Question about rendering floating window

[solomonwzs]

Hello.

I write a vim function to create a floating window like this:

function! lib#debug#popup()
  let lines = ['# abc', '## 123', '---', 'hello world']
  let buf = nvim_create_buf(v:true, v:true)
  call nvim_buf_set_lines(buf, 0, -1, v:false, lines)
  call setbufvar(buf, '&buftype', 'nofile')
  call setbufvar(buf, '&filetype', 'markdown')

  let win = nvim_open_win(buf, v:false, {
      \ 'width': 20,
      \ 'height': 10,
      \ 'col': 0,
      \ 'row': 1,
      \ 'relative': 'cursor',
      \ })
endfunction

But when I call the function in command mode like this call lib#debug#popup(), the floating window was not rendered,

until the curror entered the floating window, it was rendered:

How should I fixed the problem?

[MeanderingProgrammer]

Set the filetype after opening the buffer in a window:

function! lib#debug#popup()
  let lines = ['# abc', '## 123', '---', 'hello world']
  let buf = nvim_create_buf(v:true, v:true)
  call nvim_buf_set_lines(buf, 0, -1, v:false, lines)

  let win = nvim_open_win(buf, v:false, {
      \ 'width': 20,
      \ 'height': 10,
      \ 'col': 0,
      \ 'row': 1,
      \ 'relative': 'cursor',
      \ })

  call setbufvar(buf, '&buftype', 'nofile')
  call setbufvar(buf, '&filetype', 'markdown')
endfunction

You can keep the buftype where it is, I just moved both of them for consistency.

[solomonwzs]

Thank you for your response.

By the way, does render-markdown.nvim provide a similar rendering function like this:
input: ['# abc', '## 123', '---', 'hello world'],
output: ['󰲡 abc', ' 󰲣 123', '────────────────', 'hello world'].

[MeanderingProgrammer]

No, the plugin works at a buffer + window level, not over a list of strings.

The plugin doesn't modify text, it applies extmarks to add decorations. So when adding something like the icon before a heading the only thing the plugin pays attention to is the position to place the icon at, ignoring all the other heading text.

There are also various properties, the width of the window is what determines how many dashes to replace --- with for example, that impact rendering.