High DPI: zooming on secondary non high-dpi display blanks view


#1

I am able to use Kicad on my primary High DPI 3840x2160 display. However, when I add a second non-high dpi USB display and I move a kicad window over, scrolling causes the display on that window to disappear. This behaviour is consistent with all applications (eeschema, pcbnew, etc).

Kicad version is 5.1.4


#2

I can’t really help you but I know that the first thing a person that can help you will ask is what is your OS and in case of linux what is the display server (X or wayland)


#3

Regardles of you hardware and operating system this clearly is a display driver issue. Check with the exact OS pertinent requirements for your attached devices.

Using KiCad (master branch, or 5.1.4 on 18.04.2, amd hardware) across multiple screens of different geometry works for me just fine.


#4

Not necessarily. Different geometry is one thing but different DPI settings is another. There are some software hacks to handle DPI and scaling in KiCad code, they may break in such monitor configurations.


#5

What is your dpi difference?


#6

I am running Windows 10 on a Lenovo Yoga 720.
A website visit indicates the DPI here is 240

The secondary device is “ASUS MB169B+ 15.6” Full HD 1920x1080 IPS USB"
According to ASUS the Pixel Pitch is 0.179 mm…is this actually ~142 DPI I’m not sure.
Website says 144 DPI.


#7

Unless you have different dpi scaling configured on OS level actual pixel pitch doesn’t matter.
In this case I’m inclined to agree that it’s the drivers issue, usb monitors are god knows what in terms of graphics chipset/drivers.


#8

I’m afraid I’m not following the drivers issue.
I can zoom just fine in Inkscape, Chrome, Gimp on windows 10 on my USB monitor.
If those work fine why shouldn’t Kicad?


#9

Because different software uses different hardware capabilities and different rendering methods. KiCad uses opengl, it may be that drivers for your monitor doesn’t support it properly.
You can check if you see this issue both with accelerated mode (press F11) and with fallback (F12). If this happens only in accelerated mode the issue is more likely related to opengl support.


#10

Yes I see the issue is only in accelerated mode.
What are the opengl conformance parameters to ensure Kicad support?


#11

If I’m not mistaken minimum requirement is OpenGL 2.1 support.
Usb monitors work mostly by software rendering on CPU and passing the output to the device. Unless the manufacturer implemented opengl layer emulation in the drivers and/or some sort of hardware acceleration passthrough via main GPU you are probably out of luck and will have to use fallback mode.
Check documentation for your monitor.