我正在尝试使用以下简单代码将QChartView渲染为.png图像:
QChartView *chartView = /* pointer to chart view */;
const auto dpr = chartView->devicePixelRatioF();
chartView->setMinimumSize(500, 500);
chartView->setMaximumSize(500, 500);
QImage image(500, 500, QImage::Format_ARGB32_Premultiplied);
image.setDevicePixelRatio(dpr);
QPainter painter(&image);
painter.setRenderHint(QPainter::Antialiasing);
chartView->render(&painter);
image.save('image.png');
它工作正常,并且可以按预期保存图像。 但是,如果我尝试在渲染前更改标题,则不会显示该标题:
QChartView *chartView = /* pointer to chart view */;
const auto dpr = chartView->devicePixelRatioF();
chartView->setMinimumSize(500, 500);
chartView->setMaximumSize(500, 500);
chartView->chart()->setTitle("my title"); // <--- HERE
QImage image(500, 500, QImage::Format_ARGB32_Premultiplied);
image.setDevicePixelRatio(dpr);
QPainter painter(&image);
painter.setRenderHint(QPainter::Antialiasing);
chartView->render(&painter);
image.save('image.png');
但是,如果我创建了一个显示标题的按钮和一个应该保存图像的按钮,则我首先单击该按钮以显示标题,然后单击该按钮以保存其有效的图像。 (意思是,如果我将这两个步骤分开,那么在GUI中显示图表之间就可以了)
当我尝试显示图例时也是如此。
更新:我添加了一个完整的最小示例来重现该问题:
#include <QtWidgets/QApplication>
#include <QtWidgets/QMainWindow>
#include <QtCharts/QChartView>
#include <QtCharts/QLineSeries>
QT_CHARTS_USE_NAMESPACE
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QLineSeries *series = new QLineSeries();
series->setName("label");
series->append(0, 6);
series->append(2, 4);
series->append(3, 8);
series->append(7, 4);
series->append(10, 5);
*series << QPointF(11, 1) << QPointF(13, 3) << QPointF(17, 6) << QPointF(18, 3) << QPointF(20, 2);
QChart *chart = new QChart();
chart->addSeries(series);
chart->createDefaultAxes();
QChartView *chartView = new QChartView(chart);
chartView->setRenderHint(QPainter::Antialiasing);
chart->setTitle("");
chart->legend()->hide();
chartView->grab().toImage().save("noLabels.png");
chart->setTitle("title");
chart->legend()->show();
chartView->grab().toImage().save("withLabels.png");
QMainWindow window;
window.setCentralWidget(chartView);
window.resize(400, 300);
window.show();
return a.exec();
}
创建的图像noLabels.png
和withLabels.png
均未显示标题或图例。
答案 0 :(得分:1)
似乎当您设置标题或显示图例时,事件将排队并稍后处理。您可以通过在设置标题并显示图例后调整图表视图的大小来强制发生这些事件:
chart->setTitle("title");
chart->legend()->show();
chartView->resize(QSize(500,500));
chartView->grab().toImage().save("withLabels.png");
答案 1 :(得分:0)
设置标题之前您尝试使用repaint()
吗?