CopperSpice Overview
About CopperSpice

CopperSpice is a set of individual libraries which can be used to develop cross platform software applications in C++. It is a totally open source project released under the LGPL V2.1 license and was initially derived from the Qt framework. Over the last several years CopperSpice has completely diverged, with a goal of providing a first class GUI library to unite the C++ community.

Our motivation for developing CopperSpice was to change the fundamental design and turn the existing framework into a set of libraries for C++ developers. We are accomplishing this by leveraging modern C++ functionality, new technology, and modern tooling. CopperSpice currently requires C++17 or newer.

You can use CopperSpice with any existing tool chain such as GCC, clang, or MSVC. A C++ program using the CopperSpice libraries can be developed using any editor such as VI, emacs, or Diamond and built using CMake from a shell command line. For an integrated environment Visual Studio or QtCreator can be used for development, building, testing, and deployment.

Links for Quick Reference


CopperSpice consists of the following libraries which can be linked into any existing C++ application.

Date/Time, Containers (QVector, QList, QMap, QHash, QStack, etc), File System, JSON, Strings (UTF-8, UTF-16)
File Dialogs, Menus, Widgets (QCheckbox, QPushbutton, QLineEdit, etc), Printing
Audio, Video
TCP, HTTP, FTP, IPv6, DNS lookups, SSL, URL support
Rendering Context, Shader
JavaScript engine which can be embedded in your application
SQLite, PostgreSQL, MySQL, etc
Renderer, Widget
Web View, Web Page
DOM, Reader
Schema, Xml Query

There are also open source BSD licensed libraries which are used by CopperSpice and available as stand alone libraries for anyone developing a C++ application. Documentation for these libraries can be found on our website.

  • CsPaint
  • CsSignal
  • CsString
  • CsLibGuarded

System Requirements

To use the CopperSpice libraries a C++17 compiler and a C++17 standard library are required. CopperSpice CMake build files are provided with the source distribution. We recommend your projects should use CMake for simplicity.

For additional information about building from source, refer to our CopperSpice Overview Documentation or our KitchenSink demo application for sample CMake project files.


The CopperSpice libraries are built using the CMake build system.

Benefits of CopperSpice

Reflection / Meta Object Compiler

  • The Meta-Object Compiler is no longer required for generating reflection meta data in CopperSpice
  • Since moc is no longer required it was completely removed
  • All functionality originally provided by moc was replaced with compile time templates
  • CopperSpice automatically generates meta data for processing Signals/ Slots and Introspection
  • Removal of moc simplifies the build process
  • A template class can inherit from QObject with no restrictions on data types
  • Complex data types can be used as signal or slot arguments, for example the following is valid code in Copperspice
   CS_SLOT_1(Public, void actionAbout(QMap<QString, int>)

Extensive use of modern C++ functionality

  • templates, variadic templates, lambda expressions
  • expression SFINAE
  • threading model
  • move semantics, override
  • constexpr, decltype, type traits, tuple
  • strongly typed enums

Reimplemented all container classes

  • Composition is used to wrap the C++ standard library containers
    • QVector, QList, QStringList, QLinkedList, QSet, QStack, QQueue
    • QMap, QHash, QMultiMap, QMultiHash
  • Supports both the STL and Qt API
  • Implement QMultiHash and QMultiMap as separate classes from QHash and QMap
  • Reverse iterators
  • Removed copy on write semantics
  • Added QFlatMap
    • Ordered map which stores elements in contiguous memory as a sorted vector of pairs
    • Similar API to QMap

Key enhancements

  • CopperSpice includes a majority of the Qt 5 classes
  • Improved CsNetwork support for OpenSSL
  • Support for TLS and SPDY added
  • Add support for SHA-2 and SHA-3
  • Reimplemented atomic support (QAtomicInt, QAtomicPointer) wrapping the C++ standard library functionality
  • Removed support of obsolete platforms
  • Enhanced CopperSpice to use the STL algorithms rather than hand rolled algorithms
  • QLocale classes refactored to use UTF-8 string classes
  • Update codec classes to use UTF-8 string classes
  • High DPI Support
  • Moved to Unicode 11, added support for Harfbuzz 2 for text shaping
  • Improved platform specific support

Integration of CsSignal

  • Improved thread aware Signal/Slot delivery
  • Increased efficiency while maintaining the full Signal/Slot API
  • Deadlocks in Signal/Slot processing have been eliminated

Integration of CsString

  • Improved storage to properly represent Unicode strings
  • Added new QString8 (UTF-8) and QString16 (UTF-16) classes
  • QString is synonymous with QString8
  • Moved various formatting methods to the new QStringParser class
  • Developed a new QRegularExpression class which uses iterators internally to handle UTF-8 and UTF-16
  • Created a new QStringView class which works correctly with the new QString classes
  • Removed multiple internal partial string classes which leveraged raw pointers into the string class
  • Remove string surrogate checking since it is not required with UTF-8 / UTF-16 encoding

Migrating to CopperSpice

PepperMill is a translation utility and is run one time on your Qt header files to migrate to CopperSpice. This utility will convert your application header files to standard C++ and alter the source to use CopperSpice syntax. This mostly affects signals, slots, properties, enums, and flags.

We have made the process of converting to CopperSpice simple and straight forward. Simply convert your application header files one time using the PepperMill utility and then modify your build files to use CMake.

For sample build files you can refer to the KitchenSink demo application or the build files used in the DoxyPress project.

For more information refer to PepperMill and Migration Notes.

API Documentation

Full class documentation is available on the CopperSpice website or our downloaded page.

On line: CopperSpice API Documentation

Download: CopperSpice API Documentation

Presentations / YouTube

Our channel contains videos about C++ programming, rendering 3D Graphics, the CopperSpice libraries, and documenting with DoxyPress. Please subscribe to our YouTube channel so you will be notified when new videos are uploaded.


Links to technical presentations recorded at CppNow and CppCon. There are also several slide decks from talks given at multiple C++ user groups in the United States, Amsterdam, Munich, and London.


The CopperSpice libraries are released under the LGPL V2.1 license. The open source libraries CsPaint, CsSignal, CsString, and CsLibGuarded are released under the BSD license. For more information refer to the LICENSE files provided with each project.