can't get small size file when painter.setResolution to small number

[tigerlfj]

no effect , change the resolution when print out file.
i want to get small file size , so i change resolution when print out as below

QPainter painter;
painter.setResolution(100);

my printer support the highest dpi is 600 ( pdf printer).
but i set painter.setResolution(100); 200 300 600 , all the file is same.
how can i get small size file ?

[ChrisW67]

How are you producing the PDF? If you are sending to a virtual printer that produces PDF files then you need to ask that driver to do something different.

If you are using QPdfWriter to create the PDF then tell us what happens when you use QPdfWriter::setResolution()

[tigerlfj]

@ChrisW67 Yes, i use QPrinter sending to a virtual PDF printer,but no effect.
I will have a try by QPdfWriter::setResolution.