此类是Core Graphics框架关于path的一个封装。使用此类能够定义简单的形状。如椭圆或者矩形,或者有多个直线和曲线段组成的形状。
path假设是基于矢量形状的,都用直线和曲线段去创建。我们使用直线段去创建矩形和多边形。使用曲线段去创建弧(arc),圆或者其它复杂的曲线形状。每一段都包含一个或者多个点。画图命令定义怎样去诠释这些点。
每个直线段或者曲线段的结束的地方是下一个的開始的地方。
每个连接的直线或者曲线段的集合成为subpath。
一个UIBezierPath对象定义一个完整的路径包含一个或者多个subpaths。
创建path是第一步。包括一下步骤:
这些方法在current graphic context下渲染path的line和curve段。
从这点開始,我们能够用方法addLineToPoint:去创建一个形状的线段。
- // Only override drawRect: if you perform custom drawing.
- // An empty implementation adversely affects performance during animation.
- - (void)drawRect:(CGRect)rect
- {
- UIColor *color = [UIColor redColor];
- [color set]; //设置线条颜色
- UIBezierPath* aPath = [UIBezierPath bezierPath];
- aPath.lineWidth = 5.0;
- aPath.lineCapStyle = kCGLineCapRound; //线条拐角
- aPath.lineJoinStyle = kCGLineCapRound; //终点处理
- // Set the starting point of the shape.
- [aPath moveToPoint:CGPointMake(100.0, 0.0)];
- // Draw the lines
- [aPath addLineToPoint:CGPointMake(200.0, 40.0)];
- [aPath addLineToPoint:CGPointMake(160, 140)];
- [aPath addLineToPoint:CGPointMake(40.0, 140)];
- [aPath addLineToPoint:CGPointMake(0.0, 40.0)];
- [aPath closePath];//第五条线通过调用closePath方法得到的
- [aPath stroke];//Draws line 依据坐标点连线
- }
- Creates and returns a new UIBezierPath object initialized with a rectangular path.
- + (UIBezierPath *)bezierPathWithRect:(CGRect)rect
demo代码:
- - (void)drawRect:(CGRect)rect
- {
- UIColor *color = [UIColor redColor];
- [color set]; //设置线条颜色
- UIBezierPath* aPath = [UIBezierPath bezierPathWithRect:CGRectMake(20, 20, 100, 50)];
- aPath.lineWidth = 5.0;
- aPath.lineCapStyle = kCGLineCapRound; //线条拐角
- aPath.lineJoinStyle = kCGLineCapRound; //终点处理
- [aPath stroke];
- }
4、使用UIBezierPath创建圆形或者椭圆形
- Creates and returns a new UIBezierPath object initialized with an oval path inscribed in the specified rectangle
- + (UIBezierPath *)bezierPathWithOvalInRect:(CGRect)rect
这种方法依据传入的rect矩形參数绘制一个内切曲线。
- Creates and returns a new UIBezierPath object initialized with an arc of a circle.
- + (UIBezierPath *)bezierPathWithArcCenter:(CGPoint)center radius:(CGFloat)radius startAngle:(CGFloat)startAngle endAngle:(CGFloat)endAngle clockwise:(BOOL)clockwise
- Parameters
- center
- Specifies the center point of the circle (in the current coordinate system) used to define the arc.
- radius
- Specifies the radius of the circle used to define the arc.
- startAngle
- Specifies the starting angle of the arc (measured in radians).
- endAngle
- Specifies the end angle of the arc (measured in radians).
- clockwise
- The direction in which to draw the arc.
- Return Value
- A new path object with the specified arc.
- #define pi 3.14159265359
- #define DEGREES_TO_RADIANS(degrees) ((pi * degrees)/ 180)
- - (void)drawRect:(CGRect)rect
- {
- UIColor *color = [UIColor redColor];
- [color set]; //设置线条颜色
- UIBezierPath* aPath = [UIBezierPath bezierPathWithArcCenter:CGPointMake(150, 150)
- radius:75
- startAngle:0
- endAngle:DEGREES_TO_RADIANS(135)
- clockwise:YES];
- aPath.lineWidth = 5.0;
- aPath.lineCapStyle = kCGLineCapRound; //线条拐角
- aPath.lineJoinStyle = kCGLineCapRound; //终点处理
- [aPath stroke];
- }
曲线的形状有開始点,结束点,一个或者多个控制点的切线定义。下图显示了两种曲线类型的相似,以及控制点和curve形状的关系。
- Appends a quadratic Bézier curve to the receiver’s path.
- - (void)addQuadCurveToPoint:(CGPoint)endPoint controlPoint:(CGPoint)controlPoint
- Parameters
- endPoint
- The end point of the curve.
- controlPoint
- The control point of the curve.
- - (void)drawRect:(CGRect)rect
- {
- UIColor *color = [UIColor redColor];
- [color set]; //设置线条颜色
- UIBezierPath* aPath = [UIBezierPath bezierPath];
- aPath.lineWidth = 5.0;
- aPath.lineCapStyle = kCGLineCapRound; //线条拐角
- aPath.lineJoinStyle = kCGLineCapRound; //终点处理
- [aPath moveToPoint:CGPointMake(20, 100)];
- [aPath addQuadCurveToPoint:CGPointMake(120, 100) controlPoint:CGPointMake(70, 0)];
- [aPath stroke];
- }
- Appends a cubic Bézier curve to the receiver’s path.
- - (void)addCurveToPoint:(CGPoint)endPoint controlPoint1:(CGPoint)controlPoint1 controlPoint2:(CGPoint)controlPoint2
- Parameters
- endPoint
- The end point of the curve.
- controlPoint1
- The first control point to use when computing the curve.
- controlPoint2
- The second control point to use when computing the curve.
- - (void)drawRect:(CGRect)rect
- {
- UIColor *color = [UIColor redColor];
- [color set]; //设置线条颜色
- UIBezierPath* aPath = [UIBezierPath bezierPath];
- aPath.lineWidth = 5.0;
- aPath.lineCapStyle = kCGLineCapRound; //线条拐角
- aPath.lineJoinStyle = kCGLineCapRound; //终点处理
- [aPath moveToPoint:CGPointMake(20, 50)];
- [aPath addCurveToPoint:CGPointMake(200, 50) controlPoint1:CGPointMake(110, 0) controlPoint2:CGPointMake(110, 100)];
- [aPath stroke];
- }
假设我们希望用Core Graphics 框架函数去创建path,则我们要用到此属性。
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Mixing Core Graphics and UIBezierPath
calls
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Drawing a path in a view
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