How to recognize when number, position, or resolution of monitors has changed? [duplicate]

Question

I'm building something which needs to detect when things change with the monitor configuration. This includes Monitor added/removed, Monitor position moved (compared to main screen), or when Monitor resolution has changed. The most ideal way would be catching some windows messages, if any, which are triggered when such events occur. This information will be used to keep a real-time record of the monitor sizes/positions at any given time. For example, when a monitor's resolution is increased, my app will catch this right away and make its own adjustments to accommodate for the change. How do I catch these events?

I'm also trying to avoid using VCL (such as Vcl.Forms.Screen.MonitorCount) which is why I prefer to catch a Windows Message.

Scumble

Answer 1

The most obvious message I can think of is WM_DISPLAYCHANGE which is sent, at least, when the resolution is changed.

Choosy

At which point you can use EnumDisplayMonitors to detect new information like position, size, count, and so forth. +1. – Wiener

or just recreate the global Screen variable: Screen.Free; Screen := TScreen.Create(nil); – Coarse

Newer Delphi versions (De 10.2) offers the method Screen.UpdateDisplayInformation so you do not need to recreate the screen object – Emprise

@SchneiderInfosystemsLtd - UpdateDisplayInformation is only available for FMX. – Headliner