I got an error when using QValueAxis
in QtCharts
:
ASSERT: "width > 0.0" in file painting\qrasterizer.cpp, line 761
This happens when the QBarSet
values are all 0
.
I have this example with the minimal necessary code below:
#include <QtWidgets/QApplication>
#include <QtWidgets/QMainWindow>
#include <QtCharts>
QT_CHARTS_USE_NAMESPACE
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QChart *chart = new QChart;
QBarSeries *series = new QBarSeries(chart);
QBarSet *set = new QBarSet("BarSet", series);
series->append(set);
QValueAxis *valueAxisX = new QValueAxis(chart);
QChartView *chartView = new QChartView(chart);
for(int i = 0; i < 24; ++i) {
set->append(0); //error
//if I set like set->append(1) or anything just to make sure the values are not all 0, there will be no error.
}
chart->addSeries(series);
chart->setAxisX(valueAxisX, series);
QMainWindow window;
window.setCentralWidget(chartView);
window.resize(420, 300);
window.show();
return a.exec();
}
My program will initiate the QBarSet
dynamically from a QMap
. Like this:
for(auto it = map.cbegin(); it != map.cend(); ++it) {
set->append(it.value());
}
And the QMap
is initiated to something like this when the program starts:
QMap(("First", 0)("Second", 0)...)
Sometimes the QMap
will not add values due to the use of the program, then all the QBarSet
values will be initiated to 0
. Then the program will crash because of that error.
So how can I avoid this error when the QBarSet
values are all initiated to 0
?
As the error speaks:
ASSERT: "width > 0.0"
You need a value greater than zero.
Also QBarSet::append
,
void QBarSet::append(const qreal value)
expects a qreal
or double
value.
Perhaps you want to set it to 0.1
initially:
set->append(0.1);