GUI

WORK IN PROGRESS: I do not garantee that everything works right now

Features

• Immediate mode graphical user interface toolkit
• Written in C89 (ANSI C)
• Small codebase with roughly 2kLOC
• Focus on portability and minimal internal state
• Suited for embedding into graphical applications
• No global hidden state
• No direct dependencies (not even libc!)
• No memory allocation needed
• Renderer and platform independent
• Configurable
• UTF-8 supported

Limitations

• Does NOT provide window management
• Does NOT provide input handling
• Does NOT provide a renderer backend
• Does NOT provide overlapping panels
• Does NOT implement a font library
  Summary: It is only responsible for the actual user interface

Widgets

struct gui_input in = {0};
struct gui_canvas canvas = {...};
struct gui_button style = {...};
gui_default_config(&config);

while (1) {
    gui_input_begin(&input);
    /* record input */
    gui_input_end(&input);

    if (gui_button_text(&canvas, 0, 0, 100, 30, &style, "ok", GUI_BUTTON_DEFAULT, &input))
        fprintf(stdout, "button pressed!\n");
}

Panels

struct gui_config config;
struct gui_input in = {0};
struct gui_panel panel = {0};
struct gui_canvas canvas = {...};
gui_default_config(&config);

while (1) {
    gui_input_begin(&input);
    /* record input */
    gui_input_end(&input);

    gui_panel_begin(&panel, "Demo", panel.x, panel.y, panel.width, panel.height,
        GUI_PANEL_CLOSEABLE|GUI_PANEL_MINIMIZABLE|GUI_PANEL_BORDER|
        GUI_PANEL_MOVEABLE|GUI_PANEL_SCALEABLE, &config, &canvas, &in);
    gui_panel_layout(&panel, 30, 1);
    if (gui_panel_button_text(&panel, "button", GUI_BUTTON_DEFAULT))
        fprintf(stdout, "button pressed!\n");
    gui_panel_end(&panel);
}

Configuration

The gui toolkit provides a number of different attributes that can be configured, like spacing, padding, size and color. While the widget API even expects you to provide the configuration for each and every widget the higher layers provide you with a set of attributes in the gui_config structure. The structure either needs to be filled by the user or can be setup with some default values by the function gui_default_config. Modification on the fly to the gui_config is in true immedate mode fashion possible and supported.

FAQ

Where is Widget X?

A number of basic widgets are provided but some of the more complex widgets like comboboxes, tables and trees are not yet implemented. Maybe if I have more time I will look into adding them, except for comboboxes which are just really hard to implement.

Why did you use ANSI C and not C99 or C++?

Personally I stay out of all "discussions" about C vs C++ since they are totally worthless and never brought anything good with it. The simple answer is I personally love C and have nothing against people using C++ exspecially the new iterations with C++11 and C++14. While this hopefully settles my view on C vs C++ there is still ANSI C vs C99. While for personal projects I only use C99 with all its niceties, libraries are a little bit different. Libraries are designed to reach the highest number of users possible which brings me to ANSI C as the most portable version. In addition not all C compiler like the MSVC compiler fully support C99, which finalized my decision to use ANSI C.

Why do you typedef our own types instead of using the standard types

This Project uses ANSI C which does not have the header file <stdint.h> and therefore does not provide the fixed sized types that I need. Therefore I defined my own types which need to be set to the correct size for each plaform. But if your development environment provides the header file you can define GUI_USE_FIXED_SIZE_TYPES to directly use the correct types.

Why is font/input/window management not provided

As for window and input management it is a ton of work to abstract over all possible platforms and there are already libraries like SDL or SFML or even the platform itself which provide you with the functionality. So instead of reinventing the wheel and trying to do everything the project tries to be as indepenedent and out of the users way as possible. This means in practice a litte bit more work on the users behalf but grants a lot more freedom especially because the toolkit is designed to be embeddable.

The font management on the other hand it is litte bit more tricky. In the beginning the toolkit had some basic font handling but I removed it later. This is mainly a question of if font handling should be part of a gui toolkit or not. As for a framework the question would definitely be yes but for a toolkit library the question is not as easy. In the end the project does not have font handling since there are already a number of font handling libraries in existence or even the platform (Xlib, Win32) itself already provides a solution.

References

• Tutorial from Jari Komppa about imgui libraries
• Johannes 'johno' Norneby's article
• Casey Muratori's original introduction to imgui's
• Casey Muratori's imgui panel design 1/2
• Casey Muratori's imgui panel design 2/2
• ImGui: The inspiration for this project

License

(The MIT License)