Pascal BGIDemo Port for wx_BGI

This folder contains a port of Borland's old BGIDemo Pascal sample to the wx_BGI shared library.

Files

• bgidemo.pas: the original demo logic, adapted to use the local compatibility layer
• Graph.pas: a FreePascal compatibility shim that maps classic Borland Graph unit calls onto wx_bgi_opengl

Build with CMake

Build the C++ library first, then build the Pascal example target.

Windows

cmake -S . -B build -A x64
cmake --build build --config Debug --target bgidemo_pascal_build

Outputs:

• build/bgidemo_pascal/bgidemo.exe
• build/bgidemo_pascal/wx_bgi_opengl.dll

Linux

cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug
cmake --build build --target bgidemo_pascal_build

Outputs:

• build/bgidemo_pascal/bgidemo
• build/bgidemo_pascal/libwx_bgi_opengl.so

macOS

cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug
cmake --build build --target bgidemo_pascal_build

Outputs:

• build/bgidemo_pascal/bgidemo
• build/bgidemo_pascal/libwx_bgi_opengl.dylib

Run

Run the executable from the bgidemo_pascal output directory so the shared library is next to it.

Windows

.\build\bgidemo_pascal\bgidemo.exe

Linux/macOS

./build/bgidemo_pascal/bgidemo

Reusing <tt>Graph.pas</tt> with Other Old Pascal Programs

Graph.pas is intended as a drop-in compatibility layer for old Pascal code that used Borland's Graph unit.

Basic reuse flow:

1. Copy Graph.pas into your legacy Pascal project, or add examples/bgidemo-pascal to your FreePascal unit search path with -Fu.
2. Keep uses Graph; in the old source, or replace the Borland Graph unit reference with this local one.
3. Compile the Pascal program with FreePascal.
4. Put the matching wx_BGI shared library next to the executable, or make it available through the runtime library search path.

Example compile commands:

C:\FPC\3.2.2\bin\i386-Win32\ppcrossx64.exe -Fuexamples\bgidemo-pascal path\to\old_program.pas

ppcx64 -Fuexamples/bgidemo-pascal path/to/old_program.pas

What this shim helps with:

• classic Graph constants, types, and procedures used by many Borland graphics demos
• BGI drawing, text, viewport, palette, and image APIs that already exist in wx_BGI
• InitGraph, CloseGraph, GraphResult, and similar Borland-era calls

What it does not automatically solve:

• old Dos unit logic unrelated to graphics
• CRT-dependent console UX beyond what your program already does
• direct hardware assumptions or code that expects .BGI driver files to exist on disk

If your old program uses only the Graph unit heavily, the port is usually small. If it also relies on Dos, BIOS behavior, or direct text-mode tricks, expect additional cleanup.

<tt>KeyPressed</tt> / <tt>ReadKey</tt> Portability

The demo now uses portable keyboard input provided by wx_BGI itself.

• wx_BGI installs GLFW keyboard callbacks and keeps a translated key queue inside the library.
• Graph.pas uses that queue for KeyPressed and ReadKey, so the waits no longer depend on FreePascal Crt input behavior.
• Printable keys are delivered as normal characters.
• Extended keys follow classic DOS-style behavior by returning #0 first and the extended scan code on the next ReadKey call.

This is substantially more portable for GUI-style waits on Windows, Linux, and macOS because the input comes from the graphics window rather than the launching terminal.