shahminfikri/cimgui

c-api for imgui (https://github.com/ocornut/imgui) lookat: https://github.com/cimgui for other widgets

cimgui

This is a thin c-api wrapper programmatically generated for the excellent C++ immediate mode gui Dear ImGui. All imgui.h functions are programmatically wrapped. Generated files are: cimgui.cpp, cimgui.h for C compilation. Also for helping in bindings creation, definitions.lua with function definition information and structs_and_enums.lua. This library is intended as a intermediate layer to be able to use Dear ImGui from other languages that can interface with C (like D - see D-binding)

History:

Initially cimgui was developed by Stephan Dilly as hand-written code but lately turned into an auto-generated version by sonoro1234 in order to keep up with imgui more easily (letting the user select the desired branch and commit)

Notes:

• currently this wrapper is based on version [1.76 of Dear ImGui with internal api]
• only functions, structs and enums from imgui.h (an optionally imgui_internal.h) are wrapped.
• if you are interested in imgui implementations you should look LuaJIT-ImGui project.
• All naming is algorithmic except for those names that were coded in cimgui_overloads table (https://github.com/cimgui/cimgui/blob/master/generator/generator.lua#L60). In the official version this table is empty.
• Current overloaded function names can be found in (https://github.com/cimgui/cimgui/blob/master/generator/output/overloads.txt)

compilation

• clone
  • git clone --recursive https://github.com/cimgui/cimgui.git
  • git submodule update
• compile
  • using makefile on linux/macOS/mingw (Or use CMake to generate project)
  • or as in https://github.com/sonoro1234/LuaJIT-ImGui/tree/master/build

using generator

• this is only needed (before compilation) if you want an imgui version different from the one provided, otherwise generation is already done.
• you will need LuaJIT (https://github.com/LuaJIT/LuaJIT.git better 2.1 branch) or precompiled for linux/macOS/windows in https://luapower.com/luajit/download
• you need to use also a C++ compiler for doing preprocessing: gcc (In windows MinGW-W64-builds for example), clang or cl (MSVC). (this repo was done with gcc)
• update imgui folder to the version you desire.
• edit generator/generator.bat on windows, or generator/generator.sh on linux, to choose between gcc, clang, or cl and to choose desired implementations and whether imgui_internal is generated or not.
• edit config_generator.lua for adding includes needed by your chosen implementations (vulkan needs that).
• Run generator.bat or generator.sh with gcc, clang or cl and LuaJIT on your PATH.
• as a result some files are generated: cimgui.cpp and cimgui.h for compiling and some lua/json files with information about the binding: definitions.json with function info, structs_and_enums.json with struct and enum info, impl_definitions.json with functions from the implementations info.

generate binding

• C interface is exposed by cimgui.h when you define CIMGUI_DEFINE_ENUMS_AND_STRUCTS
• with your prefered language you can use the lua or json files generated as in:
  • https://github.com/sonoro1234/LuaJIT-ImGui/blob/master/lua/build.bat (with lua code generation in https://github.com/sonoro1234/LuaJIT-ImGui/blob/master/lua/class_gen.lua)
  • https://github.com/mellinoe/ImGui.NET/tree/autogen/src/CodeGenerator

definitions description

• It is a collection in which key is the cimgui name that would result without overloadings and the value is an array of overloadings (may be only one overloading)
• Each overloading is a collection. Some relevant keys and values are:
  • stname : the name of the struct the function belongs to (will be "" if it is top level in ImGui namespace)
  • ov_cimguiname : the overloaded cimgui name (if absent it would be taken from cimguiname)
  • cimguiname : the name without overloading (this should be used if there is not ov_cimguiname)
  • ret : the return type
  • retref : is set if original return type is a reference. (will be a pointer in cimgui)
  • argsT : an array of collections (each one with type: argument type and name: the argument name, when the argument is a function pointer also ret: return type and signature: the function signature)
  • args : a string of argsT concatenated and separated by commas
  • call_args : a string with the argument names separated by commas for calling imgui function
  • defaults : a collection in which key is argument name and value is the default value.
  • manual : will be true if this function is hand-written (not generated)
  • isvararg : is set if some argument is a vararg
  • constructor : is set if the function is a constructor for a class
  • destructor : is set if the function is a destructor for a class
  • templated : is set if the function belongs to a templated class (ImVector)
  • templatedgen: is set if the function belongs to a struct generated from template (ImVector_ImWchar)
  • nonUDT : if present the original function was returning a user defined type so that signature has been changed to accept a pointer to the UDT as first argument.
  • location : name of the header file this function comes from. (imgui, internal, imgui_impl_xxx)

structs_and_enums description

• Is is a collection with two items:
  • under key enums we get the enums collection in which each key is the enum tagname and the value is an array of the ordered values represented as a collection with keys
    • name : the name of this enum value
    • value : the C string
    • calc_value : the numeric value corresponding to value
  • under key structs we get the structs collection in which the key is the struct name and the value is an array of the struct members. Each one given as a collection with keys
    • type : the type of the struct member
    • template_type : if type has a template argument (as ImVector) here will be
    • name : the name of the struct member
    • size : the number of array elements (when it is an array)
    • bitfield : the bitfield width (in case it is a bitfield)

usage

• use whatever method is in ImGui c++ namespace in the original imgui.h by prepending ig
• methods have the same parameter list and return values (where possible)
• functions that belong to a struct have an extra first argument with a pointer to the struct.
• where a function returns UDT (user defined type) by value some compilers complain so the function is generated accepting a pointer to the UDT type as the first argument (or second if belongs to a struct).

example bindings based on cimgui

• DerelictImgui
• ImGui.NET
• ImGuiCS
• imgui-rs
• imgui-pas
• odin-imgui
• LuaJIT-ImGui

C examples based on cimgui

• sdl2-cimgui-demo
• cimgui_c_sdl2_example
• cimgui-c-example with GLFW