如何使用Objective-C在iOS中使用AspectFit UIBezierPath

Question

我正在尝试使用基于UIBezierPath的自定义按钮AspectFit。

这是我在自定义类中的代码，它是UIButton类的子类

-(id)initWithCoder:(NSCoder *)coder {
   if (self = [super initWithCoder:coder]) {
    self.contentMode = UIViewContentModeScaleAspectFill;
   }
   return self;
}

-(void)drawRect:(CGRect)rect {

 UIColor* fillColor = [UIColor colorWithRed: 0.451 green: 0.855 blue: 1 alpha: 1];

UIBezierPath* clipPath = [UIBezierPath bezierPathWithRect: CGRectMake(0, 0.01, 81.6, 40.9)];
[clipPath addClip];

UIBezierPath* bezierPath = [UIBezierPath bezierPath];
[bezierPath moveToPoint: CGPointMake(81.21, 13.63)];
[bezierPath addCurveToPoint: CGPointMake(48.11, 40.91) controlPoint1: CGPointMake(84.3, 37.04) controlPoint2: CGPointMake(68.27, 40.91)];
[bezierPath addCurveToPoint: CGPointMake(4.72, 45.04) controlPoint1: CGPointMake(33.83, 40.91) controlPoint2: CGPointMake(3.32, 40.91)];
[bezierPath addCurveToPoint: CGPointMake(20.19, 7.94) controlPoint1: CGPointMake(-1.03, 14.37) controlPoint2: CGPointMake(-1.26, 0.28)];
[bezierPath addCurveToPoint: CGPointMake(81.21, 13.63) controlPoint1: CGPointMake(40.97, 1.57) controlPoint2: CGPointMake(78.62, -6.04)];
[bezierPath closePath];
[fillColor setFill];
[bezierPath fill];
}

在xib中，我将自定义类分配给UIButton对象。我尝试在IB中使用AspectFit处理程序，并尝试在initWithCoder中，似乎没有任何工作。

Answer 1

最简单的方法是在绘制之前将AspectFit变换应用于BezierPath，或者将相同的变换应用于图形上下文。类似于以下内容：

- (CGAffineTransform) aspectFitFrom:(CGRect)originalRect to:(CGRect)targetRect
{
    CGFloat xScale = targetRect.size.width / originalRect.size.width;
    CGFloat yScale = targetRect.size.height / originalRect.size.height;
    CGFloat scale = MIN(xScale, yScale);

    CGFloat xShift = CGRectGetMidX(targetRect) - CGRectGetMidX(originalRect) * scale;
    CGFloat yShift = CGRectGetMidY(targetRect) - CGRectGetMidY(originalRect) * scale;
    return CGAffineTransformMake(scale, 0, 0, scale, xShift, yShift);
}

将其应用于Bezier路径的边界框以及目标的边界。然后在填充之前将变换应用于bezierPath，如下所示：

CGRect pathBBox = bezierPath.bounds; // the bounding box of your bezierPath
CGAffineTransform transform = [self aspectFitFrom:pathBBox to:rect];
[bezierPath applyTransform:transform];

在缩放时，您需要考虑自己想要对形状的线条粗细做什么。

Answer 2

我仔细估计了图纸的宽度和高度，它给了我82 x 42的字面。然后我在代码中应用了比例因子，因此如果按钮大小在xib中缩放，则绘图可以适合按钮。

CGContextRef context = UIGraphicsGetCurrentContext();
CGContextScaleCTM(context, rect.size.width / 82, rect.size.height/ 42);

完整的代码现在看起来像这样。

- (void)drawRect:(CGRect)rect {

  CGContextRef context = UIGraphicsGetCurrentContext();
  CGContextScaleCTM(context, rect.size.width / 82, rect.size.height/ 42);

  {

  UIColor* fillColor = [UIColor colorWithRed: 0.451 green: 0.855 blue: 1 alpha: 1];


  UIBezierPath* clipPath = [UIBezierPath bezierPathWithRect: CGRectMake(0, 0.01, 81.6, 40.9)];
  [clipPath addClip];

  UIBezierPath* bezierPath = [UIBezierPath bezierPath];


  [bezierPath moveToPoint: CGPointMake(81.21, 13.63)];
  [bezierPath addCurveToPoint: CGPointMake(48.11, 40.91) controlPoint1: CGPointMake(84.3, 37.04) controlPoint2: CGPointMake(68.27, 40.91)];
  [bezierPath addCurveToPoint: CGPointMake(0.72, 25.04) controlPoint1: CGPointMake(33.83, 40.91) controlPoint2: CGPointMake(3.32, 40.91)];
  [bezierPath addCurveToPoint: CGPointMake(20.19, 0.94) controlPoint1: CGPointMake(-1.03, 14.37) controlPoint2: CGPointMake(-1.26, 0.28)];
  [bezierPath addCurveToPoint: CGPointMake(81.21, 13.63) controlPoint1: CGPointMake(40.97, 1.57) controlPoint2: CGPointMake(78.62, -6.04)];
  [bezierPath closePath];
  [fillColor setFill];
  [bezierPath fill];

  }

}