Importing the QWT Library

Direct Import

Direct import simply requires adding QwtPlot.h and QwtPlot.cpp to your project.

Here is a CMake example for direct import:

# QwtPlot depends on Core Gui Widgets Svg Concurrent OpenGL PrintSupport modules
find_package(QT NAMES Qt6 Qt5 COMPONENTS Core REQUIRED)
find_package(Qt${QT_VERSION_MAJOR} 5.12 COMPONENTS Core Gui Widgets Svg Concurrent OpenGL PrintSupport REQUIRED)


add_executable(YOU_APP_TARGET
    main.cpp
    QwtPlot.h
    QwtPlot.cpp
    # Your other project files
)

target_link_libraries(YOU_APP_TARGET
    PUBLIC
    Qt${QT_VERSION_MAJOR}::Core
    Qt${QT_VERSION_MAJOR}::Gui
    Qt${QT_VERSION_MAJOR}::Widgets
    Qt${QT_VERSION_MAJOR}::Svg
    Qt${QT_VERSION_MAJOR}::Concurrent
    Qt${QT_VERSION_MAJOR}::OpenGL
    Qt${QT_VERSION_MAJOR}::PrintSupport
    )

if(${QT_VERSION_MAJOR} EQUAL 6)
   find_package(Qt${QT_VERSION_MAJOR} ${QWT_MIN_QT_VERSION} COMPONENTS
       OpenGLWidgets
       REQUIRED
   )
   target_link_libraries(YOU_APP_TARGET PRIVATE
       Qt${QT_VERSION_MAJOR}::OpenGLWidgets
   )
endif()
find_package(OpenGL COMPONENTS OpenGL REQUIRED)
target_link_libraries(YOU_APP_TARGET PRIVATE OpenGL::GLU)

Tip

Since Qwt 7.1, the qwtplot3d library has been merged, so OpenGL-related dependencies are required.

Importing the QWT Library via CMake

This is the recommended way to import the QWT library.

First, it is not recommended to add the entire QWT library as a subproject to your project. Instead, build and install it locally first. For build and installation instructions, refer to: QWT Build Instructions

To import the QWT library via CMake, follow these steps:

1. Specify the QWT Installation Directory

Set the qwt_DIR variable to the lib/cmake/qwt path under the installation directory. (When CMake executes find_package(xx), it first checks whether an xx_DIR variable exists. If so, it looks for the corresponding xxConfig.cmake file under xx_DIR.)

Tip

If you use the default installation directory, you can skip setting the qwt_DIR variable — CMake will find it automatically.

For example:

set(qwt_DIR "C:\src\my-install-path\cmake\qwt")

2. Use find_package to Load the Library

QWT provides standard CMake configuration files and can be imported via the find_package command.

find_package(qwt REQUIRED)

# Link QWT's 2D plotting library to your target
target_link_libraries(YOU_APP_TARGET PRIVATE qwt::plot) # Automatically adds Qt dependencies to the target

# Link QWT's 3D plotting library to your target
target_link_libraries(YOU_APP_TARGET PRIVATE qwt::plot3d) # Automatically adds Qt and OpenGL dependencies to the target

The qwt project provides three modules:

• core module — shared base library containing 28 modules of foundational utilities:
  • Color utilities: QwtColorMap (and subclasses), QwtColorCycle, QwtColorMapPreset (22 scientific colormap presets)
  • Math utilities: qwt_math.h, qwtSimdArgMinMax (SIMD-accelerated argmin/argmax)
  • Data types: QwtInterval, QwtPoint3D, QwtPointPolar, QwtSamples, QwtBoxStatistics
  • Geometry: QwtBezier (Bézier curves), QwtClipper (polygon clipping)
  • Coordinate transforms: QwtTransform, QwtScaleMap, QwtScaleDiv, QwtScaleEngine
  • Date/Time: QwtDate, QwtSystemClock
  • Algorithms & compatibility: qwt_algorithm.hpp, qwt_qt5qt6_compat.hpp (Qt5/Qt6 compatibility layer)
  • Data containers/series/raster: QwtGridData, QwtSeriesData, QwtPointData, QwtSeriesStore, QwtRasterData, QwtMatrixRasterData, QwtGridRasterData
• plot module — the 2D plotting library, integrating the original Qwt functionality
• plot3d module — the 3D plotting library, integrating the qwtplot3d functionality

    ┌────────────────────┐
    │     qwt::core      │  ← foundational utilities (color, math, types, geometry, transforms, time)
    └────────────────────┘
          ↗         ↖
 ┌────────────┐  ┌─────────────┐
 │  qwt::plot  │  │ qwt::plot3d │
 │    (2D)     │  │    (3D)     │
 └────────────┘  └─────────────┘

Dependency Notes

Both plot and plot3d depend on the core module, but are independent of each other.

• qwt::core depends only on Qt Core + Gui
• qwt::plot depends on Qt Core + Gui + Widgets (public); Concurrent + PrintSupport (private). Optional: Svg and OpenGL/OpenGLWidgets (gated by QWT_CONFIG_QWTSVG / QWT_CONFIG_QWTOPENGL). All dependencies are added automatically when importing via CMake.
• qwt::plot3d depends on Qt Core + Gui + Widgets + OpenGL::GLU + Qt OpenGL Widgets

If the 3D option is enabled, the OpenGL::GLU dependency is automatically included.

Public Predefined Macros

QWT uses several predefined macros during compilation. If you manage your project with CMake, these macros are automatically defined when loading the library via find_package — no manual configuration is needed.

However, if you use an IDE such as Visual Studio to manually import the library, you need to specify the predefined macros in addition to adding the lib files. When importing the qwtcore library, you need the predefined macro QWTCORE_DLL. When importing the qwtplot library compiled as a DLL, you need the predefined macro QWT_DLL. When importing the qwtplot3d library, you need the predefined macro QWT3D_DLL.

Tip

As a modern C++ project, it is strongly recommended to use CMake to build your project. All these predefined macros are pre-configured in the CMake configuration.