Qt Quick Ultralite loader Example

Demonstrates how to the Loader QML type.


The loader example shows how to use the Loader QML type.

It implements a simple memory game. The player has to click colors in the same order as they appear on the screen. The game ends when the player clicks a wrong color. After the last color in the sequence is clicked, the best score is updated and a new round begins.

Application UI

The application consists of three pages:

  • Logo
  • Memory game
  • Settings

The main view of the application is implemented as a loader, which ensures that only one of the pages is stored in the RAM.

Whenever a button on each side is pressed, the source of the loader is changed to the corresponding page source.

    Loader {
        id: mainView

        anchors.fill: parent
        source: "Logo.qml"

        Connections {
            target: root
            function onCurrentPageChanged(currentPage: int) {
                if (currentPage === 0) {
                    mainView.source = "memory_game/MemoryGame.qml"
                } else if (currentPage === 1) {
                    mainView.source = "settings/Settings.qml"
                    GameState.running = false
Logo page

The Logo page displays an introductory image. It appears only once, at the start of the application.

Memory Game page

The Memory game is divided into two parts, display and controls. The display is at the beginning of a round, to display the colors that a player has to remember.

The display also contains stats, current score and the best score.

The controls part is a row of colored buttons, which has to be clicked by the player in the correct order.

Rectangle {
    id: root

    color: SettingsData.backgroundColor

    Item {
        id: positioningWrapper

        anchors { fill: parent; leftMargin: parent.width/10; rightMargin: parent.width/10; }

        GameWindow {
            anchors { left: parent.left; top: parent.top; right: parent.right; bottom: gameControls.top }

        ColorButtons {
            id: gameControls

            anchors { bottom: parent.bottom; horizontalCenter: parent.horizontalCenter }
            width: parent.width
            height: width * 0.2

        StatsOverlay {
            anchors { left: parent.left; right: parent.right; }

Settings Page

The Settings page lets users adjust the background color of the application, and change the game difficulty level.

Project structure

Main Application

The main application window is defined in loader.qml

Memory Game

The game UI is defined by the QML files in the loader/memory_game directory


The loader example defines two modules:

  • SettingsData
  • GameState

The SettingsData module stores application settings, such as background color or difficulty level.

The GameState module is used to control the game.

Both modules are used as means of communication between loaded items.



See also Communication with the loaded items.

Available under certain Qt licenses.
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