使用光标和点选择

我们首先创建一个序列，填充数据并设置选择功能。重要的是不要将点的可见性设置为true ，因为光标功能是一项独立的功能，同时设置这两项功能会导致不希望出现的行为。

constexpr qreal marker_size = 20.;

auto series = new QSplineSeries;
series->append({QPointF(0., 0.),
                QPointF(0.5, 2.27),
                QPointF(1.5, 2.2),
                QPointF(3.3, 1.7),
                QPointF(4.23, 3.1),
                QPointF(5.3, 2.3),
                QPointF(6.47, 4.1)
});
series->setMarkerSize(marker_size);
series->setLightMarker(rectangle(marker_size, Qt::red));
series->setSelectedLightMarker(blueTriangle(marker_size));

QObject::connect(series, &QXYSeries::clicked, series, [=](const QPointF &point) {
    int index = series->points().indexOf(point);
    if (index != -1)
        series->toggleSelection({index});
});

然后，我们创建QChart 、QChartview 和控制 widget 及其布局，以安排自定义元素。

auto chart = new QChart;
chart->addSeries(series);
chart->createDefaultAxes();
chart->legend()->setVisible(false);
chart->layout()->setContentsMargins(0, 0, 0, 0);
chart->setTitle("Select points with mouse click");

auto chartView = new QChartView(chart, this);
chartView->setRenderHint(QPainter::Antialiasing);

auto controlWidget = new QWidget(this);
auto controlLayout = new QGridLayout(controlWidget);

下一步是创建自定义元素。

auto charPointCombobox = new QComboBox(controlWidget);
auto charPointSelectedCombobox = new QComboBox(controlWidget);
auto lineColorCombobox = new QComboBox(controlWidget);
auto showUnselectedPointsCheckbox = new QCheckBox(controlWidget);

我们为标记选择组合框创建标签，并为组合框添加填充项。此外，我们还为组合框提供了功能。考虑到灯光标记功能的实现，我们需要确保是否选中了显示未选择的点。关闭灯光标记的可见性可以通过将其设置为"empty" QImage 来实现。如果用户取消选中未选中点的显示，并更改灯光标记图像，则未选中点必须保持不可见。如果不进行检查，则会为光标设置新的QImage ，即使关闭了光标，未选中的点也会显示出来。

auto charPoint = new QLabel(tr("Char point: "), controlWidget);
charPointCombobox->addItems({tr("Red rectangle"),
                             tr("Green triangle"),
                             tr("Orange circle")
});
QObject::connect(charPointCombobox, &QComboBox::currentIndexChanged, series, [=](const int index) {
    if (showUnselectedPointsCheckbox->isChecked())
        series->setLightMarker(getPointRepresentation(PointType(index), marker_size));
});

几乎同样的步骤也适用于选定点光标和线条颜色。唯一不同的是，无需检查未选中点的可见性，因为这不会影响功能。

auto charPointSelected = new QLabel(tr("Char point selected: "), controlWidget);
charPointSelectedCombobox->addItems({tr("Blue triangle"),
                                     tr("Yellow rectangle"),
                                     tr("Lavender circle")
});
QObject::connect(charPointSelectedCombobox, &QComboBox::currentIndexChanged, series, [=](const int index) {
    series->setSelectedLightMarker(getSelectedPointRepresentation(SelectedPointType(index), marker_size));
});

auto lineColorLabel = new QLabel(tr("Line color: "), controlWidget);
lineColorCombobox->addItems({tr("Blue"),
                             tr("Black"),
                             tr("Mint")
});
QObject::connect(lineColorCombobox, &QComboBox::currentIndexChanged, series, [=](const int index) {
    series->setColor(makeLineColor(LineColor(index)));
});

在改变未选中点的可见性方面有一点不同。如前所述，将光标设置为 "空 "即可实现不可见QImage 。因此，根据复选框的状态，选定点的光标会被设置为 "空"QImage 或从相应组合框的当前索引中提取的光标。

auto showUnselectedPointsLabel = new QLabel(tr("Display unselected points: "), controlWidget);
showUnselectedPointsCheckbox->setChecked(true);
QObject::connect(showUnselectedPointsCheckbox, &QCheckBox::stateChanged, series, [=](const int state) {
    if (state)
        series->setLightMarker(getPointRepresentation(PointType(charPointCombobox->currentIndex()), marker_size));
    else
        series->setLightMarker(QImage());
});

最后一部分是排列元素，将所有部件添加到主部件中，并设置主窗口大小。

controlLayout->addWidget(charPoint, 0, 0);
controlLayout->addWidget(charPointCombobox, 0, 1);

controlLayout->addWidget(charPointSelected, 1, 0);
controlLayout->addWidget(charPointSelectedCombobox, 1, 1);

controlLayout->addWidget(lineColorLabel, 2, 0);
controlLayout->addWidget(lineColorCombobox, 2, 1);

controlLayout->addWidget(showUnselectedPointsLabel, 3, 0);
controlLayout->addWidget(showUnselectedPointsCheckbox, 3, 1, 1, 2);

m_mainWidget = new QWidget(this);
auto mainLayout = new QHBoxLayout(m_mainWidget);
mainLayout->addWidget(chartView);
mainLayout->addWidget(controlWidget);

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