CODEWITHSUNDEEP
iosswiftuiimagedrawrectcgrect
Matt S.
Matt S.

Reputation: 75

iOS - Drawing Rectangles (CGRect) on UIImage in Swift not working correctly

I am attempting to draw rectangles (array of CGRects) on a UIImage which will be rendered back to the end-user. The final result, for lack of a better phrase, just looks weird. For example, if I have an array of 2 CGRect's, only one is drawn, barely, but not fully complete. The other is omitted. Please see image below for how the image turns out with a particular array of CGRects. (FYI: I am sending the image to Google Cloud for processing, which responds with an array of CGRects)

What am I missing?

private func drawOccurrencesOnImage(_ occurrences: [CGRect], _ image: UIImage) -> UIImage? {
    let imageSize = image.size
    let scale: CGFloat = 0.0
    UIGraphicsBeginImageContextWithOptions(imageSize, false, scale)

    image.draw(at: CGPoint.zero)
    let ctx = UIGraphicsGetCurrentContext()

    ctx?.addRects(occurrences)
    ctx?.setStrokeColor(UIColor.red.cgColor)
    ctx?.setLineWidth(2.0)
    ctx?.strokePath()

    guard let drawnImage = UIGraphicsGetImageFromCurrentImageContext() else {
        presentAlert(alertTitle: "Error", alertText: "There was an issue, please try again")
        return nil
    }

    UIGraphicsEndImageContext()
    return drawnImage
}

CGRect array ("occurrences" from function above) with a value of "[(298.0, 868.0, 65.0, 43.0), (464.0, 1017.0, 67.0, 36.0)]" results in image below: Screenshot of UIImage

Further details: using Swift 4, iOS 12

Thank you!

Upvotes: 1

Views: 2227

Answers (1)

dengApro
dengApro

Reputation: 4008

Code is right .

"[(298.0, 868.0, 65.0, 43.0), (464.0, 1017.0, 67.0, 36.0)]"

Coordinates are not proper.

Please consider the iPhone Resolutions.

image

img

imageView.image = drawOccurrencesOnImage([CGRect(x: 100, y: 100, width: 59, height: 60), CGRect(x: 120, y: 50, width: 59, height: 60)], UIImage(named: "person-placeholder")!)

source

Upvotes: 2

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