Spent some time over the weekend looking at APIs in windows that give access to the monitor configuration of the system that code is running on.<\/p>\n\n\n\n
I tend to run on systems with several monitors (usually as many as is practical). Ideally, I’d like to create tools that can use the available display real-estate in helpful ways.<\/p>\n\n\n\n
The main API involved is\u00a0EnumDisplayMonitors<\/a> which will invoke your provided callback function<\/a> with the HMONITOR for each monitor that is recognized by the system. Calling\u00a0GetMonitorInfoW<\/a> can then provide some of the details of each display in a\u00a0MONITORINFOEX<\/a> structure.<\/p>\n\n\n\n One oddity in all of this is that a monitor with a scaling factor applied (my 4K monitor is set to 150% scale factor for usability reasons) returns the post-scaling size with a gap in the coordinate system that reflects the ‘missing’ pixels. In my case the small monitor I use to keep an eye on the router is logically far to the right of the left hand edge of the big monitor.<\/p>\n\n\n\n There is a supplementary API call GetScaleFactorForMonitor<\/a> which returns a\u00a0DEVICE_SCALE_FACTOR<\/a> indicating the current scale factor for a given monitor. This is a little bit strange on my system as the big monitor appears to be set for 150% scaling but the API call shows 140% scaling. The size numbers match what I’d expect for 150% so something must be a bit off here…<\/p>\n\n\n\n Interesting API to look into\u00a0GetDpiForMonitor<\/a> and\u00a0MONITOR_DPI_TYPE.<\/a><\/p>\n\n\n\n Looks as if the SetProcessDpiAwareness<\/a> API (with PROCESS_DPI_AWARENESS<\/a>\u00a0and WM_DPICHANGED<\/a>) may have a part in all of this as well…deciding whether\u00a0the process gets presented DPI aware or virtualized display metrics.<\/p>\n\n\n\n Curious translation in\u00a0GetPhysicalMonitorsFromHMONITOR\u00a0<\/a> could use a bit of a look.<\/p>\n\n\n\n I need to read more of the DPI aware and multi-monitor articles before I’m done here. I also want a better idea of how this functionality interacts with WPF user interfaces as I’m likely to build the upper layers that way.<\/p>\n\n\n\n This certainly gets more complicated with display scaling and DPI calculations in the mix.<\/p>\n\n\n\n Some more relevant articles (I haven’t read these all in detail yet):<\/p>\n\n\n\n Spent some time over the weekend looking at APIs in windows that give access to the monitor configuration of the system that code is running on. I tend to run on systems with several monitors (usually as many as is practical). Ideally, I’d like to create tools that can use the available display real-estate in … Continue reading Win32 Multiple Monitors<\/span>