QWT — Qt Plotting Library

QWT (Qt Widgets for Technical Applications) is a high-performance 2D/3D plotting library based on Qt, designed for data visualization in scientific computing and engineering applications.

Why Choose QWT?

There are only a handful of plotting libraries in the Qt ecosystem. The mainstream options are QCustomPlot, Qwt, Qt Charts, and KDChart. After Qt 6.8, the former Qt Charts (2D) and Qt DataVisualization (3D) were merged into a unified Qt Graphs module built entirely on Qt Quick Scene Graph + Qt Quick 3D, abandoning the legacy Graphics-View / QPainter pipeline. However, Qt Graphs must be embedded via QQuickWidget or QQuickWindow, requires the QML runtime, has limited C++ support, and drops support for older systems like Windows 7.

Library	License	Strengths	Weaknesses
QCustomPlot	GPL	Simple, easy to use, widely adopted	GPL is "viral" — not commercial-friendly
Qwt	LGPL	High performance, solid architecture	Original author stopped maintaining; deployment was difficult
Qt Charts	GPL	Qt official	Poor performance; GPL license
KDChart	MIT (3.0+)	Commercial-friendly	Mediocre rendering quality

This project is based on Qwt 6.2.0, adding modern features and fixes to make it a license-friendly, high-performance, and easy-to-use Qt plotting library.

Qwt 7.0 New Features

• CMake support — find_package(qwt) for one-line integration
• Qt 6 support — compatible with Qt 5.12+ and Qt 6.x
• Single-file inclusion — just QwtPlot.h + QwtPlot.cpp, like QCustomPlot
• Modernized visual style — removed legacy embossed look, flat modern UI
• Figure container — matplotlib-inspired multi-plot layout
• Multi-axis support — parasite axis architecture, unlimited axes
• Axis interaction — mouse drag and scroll-wheel zoom on axes
• Integrated 2D/3D — built-in 3D plotting module
• C++11 optimization — modern C++ throughout: override, nullptr, smart pointers, range-based for loops
• Large-scale data rendering optimization — 4 curve downsampling algorithms + SIMD acceleration, smooth rendering of millions of points
• Color cycle system — customizable color cycle that auto-assigns colors to series data
• Box chart — QwtPlotBoxChart for statistical distribution visualization
• Flat-style controls — sliders, knobs, dials and other widgets support flat styling

Quick Integration

CMake (Recommended)Single File

find_package(qwt REQUIRED)
target_link_libraries(${PROJECT_NAME} PRIVATE qwt::plot)
# 3D plotting
target_link_libraries(${PROJECT_NAME} PRIVATE qwt::plot3d)

// Add src-amalgamate/QwtPlot.h and QwtPlot.cpp to your project
#include "QwtPlot.h"

auto* plot = new QwtPlot("My Plot");
auto* curve = new QwtPlotCurve("Data");

Project Links

• GitHub: https://github.com/czyt1988/QWT
• Gitee: https://gitee.com/czyt1988/QWT
• Documentation: https://czyt1988.github.io/QWT/

Showcase

Basic Charts

• 
  examples/figure

• 
  examples/2D/simpleplot

• 
  examples/2D/barchart

• 
  examples/2D/scatterplot

• 
  examples/2D/curvedemo

• 
  examples/2D/boxchart

Real-Time Visualization

• 
  examples/2D/cpuplot

• 
  examples/2D/realtime

• 
  examples/2D/oscilloscope

• 
  examples/2D/radio

• 
  examples/2D/sysinfo

• 
  examples/2D/animation

Advanced Charts

• 
  examples/2D/spectrogram

• 
  playground/vectorfield

• 
  examples/2D/stockchart

• 
  examples/2D/polardemo

• 
  examples/parasitePlot

• 
  examples/2D/bode

• 
  playground/shapes

• 
  playground/scaleengine

• 
  examples/2D/pyplot

More Examples

• 
  examples/2D/distrowatch

• 
  examples/2D/friedberg

• 
  examples/2D/friedberg

• 
  examples/2D/itemeditor

• 
  examples/2D/rasterview

• 
  examples/2D/rasterview

• 
  examples/2D/refreshtest

• 
  examples/2D/splineeditor

• 
  examples/2D/tvplot

• 
  playground/curvetracker

• 
  playground/graphicscale

• 
  playground/plotmatrix

• 
  playground/rescaler

• 
  playground/svgmap

• 
  playground/timescale

Interactive Demos

• 
  Axis Dragging

• 
  Axis Zooming

• 
  Figure Overlay

• 
  Data Picker

License

Qwt Widget Library
Copyright (C) 1997   Josef Wilgen
Copyright (C) 2002   Uwe Rathmann

Qwt is published under the Qwt License, Version 1.0.