2014/10/15 下午 10:16:03

iphone Programming Glossary: x2

How to draw a gradient line (fading in/out) with Core Graphics/iPhone?

http://stackoverflow.com/questions/1303855/how-to-draw-a-gradient-line-fading-in-out-with-core-graphics-iphone

CGContextSetRGBStrokeColor context 1.0 1.0 1.0 1.0 CGContextMoveToPoint context x y CGContextAddLineToPoint context x2 y2 CGContextStrokePath context And I know how to do a gradient rectangle i.g. CGColorSpaceRef myColorspace CGColorSpaceCreateDeviceRGB.. instead which fortunately is what I need. I replaced CGContextMoveToPoint context x y CGContextAddLineToPoint context x2 y2 CGContextStrokePath context with CGContextSaveGState context CGContextAddRect context CGRectMake x y width height CGContextClip..

Find the tangent of a point on a cubic bezier curve (on an iPhone)

http://stackoverflow.com/questions/4089443/find-the-tangent-of-a-point-on-a-cubic-bezier-curve-on-an-iphone

c 3 c 3 t t2 d t3 CGFloat bezierTangent CGFloat t CGFloat a CGFloat b CGFloat c CGFloat d note that abcd are aka x0 x1 x2 x3 the four coefficients .. A x3 3 x2 3 x1 x0 B 3 x2 6 x1 3 x0 C 3 x1 3 x0 D x0 and then... Vx 3At2 2Bt C first calcuate.. CGFloat t CGFloat a CGFloat b CGFloat c CGFloat d note that abcd are aka x0 x1 x2 x3 the four coefficients .. A x3 3 x2 3 x1 x0 B 3 x2 6 x1 3 x0 C 3 x1 3 x0 D x0 and then... Vx 3At2 2Bt C first calcuate what are usually know as the coeffients.. a CGFloat b CGFloat c CGFloat d note that abcd are aka x0 x1 x2 x3 the four coefficients .. A x3 3 x2 3 x1 x0 B 3 x2 6 x1 3 x0 C 3 x1 3 x0 D x0 and then... Vx 3At2 2Bt C first calcuate what are usually know as the coeffients they are trivial..

Why is UIBezierPath faster than Core Graphics path?

http://stackoverflow.com/questions/6327817/why-is-uibezierpath-faster-than-core-graphics-path

CGFloat cgBaseline 100 CGFloat uiBaseline 200 CGFloat xincrement self.bounds.size.width iterations for CGFloat x1 0 x2 xincrement x2 self.bounds.size.width x1 x2 x2 xincrement CGPathAddCurveToPoint cgpath NULL x1 cgBaseline 50 x2 cgBaseline.. 100 CGFloat uiBaseline 200 CGFloat xincrement self.bounds.size.width iterations for CGFloat x1 0 x2 xincrement x2 self.bounds.size.width x1 x2 x2 xincrement CGPathAddCurveToPoint cgpath NULL x1 cgBaseline 50 x2 cgBaseline 50 x2 cgBaseline.. 200 CGFloat xincrement self.bounds.size.width iterations for CGFloat x1 0 x2 xincrement x2 self.bounds.size.width x1 x2 x2 xincrement CGPathAddCurveToPoint cgpath NULL x1 cgBaseline 50 x2 cgBaseline 50 x2 cgBaseline uipath addCurveToPoint..