First post here!
I have an NSScrollView subclass. I want a mouse's option-scrollwheel events to cause the same zooming that trackpad pinch-zooming causes. I tried the simple solution below, but that just causes lots of assertions, probably because the scroll event is the wrong type and doesn't have the needed data for a magnify event. I don't see handy NSEvent class methods for creating magnification events, like they offer for mouse, key, enter/exit, and other events.
-(void) scrollWheel:(NSEvent*)event
{
if(event.modifierFlags & NSAlternateKeyMask)
[self magnifyWithEvent:event];
else
[super scrollWheel:event];
}
Error output:
2018-01-18 11:35:59.509 BoF[71240:2227373] -_continuousScroll is deprecated for NSScrollWheel. Please use -hasPreciseScrollingDeltas.
2018-01-18 11:35:59.509 BoF[71240:2227373] -deviceDeltaX is deprecated for NSScrollWheel. Please use -scrollingDeltaX.
2018-01-18 11:35:59.509 BoF[71240:2227373] -deviceDeltaY is deprecated for NSScrollWheel. Please use -scrollingDeltaY.
2018-01-18 11:35:59.509 BoF[71240:2227373] *** Assertion failure in -[NSEvent magnification], /SourceCache/AppKit/AppKit-1348.17/AppKit.subproj/NSEvent.m:1890
2018-01-18 11:35:59.509 BoF[71240:2227373] Invalid message sent to event "NSEvent: type=ScrollWheel loc=(371,197) time=80177.1 flags=0x80120 win=0x6180001f8000 winNum=3959 ctxt=0x0 deltaX=0.000000 deltaY=0.400024 deltaZ=0.000000 deviceDeltaX=0.000000 deviceDeltaY=3.000000 deviceDeltaZ=0.000000 count:0 phase=Changed momentumPhase=None"
2018-01-18 11:35:59.643 BoF[71240:2227373] (
0 CoreFoundation 0x00007fff90c6e03c __exceptionPreprocess + 172
1 libobjc.A.dylib 0x00007fff8282176e objc_exception_throw + 43
2 CoreFoundation 0x00007fff90c6de1a +[NSException raise:format:arguments:] + 106
3 Foundation 0x00007fff8632897b -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 195
4 AppKit 0x00007fff8f96c8c2 -[NSEvent magnification] + 182
5 AppKit 0x00007fff8f96c488 -[NSScrollView magnifyWithEvent:] + 395
6 BoF 0x000000010002ceb3 -[ComicScrollView scrollWheel:] + 99
7 AppKit 0x00007fff8f7c4cfb forwardMethod + 126
8 AppKit 0x00007fff8f8f5d00 -[NSView scrollWheel:] + 507
9 AppKit 0x00007fff8f7c4cfb forwardMethod + 126
10 AppKit 0x00007fff8f8f5d00 -[NSView scrollWheel:] + 507
11 AppKit 0x00007fff8fe3b6cc -[NSWindow _reallySendEvent:isDelayedEvent:] + 6941
12 AppKit 0x00007fff8f7ccc86 -[NSWindow sendEvent:] + 470
13 AppKit 0x00007fff8f7c9137 -[NSApplication sendEvent:] + 2285
14 AppKit 0x00007fff8f6f2b68 -[NSApplication run] + 711
15 AppKit 0x00007fff8f66f244 NSApplicationMain + 1832
16 BoF 0x000000010000f232 main + 34
17 libdyld.dylib 0x00007fff848f95c9 start + 1
18 ??? 0x0000000000000003 0x0 + 3
)
Well, it's not using the standard magnifyWithEvent: code path, but it works to fake it like so, making assumptions about the multiplier to convert the scroll amount to a magnification amount.
-(void) scrollWheel:(NSEvent*)event
{
if(event.modifierFlags & NSAlternateKeyMask) {
NSPoint pt = [self.documentView convertPoint:event.locationInWindow fromView:nil];
CGFloat by = event.scrollingDeltaY * 0.001; // The smallest pinch-zoom amount seems to be about 0.002, but that was a bit too coarse.
if(!event.hasPreciseScrollingDeltas)
by *= self.verticalLineScroll;
[self setMagnification:self.magnification + by centeredAtPoint:pt];
}
else
[super scrollWheel:event];
}