I know use UIBezierPath() to draw a dash line like:
let path = UIBezierPath()
path.setLineDash([CGFloat(4), CGFloat(4)], count: 2, phase: 0)
path.lineCapStyle = CGLineCap.round
path.move(to: startPoint)
path.addLine(to: endPoint)
path.stroke()
It works fine. But how could I can draw a dash line in context? Like below code can draw a solid line no matter if i add
context.setLineDash(phase: 3, lengths: [3,2])
The whole code:
override func draw(_ rect: CGRect) {
if let context = UIGraphicsGetCurrentContext() {
let startPoint = CGPoint(x: 50, y: 10)
let endPoint = CGPoint(x: rect.width-100, y: 10)
context.setLineDash(phase: 3, lengths: [3,2])
context.setLineWidth(10)
context.move(to: startPoint)
context.addLine(to: endPoint)
context.setStrokeColor(UIColor.red.cgColor)
context.setLineCap(.round)
context.strokePath()
}
}
The result is:
Anything wrong?
Think about it...
The line width is 10.
The line cap is round.
So the radius of the line cap is 5.
N.B. The line ends at the centre point of the line cap (not at the end of the cap).
The length of each dash is 3 and the gap between the lines is 2.
So the radius of the cap is much much bigger than the gap between the lines. So each line is overlapping to the next one.
Try making the line lengths like...
[3, 12]
That should make the lines 3 points long with a cap radius of 5 and then a gap between the ends of the caps of 2 (12 - 5 - 5).
Related
I'm attempting to draw a line with a UIBezierPath that alternates between dots and dashes. Here's my code so far:
func drawAlternatingDashesAndDots() {
let path = UIBezierPath()
path.move(to: CGPoint(x: 10,y: 10))
path.addLine(to: CGPoint(x: 290,y: 10))
path.lineWidth = 8
let dots: [CGFloat] = [0.001, path.lineWidth * 2]
path.setLineDash(dots, count: dots.count, phase: 0)
for i in 0...10 {
if i % 2 == 0 {
// Even Number
path.lineCapStyle = CGLineCap.round
} else {
// Odd Number
path.lineCapStyle = CGLineCap.square
}
}
UIGraphicsBeginImageContextWithOptions(CGSize(width:300, height:20), false, 2)
UIColor.white.setFill()
UIGraphicsGetCurrentContext()!.fill(.infinite)
UIColor.black.setStroke()
path.stroke()
let image = UIGraphicsGetImageFromCurrentImageContext()
dashDotDashLineView.image = image
UIGraphicsEndImageContext()
}
However, in my image view, only dots are rendered:
I'm probably misunderstanding something about how UIBezierPath works; any help appreciated!
The UIBezierPath documentation explains the meaning of the pattern argument:
A C-style array of floating point values that contains the lengths (measured in points) of the line segments and gaps in the pattern. The values in the array alternate, starting with the first line segment length, followed by the first gap length, followed by the second line segment length, and so on.
In your code, 0.001 is the first value in the pattern, so it is a line segment length, and is small enough to be drawn as a dot. The second value in the pattern is path.lineWidth * 2, so it is a gap length, which is the distance between the dots.
If you want to alternate dots and dashes, you have to pass a pattern containing four numbers: a line segment length, a gap, another line segment length, and another gap.
let dots: [CGFloat] = [
0.001, // dot
path.lineWidth * 2, // gap
path.lineWidth * 2, // dash
path.lineWidth * 2, // gap
]
I was planning to display information of AR object in screen with arrow in 2D. So I used projectPoint to get corresponding position of object in screen. I have this function to return convert 3D position of node to 2D and CGPoint to display info text in.
func getPoint(sceneView: ARSCNView) -> (CGPoint, CGPoint){
let projectedPoint = sceneView.projectPoint(node.worldPosition)
return (point, CGPoint(x: CGFloat(projectedPoint.x), y: CGFloat(projectedPoint.y)) )
}
and this to draw line using SpriteKit:
let (f,s) = parts[3].getPoint(sceneView: sceneView)
line.removeFromParent()
let path = CGMutablePath()
path.move(to: f)
path.addLine(to: s)
line = SKShapeNode(path: path)
spriteScene.addChild(line)
This is what i get
What I expect is another end of line to be fixed in node (blue mesh). Is there something I am missing? Or does projectPoint works some other way?
edit: It seems projectPoint is returning correct value but while creating path path.addLine(to: s) this point is shifting to different position.
path.addLine(to: s) s here had reversed y so this did the trick
let frame = self.sceneView.frame
let sInversed = CGPoint(x: from.x, y: frame.height - s.y)
path.addLine(to: sInversed)
Here origin of SKScene was in bottom left of screen instead of top left.
I have 3 UIBezierPath with 2 circle and a line running from 1 circle's center to the other and it looks like the bottom picture. I want to hide the part of the line inside the circle like the top picture. Is there any easy way to do this?
My strategy would be to draw a invisible line from the centers and then draw a black line from the circumference of the 2 circles since I know the slopes etc but it seems like too much work.
private func pathForBoxCircle1() -> UIBezierPath {
let circlePath = UIBezierPath(arcCenter:circle1BoxCurrentCenter, radius: 25, startAngle: 0.0, endAngle: CGFloat(2*M_PI), clockwise: false)
//circlePath.fill()
pathBoxCircle1Global = circlePath
return circlePath
}
private func pathForBoxCircle2() -> UIBezierPath {
let circlePath = UIBezierPath(arcCenter:circle2BoxCurrentCenter, radius: 25, startAngle: 0.0, endAngle: CGFloat(2*M_PI), clockwise: false)
//circlePath.fill()
pathBoxCircle2Global = circlePath
return circlePath
}
private func pathForHorizonLine() -> UIBezierPath {
let path = UIBezierPath()
path.move(to: circle1BoxCurrentCenter)
path.addLine(to: circle2BoxCurrentCenter)
path.lineWidth = 5.0
//pathHorizonLineGlobal = path
return path
}
override func draw(_ rect: CGRect) {
pathForBoxCircle1().stroke()
pathForBoxCircle2().stroke() // same as stroke()
pathForHorizonLine().stroke()
}
You can't mix transparent and opaque lines in the same shape. You are going to have to draw 2 circles and then the line segment from the outside of the first circle to the outside of the 2nd circle.
To do that you'll need trig, or perhaps Pythagoras, to calculate the coordinates of the points where your connecting lines intersect your 2 circles.
If C1 is your first circle, C2 is your 2nd circle, C1 is at (C1.x, C1.y), C2 is at (C2.x, C2.y), the radius of C1 is R1, and the radius of C2 is R2, then the pseudo-code would look something like this:
angle1 = atan2(C1.y - C2y, C1.x - C2.x)
angle2 = atan2(C2.y - C1.y, C2.x - C1.x)
xOffset1 = R1 * cos(angle1)
yOffset1 = R1 * sin(angle1)
point1 = (C1.x + xOffset1, C1.y + yOffset1)
xOffset2 = R2 * cos(angle2)
yOffset2 = R2 * sin(angle2)
point2 = (C2.x + xOffset2, C2.y + yOffset2)
Draw your circles, then draw lines between point1 and point2.
(Note that my trig is a little rusty, and that I sketched this out on a piece of scratch paper. I think it's correct, but it's completely untested.)
my question was
I want to create a simple line graph with certain values. This is done in a view within the mainviewcontroller. I created a UIview named chart. I pass the data to the chart when its retrieved from the API. I figured out how to draw the axis but I am stuck now. I cant find anything on google on how to set labels on intervals and to make the points appear dynamically.
draw the xasis and its labels.
draw the dots in the graph.
My salution
i figured out how to do all the things i asked for.
The code I have now:
class ChartView: UIView {
//some variables
var times: [String] = []
var AmountOfRain: [Double] = []
let pathy = UIBezierPath()
let pathx = UIBezierPath()
var beginwitharray = Array<CGFloat>()
// Only override draw() if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func draw(_ rect: CGRect) {
// Drawing code
//draw the y line
pathy.move(to: CGPoint(x: 30, y: 10))
pathy.addLine(to: CGPoint(x: 30, y: 10))
pathy.addLine(to: CGPoint(x: 30, y: frame.size.height - 30))
UIColor.black.setStroke()
pathy.lineWidth = 1.0
pathy.stroke()
//draw the x line
pathx.move(to: CGPoint(x: 30, y: frame.size.height - 30))
pathx.addLine(to: CGPoint(x: 30, y: frame.size.height - 30))
pathx.addLine(to: CGPoint(x: frame.size.width - 30, y: frame.size.height - 30))
UIColor.black.setStroke()
pathx.lineWidth = 1.0
pathx.stroke()
//when the data arrives form the SUPER slow duienradar API refresh it with the data
if beginwitharray != []{
//remove the label retriving data
let label = viewWithTag(1)
DispatchQueue.main.sync {
label?.removeFromSuperview()
}
//create the dots in the graph
var point = CGPoint()
//simple way to do 2 loop in 1 loop.
var intforbeginarray = 0
let stoke = UIBezierPath()
//get the first 6 itmes out of the rain array cuz of space issues
let first6aumountarray = AmountOfRain[0...5]
stoke.move(to: CGPoint(x: 30, y: self.frame.size.height - 30))
//loop trough the data in the amounts array
for amount in first6aumountarray{
//determen the hight of the dot
let InitialHeight = (CGFloat(amount) * (self.frame.size.height - 30))/6
let pointHeight = (frame.size.height - 30) - InitialHeight
//make the point so we can draw it using UIbezierpath()
point = CGPoint(x: beginwitharray[intforbeginarray] + 20, y: pointHeight)
intforbeginarray += 1
//create the dot
let dot = UIBezierPath()
dot.addArc(withCenter: point, radius: CGFloat(5), startAngle: CGFloat(0), endAngle: CGFloat(360), clockwise: true)
UIColor.black.setFill()
dot.lineWidth = 30
dot.fill()
//create the line between dots will give a warning on the last one cuz the last one doenst go anyway
stoke.addLine(to: point)
stoke.move(to: point)
stoke.lineWidth = 1
UIColor.black.setStroke()
}
//make the strokes
stoke.stroke()
}
}
func getvalues(RainData: [Double], TimesData:[String]){
//assing the data to the subview
self.AmountOfRain = RainData
self.times = TimesData
//xaxis values
let maxint = [0, 1, 2, 3, 4, 5, 6]
//calculate the hight spacing to fit the graph
let heightperstep = ((self.frame.size.height - 5)/6)-5
var beginheight = self.frame.size.height - 35
//calculate the width spacing to fit the graph
let widthperstep = ((self.frame.size.width - 5)/6)-5
var beginwith = CGFloat(30)
//extra check to see if we have data at all.
if times != []{
//get the first 6 items out of the times array for use in our graph
let first6 = times[0...5]
//draw the label on the main queue
DispatchQueue.main.sync {
//draw the xaxis labels accroding to the spacing
for number in maxint{
let label = UILabel(frame: CGRect(x: 5, y: beginheight, width: 25, height: 15))
label.text = "\(number)"
self.addSubview(label)
beginheight = beginheight - heightperstep
}
//draw the yaxis labels according to the spacing
for time in first6{
let label = UILabel(frame: CGRect(x: beginwith, y: self.frame.size.height - 20, width: 55, height: 15))
label.text = time
self.addSubview(label)
beginwitharray.append(beginwith)
beginwith = beginwith + widthperstep
}
}
}
//redrawthe graph with new data.
setNeedsDisplay()
}}
Any help would be appreciated. I also can't use a lib or a pod since this is a school project and I need to create a simple graph.
EDIT:
Completed my code, cleared up an error when running this code
What I did first was to draw the x-asis and the y-axis. After this I considered reasonable values for the aumountofrain data. this turns out cannot really be higher then 6. Since I could fit around 6 labels in the space I have the steps where easy go down by 1 till I hit 0. The calculations I did are for my specific frame height. After I figured it all out and the padding for the y-asxis. It was a matter of figuring out how to get the dots in the right place. Since I already have the data in the beginwitharray I just needed to calculate the height. Then it was simply loop trough the data and draw each dot. Then I just had to connect the dots using the uibezierpath.
i hope my troubles will save someone a lot of time when they read how i done it.
This might be helpful: Draw Graph curves with UIBezierPath
Essentially what you need to do is for every data set you have you need to know the y-axis range of values and based on those ranges assign each value a CGFloat value (in your case inches of rain needs to correlate to a certain CGFloat value). Let's say you have your set amountOfRain = [0.1, 1.3, 1.5, 0.9, 0.1, 0] so your range is var rangeY = amountOfRain.max() - amountOfRain.min(). now lets find out where your first data point 0.1 should go on your graph by converting inches of rain to a CGFloat value that corresponds to the axis you've drawn already, this equation is just basic algebra: let y1 = (amountOfRain[0]/rangeY)*((frame.size.height-30) - 10) + 10 now it looks like your rain samples are at regular intervals so maybe let x1:CGFloat = 10 now you can add a dot or something at the CGPoint corresponding with (x1,y1). If you did this with all the data points it would create a graph that has your maximum value at the top of the graph and minimum value at the bottom. Good Luck!
I am trying to create a simple line graph which is being updated live. Some kind of seismograph .
I was thinking about UIBezierPath , by only moving a point on the y-axis according to an input var, I can create a line moving on the time axis.
The problem is that you have to "push" the previous points to free up space for the new ones.(so the graph goes from left to right)
Can anybody help with some direction ?
var myBezier = UIBezierPath()
myBezier.moveToPoint(CGPoint(x: 0, y: 0))
myBezier.addLineToPoint(CGPoint(x: 100, y: 0))
myBezier.addLineToPoint(CGPoint(x: 50, y: 100))
myBezier.closePath()
UIColor.blackColor().setStroke()
myBezier.stroke()
You're correct: you need to push the previous points. Either divide the total width of the graph so it becomes increasingly scaled but retains all data, or drop the first point each time you add a new one to the end. You'll need to store an array of these points and recreate the path each time. Something like:
//Given...
let graphWidth: CGFloat = 50
let graphHeight: CGFloat = 20
var values: [CGFloat] = [0, 4, 3, 2, 6]
//Here's how you make your curve...
var myBezier = UIBezierPath()
myBezier.moveToPoint(CGPoint(x: 0, y: values.first!))
for (index, value) in values.enumerated() {
let point = CGPoint(x: CGFloat(index)/CGFloat(values.count) * graphWidth, y: value/values.max()! * graphHeight)
myBezier.addLineToPoint(point)
}
UIColor.blackColor().setStroke()
myBezier.stroke()
//And here's how you'd add a point...
values.removeFirst() //do this if you want to scroll rather than squish
values.append(8)