随着NSRulerView滚动移动NSPopover

Question

背景

NSPopover的默认实现是在滚动显示视图时将弹出框移动（并且将附加到NSRect的滚动视图移出时具有特殊处理）。 NSPopover可以显示在NSRulerView上，但是滚动文档视图时NSPopover不会移动（显然是因为NSRulerView不能像其他视图一样处理滚动使用绘图偏移量而不是移动视口。

问题

如何为附着在NSPopover上的NSRulerView重新创建默认移动行为？

示例代码

• ViewController：

  @interface ViewController : NSViewController
  @property (weak) IBOutlet NSScrollView *scrollView;
  @property (strong) LineNumberView *ruler;
  @end
  
  @implementation ViewController
  
  - (void)viewDidLoad {
      [super viewDidLoad];
  
      self.ruler = [[LineNumberView alloc] initWithScrollView:self.scrollView orientation:NSVerticalRuler];
      self.scrollView.verticalRulerView = self.ruler;
      self.scrollView.hasVerticalRuler = YES;
      self.scrollView.rulersVisible = YES;
  }
  //...
  @end
  

• LineNumberView：

  @implementation LineNumberView
  -(void)mouseDown:(NSEvent *)event {
      [self popOver:[self convertPoint:event.locationInWindow fromView:nil]];
  }
  
  -(void)popOver:(NSPoint)point {
      NSRect anchor = [self rectForPoint:point];
      PopoverController *pop = [[PopoverController alloc] init];
      [pop showOver:anchor ofView:self];
  }
  
  -(NSRect)rectForPoint:(NSPoint)point {
      NSTextView* textView = (NSTextView*)self.scrollView.documentView;
  
      NSUInteger rectCount;
      NSRectArray frameRects = [textView.layoutManager
          rectArrayForCharacterRange: NSMakeRange(NSNotFound, 0)
          withinSelectedCharacterRange: kNullRange
          inTextContainer: textView.textContainer
          rectCount: &rectCount
      ];
  
      const CGFloat kWidth = NSWidth(self.bounds);
      const CGFloat kHeight = NSHeight(frameRects[0]);
      const CGFloat x = 0;
      CGFloat y = point.y - fmod(point.y, kHeight);
      //y += NSMinY(self.scrollView.contentView.bounds);
  
      return NSMakeRect(x, y, kWidth, kHeight);
  }
  
  @end
  

• PopoverController：

  @interface PopoverController : NSViewController<NSPopoverDelegate>
  @property (strong) NSPopover *popover;
  @end
  
  @implementation PopoverController
  -(instancetype)init {
      if ((self = [super init])) {        
          NSTextField *label = [NSTextField labelWithString:@"Pop!"];
          [label setFrameOrigin:NSMakePoint(kPadding, kPadding)];
          self.view = [[NSView alloc]
              initWithFrame:NSMakeRect(
                  0, 0,
                  2 * kPadding + label.frame.size.width,
                  2 * kPadding + label.frame.size.height)];
          [self.view addSubview:label];
  
          self.popover = [[NSPopover alloc] init];
          self.popover.contentViewController = self;
          self.popover.behavior = NSPopoverBehaviorTransient;
      }
      return self;
  }
  
  -(void)showOver:(NSRect)anchor ofView:(NSView*)view {
      [self.popover showRelativeToRect:anchor ofView:view preferredEdge:NSMaxYEdge];
  }
  

• 在主故事板上，ViewController's scene has an NSScrollView as a descendent view, connected to the ViewController 's scrollView`出口。