如何去除圆形矩形贝塞尔路径的角落

Question

我是第一次使用 Core Graphics 进行编程，所以不太清楚我该如何解决这个问题。

我正在绘制圆角矩形贝塞尔路径以及渐变和笔触作为 UITableviewCells 的背景视图。一切都很好，除了如图所示的额外黑角。

我不知道他们为什么要展示以及它们到底是什么。请问有人可以帮我吗？谢谢..

创建单元格的代码

#import "CustomCellBackground.h"
.
.
.

-(UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView 
                             dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:CellIdentifier];
        cell.backgroundView = [[CustomCellBackground alloc] init];
        cell.selectedBackgroundView = [[CustomCellBackground alloc]init];
    }

    // Configure the cell.

    cell.selectionStyle = UITableViewCellSelectionStyleNone;

    cell.textLabel.textColor = [UIColor whiteColor];
    cell.textLabel.backgroundColor = [UIColor clearColor];
    return cell;

}

在 CustomCellBackground.m 中

- (void)drawRect:(CGRect)rect
{
    // Drawing code
    CGContextRef context = UIGraphicsGetCurrentContext();

    CGPathRef path = [[UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:10.0] CGPath];
    CGContextAddPath(context, path);
    CGContextClip(context);
    //CGContextSetLineJoin(context, kCGLineJoinRound);

    drawLinearGradientWithFourColors(context, self.bounds);

    CGContextSaveGState(context);

    CGContextSetStrokeColorWithColor(context,[UIColor whiteColor].CGColor);
    CGContextSetLineWidth(context, 1.0);
    CGContextAddPath(context, path);
    CGContextStrokePath(context);
    CGContextRestoreGState(context);

   }

void drawLinearGradientWithFourColors(CGContextRef context, CGRect rect)
{
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    CGFloat locations[] = {0.0, 0.2, 0.5, 1.0};

    CGFloat colors[16] = {
        85/255.0, 85/255.0, 85/255.0, 1.0,
        45/255.0, 45/255.0, 45/255.0, 1.0,
        22/255.0, 22/255.0, 22/255.0, 1.0,
        0, 0, 0, 1.0
    };

    CGGradientRef gradient = CGGradientCreateWithColorComponents(colorSpace, colors, locations, 4);

    CGPoint startPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMinY(rect));
    CGPoint endPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMaxY(rect));

    CGContextSaveGState(context);
    CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, 0);
    CGContextRestoreGState(context);
    CGGradientRelease(gradient);
    CGColorSpaceRelease(colorSpace);
}

Answer 1

初始化视图时，为视图和视图的图层设置Opaque 参数。

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        [self setOpaque:NO];
        [self.layer setOpaque:NO];
    }
    return self;
}

Answer 2

我用谷歌搜索并粘贴了下面的代码。更多信息请参考link:

使用下面的代码：

typedef enum  {
    CustomCellBackgroundViewPositionTop, 
    CustomCellBackgroundViewPositionMiddle, 
    CustomCellBackgroundViewPositionBottom,
    CustomCellBackgroundViewPositionSingle
} CustomCellBackgroundViewPosition;

@interface CustomCellBackgroundView : UIView {
    UIColor *borderColor;
    UIColor *fillColor;
    CustomCellBackgroundViewPosition position;
}

    @property(nonatomic, retain) UIColor *borderColor, *fillColor;
    @property(nonatomic) CustomCellBackgroundViewPosition position;
@end


- (void)drawRect:(CGRect)rect {
    // Drawing code
    CGContextRef c = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(c, [fillColor CGColor]);
    CGContextSetStrokeColorWithColor(c, [borderColor CGColor]);

    if (position == CustomCellBackgroundViewPositionTop) {
        CGContextFillRect(c, CGRectMake(0.0f, rect.size.height - 10.0f, rect.size.width, 10.0f));
        CGContextBeginPath(c);
        CGContextMoveToPoint(c, 0.0f, rect.size.height - 10.0f);
        CGContextAddLineToPoint(c, 0.0f, rect.size.height);
        CGContextAddLineToPoint(c, rect.size.width, rect.size.height);
        CGContextAddLineToPoint(c, rect.size.width, rect.size.height - 10.0f);
        CGContextStrokePath(c);
        CGContextClipToRect(c, CGRectMake(0.0f, 0.0f, rect.size.width, rect.size.height - 10.0f));
    } else if (position == CustomCellBackgroundViewPositionBottom) {
        CGContextFillRect(c, CGRectMake(0.0f, 0.0f, rect.size.width, 10.0f));
        CGContextBeginPath(c);
        CGContextMoveToPoint(c, 0.0f, 10.0f);
        CGContextAddLineToPoint(c, 0.0f, 0.0f);
        CGContextStrokePath(c);
        CGContextBeginPath(c);
        CGContextMoveToPoint(c, rect.size.width, 0.0f);
        CGContextAddLineToPoint(c, rect.size.width, 10.0f);
        CGContextStrokePath(c);
        CGContextClipToRect(c, CGRectMake(0.0f, 10.0f, rect.size.width, rect.size.height));
    } else if (position == CustomCellBackgroundViewPositionMiddle) {
        CGContextFillRect(c, rect);
        CGContextBeginPath(c);
        CGContextMoveToPoint(c, 0.0f, 0.0f);
        CGContextAddLineToPoint(c, 0.0f, rect.size.height);
        CGContextAddLineToPoint(c, rect.size.width, rect.size.height);
        CGContextAddLineToPoint(c, rect.size.width, 0.0f);
        CGContextStrokePath(c);
        return; // no need to bother drawing rounded corners, so we return
    }

    // At this point the clip rect is set to only draw the appropriate
    // corners, so we fill and stroke a rounded rect taking the entire rect

    CGContextBeginPath(c);
    addRoundedRectToPath(c, rect, 10.0f, 10.0f);
    CGContextFillPath(c);  

    CGContextSetLineWidth(c, 1);  
    CGContextBeginPath(c);
    addRoundedRectToPath(c, rect, 10.0f, 10.0f);  
    CGContextStrokePath(c); 
}

static void addRoundedRectToPath(CGContextRef context, CGRect rect,
                                float ovalWidth,float ovalHeight)

{
    float fw, fh;

    if (ovalWidth == 0 || ovalHeight == 0) {// 1
        CGContextAddRect(context, rect);
        return;
    }

    CGContextSaveGState(context);// 2

    CGContextTranslateCTM (context, CGRectGetMinX(rect),// 3
                           CGRectGetMinY(rect));
    CGContextScaleCTM (context, ovalWidth, ovalHeight);// 4
    fw = CGRectGetWidth (rect) / ovalWidth;// 5
    fh = CGRectGetHeight (rect) / ovalHeight;// 6

    CGContextMoveToPoint(context, fw, fh/2); // 7
    CGContextAddArcToPoint(context, fw, fh, fw/2, fh, 1);// 8
    CGContextAddArcToPoint(context, 0, fh, 0, fh/2, 1);// 9
    CGContextAddArcToPoint(context, 0, 0, fw/2, 0, 1);// 10
    CGContextAddArcToPoint(context, fw, 0, fw, fh/2, 1); // 11
    CGContextClosePath(context);// 12

    CGContextRestoreGState(context);// 13
}