CODEWITHSUNDEEP
swiftios8core-graphics
hededo
hededo

Reputation: 381

Incorrectly using Core Graphics

I am trying to make a custom UISlider by creating a class that extends UIControl. I am having issues trying to fill and stroke CGRects using core graphics. I am able to correctly stroke and fill a CGRect at position (0,0), but cannot at any other position.

Here is what I see when I draw my UISlider at (0,0)enter image description here

Here is what I see when I draw my UISlider at (%10,%10)

enter image description here

my slider is made in in the AppDelegate

var slider:RGBSlider        
slider = RGBSlider(frame: CGRectMake(bounds.width * 0.1, bounds.height * 0.1, bounds.width * 0.6, bounds.height * 0.15), leftColor: UIColor.blackColor(), rightColor: UIColor.redColor())

here is the class declaration:

class RGBSlider: UIControl

{

//member vars
private var _sliderRec: CGRect = CGRectZero
private var _cursorRec: CGRect = CGRectZero
private var _gradient: CAGradientLayer

//initlizer
init(frame: CGRect, leftColor: UIColor, rightColor: UIColor)
{
    _sliderRec = frame

    //and this does not
    //_sliderRec.origin.x = frame.origin.x
    //_sliderRec.origin.y = frame.origin.y

    //this works for some reason
    //_sliderRec.origin.x = 0
    //_sliderRec.origin.y = 0

    _gradient = CAGradientLayer()
    _gradient.colors = [leftColor, rightColor]
    _gradient.locations = [0.0, 255.0]

    super.init(frame: _sliderRec)
}

required init(coder aDecoder: NSCoder)
{
    fatalError("init(coder:) has not been implemented")
}

//defines how to draw the slider
override func drawRect(rect: CGRect)
{

    let context: CGContext! = UIGraphicsGetCurrentContext()
    let strokeSize:Float = 3.0

    var smallerRec = CGRectMake( _sliderRec.origin.x + CGFloat(strokeSize/2), _sliderRec.origin.y + CGFloat(strokeSize/2), (_sliderRec.size.width - CGFloat(strokeSize)), (_sliderRec.size.height - CGFloat(strokeSize)) )

    //fills the rectangle
    CGContextAddRect(context, smallerRec)
    CGContextSetFillColorWithColor(context, UIColor.whiteColor().CGColor)
    CGContextDrawPath(context, kCGPathFill)

    //stroke in the rectangle        
    CGContextAddRect(context, _sliderRec)
    CGContextSetStrokeColorWithColor(context, _gradient.colors[1].CGColor)
    CGContextStrokeRectWithWidth(context, _sliderRec, CGFloat(strokeSize))
    CGContextStrokeRect(context, _sliderRec)
    CGContextDrawPath(context, kCGPathStroke)


}

}

Why is my slider not drawing at the origin of my CGRect when it is not at the origin? How can I fix this? Thank You!

Upvotes: 1

Views: 109

Answers (1)

Jawwad
Jawwad

Reputation: 1336

Try using bounds in drawRect in place of _sliderRec. The _sliderRec is the frame of the view which is its position in its superview. When drawing within the view you'll want to use the view's bounds property instead.

Upvotes: 3

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