mac: report modifier keys on precise scrolling

modifier keys weren't reported when using the trackpad to scroll.

Fixes mpv-player#11195

osdep/macos/mpv_helper.swift

@@ -67,8 +67,8 @@ class MPVHelper {
         mp_input_set_mouse_pos(input, Int32(pos.x), Int32(pos.y))
     }
 
-    func putAxis(_ mpkey: Int32, delta: Double) {
-        mp_input_put_wheel(input, mpkey, delta)
+    func putAxis(_ mpkey: Int32, modifiers: NSEvent.ModifierFlags, delta: Double) {
+        mp_input_put_wheel(input, mpkey | mapModifier(modifiers), delta)
     }
 
     func nextChangedOption(property: inout UnsafeMutableRawPointer?) -> Bool {
@@ -111,6 +111,27 @@ class MPVHelper {
         free(UnsafeMutablePointer(mutating: cCmd))
     }
 
+    func mapModifier(_ modifiers: NSEvent.ModifierFlags) -> Int32 {
+        var mask: UInt32 = 0;
+
+        if modifiers.contains(.shift) {
+            mask |= MP_KEY_MODIFIER_SHIFT
+        }
+        if modifiers.contains(.control) {
+            mask |= MP_KEY_MODIFIER_CTRL
+        }
+        if modifiers.contains(.command) {
+            mask |= MP_KEY_MODIFIER_META
+        }
+        if modifiers.rawValue & UInt(NX_DEVICELALTKEYMASK) != 0 ||
+           modifiers.rawValue & UInt(NX_DEVICERALTKEYMASK) != 0 && !mp_input_use_alt_gr(input)
+        {
+            mask |= MP_KEY_MODIFIER_ALT
+        }
+
+        return Int32(mask)
+    }
+
     // (__bridge void*)
     class func bridge<T: AnyObject>(obj: T) -> UnsafeMutableRawPointer {
         return UnsafeMutableRawPointer(Unmanaged.passUnretained(obj).toOpaque())

video/out/mac/view.swift

@@ -227,7 +227,7 @@ class View: NSView {
             cmd = delta > 0 ? SWIFT_WHEEL_LEFT : SWIFT_WHEEL_RIGHT
         }
 
-        mpv?.putAxis(cmd, delta: abs(delta))
+        mpv?.putAxis(cmd, modifiers: event.modifierFlags, delta: abs(delta))
     }
 
     override func scrollWheel(with event: NSEvent) {