Some functions aren't found

[GildedHonour]

A web app.
I want to take a requested an image file, put watermark on it on the fly via LuaJit and return an output image without creating an image file with a watermark. All via nginx.

I've faced with several "not found this functions" errors.

a part of my code:

  local vips = require("vips")
  local img = vips.Image.new_from_file("/path/to/image123.png", {access = "sequential"})
  local text = vips.Image.text("watermark123", {width = 200, dpi = 200, align = "centre", font = "sans bold"})


  -- NOTE 1
  text = text:rotate(-45)

  -- make the text transparent
  text = (text * 0.3):cast("uchar")



  -- NOTE 2
  text = text:gravity("centre", 200, 200)



  -- this block of pixels will be reused many times ... make a copy
  --text = text:copy_memory()

  text = text:replicate(1 + img:width() / text:width(), 1 + img:height() / text:height())
  text = text:crop(0, 0, img:width(), img:height())

  -- we make a constant colour image and attach the text mask as the alpha
  local overlay = text:new_from_image({255, 128, 128}):copy({interpretation = "srgb"})
  overlay = overlay:bandjoin(text)

  -- overlay the text
  img = img:composite(overlay, "over")


  --  buff = img:write_to_buffer(".jpg")
  buff = img:write_to_buffer(".png")

  ngx.print(buff)
  ngx.flush(true)

Errors:

    * VipsOperation: class "rotate" not found

    stack traceback:
    coroutine 0:
      [C]: in function 'error'
      /usr/local/share/lua/5.1/vips/voperation.lua:155: in function 'rotate'

    * VipsOperation: class "gravity" not found

    stack traceback:
    coroutine 0:
      [C]: in function 'error'
      /usr/local/share/lua/5.1/vips/voperation.lua:155: in function 'gravity'

      * lua entry thread aborted: runtime error: /usr/local/share/lua/5.1/vips/gvalue.lua:76: no such enum over
      lua-vips: no such enum type

      stack traceback:
      coroutine 0:
        [C]: in function 'error'
        /usr/local/share/lua/5.1/vips/gvalue.lua:76: in function 'to_enum'
        /usr/local/share/lua/5.1/vips/Image_methods.lua:555: in function 'composite'

What can cause them?

---

lua -v
Lua 5.1.5  Copyright (C) 1994-2012 Lua.org, PUC-Rio

luajit -v
LuaJIT 2.0.4 -- Copyright (C) 2005-2015 Mike Pall. http://luajit.org/

# or, obtained via nginx itself

LuaJIT 2.1.0-beta3

Ubuntu 18

---

I commented out the code with "rotate", then got "gravity" error. Then I commented out "gravity" and got the 3rd error.

[GildedHonour]

vips -v
vips-8.2.2-Sat Jan 30 17:12:08 UTC 2016

[GildedHonour]

My libvips turned out to be outdated

[jcupitt]

Hi, yes, lua-vips is a dynamic binding, so it presents the operations it find in your libvips at run-time.

[GildedHonour]

Ok
In the documentation there's no mention of how to save to a buffer in the png format, only in the jpg. Is this a correct way

buff = img:write_to_buffer(".png")
?

[jcupitt]

Hey Alex, yes, it should work.

That will search for a loader that has .png as a save suffix, then run that for you. You can also just call the PNG saver directly:

buff = img:pngsave_buffer()

[GildedHonour]

Thx