Hi ErkangHui,
there are multiple items in the marketplace that allow you to create a screenshot and safe it as a PDF.
For example:
https://marketplace.mendix.com/link/component/119983
https://marketplace.mendix.com/link/component/203903
You can also use the mendix "PDF Document Generation", which also saves a pdf file.
https://marketplace.mendix.com/link/component/211553
If you want it to be an image, you can have a look at the source code of the "Mendix feedback module", which captures an image of the page.