只有两个圆角？

Question

在我的iPad应用程序中,当用户单击按钮时,我希望第二个视图显示在主视图中.新视图将小于第一个视图,并在显示时使背景变暗.我希望新视图的前两个角显示为圆角,但使用cornerRadius将所有圆角设置为圆角.我怎样才能使两个圆角变圆？

Answer 1

在目标C中

   // Create the path (with only the top-left corner rounded)
UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:imageView.bounds 
                          byRoundingCorners:UIRectCornerTopLeft| UIRectCornerTopRight
                          cornerRadii:CGSizeMake(10.0, 10.0)];
// Create the shape layer and set its path
CAShapeLayer *maskLayer = [CAShapeLayer layer];
maskLayer.frame = imageView.bounds;
maskLayer.path = maskPath.CGPath;
// Set the newly created shape layer as the mask for the image view's layer
imageView.layer.mask = maskLayer;

这是另一种使用顶部圆角. UIView的两个角落

在斯威夫特!

myView.clipsToBounds = true
myView.layer.cornerRadius = 10
myView.layer.maskedCorners = [.layerMinXMinYCorner,.layerMaxXMinYCorner]

Answer 2

你必须在drawRect:中执行此操作.我实际上修改了经典的addRoundedRectToPath:所以它需要一个位图并对你请求的角进行舍入:

static void addRoundedRectToPath(CGContextRef context, CGRect rect, float radius, UIImageRoundedCorner cornerMask)
{
    CGContextMoveToPoint(context, rect.origin.x, rect.origin.y + radius);
    CGContextAddLineToPoint(context, rect.origin.x, rect.origin.y + rect.size.height - radius);
    if (cornerMask & UIImageRoundedCornerTopLeft) {
        CGContextAddArc(context, rect.origin.x + radius, rect.origin.y + rect.size.height - radius, 
                        radius, M_PI, M_PI / 2, 1);
    }
    else {
        CGContextAddLineToPoint(context, rect.origin.x, rect.origin.y + rect.size.height);
        CGContextAddLineToPoint(context, rect.origin.x + radius, rect.origin.y + rect.size.height);
    }

    CGContextAddLineToPoint(context, rect.origin.x + rect.size.width - radius, 
                          rect.origin.y + rect.size.height);

    if (cornerMask & UIImageRoundedCornerTopRight) {
        CGContextAddArc(context, rect.origin.x + rect.size.width - radius, 
                        rect.origin.y + rect.size.height - radius, radius, M_PI / 2, 0.0f, 1);
    }
    else {
        CGContextAddLineToPoint(context, rect.origin.x + rect.size.width, rect.origin.y + rect.size.height);
        CGContextAddLineToPoint(context, rect.origin.x + rect.size.width, rect.origin.y + rect.size.height - radius);
    }

    CGContextAddLineToPoint(context, rect.origin.x + rect.size.width, rect.origin.y + radius);

    if (cornerMask & UIImageRoundedCornerBottomRight) {
        CGContextAddArc(context, rect.origin.x + rect.size.width - radius, rect.origin.y + radius, 
                        radius, 0.0f, -M_PI / 2, 1);
    }
    else {
        CGContextAddLineToPoint(context, rect.origin.x + rect.size.width, rect.origin.y);
        CGContextAddLineToPoint(context, rect.origin.x + rect.size.width - radius, rect.origin.y);
    }

    CGContextAddLineToPoint(context, rect.origin.x + radius, rect.origin.y);

    if (cornerMask & UIImageRoundedCornerBottomLeft) {
        CGContextAddArc(context, rect.origin.x + radius, rect.origin.y + radius, radius, 
                        -M_PI / 2, M_PI, 1);
    }
    else {
        CGContextAddLineToPoint(context, rect.origin.x, rect.origin.y);
        CGContextAddLineToPoint(context, rect.origin.x, rect.origin.y + radius);
    }

    CGContextClosePath(context);
}

这需要一个位掩码(我称之为UIImageRoundedCorner,因为我是为图像做这个,但你可以调用它),然后根据你想要舍入的角建立一个路径.然后将该路径应用于drawRect中的视图:

CGContextBeginPath(context);
addRoundedRectToPath(context, rect, radius, yourMask);
CGContextClosePath(context);
CGContextClip(context);

正如我所说,我是为UIImages做的,所以我的代码并没有完全设置为在drawRect:中使用,但它应该很容易适应它.您基本上只是构建一个路径,然后将上下文剪切到它.

编辑:为了解释位掩码部分,它只是一个枚举:

typedef enum {
    UIImageRoundedCornerTopLeft = 1,
    UIImageRoundedCornerTopRight = 1 << 1,
    UIImageRoundedCornerBottomRight = 1 << 2,
    UIImageRoundedCornerBottomLeft = 1 << 3
} UIImageRoundedCorner;

通过这种方式,您可以将OR组合在一起以形成标识角的位掩码,因为枚举的每个成员在位掩码中表示不同的2的幂.

很久以后编辑: 我发现了一个更简单的方法来做到这一点使用UIBezierPath的bezierPathWithRoundedRect:byRoundingCorners:cornerRadii:.只需CGPath在上下文中使用bezier路径对象即可.

Answer 3

TomekKuźma完成的精彩工作.这是适合您需求的新TKRoundedView类.
您的要求只能通过此参数来满足.

TKRoundedView *view = [[TKRoundedView alloc] initWithFrame:frame];
view.roundedCorners = TKRoundedCornerTopLeft | TKRoundedCornerTopRight;

但它还提供以下额外功能.

TKRoundedView *view = [[TKRoundedView alloc] initWithFrame:frame];
view.roundedCorners = TKRoundedCornerTopLeft
view.borderColor = [UIColor greenColor];
view.fillColor = [UIColor whiteColor];
view.drawnBordersSides = TKDrawnBorderSidesLeft | TKDrawnBorderSidesTop;
view.borderWidth = 5.0f;
view.cornerRadius = 15.0f;

请查看示例项目https://github.com/mapedd/TKRoundedView的以下链接