how to set alignment of QChart axis

April Zhang

![alt text]( image url)
using QGraphicsView and scene and Qchart，but i can't set alignment of them , give some advice

Diracsbracket

@April-Zhang
Hi
The QChart class has the setMargins method which you could use to set a left margin on the plot with the smallest Y max label value, but the problem is then to determine which margin value would align the two axes exactly and in all cases.

The following seems to work:

    QFont labelFont = m_chart1->axisY()->labelsFont();

    QString str1("10000.0"); //set max. y label value here for chart1
    QString str2("10.0");    //set max. y label value here for chart2

    QFontMetrics fm(labelFont);

    int width1 = fm.boundingRect(str1).width();
    int width2 = fm.boundingRect(str2).width();

    QMargins margins = m_chart1->margins();

    int marg1 = margins.left();

    margins.setLeft(marg1 + width1 - width2);
    m_chart2->setMargins(margins);

So if you can get the maximum label strings on both Y axes, the above will align the two Y axes.

FYI:
Although I have no experience with QChart, I have been using the very convenient QCustomPlot widget to some limited extend:
http://www.qcustomplot.com/

It has a feature called QCPMarginGroup which allows you to obtain the alignment you seek.
http://www.qcustomplot.com/documentation/classQCPMarginGroup.html

The QCustomPlot widget is simply added to your project by including only 2 files: a header and a .cpp file with no further dependencies and which you are free to modify to your needs.

Diracsbracket

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