "%b{}" .. ")",
       ---@param w string
       function(w)
-        local inner = w:sub(2, -2)
+        local inner = w:sub(2 + #(opts.prefix or ""), -2)
         local key, default = inner:match("^(.-):(.*)$")
         local ret = data[key or inner]
         if ret == "" and default then
@@ -188,6 +190,17 @@ function M.tpl(str, data)
       end
     )
   )
+  if opts.indent then
+    local lines = vim.split(ret:gsub("\t", "  "), "\n", { plain = true })
+    local indent = 1000
+    for _, line in ipairs(lines) do
+      indent = math.min(indent, line:find("%S") or 1000)
+    end
+    for l, line in ipairs(lines) do
+      lines[l] = line:sub(indent)
+    end
+  end
+  return ret
 end
 
 ---@param str string