为NSTabView实现“空视图”

Question

我一直在试验JUEmptyView (一个自定义Cocoa控件/ NSView子类，当所有子视图被移除时，它在视图中间显示一个自定义中心对齐占位符)。

因此，我尝试为NSTabView实现相同的功能--只需将其设置为NSTabView子类(并重新设置初始的NSTabView项类)。

通常，它确实有效-它确实显示占位符(当最后一个选项卡关闭时)。然而，仍存在一些问题：

• 背景仍然是一个表项的背景(虽然它们都已关闭)
• 当调整窗口大小时(考虑到NSTabView从左到右、从上到下一直延伸)，视图似乎无法正确地重新绘制自己。

示例:

​

​

完整代码:

接口

#import <Cocoa/Cocoa.h>

@interface JUTabEmptyView : NSTabView
{
@private
    BOOL forceShow;

    NSString *title;
    NSColor  *titleColor;
    NSFont   *titleFont;

    NSColor *backgroundColor;
}

@property (nonatomic, copy) NSString  *title;
@property (nonatomic, retain) NSFont  *titleFont;
@property (nonatomic, retain) NSColor *titleColor;
@property (nonatomic, retain) NSColor *backgroundColor;

@property (nonatomic, assign) BOOL forceShow;

- (id)initWithTitle:(NSString *)title;
- (id)initWithTitle:(NSString *)title andFont:(NSFont *)font;
- (id)initWithTitle:(NSString *)title font:(NSFont *)font color:(NSColor *)color andBackgroundColor:(NSColor *)backgroundColor;

@end

实现

#import "JUTabEmptyView.h"

@implementation JUTabEmptyView
@synthesize title, titleFont, titleColor, backgroundColor;
@synthesize forceShow;

#pragma mark -
#pragma mark Setter

- (void)setTitle:(NSString *)ttitle
{
    [title autorelease];
    title = [ttitle copy];

    [self setNeedsDisplay:YES];
}

- (void)setTitleFont:(NSFont *)ttitleFont
{
    [titleFont autorelease];
    titleFont = [ttitleFont retain];

    [self setNeedsDisplay:YES];
}

- (void)setTitleColor:(NSColor *)ttitleColor
{
    [titleColor autorelease];
    titleColor = [ttitleColor retain];

    [self setNeedsDisplay:YES];
}

- (void)setBackgroundColor:(NSColor *)tbackgroundColor
{
    [backgroundColor autorelease];
    backgroundColor = [tbackgroundColor retain];

    [self setNeedsDisplay:YES];
}

- (void)setForceShow:(BOOL)tforceShow
{
    forceShow = tforceShow;

    [self setNeedsDisplay:YES];
}

#pragma mark -
#pragma Drawing

- (void)drawRect:(NSRect)dirtyRect
{
    if(forceShow || [[self subviews] count] == 0)
    {
        NSRect rect = [self bounds];
        NSSize size = [title sizeWithAttributes:[NSDictionary dictionaryWithObject:titleFont forKey:NSFontAttributeName]];
        NSSize bezierSize = NSMakeSize(size.width + 40.0, size.height + 20.0);
        NSRect drawRect;


        // Background
        drawRect = NSMakeRect(0.0, 0.0, bezierSize.width, bezierSize.height);
        drawRect.origin.x = round((rect.size.width * 0.5) - (bezierSize.width * 0.5));
        drawRect.origin.y = round((rect.size.height * 0.5) - (bezierSize.height * 0.5));

        [backgroundColor setFill];
        [[NSBezierPath bezierPathWithRoundedRect:drawRect xRadius:8.0 yRadius:8.0] fill];


        // String
        drawRect = NSMakeRect(0.0, 0.0, size.width, size.height);
        drawRect.origin.x = round((rect.size.width * 0.5) - (size.width * 0.5));
        drawRect.origin.y = round((rect.size.height * 0.5) - (size.height * 0.5));

        [title drawInRect:drawRect withAttributes:[NSDictionary dictionaryWithObjectsAndKeys:titleColor, NSForegroundColorAttributeName,
                                                   titleFont, NSFontAttributeName, nil]];
    }
}


- (void)willRemoveSubview:(NSView *)subview
{
    [super willRemoveSubview:subview];
    [self setNeedsDisplay:YES];
}

- (void)didAddSubview:(NSView *)subview
{
    [super didAddSubview:subview];
    [self setNeedsDisplay:YES];
}

#pragma mark -
#pragma mark Constructor / Destructor

- (void)constructWithTitle:(NSString *)ttitle font:(NSFont *)font color:(NSColor *)color andBackgroundColor:(NSColor *)tbackgroundColor
{
    title = ttitle ? [ttitle copy] : [[NSString alloc] initWithString:@"No active document"];
    titleFont = font ? [font retain] : [[NSFont boldSystemFontOfSize:[NSFont smallSystemFontSize]] retain];
    titleColor = color ? [color retain] : [[NSColor colorWithCalibratedRed:0.890 green:0.890 blue:0.890 alpha:1.0] retain];
    backgroundColor = tbackgroundColor ? [tbackgroundColor retain] : [[NSColor colorWithCalibratedRed:0.588 green:0.588 blue:0.588 alpha:1.000] retain];
}

- (id)initWithCoder:(NSCoder *)decoder
{
    if(self = [super initWithCoder:decoder])
    {
        [self constructWithTitle:nil font:nil color:nil andBackgroundColor:nil];
    }

    return self;
}

- (id)initWithFrame:(NSRect)frameRect
{
    if(self = [super initWithFrame:frameRect])
    {
        [self constructWithTitle:nil font:nil color:nil andBackgroundColor:nil];
    }

    return self;
}

- (id)initWithTitle:(NSString *)ttitle
{
    if((self = [super init]))
    {
        [self constructWithTitle:ttitle font:nil color:nil andBackgroundColor:nil];
    }

    return self;
}

- (id)initWithTitle:(NSString *)ttitle andFont:(NSFont *)font
{
    if((self = [super init]))
    {
        [self constructWithTitle:ttitle font:font color:nil andBackgroundColor:nil];
    }

    return self;
}

- (id)initWithTitle:(NSString *)ttitle font:(NSFont *)font color:(NSColor *)color andBackgroundColor:(NSColor *)tbackgroundColor
{
    if((self = [super init]))
    {
        [self constructWithTitle:ttitle font:font color:color andBackgroundColor:tbackgroundColor];
    }

    return self;
}

- (void)dealloc
{
    [title release];
    [titleFont release];
    [titleColor release];
    [backgroundColor release];

    [super dealloc];
}

@end

Answer 1

好吧，这就是我怎么解决的。

原来这个“空视图”实现，除了打印一个带有标签的圆角框外，在父视图的中间，未能重新绘制主背景。所以，只要重新粉刷一下.

drawRect: In 只需添加:

[[NSColor grayColor] set]; // or any other color you prefer
NSRectFill([self bounds]);