CrossOpenCV-FPC

Cross-platform OpenCV wrapper for Delphi and FreePascal with fully dynamic library loading

Overview

This project is a fork of Laex/Delphi-OpenCV, re-engineered to work on both Windows and Ubuntu Linux.
All OpenCV functions are bound dynamically at run-time (LoadLibrary / dlopen), so you can replace or remove the native libraries without recompiling the Pascal code.

Key differences from the original

1. Delphi + FreePascal – one code-base, works with both compilers.
2. Windows + Linux – tested on Windows x86 / x64 and Ubuntu x64.
3. Dynamic loading – no static linking; pointers are resolved at run-time.
4. Graceful fallback – if a .dll/.so is missing, function pointers stay nil and the application keeps running.
5. Self-contained Linux libs – every OpenCV .so is built/patched with an internal RPATH ($ORIGIN), so the libraries inside the same folder can see each other without LD_LIBRARY_PATH.

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Building from source

1. Clone the repo

   git clone https://github.com/pisarev/CrossOpenCV-FPC.git
   cd CrossOpenCV-FPC

2. Fetch the native libraries
   Download the correct archive from the Releases page (see below) or just run the helper script:

   # Linux
   ./scripts/download_binaries.sh
   # Windows (PowerShell)
   scripts\download_binaries.ps1

3. Compile

   Delphi – open the project file and press Build.
   FreePascal – for example:

   fpc src/examples/example.pas

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OpenCV library placement and packaging

The wrapper already contains the logic that calls LoadLibrary / dlopen with hard-coded paths.
Just place the libraries exactly as described below – no extra environment variables or RPATH tweaks are needed.

Windows (32-bit & 64-bit)

Archive	Architecture
opencv_2.4.13-win32.zip	Win 32-bit
opencv_2.4.13-win64.zip	Win 64-bit

1. Unzip next to your executable so the layout becomes

   MyApp.exe
   └── opencv_2.4.13/
       ├── opencv_core2413.dll
       ├── opencv_imgproc2413.dll
       └── … other DLLs
   

2. Do not rename or move the opencv_2.4.13 folder – the Pascal code loads DLLs from
   <exe_dir>/opencv_2.4.13/....

Ubuntu Linux (64-bit only)

Archive	Architecture
opencv_2.4.13-linux-x86_64.tar.xz	Linux x86-64

1. Extract the archive next to the executable so the layout becomes

   /path/to/myapp               (ELF executable)
   └── bin/
       └── opencv_2.4.13/
           ├── libopencv_core.so.2.4.13
           ├── libopencv_core.so -> ./libopencv_core.so.2.4.13
           └── … other .so + relative symlinks
   

2. The wrapper calls

   dlopen(<exe_dir>/bin/opencv_2.4.13/libopencv_*.so.2.4.13)
   

   so do not move the folder.
   The archive is packed with tar.xz to preserve symbolic links, and every .so already contains an $ORIGIN RPATH, allowing the libraries in the same folder to resolve their mutual dependencies automatically.

3. 32-bit Linux is not supported in this fork.

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Quick examples

Linux

cd /home/user
tar xJf opencv_2.4.13-linux-x86_64.tar.xz
./myapp        # the program now loads all .so files from bin/opencv_2.4.13

Windows

Expand-Archive opencv_2.4.13-win64.zip -DestinationPath 'C:\Projects\MyApp\opencv_2.4.13'
C:\Projects\MyApp\MyApp.exe   # DLLs are loaded from .\opencv_2.4.13

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Releases

All native libraries live in the Releases section so the git repository stays small.
Direct download links (always point to the latest release):

Platform	Asset
Windows 32-bit	https://github.com/pisarev/CrossOpenCV-FPC/releases/download/v1.0.0/opencv_2.4.13-win32.zip
Windows 64-bit	https://github.com/pisarev/CrossOpenCV-FPC/releases/download/v1.0.0/opencv_2.4.13-win64.zip
Linux 64-bit	https://github.com/pisarev/CrossOpenCV-FPC/releases/download/v1.0.0/opencv_2.4.13-linux-x86_64.tar.xz

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License

Distributed under the MPL 1.1. See the LICENSE file for details.

Contact

Create issues or pull requests on GitHub if you encounter problems or have improvements.