IUP is a multi-platform toolkit for building graphical user interfaces.

Easy to use API for building desktop applications. Same code runs on Linux and Windows.

Tested with Nim 1.6.0 and IUP 3.30

• Linux, GTK
• Windows on Linux (cross-compiling, mingw, wine)
• Windows (reported working)

• Installation
• QuickStart
• NIUPC module
• NIUPEXT module
• Documentation
• Examples
• screenshots

Prerequisites

Install IUP libraries...

Pre-built binaries: https://sourceforge.net/projects/iup/files/

Download tips: https://webserver2.tecgraf.puc-rio.br/iup/en/download_tips.html

Compile from source: https://webserver2.tecgraf.puc-rio.br/iup/en/guide.html#buildlib

NIUP package for Nim

nimble install niup

hello.nim

import niup

proc btn_exit_cb(ih:PIhandle):cint {.cdecl.} =
  # Exits the main loop
  return IUP_CLOSE

proc mainProc =
  Open()

  var
    label = Label("Hello world from IUP.")
    button = Button("OK")
    vbox = Vbox(label, button)

  vbox.alignment = IUP_ACENTER
  vbox.gap(10)
  vbox.margin(10, 10)

  var dlg = Dialog(vbox)
  dlg.title = "Hello World"

  # callbacks
  button.action = btn_exit_cb

  ShowXY(dlg, IUP_CENTER, IUP_CENTER)

  MainLoop()
  Close()

if isMainModule:
  mainProc()

NIUP module is strong typed API, wrapper around NIUPC.
API is generated with help of https://github.com/batiati/IUPMetadata

helloworldcb.nim

import niup/niupc
import niup/niupext

proc btn_exit_cb(ih:PIhandle):cint {.cdecl.}=
  # Exits the main loop
  return IUP_CLOSE

proc mainProc =
  Open()

  var
    label =  Label("Hello world from IUP.")
    button = Button("OK", nil)

  var vbox = Vbox(label, button, nil)
  withPIhandle vbox:
    "ALIGNMENT" "ACENTER"
    "GAP"       "10"
    "MARGIN"    "10x10"

  var dlg = Dialog(vbox)
  SetAttribute(dlg, "TITLE", "Hello World with callback")

  # Registers callbacks
  SetCallback(button, "ACTION", btn_exit_cb)

  ShowXY(dlg, IUP_CENTER, IUP_CENTER)

  MainLoop()
  Close()

if isMainModule:
  mainProc()

Program helloworldcb.nim displays Dialog with Label and Button. Click on button activates callback btn_exit_cb which terminates program. PIhandle (Ihandle in C) is type for IUP objects. SetAttribute (IupSetAttribute in C) sets values to propertie labels. This method for setting options is used for everything: numeric and text properties, options, callback functions. ShowXY (IupShowXY in C) displays a dialog in a given position on the screen. MainLoop (IupMainLoop in C) executes the user interaction until a callback returns IUP_CLOSE, ExitLoop (IupExitLoop in C) is called, or hiding the last visible dialog.

NIUPC is low level wrapper for IUP libraries. API is very similiar to C.

IUP is main library which depends on IM (image library) and CD (canvas draw library). Each library prefixes functions with Iup, im or cd.

Main difference with C API is that functions from IUP don't have prefix Iup. I'ts SetAttribute instead IupSetAttribute. IM and CD function have same names as in C.

This is low level API so for callbacks Nim binary compatible types should be used.

NIUPEXT is set of templates, functions and macros to provide better Nim API and simplify coding.

Focus is mainly on using Nim types.

It doesn't wrapp IUP objects into Nim types. When interfacing with IUP, take care about object visibility and life time.

Main guide to IUP and detailed documentation is at https://www.tecgraf.puc-rio.br/iup/. It's focused on C but matches Nim API with very few exceptions.

API docs: https://dariolah.github.io/niup

Examples are at https://github.com/dariolah/nim-iup-examples