Warping cursor from local coordinates when using several screens - objective-c

Question

I'm trying to warp the mouse using NSWindow local coordinates (but I'm starting from local coordinates in px instead of pt, with the y-axis reversed).
-(void)setProperRelativeMouseLocationTo:(NSPoint)loc
{
CGFloat scale = [[m_window screen] backingScaleFactor];
NSPoint point = NSMakePoint(loc.x / scale, loc.y / scale);
point.y = [m_view frame].size.height - point.y;
NSRect rect = NSZeroRect;
rect.origin = point;
rect = [m_window convertRectToScreen:rect];
point = rect.origin;
const float screenHeight = [[m_window screen] frame].size.height;
point.y = screenHeight - point.y;
warpCursor(point);
}
void warpCursor(NSPoint loc)
{
CGPoint newCursorPosition = CGPointMake(loc.x, loc.y);
CGWarpMouseCursorPosition(newCursorPosition);
}
However, the result is unexpected on one of my screens, the x-axis is correct, but the y-axis is off by 280pt.
This value is not random, it corresponds to the gap between the two screens I'm using : the left is 1280*800 (pt) and the second one is 1920*1080 (pt) (the left one has backing scale factor of 2, while the right one has factor 1).
On the left screen, the mouse is warped exactly where it should be (if I read its local coordinates, they correspond to the ones I asked it to warp to).

Answer 1

Cocoa screen coordinates have their origin at the lower-left of the primary screen. Core Graphics coordinates have their origin at the top-left of the primary screen. Therefore, you have to use the primary screen's height to convert between the two.
You have:
const float screenHeight = [[m_window screen] frame].size.height;
point.y = screenHeight - point.y;
You need:
const float screenHeight = [[NSScreen screens][0] frame].size.height;
point.y = screenHeight - point.y;