I am drawing some precision vector graphics on a canvas and am attempting to use PenSize to dictate the thickness of various lines. The trouble I have is large number PenSize values distort the end points of the lines. I could adjust the endpoints of my line if I knew the method XOJO uses to thicken lines when PenSize is not equal to 1. Anybody have information on this?

Below is sample code that shows my question. I draw PenSize =1 crosses at the end points, then a line between the two points with a PenSize of 20. The line is not on the end points and the delta seems to vary depending on the slope of the line.

Var x1 As Double
Var x2 As Double
Var y1 As Double
Var y2 As Double
g.DrawingColor = Color.TextColor
x1 = g.width * .1
x2 = g.width * .9
y1 = g.height * .5
y2 = g.height * .9
Var xSize As Double = 30
'draw cross at pts 1 and 2 with pensize of 1
g.PenSize =1
g.DrawLine(x1-xSize/2, y1, x1+ xSize/2, y1)
g.DrawLine(x1, y1-xSize/2, x1, y1 + xSize/2)
g.DrawLine(x2-xSize/2, y2, x2+ xSize/2, y2)
g.DrawLine(x2, y2-xSize/2, x2, y2 + xSize/2)
'draw line with large PenSize
g.PenSize = 20
g.LineCap = graphics.LineCapTypes.Square 'make end of line square
g.DrawLine(x1, y1, x2, y2)

/Sigh We’re 12 now can someone remove b u t t from the “swear filter”?

Technically the center of Graphics.LineCapTypes.■■■■ should end on the coordinates of the line.

Looking quickly at the output of the above code and only changing the LineCapType to ■■■■ shows there is a negative Half Pen Size offset required which, without my replicating the code in VS looks like a bug. So you’d need the following code to have ■■■■ land on the correct coordinates.

As for landing a Round or Square in the right place, someone with better maths than mine would need to help there.

Var x1 As Double
Var x2 As Double
Var y1 As Double
Var y2 As Double
g.DrawingColor = Color.TextColor
x1 = g.width * .1
x2 = g.width * .9
y1 = g.height * .5
y2 = g.height * .9
Var xSize As Double = 30
'draw cross at pts 1 and 2 with pensize of 1
g.PenSize = 1
g.DrawLine(x1 - xSize / 2, y1, x1 + xSize / 2, y1)
g.DrawLine(x1, y1 - xSize / 2, x1, y1 + xSize / 2)
g.DrawLine(x2 - xSize / 2, y2, x2 + xSize / 2, y2)
g.DrawLine(x2, y2 - xSize / 2, x2, y2 + xSize / 2)
'draw line with large PenSize
g.PenSize = 20
Var halfPenSize As Double = g.PenSize / 2
g.LineCap = Graphics.LineCapTypes.■■■■ 'make end of line square
g.DrawLine(x1 - halfPenSize, y1 - halfPenSize, x2 - halfPenSize, y2 - halfPenSize)