我在 QChartView 中找不到缩放图形的鼠标滚轮滚动事件
I can't find mouse wheel scroll events for zoom graphics in QChartView
我在程序 window 上有 QChartView。有数据数组在图表上正确显示为 QLineSeries(温度与时间曲线)。我在 QChartView 上找不到 'mousewheelup zoom-in' 和 'mousewheeldown zoom-out' 的鼠标滚轮事件?需要能够仅在垂直方向进行缩放,如 setRubberBand(QChartView::VerticalRubberBand)
但只能通过鼠标滚轮滚动。需要帮助
QChartView
继承自 QGraphicsView
,后者提供 QGraphicsSceneWheelEvent
QChartView
是一个 QWidget
,因此您可以使用 wheelEvent()
方法实现该逻辑:
#include <QApplication>
#include <QChartView>
#include <QLineSeries>
#include <random>
QT_CHARTS_USE_NAMESPACE
class ChartView : public QChartView
{
public:
using QChartView::QChartView;
enum DirectionZoom{
NotZoom,
VerticalZoom,
HorizontalZoom,
BothDirectionZoom = VerticalZoom | HorizontalZoom
};
DirectionZoom directionZoom() const{
return mDirectionZoom;
}
void setDirectionZoom(const DirectionZoom &directionZoom){
mDirectionZoom = directionZoom;
}
protected:
void wheelEvent(QWheelEvent *event)
{
if(chart() && mDirectionZoom != NotZoom){
const qreal factor = 1.001;
QRectF r = chart()->plotArea();
QPointF c = r.center();
qreal val = std::pow(factor, event->delta());
if(mDirectionZoom & VerticalZoom)
r.setHeight(r.height()*val);
if (mDirectionZoom & HorizontalZoom) {
r.setWidth(r.width()*val);
}
r.moveCenter(c);
chart()->zoomIn(r);
}
QChartView::wheelEvent(event);
}
private:
DirectionZoom mDirectionZoom = NotZoom;
};
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QChart *chart = new QChart();
chart->legend()->hide();
chart->setTitle("Simple line chart example");
std::random_device rd;
std::mt19937 rng(rd());
std::uniform_int_distribution<int> uni(0, 10);
for(size_t i=0; i< 5; i++){
QLineSeries *series = new QLineSeries();
for(size_t j=0; j < 10; j++){
*series << QPointF(j, uni(rng));
}
chart->addSeries(series);
}
chart->createDefaultAxes();
ChartView chartView(chart);
chartView.setDirectionZoom(ChartView::VerticalZoom);
chartView.setRenderHint(QPainter::Antialiasing);
chartView.resize(640, 480);
chartView.show();
return a.exec();
}
我在程序 window 上有 QChartView。有数据数组在图表上正确显示为 QLineSeries(温度与时间曲线)。我在 QChartView 上找不到 'mousewheelup zoom-in' 和 'mousewheeldown zoom-out' 的鼠标滚轮事件?需要能够仅在垂直方向进行缩放,如 setRubberBand(QChartView::VerticalRubberBand)
但只能通过鼠标滚轮滚动。需要帮助
QChartView
继承自 QGraphicsView
,后者提供 QGraphicsSceneWheelEvent
QChartView
是一个 QWidget
,因此您可以使用 wheelEvent()
方法实现该逻辑:
#include <QApplication>
#include <QChartView>
#include <QLineSeries>
#include <random>
QT_CHARTS_USE_NAMESPACE
class ChartView : public QChartView
{
public:
using QChartView::QChartView;
enum DirectionZoom{
NotZoom,
VerticalZoom,
HorizontalZoom,
BothDirectionZoom = VerticalZoom | HorizontalZoom
};
DirectionZoom directionZoom() const{
return mDirectionZoom;
}
void setDirectionZoom(const DirectionZoom &directionZoom){
mDirectionZoom = directionZoom;
}
protected:
void wheelEvent(QWheelEvent *event)
{
if(chart() && mDirectionZoom != NotZoom){
const qreal factor = 1.001;
QRectF r = chart()->plotArea();
QPointF c = r.center();
qreal val = std::pow(factor, event->delta());
if(mDirectionZoom & VerticalZoom)
r.setHeight(r.height()*val);
if (mDirectionZoom & HorizontalZoom) {
r.setWidth(r.width()*val);
}
r.moveCenter(c);
chart()->zoomIn(r);
}
QChartView::wheelEvent(event);
}
private:
DirectionZoom mDirectionZoom = NotZoom;
};
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QChart *chart = new QChart();
chart->legend()->hide();
chart->setTitle("Simple line chart example");
std::random_device rd;
std::mt19937 rng(rd());
std::uniform_int_distribution<int> uni(0, 10);
for(size_t i=0; i< 5; i++){
QLineSeries *series = new QLineSeries();
for(size_t j=0; j < 10; j++){
*series << QPointF(j, uni(rng));
}
chart->addSeries(series);
}
chart->createDefaultAxes();
ChartView chartView(chart);
chartView.setDirectionZoom(ChartView::VerticalZoom);
chartView.setRenderHint(QPainter::Antialiasing);
chartView.resize(640, 480);
chartView.show();
return a.exec();
}