From b5393e8bdcf704f660fa86cace89033c5fc95504 Mon Sep 17 00:00:00 2001
From: nolbap <61060256+nolbap@users.noreply.github.com>
Date: Fri, 17 Nov 2023 13:02:09 -0300
Subject: [PATCH] feat: add LaTex rendering for inline equations (#1133)

This commit adds `image.nvim` integration as well as latex rendering integration into Neorg.
---
 lua/neorg/modules/core/defaults/module.lua    |   4 +-
 .../core/integrations/image/module.lua        |  55 +++++
 .../modules/core/latex/renderer/module.lua    | 219 ++++++++++++++++++
 3 files changed, 277 insertions(+), 1 deletion(-)
 create mode 100644 lua/neorg/modules/core/integrations/image/module.lua
 create mode 100644 lua/neorg/modules/core/latex/renderer/module.lua

diff --git a/lua/neorg/modules/core/defaults/module.lua b/lua/neorg/modules/core/defaults/module.lua
index c1dcc0f90..9e433b542 100644
--- a/lua/neorg/modules/core/defaults/module.lua
+++ b/lua/neorg/modules/core/defaults/module.lua
@@ -34,6 +34,7 @@ return modules.create_meta(
     "core.esupports.indent",
     "core.esupports.metagen",
     "core.integrations.treesitter",
+    "core.integrations.image",
     "core.itero",
     "core.journal",
     "core.keybinds",
@@ -46,5 +47,6 @@ return modules.create_meta(
     "core.qol.todo_items",
     "core.storage",
     "core.tangle",
-    "core.upgrade"
+    "core.upgrade",
+    "core.latex.renderer"
 )
diff --git a/lua/neorg/modules/core/integrations/image/module.lua b/lua/neorg/modules/core/integrations/image/module.lua
new file mode 100644
index 000000000..b5f86e9ac
--- /dev/null
+++ b/lua/neorg/modules/core/integrations/image/module.lua
@@ -0,0 +1,55 @@
+local neorg = require("neorg.core")
+local module = neorg.modules.create("core.integrations.image")
+
+module.load = function()
+    local success, image = pcall(require, "image")
+
+    assert(success, "Unable to load image.nvim plugin")
+
+    module.private.image = image
+end
+
+module.private = {
+    image = nil,
+}
+
+module.public = {
+    new_image = function(buffernr, png_path, position, window, scale, virtual_padding)
+        local geometry = {
+            x = position.column_start,
+            y = position.row_start + (virtual_padding and 1 or 0),
+            width = position.column_end - position.column_start,
+            height = scale,
+        }
+        local image = require("image").from_file(png_path, {
+            window = window,
+            buffer = buffernr,
+            with_virtual_padding = virtual_padding,
+        })
+        image:render(geometry)
+    end,
+    get_images = function()
+        return (require("image").get_images())
+    end,
+    render = function(images)
+        for _, image in pairs(images) do
+            image:clear()
+            image:render()
+        end
+    end,
+    clear = function()
+        local images = module.public.get_images()
+        for _, image in pairs(images) do
+            image:clear()
+        end
+    end,
+    clear_at_cursor = function(images, row)
+        for _, image in pairs(images) do
+            if image.geometry.y == row then
+                image:clear()
+            end
+        end
+    end,
+}
+
+return module
diff --git a/lua/neorg/modules/core/latex/renderer/module.lua b/lua/neorg/modules/core/latex/renderer/module.lua
new file mode 100644
index 000000000..2394ef122
--- /dev/null
+++ b/lua/neorg/modules/core/latex/renderer/module.lua
@@ -0,0 +1,219 @@
+local neorg = require("neorg.core")
+local module = neorg.modules.create("core.latex.renderer")
+local modules = neorg.modules
+
+assert(vim.re ~= nil, "Neovim 0.10.0+ is required to run the `core.renderer.latex` module! ")
+
+module.setup = function()
+    return {
+        requires = {
+            "core.integrations.treesitter",
+            "core.autocommands",
+            "core.neorgcmd",
+        },
+    }
+end
+
+module.load = function()
+    local success, image = pcall(neorg.modules.get_module, module.config.public.renderer)
+
+    assert(success, "Unable to load image module")
+
+    module.private.image = image
+
+    module.required["core.autocommands"].enable_autocommand("BufWinEnter")
+    module.required["core.autocommands"].enable_autocommand("CursorMoved")
+    module.required["core.autocommands"].enable_autocommand("TextChanged")
+    module.required["core.autocommands"].enable_autocommand("TextChangedI")
+    module.required["core.autocommands"].enable_autocommand("TextChangedP")
+    module.required["core.autocommands"].enable_autocommand("TextChangedT")
+
+    modules.await("core.neorgcmd", function(neorgcmd)
+        neorgcmd.add_commands_from_table({
+            ["render-latex"] = {
+                name = "core.latex.renderer.render",
+                args = 0,
+                condition = "norg",
+            },
+        })
+    end)
+end
+
+module.public = {
+    latex_renderer = function()
+        Ranges = {}
+        module.required["core.integrations.treesitter"].execute_query(
+            [[
+                (
+                    (inline_math) @latex
+                    (#offset! @latex 0 1 0 -1)
+                )
+            ]],
+            function(query, id, node)
+                if query.captures[id] ~= "latex" then
+                    return
+                end
+
+                local latex_snippet =
+                    module.required["core.integrations.treesitter"].get_node_text(node, vim.api.nvim_get_current_buf())
+
+                local png_location = module.public.parse_latex(latex_snippet)
+
+                module.private.image.new_image(
+                    vim.api.nvim_get_current_buf(),
+                    png_location,
+                    module.required["core.integrations.treesitter"].get_node_range(node),
+                    vim.api.nvim_get_current_win(),
+                    module.config.public.scale,
+                    not module.config.public.conceal
+                )
+
+                table.insert(Ranges, { node:range() })
+            end
+        )
+        Images = module.private.image.get_images()
+    end,
+    create_latex_document = function(snippet)
+        local tempname = vim.fn.tempname()
+
+        local tempfile = io.open(tempname, "w")
+
+        if not tempfile then
+            return
+        end
+
+        local content = table.concat({
+            "\\documentclass[6pt]{standalone}",
+            "\\usepackage{amsmath}",
+            "\\usepackage{amssymb}",
+            "\\usepackage{graphicx}",
+            "\\begin{document}",
+            snippet,
+            "\\end{document}",
+        }, "\n")
+
+        tempfile:write(content)
+        tempfile:close()
+
+        return tempname
+    end,
+
+    -- Returns a handle to an image containing
+    -- the rendered snippet.
+    -- This handle can then be delegated to an external renderer.
+    parse_latex = function(snippet)
+        local document_name = module.public.create_latex_document(snippet)
+
+        if not document_name then
+            return
+        end
+
+        local cwd = vim.fn.fnamemodify(document_name, ":h")
+        vim.fn.jobwait({
+            vim.fn.jobstart(
+                "latex  --interaction=nonstopmode --output-dir=" .. cwd .. " --output-format=dvi " .. document_name,
+                { cwd = cwd }
+            ),
+        })
+
+        local png_result = vim.fn.tempname()
+        -- TODO: Make the conversions async via `on_exit`
+        vim.fn.jobwait({
+            vim.fn.jobstart(
+                "dvipng -D "
+                    .. tostring(module.config.public.dpi)
+                    .. " -T tight -bg Transparent -fg 'cmyk 0.00 0.04 0.21 0.02' -o "
+                    .. png_result
+                    .. " "
+                    .. document_name
+                    .. ".dvi",
+                { cwd = vim.fn.fnamemodify(document_name, ":h") }
+            ),
+        })
+
+        return png_result
+    end,
+    render_inline_math = function(images)
+        local conceal_on = (vim.wo.conceallevel >= 2) and module.config.public.conceal
+        if conceal_on then
+            table.sort(images, function(a, b)
+                return a.internal_id < b.internal_id
+            end)
+
+            for i, range in ipairs(Ranges) do
+                vim.api.nvim_buf_set_extmark(
+                    vim.api.nvim_get_current_buf(),
+                    vim.api.nvim_create_namespace("concealer"),
+                    range[1],
+                    range[2],
+                    {
+                        id = i,
+                        end_col = range[4],
+                        conceal = "",
+                        virt_text = { { (" "):rep(images[i].rendered_geometry.width) } },
+                        virt_text_pos = "inline",
+                    }
+                )
+            end
+        end
+    end,
+}
+
+module.config.public = {
+    -- TODO: Documentation
+    conceal = true,
+    dpi = 350,
+    render_on_enter = false,
+    renderer = "core.integrations.image",
+    scale = 1,
+}
+
+local function render_latex()
+    module.private.image.clear(Images)
+    neorg.modules.get_module("core.latex.renderer").latex_renderer()
+    neorg.modules.get_module("core.latex.renderer").render_inline_math(Images)
+end
+
+local function clear_latex()
+    module.private.image.clear(Images)
+end
+
+local function clear_at_cursor()
+    if Images ~= nil then
+        module.private.image.render(Images)
+        module.private.image.clear_at_cursor(Images, vim.api.nvim_win_get_cursor(0)[1] - 1)
+    end
+end
+
+local event_handlers = {
+    ["core.neorgcmd.events.core.latex.renderer.render"] = render_latex,
+    ["core.autocommands.events.bufwinenter"] = render_latex,
+    ["core.autocommands.events.cursormoved"] = clear_at_cursor,
+    ["core.autocommands.events.textchanged"] = clear_latex,
+    ["core.autocommands.events.textchangedi"] = clear_latex,
+    ["core.autocommands.events.textchangedp"] = clear_latex,
+    ["core.autocommands.events.textchangedt"] = clear_latex,
+}
+
+module.on_event = function(event)
+    if event.referrer == "core.autocommands" and vim.bo[event.buffer].ft ~= "norg" then
+        return
+    end
+
+    return event_handlers[event.type](event)
+end
+
+module.events.subscribed = {
+    ["core.autocommands"] = {
+        bufwinenter = module.config.public.render_on_enter,
+        cursormoved = true,
+        textchanged = true,
+        textchangedi = true,
+        textchangedp = true,
+        textchangedt = true,
+    },
+    ["core.neorgcmd"] = {
+        ["core.latex.renderer.render"] = true,
+    },
+}
+return module