c_cpp 创建一个带有圆角矩形背景的UILabel，就像在iPhone Mail应用程序中一样。 （比使用UILabel.layer.cornerRadius快得多）

Posted 2021-05-14

//
//  RoundedRectLabel.m
//

#import "RoundedRectLabel.h"
#import <QuartzCore/QuartzCore.h>

@implementation CountLabel

@synthesize cornerRadius;
@synthesize rectColor;

- (void)dealloc {
	[rectColor release];
	[super dealloc];
}

- (id)initWithFrame:(CGRect)frame {
    if ((self = [super initWithFrame:frame])) {
        // Initialization code
    }
    return self;
}
- (void) setBackgroundColor:(UIColor *)color
{
	self.rectColor = color;
	[super setBackgroundColor:[UIColor clearColor]];
}

- (void)drawRect:(CGRect)rect {
	CGContextRef context = UIGraphicsGetCurrentContext();
	if(cornerRadius == 0)
		self.cornerRadius = 4;
	[self drawRoundedRect:context rect:rect radius:cornerRadius color:rectColor];
	[super drawRect:rect];
}

- (void) drawRoundedRect:(CGContextRef)c rect:(CGRect)rect radius:(int)corner_radius color:(UIColor *)color
{
	int x_left = rect.origin.x;
	int x_left_center = rect.origin.x + corner_radius;
	int x_right_center = rect.origin.x + rect.size.width - corner_radius;
	int x_right = rect.origin.x + rect.size.width;
	
	int y_top = rect.origin.y;
	int y_top_center = rect.origin.y + corner_radius;
	int y_bottom_center = rect.origin.y + rect.size.height - corner_radius;
	int y_bottom = rect.origin.y + rect.size.height;

	/* Begin! */
	CGContextBeginPath(c);
	CGContextMoveToPoint(c, x_left, y_top_center);
	
	/* First corner */
	CGContextAddArcToPoint(c, x_left, y_top, x_left_center, y_top, corner_radius);
	CGContextAddLineToPoint(c, x_right_center, y_top);
	
	/* Second corner */
	CGContextAddArcToPoint(c, x_right, y_top, x_right, y_top_center, corner_radius);
	CGContextAddLineToPoint(c, x_right, y_bottom_center);
	
	/* Third corner */
	CGContextAddArcToPoint(c, x_right, y_bottom, x_right_center, y_bottom, corner_radius);
	CGContextAddLineToPoint(c, x_left_center, y_bottom);
	
	/* Fourth corner */
	CGContextAddArcToPoint(c, x_left, y_bottom, x_left, y_bottom_center, corner_radius);
	CGContextAddLineToPoint(c, x_left, y_top_center);
	
	/* Done */
	CGContextClosePath(c);
	
	CGContextSetFillColorWithColor(c, color.CGColor);
	
	CGContextFillPath(c);
}

@end

//
//  RoundedRectLabel.h
//

#import <UIKit/UIKit.h>

@interface CountLabel : UILabel {
	NSInteger cornerRadius;
	UIColor *rectColor;
}

@property (nonatomic) NSInteger cornerRadius;
@property (nonatomic, retain) UIColor *rectColor;

- (void) setBackgroundColor:(UIColor *)color;
- (void) drawRoundedRect:(CGContextRef)c rect:(CGRect)rect radius:(int)corner_radius color:(UIColor *)color;

@end