Printing plot black & white

[maybe78]

Hallo!

I got some problems printing my plot. The only available print-options are QPrinter::Color and QPrinter::GrayScale, so when i print my plot on black & white printer i see my curves too light to identish.

I want to print all curves black on white background.

Should I modify each curve Pen manually?

I saw a function QwtPlotPrintFilter::color, but i don't think it will help me someway.

[Uwe]

I saw a function QwtPlotPrintFilter::color, but i don't think it will help me someway.

Well, it was made for exactly your usecase.

Uwe

[maybe78]

Well, it was made for exactly your usecase.

Uwe

But how should i use it? I thought that it simple returns the grayscale color that would be used instead of my color in print.
I tried different variants, but couldn't get result.

the last thing i wrote was:

QwtPlotPrintFilter filter;
 filter.color(QColor(Qt::red),QwtPlotPrintFilter::Curve) = Qt::black;

QwtPlotPrintFilter filter;
 filter.color(QColor(Qt::red),QwtPlotPrintFilter::Curve) = Qt::black;

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[Uwe]

Of course you have to subclass QwtPlotFilter and implement the color method.

Uwe

[maybe78]

Of course you have to subclass QwtPlotFilter and implement the color method.

Uwe

Entschuldigung, but i still don't quite sure how to use it (

in header file i included:

class MyPrintFilter : public QwtPlotPrintFilter
{
public:
QColor MyPrintFilter::color(const QColor &c, Item item) const
{
    if ( !(options() & PrintBackground))
    {
        switch(item)
        {
            case MajorGrid:
                return Qt::darkGray;
            case MinorGrid:
                return Qt::gray;
            case Curve:
                return Qt::black;
            default:;
        }
    }
    return c;
}
};

class MyPrintFilter : public QwtPlotPrintFilter
{
public:
QColor MyPrintFilter::color(const QColor &c, Item item) const
{
    if ( !(options() & PrintBackground))
    {
        switch(item)
        {
            case MajorGrid:
                return Qt::darkGray;
            case MinorGrid:
                return Qt::gray;
            case Curve:
                return Qt::black;
            default:;
        }
    }
    return c;
}
};

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and then created filter using this type. But nothing still happens(

UPD: Oh, i got it working. The line was to thin to see the difference at first look.
Thank you, Uwe!