I am having an issue with the arc drawing of a UIBezierPath on IOS.
Whilst I get the semblance of an arc, as can be seen from the image, the top, and two sides have flat edges.
The code I am using looks like this:
let path2 = UIBezierPath()
path2.addArc(withCenter: arcCentre, radius: radius, startAngle: arcStart, endAngle: arcEnd, clockwise: false)
path2.addLine(to: finalPoint)
path2.close()
color.set()
path2.fill()
The produced arc is shown in black on the image below.
Any clues as to why this is so, and how to get a perfectly rounded image?
Related
My question requires quite a bit of explanation. If you want to skip to the question, look for the bold "Question:" towards the end.
It's fairly easy to create a "circle wipe" animation in iOS or Mac OS using a Core Animation and masks.
One way is to install a CAShapeLayer as a mask on a view (typically an image view), and installing a circle in the shape layer, and animating the circle from 0 size to large enough to cover the whole image (r = sqrt(height^2 + width^2)
Another way is to use a radial CAGradientLayer as a mask, set up the center of the gradient as an opaque color, and have a sudden transition to clear just beyond the corners of the image. You then animate the "positions" values of the gradient layer to move the clear color in to the center of the image.
Both of these approaches create a sharp-edged "circle wipe" that causes the image to shrink to a point and disappear.
That effect looks like this:
The classic cinematic circle wipe animation has a feathered edge, however, rather than a sharp border. The outer edge of the circle is completely transparent. As you move in towards the center the image becomes more and more solid over a fairly short distance, and then the image is completely opaque from there into the center. As the circle shrinks, the thickness of the transition from transparent to opaque remains constant, and the circle stinks down to a point and disappears. (The mask is a circle is opaque in the middle and has a slightly blurred edge, and the radius of the circle shrinks to 0 while the thickness of the blurred edge remains constant.)
Here is an example of an old school circle wipe. This is technically an "Iris Out" where the transition is to black, but the idea is the same:
https://youtu.be/IqDhAW3TDR8?t=90
I have no idea how to achieve a circle wipe with a feathered edge using a shape layer as a mask. Shape layers are always sharp-edged. I could get fairly close by using a shape layer where the circle is stroked with 50% opacity, and the middle of the circle is filled with a color at 100% opacity, but that wouldn't get the smooth transition from transparent to opaque that I'm after.
Another approach I've tried is using a radial gradient with 3 colors in it. I set the inner colors as opaque, and the outer color as clear. I set the location of the outer color as > 1 (say 1.2), the middle location to 1, and the inner location to 0. The locations array contains [1.2, 1.0, 0] That makes the whole part of the mask that covers the image opaque, with a feathered transition to clear that happens past the edges of the image.
I then do an animation of the locations array in 2 steps.
In the first step, I animate the locations array to [0, 0, 0.2]. That causes a band of feathering to move in from the corners and stop at 0.2 from the center of the image.
In the 2nd step, I animate the locations array from [0, 0, 0.2] to [0,0,0]. That causes an inner, transparent-to-opaque center to shrink to a point and disappear.
The effect is ok, and if I run it with a narrow blur band and a fast duration, it looks decent, but it's not perfect.
Here is what it looks like with a blur range of 0.2, and a duration of (I think) 0.25 seconds:
If I introduce a pause between the animation steps, however, you can see the imperfections in the effect:
Question: Is there a way to animate a circle with a small blur radius (5 points or so) from the full size of a view down to 0 using Core Animation?
The same question applies to other types of wipe animations as well: Keyhole, star, side wipe, box, and many others. For those, the radial gradient trick I'm using for a feathered circle wipe wouldn't work at all. (You create those specialized wipe animations using a CAShapeLayer that's the shape you want to animate, and then adjust it's size from large to small.
It would be easy to create a static blurred circle (or other shape) by first drawing a circle and then applying a Core Image blur filter to it, but there's no way to animate that in iOS, and the CI blur filter is too slow on iOS even if you could.
Here is a link to the project I used to create the animations in this post using the 3-color radial gradient I describe: https://github.com/DuncanMC/GradientView.git.
Edit:
Based On James' comment, I tried using a shape layer with a shadow on it as a mask. The effect is on the right track, but there is still a stark transition from the opaque part of the image to the mostly transparent part which is masked by the shadow layer. Even with a shadow opacity of 1.0 the shadow is still mostly transparent. Here's what it looks like:
Making the line color of the circle shape partly transparent helps some, and gives a transition between the opaque part of the image and the mostly transparent shadow. Here's the image above but stroking the shape layer at a line width of 2 points and an opacity of 0.6:
Edit #2: SOLVED!
James' idea of using a shadowPath is the solution. You don't want anything in your mask layer other than a shadowPath. If you do that you can use the shadowRadius property to control the amount of blurring, and smoothly animate a shadow path from a circle that fully encloses the view down to a vanishing point all in one step.
I've updated my github project at https://github.com/DuncanMC/GradientView.git to include both the radial gradient animation and the shadowPath animation for comparison.
Here is what the finished effect looks like, first with a 5 pixel blur radius:
And then with a 30 pixel blur radius:
You could use the shadowPath on a CAShapeLayer to create a circle with a blurred outline to use as the mask.
Create a shape layer with no fill or stroke (we only want to see the shadow) and add it as the layer mask to your view.
let shapeLayer = CAShapeLayer()
shapeLayer.shadowColor = UIColor.black.cgColor
shapeLayer.shadowOffset = CGSize(width: 0, height: 0)
shapeLayer.shadowOpacity = 1
shapeLayer.shadowRadius = 5
self.maskLayer = shapeLayer
self.layer.mask = shapeLayer
And animate it with a CABasicAnimation.
func show(_ show: Bool) {
let center = CGPoint(x: self.bounds.width/2, y: self.bounds.height/2)
var newPath: CGPath
if show {
let radius = sqrt(self.bounds.height*self.bounds.height + self.bounds.width*self.bounds.width)/2 //assumes view is square
newPath = UIBezierPath(arcCenter: center, radius: radius, startAngle: 0, endAngle: CGFloat.pi * 2, clockwise: true).cgPath
} else {
newPath = UIBezierPath(arcCenter: center, radius: 0.01, startAngle: 0, endAngle: CGFloat.pi * 2, clockwise: true).cgPath
}
let shadowAnimation = CABasicAnimation(keyPath: "shadowPath")
shadowAnimation.fromValue = self.maskLayer.shadowPath
shadowAnimation.toValue = newPath
shadowAnimation.duration = totalDuration
self.maskLayer.shadowPath = newPath
self.maskLayer.add(shadowAnimation, forKey: "shadowAnimation")
}
As you can set any path for the shadow it should also work for other shapes (star, box etc.).
I'm trying to create a semi circle button as per wireframe.
But it's not turning out right.
This is the code I've written in C#:
PORCalculatorButton.Layer.CornerRadius = PORCalculatorButton.Layer.Bounds.Width / 2;
PORCalculatorButton.ClipsToBounds = true;
PORCalculatorButton.Layer.MaskedCorners = (CoreAnimation.CACornerMask)3;
There are layout constraints on the button too.
Can anyone tell me where I've gone wrong or if there's a better way?
I'll accept any answers in ObjC, Swift or C#
Thanks.
Try the below Code:
let circlePath = UIBezierPath.init(arcCenter:
CGPointMake(PORCalculatorButton.bounds.size.width / 2, PORCalculatorButton.bounds.size.height), radius: PORCalculatorButton.bounds.size.height, startAngle: 0.0, endAngle: CGFloat(M_PI), clockwise: false)
let circleShape = CAShapeLayer()
circleShape.path = circlePath.CGPath
PORCalculatorButton.layer.mask = circleShape
Because of layout constraints, your button will resize according to your outer views. You need to make sure to apply the layer properties, after your button is rendered, to ensure you have the final frame/bounds, and also re-apply the same properties if the button size changes (say due to rotation etc)
You are trying to clip/mask the button vertically, but you are using width, not height, to calculate corner radius. Is this the intended implementation?
I'm struggling to understand how to achieve the following component:
Theory:
I've managed to create 4 draggable UIView'. When one of the UIView change position I'm creating UIBezierPath from connecting each UIView center, to a box shape and displaying it using CAShapeLayer.
I can't understand how to calculate the "addQuadCurve" control point to achieve the curved lines in the illustration.
Current Code:
func updateLines() {
let path = UIBezierPath()
path.move(to: v.center)
path.addLine(to: v2.center)
path.addLine(to: v4.center)
path.addLine(to: v3.center)
path.close()
line.path = path.cgPath
line.strokeColor = UIColor.black.cgColor
line.fillColor = UIColor.red.cgColor
}
Any help or advice for the right direction will be highly appreciated.
Best regards,
Roi
It looks to me like a connected set of cubic Bezier curves where the beginning and end are the same point. If you watch the animation, it looks like as you drag different points, the point that's the beginning/end of the curve gets changed.
Watch carefully and you'll see that 3 of the 4 corners are smooth curves, and one has a "kink" in it. The kinked corner seems to be a point other than the one that's being moved. That's probably the begin/end point.
This issue is tied with this: Set SKShapeNode frame to calculateAccumutedFrame
Is there a way to resize an SKShapeNode's frame. I do not want to scale it, (suggested here: Resizing a SKShapeNode). Using whatever scale function makes its contents shrink and resize aswell (the line width of 200x200 is way different than 50x50)
I need to take a frame and set it to a specific size. For example this:
shape.frame = CGRect(...)
Can't do that since frame is get-only. I attempted to override calculateAccumulatedFrame but that does nothing (see top link).
Can someone please suggest an alternative to the same functionality of SKShapeNode that is not halfway built... Or a way to actually change the frame. The basic functionality I need is to create an arc (seen in pictures of link on top) and have that in some sort of SKNode so I can resize, shrink it, etc. the same as you can do with SKSpriteNode
SKShapeNode is a node based on the Core Graphics path (CGPath).
So there is no direct method of resizings different from scaling as you want.
If you use a SKSpriteNode for example you have actions like resizeByWidth or resizeToWidth.
But about node like shapes you should think to him as you must resize a CGPath or UIBezierPath using method like :
apply(_ transform: CGAffineTransform)
or directly by rebuild your path as for example:
let π:CGFloat = CGFloat(M_PI)
let startAngle: CGFloat = 3 * π / 4
let endAngle: CGFloat = π / 4
myShape.path = UIBezierPath(arcCenter: CGPoint.zero, radius: 33.5, startAngle: startAngle, endAngle: endAngle, clockwise: true).cgPath
I would recommend making an SKSpriteNode out of your SKShapeNode because SKShapeNode is buggy.
let node = SKNode()
node.addChild(shapeNode) //we do this because of the bugs with SKShapeNode
let texture = view.textureFromNode(node, crop:node.calculateAccumulatedFrame)
let spriteNode = SKSpriteNode(texture:texture)
Optionally, I would look up ways to save this texture to disk, so that you do not have to render the shape every time.
I'm fairly new to Swift and I'm coding for my kids. I'm using sprite-kit to create a simple game for them. At the moment I'm struggling with how to draw a face to an arbitrary skshapenode? I know that there is no holes within the shape but other than that it can be of any shape. Dispite what shape it is, I would like to draw eyes and mouth to it programmatically. The shapes can came in many sizes.
Any suggestions how to approach this?
Here's an example of how to draw a smiley face with an SKShapeNode. It provides a framework that you can expand upon to draw more complex faces.
We start by extending the UIBezierPath class to add instance methods that are useful for drawing faces. The first method adds a circle to a path at a given location and with a specified radius. The moveToPoint statement moves the current point of a path to a new location. This is the equivalent of picking up a "pen" and moving it to a new location to draw a different, non-connected object. The second method draws a half circle with the open side facing up. This can be used to draw a smile. Note that extensions cannot be defined within a class. You can place it above your GameScene definition.
extension UIBezierPath {
func addCircle(center:CGPoint, radius:CGFloat) {
self.moveToPoint(CGPointMake(center.x+radius, center.y))
self.addArcWithCenter(center, radius: radius, startAngle: 0, endAngle: CGFloat(2*M_PI), clockwise: true)
}
func addHalfCircle(center:CGPoint, radius:CGFloat) {
self.moveToPoint(CGPointMake(center.x+radius, center.y))
self.addArcWithCenter(center, radius: radius, startAngle: 0, endAngle: CGFloat(M_PI), clockwise: false)
}
}
We can now use the extended UIBezierPath class to draw a face consisting of a face outline (a large circle), eyes (two small circles), and a mouth (a half circle). The face is constructed by adding components of the face to a path and then attaching the path to an SKShapeNode.
class GameScene: SKScene {
override func didMoveToView(view: SKView) {
scaleMode = .ResizeFill
let face = SKShapeNode()
// The argument determines the size of the face
face.path = drawFace(50)
face.lineWidth = 2
// Place the face in the center of the scene
face.position = CGPointMake (CGRectGetMidX(view.frame),CGRectGetMidY(view.frame))
addChild(face)
}
func drawFace(radius:CGFloat) -> CGPathRef {
var path = UIBezierPath()
// Add the outline of the face
let center = CGPointZero
path.addCircle(center, radius: radius)
// Add the eyes
let eyeOffset = radius * 0.35
let eyeRadius = radius * 0.125
let left = CGPointMake(-eyeOffset, eyeOffset)
path.addCircle(left, radius: eyeRadius)
let right = CGPointMake(eyeOffset, eyeOffset)
path.addCircle(right, radius: eyeRadius)
// Add the mouth
let smileRadius = radius*0.65
path.addHalfCircle(center, radius: smileRadius)
return path.CGPath
}
}