Make GUI tabs track Vim tabs in updates and animate correctly

src/MacVim/MMBackend.m

@@ -764,32 +764,36 @@ - (void)selectTab:(int)index
 
 - (void)updateTabBar
 {
+    // Update the tab bar with the most up-to-date info, including number of
+    // tabs and titles/tooltips. MacVim would also like to know which specific
+    // tabs were moved/added/deleted in order for animation to work, but Vim
+    // does not have specific callbacks to listen to that. Instead, since the
+    // tabpage_T memory address is constant per tab, we use that as a permanent
+    // identifier for each GUI tab so MacVim can do the association.
     NSMutableData *data = [NSMutableData data];
 
+    // 1. Current selected tab index
     int idx = tabpage_index(curtab) - 1;
     [data appendBytes:&idx length:sizeof(int)];
 
     tabpage_T *tp;
+    // 2. Unique id for all the tabs
+    // Do these first so they appear as a consecutive memory block.
     for (tp = first_tabpage; tp != NULL; tp = tp->tp_next) {
-        // Count the number of windows in the tabpage.
-        //win_T *wp = tp->tp_firstwin;
-        //int wincount;
-        //for (wincount = 0; wp != NULL; wp = wp->w_next, ++wincount);
-        //[data appendBytes:&wincount length:sizeof(int)];
-
-        int tabProp = MMTabInfoCount;
-        [data appendBytes:&tabProp length:sizeof(int)];
-        for (tabProp = MMTabLabel; tabProp < MMTabInfoCount; ++tabProp) {
+        [data appendBytes:&tp length:sizeof(void*)];
+    }
+    // Null terminate the unique IDs.
+    tp = 0;
+    [data appendBytes:&tp length:sizeof(void*)];
+    // 3. Labels and tooltips of each tab
+    for (tp = first_tabpage; tp != NULL; tp = tp->tp_next) {
+        for (int tabProp = MMTabLabel; tabProp < MMTabInfoCount; ++tabProp) {
             // This function puts the label of the tab in the global 'NameBuff'.
             get_tabline_label(tp, (tabProp == MMTabToolTip));
-            NSString *s = [NSString stringWithVimString:NameBuff];
-            int len = [s lengthOfBytesUsingEncoding:NSUTF8StringEncoding];
-            if (len < 0)
-                len = 0;
-
-            [data appendBytes:&len length:sizeof(int)];
+            size_t len = STRLEN(NameBuff);
+            [data appendBytes:&len length:sizeof(size_t)];
             if (len > 0)
-                [data appendBytes:[s UTF8String] length:len];
+                [data appendBytes:NameBuff length:len];
         }
     }
 

src/MacVim/MMTabline/MMTab.h

@@ -14,6 +14,7 @@ typedef enum : NSInteger {
 
 @interface MMTab : NSView
 
+@property (nonatomic, readwrite) NSInteger tag; ///< Unique identifier that caller can set for the tab
 @property (nonatomic, copy) NSString *title;
 @property (nonatomic, getter=isCloseButtonHidden) BOOL closeButtonHidden;
 @property (nonatomic) MMTabState state;

src/MacVim/MMTabline/MMTab.m

@@ -20,6 +20,8 @@ @implementation MMTab
     NSTextField *_titleLabel;
 }
 
+@synthesize tag = _tag;
+
 + (id)defaultAnimationForKey:(NSAnimatablePropertyKey)key
 {
     if ([key isEqualToString:@"fillColor"]) {

src/MacVim/MMTabline/MMTabline.h

@@ -10,7 +10,8 @@
 
 @interface MMTabline : NSView
 
-@property (nonatomic) NSInteger selectedTabIndex;
+/// The index of the selected tab. Can be -1 if nothing is selected.
+@property (nonatomic, readonly) NSInteger selectedTabIndex;
 @property (nonatomic) NSInteger optimumTabWidth;
 @property (nonatomic) NSInteger minimumTabWidth;
 @property (nonatomic) BOOL showsAddTabButton;
@@ -24,10 +25,31 @@
 @property (nonatomic, retain) NSColor *tablineFillFgColor;
 @property (nonatomic, weak) id <MMTablineDelegate> delegate;
 
+/// Add a tab at the end. It's not selected automatically.
 - (NSInteger)addTabAtEnd;
+/// Add a tab after the selected one. It's not selected automatically.
 - (NSInteger)addTabAfterSelectedTab;
+/// Add a tab at specified index. It's not selected automatically.
 - (NSInteger)addTabAtIndex:(NSInteger)index;
+
 - (void)closeTab:(MMTab *)tab force:(BOOL)force layoutImmediately:(BOOL)layoutImmediately;
+
+/// Batch update all the tabs using tab tags as unique IDs. Tab line will handle
+/// creating / removing tabs as necessary, and moving tabs to their new
+/// positions.
+///
+/// The tags array has to have unique items only, and each existing MMTab also
+/// has to have unique tags.
+///
+/// @param tags The list of unique tags that are cross-referenced with each
+///        MMTab's tag. Order within the array indicates the desired tab order.
+/// @param len The length of the tags array.
+/// @param delayTabResize If true, do not resize tab widths until the the tab
+///        line loses focus. This helps preserve the relative tab positions and
+///        lines up the close buttons to the previous tab. This will also
+///        prevent scrolling to the new selected tab.
+- (void)updateTabsByTags:(NSInteger *)tags len:(NSUInteger)len delayTabResize:(BOOL)delayTabResize;
+
 - (void)selectTabAtIndex:(NSInteger)index;
 - (MMTab *)tabAtIndex:(NSInteger)index;
 - (void)scrollTabToVisibleAtIndex:(NSInteger)index;