绘制自定义NSScroller

我想画一个自定义的NSScroller，我得到了大部分的一切，我想工作工作，但，当我尝试摆脱knobSlot的，它只会不断地重新绘制旋钮：绘制自定义NSScroller

alt text

这就是当我使用的drawRect：绘制背景的。当我删除的drawRect：我得到：

alt text

我似乎仍不能摆脱knobSlot的。这里是我的所有代码：

#import "UIScroller.h" 

@interface UIScroller (Private) 
- (void)drawKnobSlot; 
@end 

@implementation UIScroller 

- (BOOL)isVertical { 
    NSRect bounds = [self bounds]; 
    return NSHeight(bounds) < NSWidth(bounds); 
} 

+ (CGFloat)scrollerWidth { 
    return 13; 
} 

+ (CGFloat)scrollerWidthForControlSize:(NSControlSize)controlSize { 
    return 13; 
} 

/* 
- (void)drawRect:(NSRect)aRect; 
{ 
//[[NSColor blueColor] set]; 
NSRectFill([self bounds]); 

    [self drawKnobSlot]; 
} 
*/ 

- (void)drawKnobSlot; 
{ 
NSRect slotRect = [self rectForPart:NSScrollerKnobSlot]; 

if ([self isVertical]) 
    NSDrawThreePartImage(slotRect, [NSImage imageNamed:@"lazyarrow"], [NSImage imageNamed:@"lazyarrow"], [NSImage imageNamed:@"lazyarrow"], YES, NSCompositeSourceOver, 1, NO); 
else 
    NSDrawThreePartImage(slotRect, [NSImage imageNamed:@"lazyarrow"], [NSImage imageNamed:@"lazyarrow"], [NSImage imageNamed:@"lazyarrow"], NO, NSCompositeSourceOver, 1, NO); 
} 

- (void)drawPart:(NSScrollerPart)part highlight:(BOOL)highlight { 
    //NSLog(@"drawPart:%@ highlight:%@", NSScrollerPartDescription(part), highlight ? @"YES":@"NO"); 

NSRect partRect = [self rectForPart:part]; 

    switch (part) { 
     case NSScrollerKnob: { 
      assert(!highlight); 

      if ([self isVertical]) { 
       partRect.origin.y++; 
       partRect.size.height -= 2; 
      } else { 
       // FIXME really vertical 
       partRect.origin.x++; 
       partRect.size.width -= 2; 
      } 


    NSRect newRect = NSMakeRect(partRect.origin.x+4, [self isVertical] ? partRect.origin.y+3 : partRect.origin.y, partRect.size.width - 6,[self isVertical] ? partRect.size.height-5 : partRect.size.height - 4); 
    NSBezierPath *path = [NSBezierPath bezierPathWithRoundedRect:newRect 
       xRadius:[self isVertical] ? 4: 4 
       yRadius:[self isVertical] ? 4 : 4]; 

    [path setLineWidth:2]; 
    [[NSColor colorWithDeviceRed:0.114 green:0.114 blue:0.114 alpha:.6] set]; 
    [path fill]; 
    [[NSColor colorWithDeviceWhite:1.0 
      alpha:0.100] set]; 

    [path addClip]; 
    [path stroke]; 

     //  NSBezierPath *knobPath = [NSBezierPath bezierPathWithRoundedRect:partRect 
     //               xRadius:5 
      //               yRadius:5]; 

      //[[NSColor colorWithDeviceRed:89./255. green:105./255. blue:131./255. alpha:1.] set]; 
    /* 
    NSGradient *gradient = [[[NSGradient alloc] initWithColorsAndLocations: 
      [NSColor colorWithDeviceRed:(89.0/255.0) green:(105/255.0) blue:(131/255.0) alpha:1.0], 0.0, 
      [NSColor colorWithDeviceRed:(89.0/255.0) green:(105/255.0) blue:(131/255.0) alpha:1.0], 0.0768, 
      [NSColor colorWithDeviceRed:(154.0/255.0) green:(169/255.0) blue:(190/255.0) alpha:1.0], 0.0769, 
      [NSColor colorWithDeviceRed:(94.0/255.0) green:(113/255.0) blue:(144/255.0) alpha:1.0], 0.9231, 
      [NSColor colorWithDeviceRed:(61.0/255.0) green:(80/255.0) blue:(111/255.0) alpha:1.0], 0.9232, 
      [NSColor colorWithDeviceRed:(61.0/255.0) green:(80/255.0) blue:(111/255.0) alpha:1.0], 1.0, 
      nil 
      ] autorelease]; 
    */ 
    //   [knobPath setLineWidth:2.0]; 
    //   [knobPath stroke]; 
    //[gradient drawInBezierPath:knobPath 
    //  angle:[self isVertical] ? 90. : 0.]; 

      //-- 

      /*[[NSColor colorWithDeviceRed:0. green:0. blue:255/128 alpha:1.0] set]; 
    [[NSBezierPath bezierPathWithRoundedRect:partRect 
    xRadius:6.0 
    yRadius:6.0] fill];*/ 
      //NSRectFill(partRect); 
     } break; 
     case NSScrollerIncrementLine: { 
} break; 
     case NSScrollerKnobSlot: { 
      NSAssert(!highlight, nil); 
#if 0 
      [[NSColor darkGrayColor] set]; 
     // NSRectFill(partRect); 
#else 
      partRect = [self bounds]; 

    /* 
    NSGradient *gradient = [[[NSGradient alloc] initWithColorsAndLocations: 
      [NSColor colorWithDeviceRed:(89.0/255.0) green:(105/255.0) blue:(131/255.0) alpha:1.0], 0.0, 
      [NSColor colorWithDeviceRed:(89.0/255.0) green:(105/255.0) blue:(131/255.0) alpha:1.0], 0.0768, 
      [NSColor colorWithDeviceRed:(154.0/255.0) green:(169/255.0) blue:(190/255.0) alpha:1.0], 0.0769, 
      [NSColor colorWithDeviceRed:(94.0/255.0) green:(113/255.0) blue:(144/255.0) alpha:1.0], 0.9231, 
      [NSColor colorWithDeviceRed:(61.0/255.0) green:(80/255.0) blue:(111/255.0) alpha:1.0], 0.9232, 
      [NSColor colorWithDeviceRed:(61.0/255.0) green:(80/255.0) blue:(111/255.0) alpha:1.0], 1.0, 
      nil 
      ] autorelease]; 
    */ 

      NSGradient *gradient = [[[NSGradient alloc] initWithColorsAndLocations: 
      [NSColor colorWithDeviceRed:(161.0/255.0) green:(161/255.0) blue:(161/255.0) alpha:1.0], 0.0, 
      [NSColor colorWithDeviceRed:(186.0/255.0) green:(186/255.0) blue:(186/255.0) alpha:1.0], 0.067, 
      [NSColor colorWithDeviceRed:(219.0/255.0) green:(219/255.0) blue:(219/255.0) alpha:1.0], 0.2, 
      [NSColor colorWithDeviceRed:(230.0/255.0) green:(230/255.0) blue:(230/255.0) alpha:1.0], 0.333, 
      [NSColor colorWithDeviceRed:(240.0/255.0) green:(240/255.0) blue:(240/255.0) alpha:1.0], 0.667, 
      [NSColor colorWithDeviceRed:(223.0/255.0) green:(223/255.0) blue:(223/255.0) alpha:1.0], 0.8, 
      [NSColor colorWithDeviceRed:(204.0/255.0) green:(204/255.0) blue:(204/255.0) alpha:1.0], 0.867, 
      [NSColor colorWithDeviceRed:(178.0/255.0) green:(178/255.0) blue:(178/255.0) alpha:1.0], 1.0, 
      nil 
      ] autorelease]; 


    // CGContextRef context = (CGContextRef) [[NSGraphicsContext currentContext] graphicsPort]; 
    // CGContextSetRGBFillColor(context, 0,0,0,0); 
    // CGContextFillRect(context, partRect); 
      [gradient drawInRect:partRect angle:[self isVertical] ? 90. : 0.]; 
    // NSRectFillUsingOperation(partRect, NSCompositeClear); 
#endif 
     } 

}} 

- (void)drawKnob 
{ 
[self drawPart:NSScrollerKnob highlight:NO]; 
[self setArrowsPosition:NSScrollerArrowsNone]; 
/* 
NSRect knobRect = [self rectForPart:NSScrollerKnob]; 
NSRect newRect = NSMakeRect(knobRect.origin.x+3, knobRect.origin.y, knobRect.size.width - 6, knobRect.size.height); 
NSBezierPath *path = [NSBezierPath bezierPathWithRoundedRect:newRect 
       xRadius:5 
       yRadius:5]; 

[path setLineWidth:2]; 
[[NSColor colorWithDeviceRed:0.114 green:0.114 blue:0.114 alpha:0.3] set]; 
[path fill]; 
[[NSColor colorWithDeviceWhite:1.0 
     alpha:0.100] set]; 

[path addClip]; 
[path stroke]; 


    */ 
} 

- (void)drawKnobSlotInRect:(NSRect)slotRect highlight:(BOOL)flag; 
{ 
[self drawPart:NSScrollerKnobSlot highlight:NO]; 
/* 
NSRect newRect = NSMakeRect(slotRect.origin.x, slotRect.origin.y, slotRect.size.width, slotRect.size.height); 
NSBezierPath *path = [NSBezierPath bezierPathWithRoundedRect:newRect 
       xRadius:10 
       yRadius:10]; 

[path setLineWidth:2]; 
[[NSColor colorWithDeviceRed:0.114 green:0.114 blue:0.114 alpha:0.3] set]; 
[path fill]; 
[[NSColor colorWithDeviceWhite:1.0 
     alpha:0.100] set]; 

[path addClip]; 
[path stroke]; 
    */ 
} 

@end

任何人都知道如何解决这个问题，以便它可以最终看起来像iOS版”的UIScrollView/UIScroller ?:

alt text