Ellipse

[lespaul36]

I am working on a icon editing program and want the user to have the ability to make ellipses. I have considered using the graphics drawellipse, but think that it would cause alot of overhead since I am using a grid of pictureboxes (one picturebox per pixel of the image). I would have to loop through all the pixels and reset the grid everytime the mouse moved to a new section of the grid. I was thinking of using a formula to draw it myself on the mouse movements, but haven't found any code to really help me. Any one got some code or ideas?

 

[DiskJunky]

to calculate the points on an ellipse, I used the following code;

    'calculate the radius for intWidth and intHeight
    intHeight = intHeight / 2
    intWidth = (intWidth / 2) - intHeight
    
    'calculate the starting point of the ellipse
    sngTiltX = Sin(sngTiltAngle * PIdiv180) * intWidth
    sngTiltY = Cos(sngTiltAngle * PIdiv180) * intWidth
    
    'draw the ellipse using one line for every three pixels
    'This will increase drawing speed on small ellipses and produce
    'detailed ones for large ellipses.
    sngNumOfPoints = (2 * PI * (intWidth + intHeight)) / 4 '2.Pi.r = circumfrence, /4=per 4 pixels
    
    'size the array to match the number of points to be calculated
    ReDim udtEllipse(sngNumOfPoints)
    
    'calculate the number of degrees between points
    sngDegPerPoint = (360 / sngNumOfPoints)
    
    For sngCounter = 0 To 360 Step sngDegPerPoint
        sngMoveCenterX = intCenterX + (Cos(sngCounter * PIdiv180) * sngTiltX)
        sngMoveCenterY = intCenterY + (Cos(sngCounter * PIdiv180) * sngTiltY)
        
        'calculate the new position
        sngCircleX = Sin((sngCounter + sngTiltAngle) * PIdiv180) * intHeight
        sngCircleY = Cos((sngCounter + sngTiltAngle) * PIdiv180) * intHeight
        
        'add the points
        udtEllipse(Round(sngCounter / sngDegPerPoint)).X = sngMoveCenterX + sngCircleX
        udtEllipse(Round(sngCounter / sngDegPerPoint)).Y = sngMoveCenterY + sngCircleY
    Next sngCounter

I'd have to ask though, why are you using an entire picture box as a pixel?

 

[lespaul36]

It seemed like the easies way to get mouse movement and resize pixels for editing. I may end up changing that idea. I have a pretty fast computer and originally wrote this for my own use, but I may end up sharing it. If I do share it then I will have to make it run smoother for those that aren't running dual processors.