Unset default "center" anchor when applying a style

Edges almost always want to be anchored to the "center" of an unstyled
(style=none) node, as otherwise edges won't join up.  However, this
anchor should be discarded if a style is then set on the node, otherwise
arrowheads tend to disappear.

2 files changed, 37 insertions, 6 deletions

diff --git a/tikzit/src/common/Edge.m b/tikzit/src/common/Edge.m
index 7b538b5..ea20d2a 100644
--- a/tikzit/src/common/Edge.m
+++ b/tikzit/src/common/Edge.m
@@ -325,6 +325,12 @@
 		[source removeObserver:self
 		            forKeyPath:@"style"];
 
+		if ([s style] == nil) {
+			[self setSourceAnchor:@"center"];
+		} else if ([sourceAnchor isEqual:@"center"]) {
+			[self setSourceAnchor:@""];
+		}
+
 		[source release];
 		source = [s retain];
 		
@@ -336,6 +342,7 @@
 		[source addObserver:self
 		         forKeyPath:@"style"
 		            options:NSKeyValueObservingOptionNew
+		                    | NSKeyValueObservingOptionOld
 		            context:NULL];
 		
 		dirty = YES;
@@ -348,6 +355,12 @@
 		[target removeObserver:self
 		            forKeyPath:@"style"];
 
+		if ([t style] == nil) {
+			[self setTargetAnchor:@"center"];
+		} else if ([targetAnchor isEqual:@"center"]) {
+			[self setTargetAnchor:@""];
+		}
+
 		[target release];
 		target = [t retain];
 		
@@ -359,6 +372,7 @@
 		[target addObserver:self
 		         forKeyPath:@"style"
 		            options:NSKeyValueObservingOptionNew
+		                    | NSKeyValueObservingOptionOld
 		            context:NULL];
 		
 		dirty = YES;
@@ -371,6 +385,27 @@
 					   context:(void *)context
 
 {
+	if ([keyPath isEqual:@"style"]) {
+		id oldStyle = [change objectForKey:NSKeyValueChangeOldKey];
+		id newStyle = [change objectForKey:NSKeyValueChangeNewKey];
+		id none = [NSNull null];
+		if (object == source) {
+			if (oldStyle != none && newStyle == none) {
+				[self setSourceAnchor:@"center"];
+			} else if (oldStyle == none && newStyle != none &&
+			           [sourceAnchor isEqual:@"center"]) {
+				[self setSourceAnchor:@""];
+			}
+		}
+		if (object == target) {
+			if (oldStyle != none && newStyle == none) {
+				[self setTargetAnchor:@"center"];
+			} else if (oldStyle == none && newStyle != none &&
+			           [targetAnchor isEqual:@"center"]) {
+				[self setTargetAnchor:@""];
+			}
+		}
+	}
 	dirty = YES;
 }
 
diff --git a/tikzit/src/common/Graph.m b/tikzit/src/common/Graph.m
index 2a01bae..33a81f6 100644
--- a/tikzit/src/common/Graph.m
+++ b/tikzit/src/common/Graph.m
@@ -736,17 +736,13 @@
         NSString *srcAnchor;
         NSString *tgtAnchor;
         
-        if ([[e source] style] == nil) {
-            srcAnchor = @".center";
-        } else if ([[e sourceAnchor] isEqual:@""]) {
+        if ([[e sourceAnchor] isEqual:@""]) {
             srcAnchor = @"";
         } else {
             srcAnchor = [NSString stringWithFormat:@".%@", [e sourceAnchor]];
         }
         
-        if ([[e target] style] == nil) {
-            tgtAnchor = @".center";
-        } else if ([[e targetAnchor] isEqual:@""]) {
+        if ([[e targetAnchor] isEqual:@""]) {
             tgtAnchor = @"";
         } else {
             tgtAnchor = [NSString stringWithFormat:@".%@", [e targetAnchor]];