Center tab labels as though there is no close button. If the label is so long...

Center tab labels as though there is no close button. If the label is so long that it would overlap the close button, left align it just after the close button. Issue 4915.

ThirdParty/PSMTabBarControl/source/PSMYosemiteTabStyle.m

@@ -15,6 +15,36 @@
 #define kPSMMetalCounterMinWidth 20
 static const CGFloat kPSMTabBarCellBaselineOffset = 14.5;
+@interface NSAttributedString(PSM)
+- (NSAttributedString *)attributedStringWithTextAlignment:(NSTextAlignment)textAlignment;
+@end
+
+@implementation NSAttributedString(PSM)
+
+- (NSAttributedString *)attributedStringWithTextAlignment:(NSTextAlignment)textAlignment {
+    // First try to do it the easy way.
+    NSDictionary *immutableAttributes = [self attributesAtIndex:0 effectiveRange:nil];
+    NSMutableParagraphStyle *paragraphStyle = immutableAttributes[NSParagraphStyleAttributeName];
+    if ([paragraphStyle isKindOfClass:[NSMutableParagraphStyle class]]) {
+        paragraphStyle.alignment = textAlignment;
+        return self;
+    }
+    
+    // If that fails do it the right way.
+    NSMutableDictionary *attributes = [[immutableAttributes mutableCopy] autorelease];
+    paragraphStyle = [[attributes[NSParagraphStyleAttributeName] mutableCopy] autorelease];
+    if (!paragraphStyle) {
+        paragraphStyle = [[[NSParagraphStyle defaultParagraphStyle] mutableCopy] autorelease];
+    }
+    paragraphStyle.alignment = textAlignment;
+    NSMutableAttributedString *temp = [[self mutableCopy] autorelease];
+    attributes[NSParagraphStyleAttributeName] = paragraphStyle;
+    [temp setAttributes:attributes range:NSMakeRange(0, temp.length)];
+    return temp;
+}
+
+@end
+
 @interface PSMTabBarCell(PSMYosemiteTabStyle)
 @property(nonatomic) NSAttributedString *previousAttributedString;
@@ -537,10 +567,21 @@ static const CGFloat kPSMTabBarCellBaselineOffset = 14.5;
         closeButton = _closeButtonDown;
     }
+    CGFloat reservedSpace = 0;
     closeButtonSize = [closeButton size];
     if ([cell hasCloseButton]) {
-        // scoot label over
-        labelPosition += closeButtonSize.width + kPSMTabBarCellPadding;
+        if (cell.isCloseButtonSuppressed && _orientation == PSMTabBarHorizontalOrientation) {
+            // Do not use this much space on the left for the label, but the label is centered as
+            // though it is not reserved if it's not too long.
+            //
+            //                Center
+            //                   V
+            // [(reserved)  short-label            ]
+            // [(reserved)long-------------label   ]
+            reservedSpace = closeButtonSize.width + kPSMTabBarCellPadding;
+        } else {
+            labelPosition += closeButtonSize.width + kPSMTabBarCellPadding;
+        }
     }
     // Draw close button
@@ -613,6 +654,17 @@ static const CGFloat kPSMTabBarCellBaselineOffset = 14.5;
             labelRect.size.width -= ([self objectCounterRectForTabCell:cell].size.width + kPSMTabBarCellPadding);
         }
+        if (_orientation == PSMTabBarHorizontalOrientation) {
+            NSSize size = [attributedString boundingRectWithSize:labelRect.size options:0].size;
+            CGFloat effectiveLeftMargin = (labelRect.size.width - size.width) / 2;
+            if (effectiveLeftMargin < reservedSpace) {
+                attributedString = [attributedString attributedStringWithTextAlignment:NSLeftTextAlignment];
+
+                labelRect.origin.x += reservedSpace;
+                labelRect.size.width -= reservedSpace;
+            }
+        }
+
         [attributedString drawInRect:labelRect];
     }
 }