setContentScaleFactor - 4.0 ; always 1:1 mapping

on iOS I find I have to set this to 0.5 on an iPad to get it to show a 1:1 image as full screen. This fails on an iPhone.

auto frameSize = glview->getFrameSize();
glview->setDesignResolutionSize(fWidth, fHeight, ResolutionPolicy::NO_BORDER);

is this expected behavior due to the iPad historically being 1024x768. So to scale a 2048x1536 down you need to do 0.5.
Is there also a size I need to be relative to on iPhone to get a 1:1 mapping?

setting it to 1.0 gets me this

This bug was proudly sponsored by XCode is garbage and doesn’t colour highlight the pre-processor.