Printing sufficient curve thickness requires explicit increase of curve line width?

[philw]

We're finding that we have to programmatically increase the pen width of all of the curves within our plot DURING PRINTING (to PDF or an actual printer) by a factor of about 20 -- and then restore the normal pen widths for screen display -- in order for those curves to show up in the printed output with anything more than a hairline width. It looks like the rendering algorithm for screen and print output are the same, with no special provision to re-scale curve line thickness for the much higher resolution of print output.

This is with Qwt 5.2.3. See the accompanying image. Are we missing something? And does Qwt 6.1 (effectively) support curve pen width rescaling for printing?

9642

Thank you in advance,
Phil Weinstein, CADSWES

[Uwe]

Qwt 6 has a floating point based render engine and is using painter transformations ( scaling ) for PDF generation. When using non cosmetic pens ( https://qt-project.org/doc/qt-5.1/qtgui/qpen.html#isCosmetic ) for the curve the lines in the PDF document will appear comparable to screen.

Note that when using non cosmetic pens, that the lines will be scaled when zooming in in a PDF viewer too.

Uwe