[9front] drawterm/gui-cocoa/screen.m: mouse button emulation a la plan9port

[boehm.igor@gmail.com]

Dear all,

Inline is a patch that eases the use of drawterm on mac laptops that
lack mouse buttons.

For consistency reasons it behaves the same as on plan9port, namely
like this:

"For systems without a three button mouse, the keyboard modifier keys
can be used to modify the effect of the main mouse button.  On Mac
systems, the option key changes the main button to button 2, and the
Command key changes it to button 3.

Pressing the key after the button is held down adds the button to form
a chord, so that for example on Macs selecting text with the trackpad
button and then typing Option without letting go of the button will
cause a 1-2 chord, cutting the selection.

These changes were inspired by rsc's plan9port."

If you prefer to view this diff on GitHub here is a link:
https://github.com/1g0rb0hm/drawterm/commit/6cc968737b0ba5476516b698d8a539d5a2b26b62

If this is not the right place to propose drawterm patches or if
changes should be made please let me know.

Cheers,
Igor


diff -r 1f70be1f0305 gui-cocoa/screen.m
--- a/gui-cocoa/screen.m	Wed Nov 18 23:01:01 2020 +0100
+++ b/gui-cocoa/screen.m	Mon Dec 21 15:12:23 2020 +0100
@@ -364,43 +364,76 @@
 		kbdkey(m, 0);
 }
 
+- (void)sendmouse:(NSUInteger)b
+{
+	NSPoint p;
+	Point q;
+
+	p = [self.window mouseLocationOutsideOfEventStream];
+	q.x = p.x;
+	q.y = p.y;
+	if(!ptinrect(q, gscreen->clipr)) return;
+	absmousetrack(p.x, self.frame.size.height - p.y, b, ticks());
+}
+
 - (void)flagsChanged:(NSEvent*)event {
-	static NSEventModifierFlags y;
-	NSEventModifierFlags x;
+	static NSEventModifierFlags omod;
+	NSEventModifierFlags m;
+	NSUInteger b;
 
-	x = [event modifierFlags];
-	if((x & ~y & NSEventModifierFlagShift) != 0)
-		kbdkey(Kshift, 1);
-	if((x & ~y & NSEventModifierFlagControl) != 0)
-		kbdkey(Kctl, 1);
-	if((x & ~y & NSEventModifierFlagOption) != 0)
-		kbdkey(Kalt, 1);
-	if((x & ~y & NSEventModifierFlagCapsLock) != 0)
-		kbdkey(Kcaps, 1);
-	if((~x & y & NSEventModifierFlagShift) != 0)
-		kbdkey(Kshift, 0);
-	if((~x & y & NSEventModifierFlagControl) != 0)
-		kbdkey(Kctl, 0);
-	if((~x & y & NSEventModifierFlagOption) != 0)
-		kbdkey(Kalt, 0);
-	if((x & ~y & NSEventModifierFlagCapsLock) != 0)
-		kbdkey(Kcaps, 0);
-	y = x;
+	m = [event modifierFlags];
+	b = [NSEvent pressedMouseButtons];
+	b = b & ~6 | b << 1 & 4 | b >> 1 & 2;
+	if(b){
+		if(m & ~omod & NSEventModifierFlagControl)
+			b |= 1;
+		if(m & ~omod & NSEventModifierFlagOption)
+			b |= 2;
+		if(m & ~omod & NSEventModifierFlagCommand)
+			b |= 4;
+		[self sendmouse:b];
+	}else{
+		if((m & ~omod & NSEventModifierFlagShift) != 0)
+			kbdkey(Kshift, 1);
+		if((m & ~omod & NSEventModifierFlagControl) != 0)
+			kbdkey(Kctl, 1);
+		if((m & ~omod & NSEventModifierFlagOption) != 0)
+			kbdkey(Kalt, 1);
+		if((m & ~omod & NSEventModifierFlagCapsLock) != 0)
+			kbdkey(Kcaps, 1);
+		if((~m & omod & NSEventModifierFlagShift) != 0)
+			kbdkey(Kshift, 0);
+		if((~m & omod & NSEventModifierFlagControl) != 0)
+			kbdkey(Kctl, 0);
+		if((~m & omod & NSEventModifierFlagOption) != 0)
+			kbdkey(Kalt, 0);
+		if((m & ~omod & NSEventModifierFlagCapsLock) != 0)
+			kbdkey(Kcaps, 0);
+	}
+	omod = m;
 }
 
 - (void)mouseevent:(NSEvent*)event
 {
-	NSPoint p;
-	Point q;
-	NSUInteger u;
+	NSUInteger b;
+	NSEventModifierFlags m;
 
-	p = [self.window mouseLocationOutsideOfEventStream];
-	u = [NSEvent pressedMouseButtons];
-	q.x = p.x;
-	q.y = p.y;
-	if(!ptinrect(q, gscreen->clipr)) return;
-	u = u & ~6 | u << 1 & 4 | u >> 1 & 2;
-	absmousetrack(p.x, self.frame.size.height - p.y, u, ticks());
+	b = [NSEvent pressedMouseButtons];
+	b = b & ~6 | b << 1 & 4 | b >> 1 & 2;
+	if(b==1){
+		m = [event modifierFlags];
+		if(m & NSEventModifierFlagOption)
+			b=2;
+		else if(m & NSEventModifierFlagCommand)
+			b=4;
+		else if(m & NSEventModifierFlagControl)
+			b=8;
+	}else if(b==4){
+		m = [event modifierFlags];
+		if(m & NSEventModifierFlagCommand)
+			b=8;
+	}
+	[self sendmouse:b];
 }
 
 - (void) mouseDown:(NSEvent*)event { [self mouseevent:event]; }