SXUI - Simple eXtensible UI Library

A high-level, plug-and-play UI library for C built on SDL2. SXUI provides a simplified interface for creating responsive desktop-class interfaces without managing low-level SDL state.

Features

Core Widgets

• Buttons: Click events, hover effects, and press animations.
• Labels: Static and dynamic text display.
• Text Inputs: Full editing suite including selection, copy/paste, and word navigation.
• Checkboxes: State-based toggles with value callbacks.
• Sliders: Normalized value selection (0.0 - 1.0).
• Dropdowns: Expanded selection menus with custom callbacks.
• Canvas: Low-level drawing surface for custom animations and tools.
• Frames: Container elements with automated layout management.

Layout Engine

• Vertical & Horizontal Lists: Automated element stacking.
• Grid Layout: Auto-wrapping grid with configurable column limits.
• Scrollable Containers: Clipping support with automated, fading scrollbars.
• Dynamic Switching: Change layout modes at runtime without recreating elements.

Advanced Input System

• Strict Mouse Logic: sxui_on_mouse_click ensures clicks only fire if pressed and released on the same widget.
• Real-time Access: Check sxui_is_key_down or sxui_is_mouse_button_pressed anywhere in your code.
• Window Utilities: Built-in support for window resizing events and resolution getters.

Text Editing Support

• Selection via Shift + Arrow keys.
• Standard shortcuts: Ctrl+A (Select All), Ctrl+C/X/V (Copy/Cut/Paste).
• Navigation: Ctrl+Left/Right (Word-jump), Home/End.
• Word deletion: Ctrl+Backspace and Ctrl+Delete.
• Native mouse selection and horizontal auto-scrolling for long strings.

Installation

Dependencies

Ensure you have the SDL2 and SDL2_ttf development headers installed.

Ubuntu/Debian: sudo apt install libsdl2-dev libsdl2-ttf-dev

macOS: brew install sdl2 sdl2_ttf

Project Structure

• SXUI depends on the SXList library. For best results, place the SXList source files in deps/ directory within your project.

  git clone --recursive https://github.com/SwirX/SXUI
  cd SXUI

• Font: Ensure Montserrat-Regular.ttf is in the root directory

Building the Library

To compile SXUI as a static library:

# Compile dependencies and library
make lib

To link SXUI to your application:

gcc main.c libsxui.a -lSDL2 -lSDL2_ttf -lm -o my_app

Or to run the showcase directly:

make
./showcase

Quick Start

#include "sxui.h"

void on_button_click(void* element) {
    printf("Button clicked!\n");
}

int main() {
    sxui_init("Application", 800, 600, 0x00FF7AFF);
    
    UIElement* btn = sxui_button(NULL, "Click Me", on_button_click);
    sxui_set_size(btn, 200, 50);
    sxui_set_position(btn, 300, 275);
    
    while (!sxui_should_quit()) {
        sxui_poll_events();
        sxui_render();
    }
    
    sxui_cleanup();
    return 0;
}

Learning & Examples

If you are new to SXUI or C programming, I maintain a dedicated Showcases Repository.

Unlike standard documentation, the showcases are designed as mini-courses. Each example includes:

• Commented Source: Step-by-step explanations of the implementation.
• Technical Deep-Dives: READMEs that explain the underlying C concepts (Pointers, Memory Management, Bitwise Logic, etc.).

Available Showcases:

• Simple Login Form: Learn about frames, inputs, and state management.
• More coming soon: Sliders, Custom Styling, and Advanced Layouts.

API Reference

Initialization & Core

• sxui_init(title, w, h, seed): Initialize the engine and window.
• sxui_set_theme(seed, mode): Update the procedural theme.
• sxui_poll_events(): Process input and internal logic.
• sxui_render(): Draw the current frame.
• sxui_cleanup(): Free all library resources.

Layout Flags

• UI_SCROLLABLE: Enable mouse-wheel scrolling.
• UI_LAYOUT_GRID: Enable auto-grid positioning.
• UI_FLAG_CLIP: Clip children to frame boundaries.
• UI_FLAG_DRAGGABLE: Allow user to move the element.

Customization

Fonts

SXUI ships with Montserrat-Regular as the default fallback. You can load your own .ttf font at any time:

sxui_init("My App", 800, 600, 0x00FF7AFF);
sxui_load_font("path/to/my_font.ttf", 18);

If your custom font fails to load or the path is incorrect, the library will automatically fallback to Montserrat to ensure the UI remains usable.

Licenses

• SXUI: MIT License.
• Montserrat Font: Licensed under the SIL Open Font License.
• SXList: MIT License.