Capturing high-quality(300dpi) screenshots of QT-based app in Linux

Question

I need to make a screenshot of my form created in QT designer. There are numerous approaches to do screenshots(gimp, import, etc..) but alt of them deal with same dpi as on my monitor(about 100dpi). This is quite enough to publish on web site, but 300dpi images are required for paper publications. Are there any ways to create 300dpi screenshots?

Answer 1

You can't have more pixels on your screenshot than your widget displays.

For a given widget size (say 900x900px) you can have your image printed at 300dpi, but it will only make a 3 inch square on your paper.

Answer 2

You can not grab screenshot in a best resolution than the one of your monitor. DPI has no sense in computer display. Some software convert pixel per point (ppp) to dot per inch (dpi) for paper publication. Once you have made your screenshots, you can convert them to 300 dpi using a software like photoshop or equivalent.

Answer 3

I don't think that the 300dpi requirement for publication applies to things like screenshots, where the data is inherently pixelated. It's meant for things like graphs that can and should be generated in a vector format.

Just get the best results you can, and only use screenshots for things that are absolutely necessary, and not, for example, commandline I/O or results graphs.

If the final images are being shown smoothed and blurry, either find settings in your PDF creator to prevent this, or manually blow up the image to a multiple of its original size to preserve the original sharp pixelation.

Answer 4

Painting can be done on any QPaintDevice, which includes QPrinter. If you wanted to, you could set up painting redirection to a given device, then have the widget repaint itself. This might give you the higher precision you desire. For more information, look on Qt's website for the Paint System overview, and also maybe look at the QPixmap::grabWidget functions.