Qt Quick 2 Scatter Example

The Qt Quick 2 scatter example shows how to make a simple scatter graph visualization using Scatter3D and Qt Quick 2.

For instructions about how to interact with the graph, see this page.

For instructions how to create a new Qt Quick 2 application of your own, see Qt Creator help.

Running the Example

To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.

Application Basics

Before diving into the QML code, let's take a look at the application main.cpp.

This application implements a 'Quit' button in the UI, so we want to connect the QQmlEngine::quit() signal to our application's QWindow::close() slot:

QObject::connect(viewer.engine(), &QQmlEngine::quit, &viewer, &QWindow::close);

To make deployment little simpler, we gather all of the application's .qml files to a resource file (qmlscatter.qrc):

<RCC>
    <qresource prefix="/">
        <file>qml/qmlscatter/Data.qml</file>
        <file>qml/qmlscatter/main.qml</file>
    </qresource>
</RCC>

This also requires us to set the main.qml to be read from the resource (qrc:):

viewer.setSource(QUrl("qrc:/qml/qmlscatter/main.qml"));

Lastly, we want the application to run in a maximized window:

viewer.showMaximized();

Setting up the Graph

First we'll import all the QML modules we need:

import QtQuick
import QtQuick.Controls
import QtDataVisualization
import "."

The last import just imports all the qml files in the same directory as our main.qml, because that's where Data.qml is.

Then we create our main Item and call it mainView:

Item {
    id: mainView

Then we'll add another Item inside the main Item, and call it dataView. This will be the item to hold the Scatter3D graph. We'll anchor it to the parent bottom:

Item {
    id: dataView
    anchors.bottom: parent.bottom

Next we're ready to add the Scatter3D graph itself. We'll add it inside the dataView and name it scatterGraph. Let's make it fill the dataView:

Scatter3D {
    id: scatterGraph
    width: dataView.width
    height: dataView.height

Now the graph is ready for use, but has no data. It also has the default axes and visual properties.

Let's modify some visual properties first by adding the following inside scatterGraph:

theme: themeIsabelle
shadowQuality: AbstractGraph3D.ShadowQualitySoftLow

We added a customized theme and changed the shadow quality. We're happy with the other visual properties, so we won't change them.

The custom theme is based on a predefined theme, but we change the font in it:

Theme3D {
    id: themeIsabelle
    type: Theme3D.ThemeIsabelle
    font.pointSize: 40
}

Then it's time to start feeding the graph some data.

Adding Data to the Graph

Let's create a Data item inside the mainView and name it seriesData:

Data {
    id: seriesData
}

The seriesData item contains the data models for all three series we use in this example.

This is the component that holds our data in Data.qml. It has an Item as the main component.

In the main component we'll add the data itself in a ListModel and name it dataModel:

ListModel {
    id: dataModel
    ListElement{ xPos: -10.0; yPos: 5.0; zPos: -5.0 }
    ...

We'll add two more of these for the other two series, and name them dataModelTwo and dataModelThree.

Then we need to expose the data models to be usable from main.qml. We do this by defining them as aliases in the main data component:

property alias model: dataModel
property alias modelTwo: dataModelTwo
property alias modelThree: dataModelThree

Now we can use the data from Data.qml with scatterGraph in main.qml. First we'll add a Scatter3DSeries and call it scatterSeries:

Scatter3DSeries {
    id: scatterSeries

Then we'll set up selection label format for the series:

itemLabelFormat: "Series 1: X:@xLabel Y:@yLabel Z:@zLabel"

And finally the data for series one in a ItemModelScatterDataProxy. We set the data itself as itemModel for the proxy:

ItemModelScatterDataProxy {
    itemModel: seriesData.model
    xPosRole: "xPos"
    yPosRole: "yPos"
    zPosRole: "zPos"
}

We'll add the other two series in the same way, but modify some series-specific details a bit:

Scatter3DSeries {
    id: scatterSeriesTwo
    itemLabelFormat: "Series 2: X:@xLabel Y:@yLabel Z:@zLabel"
    itemSize: 0.1
    mesh: Abstract3DSeries.MeshCube
    ...

Then we'll modify the properties of the default axes in scatterGraph a bit:

axisX.segmentCount: 3
axisX.subSegmentCount: 2
axisX.labelFormat: "%.2f"
axisZ.segmentCount: 2
axisZ.subSegmentCount: 2
axisZ.labelFormat: "%.2f"
axisY.segmentCount: 2
axisY.subSegmentCount: 2
axisY.labelFormat: "%.2f"

After that we'll just add a few buttons to the mainView to control the graph. We'll only show one as an example:

Button {
    id: shadowToggle
    width: portraitMode ? implicitWidth : (mainView.width / 6 - 6)
    anchors.left: parent.left
    anchors.top: parent.top
    anchors.margins: 5
    text: scatterGraph.shadowsSupported ? "Hide Shadows" : "Shadows not supported"
    enabled: scatterGraph.shadowsSupported
    onClicked: {
        if (scatterGraph.shadowQuality === AbstractGraph3D.ShadowQualityNone) {
            scatterGraph.shadowQuality = AbstractGraph3D.ShadowQualitySoftLow;
            text = "Hide Shadows";
        } else {
            scatterGraph.shadowQuality = AbstractGraph3D.ShadowQualityNone;
            text = "Show Shadows";
        }
    }
}

Then we'll modify dataView to make room for the buttons at the top:

Item {
    id: dataView
    anchors.bottom: parent.bottom
    width: parent.width
    height: parent.height - (portraitMode ? shadowToggle.implicitHeight * 3 + 25
                                          : shadowToggle.implicitHeight + 10)
    ...

And we're done!

Example Contents

Example project @ code.qt.io