Adding custom attributes?

[ghost]

I'm having a bit of trouble adding my own attributes to Highlightr.

When not using Highlightr, I can add attributes to a UITextView using addAttribute(). What's a good way to add my own (e.g. for increasing line-height and changing the alignment programmatically)?

This is the code which doesn't work (creating and adding an attribute). Normally "attempt 2" is all that's needed to add an attribute to a text view.

let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.minimumLineHeight = 15
paragraphStyle.alignment = .center

// Attempt 1:  add attribute to text storage
textStorage.addAttribute(NSParagraphStyleAttributeName, value: paragraphStyle, range: NSMakeRange(0, attributedString.length))

// Attempt 2: Add attribute to text view
let attributedString = NSMutableAttributedString(attributedString: textView.attributedText)

attributedString.addAttribute(NSParagraphStyleAttributeName, value: paragraphStyle, range: NSMakeRange(0, attributedString.length))

textView.attributedText = attributedString

[ghost]

Update

Subclassing to provide an attribute works, but seems very hacky.

Is there a better way?

class CustomCodeAttributedString: CodeAttributedString {
    override func attributes(at location: Int, effectiveRange range: NSRangePointer?) -> [String : Any]
    {
        var attributes = super.attributes(at: location, effectiveRange: range)
        
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.minimumLineHeight = 30
        paragraphStyle.alignment = .center
        attributes[NSParagraphStyleAttributeName] = paragraphStyle
        
        return attributes
    }
}

[raspu]

Hi @droidery, there's no support for that right now, but I can totally add this on a future release. CodeAttributedString will dynamically add attributes to the text, and this as a side effect will remove the current attributes of the line being processed.

I will need to take some time to think of a proper solution, but for now I think your approach is the best one.

[ivancantarino]

@raspu I would definitely love a solution for this!
We could use your on the fly parser (I'm using it for Markdown) but with our default attributes, such as a custom font being processed with your engine.

But it's been so long since this was requested.

Is there at least a way for us to hardcode the font we want throughout the whole themes and parsing? If there's that option we can force a font there.

[raspu]

@ivan-cantarino You will need to call setCodeFont on the Theme instance every time you change a theme, there's no other way right now.

[geberl]

2019 / Swift 4.2 version of ghost's code snipplet from above:

class CustomCodeAttributedString: CodeAttributedString {
    override func attributes(at location: Int, effectiveRange range: NSRangePointer?) -> [AttributedStringKey : Any] {
        var attributes = super.attributes(at: location, effectiveRange: range)
        
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.minimumLineHeight = 30
        paragraphStyle.alignment = .center
        attributes[NSAttributedString.Key.paragraphStyle] = paragraphStyle

        return attributes
    }
}