EnhancedGEM Library v2.20

A comprehensive GEM (Graphics Environment Manager) UI library for Atari ST/TT/Falcon computers, originally written in C and 68k assembly by Christian Grunenberg (1994). Adapted for modern cross-compilation with m68k-atari-mint-gcc and the current GemLib.

Original author: Christian Grunenberg, 1994 License: Freeware (including all source code and example programs)

Overview

EnhancedGEM extends the native GEM AES/VDI APIs into a higher-level, event-driven GUI toolkit. It provides window management, dialog handling, popup menus, font selection, drag & drop, inter-application communication, and much more.

Features

• Window management — open, close, resize, scroll, iconify, with automatic redraw clipping
• Dialog system — flying, windowed, and modal dialogs with edit fields, sliders, and popups
• Popup menus — standard, cycle, checkbox/radio styles with keyboard navigation
• Font selector — fully parametric dialog with preview, effects, and color selection
• Event handling — extended event model with 4 mouse areas, 4 timers, dual mouse buttons
• Object enhancements — checkboxes, radio buttons, hotkeys, headers, cycle buttons, and more
• Drag & Drop — MiNT D&D protocol and AV protocol support
• Inter-app communication — XAcc 2.0, AV, and PAULA protocols
• File utilities — wildcard matching, path parsing, file selector wrapper, settings persistence
• Clipboard — scrap path management and change notifications
• Cookie jar — read, write, create, and remove TOS cookies
• Conditional compilation — over 15 feature flags allow aggressive size reduction for minimal builds

Directory Structure

source/         Library source code
  e_gem.h       Main library header
  proto.h       Internal prototypes
  makefile.gcc  GCC cross-compilation Makefile
example/        Example programs
  dialdemo/     Dialog demonstrations
  windemo/      Window demonstrations (sample, hello, mouse, lines, balls)
  winview/      File viewer / clipboard viewer
  font/         Font palette and selector examples
  play_it/      Puzzle game example
  preview/      Resource file previewer
doku/           Documentation (German)

Building

Cross-compilation with m68k-atari-mint-gcc (recommended)

Requires m68k-atari-mint-gcc with MiNTLib and GemLib installed.

cd source
make -f makefile.gcc            # build the library
make -f makefile.examples       # build example programs

Produces libe_gem.a and example .tos executables. Builds with 32-bit int (no -mshort) using the modern GemLib (gem.h). See README-GEMLIB.md for details on GemLib compatibility.

Pure C (native Atari, 16-bit int)

Open source/e_gem.prj in the Pure C IDE. For a minimal build, use source/egemlght.prj.

Linking

m68k-atari-mint-gcc -o myapp.tos myapp.c -I source -L source -le_gem -lgem

Light Version

Define SMALL_LIGHT to disable all optional features, or selectively disable individual features:

Flag	Disables
SMALL_NO_XACC_AV	XAcc/AV protocol
SMALL_NO_EDIT	Text editing fields
SMALL_NO_DD	Drag & Drop
SMALL_NO_GRAF	Graphics/slider functions
SMALL_NO_POPUP	Popup menus
SMALL_NO_FONT	Font handling
SMALL_NO_SCROLL	Window scrolling
SMALL_NO_CLIPBRD	Clipboard support
SMALL_NO_MENU	Menu system
SMALL_NO_ICONIFY	Window iconification
SMALL_NO_XTEXT	Extended text rendering
SMALL_ALERT	Minimal alert icons (8 instead of 17)

Quick Start

#include <e_gem.h>

int Init(XEVENT *ev, int avail) {
    return (MU_MESAG | MU_KEYBD) & avail;
}

int Event(XEVENT *ev) {
    if (ev->ev_mwich & MU_MESAG) {
        switch (ev->ev_mmgpbuf[0]) {
            case AP_TERM: exit_gem(TRUE, 0); break;
        }
    }
    return ev->ev_mwich;
}

int main(void) {
    if (init_gem(NULL, "  MyApp", "MyApp", NULL, 0, 0, 0)) {
        Event_Handler(Init, Event);
        Event_Multi(NULL);
        exit_gem(TRUE, 0);
    }
    return -1;
}

Documentation

• README-GEMLIB.md — Modern GemLib compatibility layer
• README-32BIT.md — 32-bit int support details
• doku/manual.txt — Complete reference manual (German)
• doku/usage.txt — Usage guide (German)
• doku/history.txt — Version history