Complete solution here (based on all answers). I have added a parameter MinPercentOnScreen
where at least this % of pixels must be visible across all screens/displays. So if this returns false
you will need to move the window's position back to default.
// Return True if a certain percent of a rectangle is shown across the total screen area of all monitors, otherwise return False.
public bool IsOnScreen(System.Drawing.Point RecLocation, System.Drawing.Size RecSize, double MinPercentOnScreen = 0.2)
{
double PixelsVisible = 0;
System.Drawing.Rectangle Rec = new System.Drawing.Rectangle(RecLocation, RecSize);
foreach (Screen Scrn in Screen.AllScreens)
{
System.Drawing.Rectangle r = System.Drawing.Rectangle.Intersect(Rec, Scrn.WorkingArea);
// intersect rectangle with screen
if (r.Width != 0 & r.Height != 0)
{
PixelsVisible += (r.Width * r.Height);
// tally visible pixels
}
}
return PixelsVisible >= (Rec.Width * Rec.Height) * MinPercentOnScreen;
}
Implementation:
return IsOnScreen(this.Location, this.Size);