更改条形图的颜色和状态
注意：这是 “带小部件的图表”示例库的一部分。
该示例演示了如何使用 setBarSelected() 方法更改条形图的颜色和状态。
我们创建数据集并向其中填充数据。然后创建一个数据系列并向其中追加数据。
QBarSet *setChicken = createChickenSet();
QBarSet *setPork = createPorkSet();
QBarSet *setTurkey = createTurkeySet();
QBarSet *setHam = createHamSet();
qreal totalSum = setChicken->sum() + setPork->sum() + setTurkey->sum() + setHam->sum();
QList<QBarSet *> setList = QList<QBarSet *>{setChicken, setPork, setTurkey, setHam};
auto series = new QBarSeries;
series->append(setList);我们创建图表并向其中添加系列。此外，我们为图表添加标题、设置动画效果，并调整图例对齐方式。
auto chart = new QChart;
chart->addSeries(series);
chart->setTitle(tr("Meat Consumption (Click on bars to select them)"));
chart->setAnimationOptions(QChart::SeriesAnimations);
chart->legend()->setVisible(true);
chart->legend()->setAlignment(Qt::AlignBottom);
chart->layout()->setContentsMargins(0, 0, 0, 0);在此，我们为选中的条形图设置颜色。
const auto barSets = series->barSets();
for (QBarSet *barSet : barSets)
barSet->setSelectedColor(barSet->brush().color().darker());下一步是添加坐标轴：QBarCategoryAxis 用于测量年份，QValueAxis 用于数值范围。
QStringList categories = createYearCategories();
auto axisX = new QBarCategoryAxis;
axisX->setCategories(categories);
chart->addAxis(axisX, Qt::AlignBottom);
series->attachAxis(axisX);
auto axisY = new QValueAxis;
axisY->setRange(0, 20);
axisY->setTitleText(tr("Tons"));
axisY->setLabelsAngle(-90);
axisY->setTitleVisible(true);
chart->addAxis(axisY, Qt::AlignLeft);
series->attachAxis(axisY);然后，我们将图表视图添加进去以容纳该图表。
auto chartView = new QChartView(chart, this);
chartView->setRenderHint(QPainter::Antialiasing);在此，我们创建一个小部件，用于显示已选中和未选中柱状图条的数值标签。
auto labelWidget = new QWidget(this);
auto labelLayout = new QHBoxLayout(labelWidget);
labelLayout->setAlignment(Qt::AlignCenter);
auto totalSumLabel = new QLabel(tr("Total sum: %1 T").arg(totalSum), this);
labelLayout->addWidget(totalSumLabel);
totalSumLabel->setContentsMargins(0, 0, 54, 0);
auto selectedSumLabel = new QLabel(tr("Selected sum: 0 T"), this);
labelLayout->addWidget(selectedSumLabel);
auto unselectedSumLabel = new QLabel(tr("Unselected sum: %1 T").arg(totalSum), this);
labelLayout->addWidget(unselectedSumLabel);
unselectedSumLabel->setContentsMargins(54, 0, 0, 0);我们使用 lambda 表达式将特定柱状图的选中操作与数值标签关联起来。set->toggleSelection({index}) 用于设置选中的柱状图。
QObject::connect(series, &QAbstractBarSeries::clicked, series, [=](int index, QBarSet *set) {
set->toggleSelection({index});
qreal selectedSum = 0.;
for (int i = 0; i < setList.size(); ++i) {
auto selectedIndices = setList.at(i)->selectedBars();
for (int k = 0; k < selectedIndices.size(); ++k)
selectedSum += setList.at(i)->at(selectedIndices.at(k));
}
selectedSumLabel->setText(tr("Selected sum: %1 T").arg(selectedSum));
// Because of rounding errors, selectedSum can result in being bigger than total sum
qreal unselectedSum = totalSum - selectedSum < 0 ? 0. : totalSum - selectedSum;
unselectedSumLabel->setText(
tr("Unselected sum: %1 T")
.arg(unselectedSum)
);
});最后，我们创建主布局。
auto mainLayout = new QVBoxLayout(this);
mainLayout->addWidget(chartView);
mainLayout->addWidget(labelWidget);© 2026 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.
