vnm_plot

A GPU-accelerated 2D time-series plotting library for Qt Quick, using Qt RHI. It provides interactive plots with automatic level-of-detail selection for large datasets, line and area styles, stacked series, previews, and shared time axes. Applications supply their own sample types and data sources.

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Getting started

You need a C++20 compiler, CMake, and Qt 6.12 or newer with Core, Gui, Qml, Quick, GuiPrivate, and ShaderTools. The source build obtains its other dependencies when they are not already supplied.

To build the library and the hello/preview examples:

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release -DVNM_PLOT_BUILD_EXAMPLES=ON
cmake --build build --config Release

Start with hello_plot for a runnable Qt Quick application. Building and integration covers dependency selection, other examples, and installed packages.

To use a source checkout in an existing CMake application:

add_subdirectory(vnm_plot)
target_link_libraries(your_app PRIVATE vnm_plot::qtquick)

Plotting samples

Given a vnm::plot::Plot_widget* plot_widget from your Qt Quick view, create a data source and describe how to read its timestamps and values:

#include <vnm_plot/vnm_plot.h>

struct sample_t
{
    std::int64_t t_ns;
    float        value;
};

std::vector<sample_t> samples;
samples.push_back({0, 0.0f});
samples.push_back({1'000'000'000, 1.0f});

auto source = std::make_shared<vnm::plot::Vector_data_source<sample_t>>();
source->set_data(std::move(samples));

auto access = vnm::plot::make_access_policy<sample_t>(
    &sample_t::t_ns,
    &sample_t::value);

auto series = vnm::plot::Series_builder()
    .style(vnm::plot::Display_style::LINE)
    .color(vnm::plot::rgba_u8(51, 153, 255))
    .data_source(source)
    .access(access)
    .build_shared();

plot_widget->add_series(0, series);

The widget renders on Qt's RHI render thread. Keep registered series configuration immutable, replace it with add_series when it changes, and make data sources safe to read from that thread.

Using vnm_plot explains QML setup, custom samples, rendering configuration, and stacking. The benchmark guide covers performance measurements.

License

BSD-2-Clause. Embedded fonts keep their own licences; see third-party notices and licence texts.