When view a image with size 1000*1000 on a HiDPI (4K) display, the zoom function doesn't work as other systems. The actual size of the image when viewing at 100% zoom is about 2000*2000 if the scalefactor of the display is set to 2. Gimp handles this correctly with 2.9.4 on the same display, For the image and video output we should ignore the system scalefactor and just render them pixel to pixel. which is the one Mac and Windows do. Reproducible: Always Steps to Reproduce: 1.Open a image with any supported format 2.Change the zoom ratio to 100% 3. Check the real size of the image showed on HiDPI display, based on the system scale factor, you may get some different size which usually greater than the original image size. Actual Results: the image with 100% zoom ratio also changed size based on the system scale factor Expected Results: the image part should ignore the system scale factor which just show the size as the image property shows. This bug happens on most of KDE and QT image and video application, for example, digikam.
Just tried xnviewmp. And it shows the image correct, just behave like on others platforms. So this is an issue of our code implementation.
I tried to learn QT programming and just tested with QGraphicView, it does show the image based on the scale_factor settings which is not right based on my experience on other platforms. So this may be a Qt bug. but can we do something on our codes to make the behaviour better?
*** This bug has been marked as a duplicate of bug 373178 ***