feat: add remote image support and integrate it with markdown

lua/image/image.lua

@@ -148,6 +148,51 @@ local from_file = function(path, options, state)
   return create_image(path, options, state)
 end
 
+---@param url string
+---@param options? ImageOptions
+---@param callback fun(image: Image|nil)
+---@param state State
+local from_url = function(url, options, callback, state)
+  if state.remote_cache[url] then
+    callback(state.remote_cache[url])
+    return
+  end
+
+  local tmp_path = os.tmpname() .. ".png"
+  local stdout = vim.loop.new_pipe()
+
+  vim.loop.spawn("curl", {
+    args = { "-s", "-o", tmp_path, url },
+    stdio = { nil, stdout, nil },
+    hide = true,
+  }, function(code, signal)
+    if code ~= 0 then
+      utils.throw("image: curl errored while downloading " .. url, {
+        code = code,
+        signal = signal,
+      })
+    end
+  end)
+
+  vim.loop.read_start(stdout, function(err, data)
+    assert(not err, err)
+    if not data then utils.debug("image: downloaded " .. url .. " to " .. tmp_path) end
+    local ok = pcall(utils.png.get_dimensions, tmp_path)
+    if not ok then
+      utils.debug("image: invalid png file", tmp_path)
+      callback(nil)
+      return
+    end
+
+    vim.defer_fn(function()
+      local image = create_image(tmp_path, options, state)
+      state.remote_cache[url] = image
+      callback(image)
+    end, 0)
+  end)
+end
+
 return {
   from_file = from_file,
+  from_url = from_url,
 }

lua/image/init.lua

@@ -26,6 +26,7 @@ local state = {
   options = default_options,
   images = {},
   extmarks_namespace = nil,
+  remote_cache = {},
 }
 
 ---@type API
@@ -61,7 +62,7 @@ api.setup = function(options)
   local window_history = {}
   vim.api.nvim_set_decoration_provider(state.extmarks_namespace, {
     on_win = function(_, winid, bufnr, topline, botline)
-      -- utils.debug("on_win", { winid = winid })
+      utils.debug("on_win", { winid = winid })
 
       local prev = window_history[winid]
       if not prev then
@@ -174,6 +175,13 @@ api.from_file = function(path, options)
   return image.from_file(path, options, state)
 end
 
+---@param url string
+---@param options? ImageOptions
+---@param callback fun(image: Image|nil)
+api.from_url = function(url, options, callback)
+  image.from_url(url, options, callback, state)
+end
+
 ---@param id? string
 api.clear = function(id)
   local target = state.images[id]

lua/image/integrations/markdown.lua

@@ -1,13 +1,17 @@
 local utils = require("image/utils")
 
-local resolve = function(markdown_file_path, image_path)
+local resolve_absolute_path = function(markdown_file_path, image_path)
   if string.sub(image_path, 1, 1) == "/" then return image_path end
   local markdown_dir = vim.fn.fnamemodify(markdown_file_path, ":h")
   local absolute_image_path = markdown_dir .. "/" .. image_path
   absolute_image_path = vim.fn.fnamemodify(absolute_image_path, ":p")
   return absolute_image_path
 end
 
+local is_remote_url = function(url)
+  return string.sub(url, 1, 7) == "http://" or string.sub(url, 1, 8) == "https://"
+end
+
 ---@return { node: any, range: { start_row: number, start_col: number, end_row: number, end_col: number }, url: string }[]
 local query_buffer_images = function(buffer)
   local buf = buffer or vim.api.nvim_get_current_buf()
@@ -57,13 +61,11 @@ local render = function(ctx)
       local file_path = vim.api.nvim_buf_get_name(window.buffer)
 
       for _, match in ipairs(matches) do
-        local url = resolve(file_path, match.url)
-
-        local ok = pcall(utils.png.get_dimensions, url)
-        if ok then
-          local id = string.format("%d:%d:%d", window.id, window.buffer, match.range.start_row)
-          local height = nil
+        local id = string.format("%d:%d:%d", window.id, window.buffer, match.range.start_row)
+        local height = nil
 
+        ---@param image Image
+        local render_image = function(image)
           if ctx.options.sizing_strategy == "height-from-empty-lines" then
             local empty_line_count = -1
             for i = match.range.end_row + 2, #lines do
@@ -75,19 +77,37 @@ local render = function(ctx)
             end
             height = math.max(1, empty_line_count)
           end
-
-          local image = ctx.api.from_file(url, {
-            id = id,
+          image.render({
             height = height,
             x = match.range.start_col,
             y = match.range.start_row + 1,
+          })
+          table.insert(new_image_ids, id)
+        end
+
+        -- remote
+        if is_remote_url(match.url) then
+          ctx.api.from_url(
+            match.url,
+            { id = id, window = window.id, buffer = window.buffer, with_virtual_padding = true },
+            function(image)
+              if not image then return end
+              render_image(image)
+            end
+          )
+        else
+          -- local
+          local url = resolve_absolute_path(file_path, match.url)
+
+          local ok = pcall(utils.png.get_dimensions, url)
+          if not ok then return end
+          local image = ctx.api.from_file(url, {
+            id = id,
             window = window.id,
             buffer = window.buffer,
             with_virtual_padding = true,
           })
-          image.render()
-
-          table.insert(new_image_ids, id)
+          render_image(image)
         end
       end
 

lua/types.lua

@@ -3,6 +3,7 @@
 ---@class API
 ---@field setup fun(options?: Options)
 ---@field from_file fun(path: string, options?: ImageOptions): Image
+---@field from_url fun(url: string, options?: ImageOptions, callback: fun(image: Image| nil))
 ---@field clear fun(id?: string)
 ---@field get_images fun(opts?: { window?: number, buffer?: number }): Image[]
 
@@ -11,6 +12,7 @@
 ---@field options Options
 ---@field images { [string]: Image }
 ---@field extmarks_namespace any
+---@field remote_cache { [string]: Image }
 
 ---@class MarkdownIntegrationOptions
 ---@field enabled boolean