QMLThemeToolKit

A modular Qt 6 toolkit for building themed Qt Quick applications. Provides a reactive dark/light theme system and a matching set of Qt Quick Controls overrides, designed to be dropped into any project with a single add_subdirectory.

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Modules

CMake target	QML URI	Description
ThemeToolKit::Theme	io.github.ven96.theme 1.0	C++ singleton that drives dark/light switching
ThemeToolKit::Style	io.github.ven96.controls 1.0	Qt Quick Controls overrides + design tokens

ThemeToolKit::Style depends on ThemeToolKit::Theme — linking Style is sufficient to pull in both.

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Requirements

• Qt ≥ 6.5 (Quick, QuickControls2)
• CMake ≥ 3.16
• C++20

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Integration

Option A — add_subdirectory (submodule / local copy)

add_subdirectory(QMLThemeToolKit)

target_link_libraries(MyApp PRIVATE ThemeToolKit::Style)
qt_import_qml_plugins(MyApp)

Option B — FetchContent

include(FetchContent)
FetchContent_Declare(QMLThemeToolKit
    GIT_REPOSITORY https://github.com/96Ven96/QMLThemeToolKit.git
    GIT_TAG        main
)
FetchContent_MakeAvailable(QMLThemeToolKit)

target_link_libraries(MyApp PRIVATE ThemeToolKit::Style)
qt_import_qml_plugins(MyApp)

CMake options

Option	Default	Effect
QMLTHEMETOOLKIT_THEME	ON	Build ThemeToolKit::Theme
QMLTHEMETOOLKIT_STYLE	ON	Build ThemeToolKit::Style (requires Theme)
QMLTHEMETOOLKIT_SETTINGS	ON	Fetch qsettings-mapper and expose ThemeSettings.h

Set options before the add_subdirectory / FetchContent_MakeAvailable call:

set(QMLTHEMETOOLKIT_SETTINGS OFF)   # skip if you don't persist theme preferences
add_subdirectory(QMLThemeToolKit)

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main.cpp

#include <QQmlApplicationEngine>

// Make the embedded QML modules visible to the engine.
engine.addImportPath("qrc:/qt/qml");

engine.loadFromModule("MyApp", "Main");

ThemeManager is registered automatically as a QML singleton via QML_ELEMENT + QML_SINGLETON — no manual qmlRegisterSingletonInstance needed. Access it from C++ via ThemeManager::instance():

#include <ThemeManager.h>

ThemeManager::instance().setColorTheme(ThemeManager::Dark);

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QML usage

import io.github.ven96.controls

// Style singleton — reactive design tokens
Rectangle {
    color: Style.surfaceApp

    Text {
        color: Style.textPrimary
        font.pixelSize: Style.fontSizeBody
    }
}

import QtQuick.Controls
import io.github.ven96.controls

Column {
    Button { text: "Cancel" }                    // secondary style
    Button { text: "Confirm"; highlighted: true } // primary style

    SearchBar { placeholderText: "Filter..." }

    Toast { id: toast }
}

For the full component reference (tokens, SearchBar, Toast, Dialog) see QtQMLSyleKit/README.md.

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Persisting theme preference

When QMLTHEMETOOLKIT_SETTINGS=ON, include ThemeSettings.h to get a ready-made QSettings mapping:

#include <ThemeSettings.h>

QSettings s("MyOrg", "MyApp");
SettingsHelper::load<ThemeSettings>(s, ThemeManager::instance());  // on startup
SettingsHelper::save<ThemeSettings>(s, ThemeManager::instance());  // on change

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Dependencies

Library	How it arrives
cpp-template-toolkit	FetchContent (only when QMLTHEMETOOLKIT_SETTINGS=ON)
qsettings-mapper	FetchContent (only when QMLTHEMETOOLKIT_SETTINGS=ON)

Both use an if(NOT TARGET ...) guard: if your project already pulls in either library, CMake reuses the existing target and skips the fetch entirely.