NSImage Getting Resized when I draw Text on it

Question

I have the following code to draw a text over an NSImage. But the resulting image is getting resized to smaller one when I save it to disk.

What i\'m i doing wrong?

Answer 1

This is a different approach using a temporary NSView to draw the image and the text and cache the result in a new image (code is Swift 4). The benefit it you don't need to deal with pixels

class ImageView : NSView  {

    var image : NSImage
    var text : String

    init(image: NSImage, text: String)
    {
        self.image = image
        self.text = text
        super.init(frame: NSRect(origin: NSZeroPoint, size: image.size))
    }

    required init?(coder decoder: NSCoder) { fatalError() }

    override func draw(_ dirtyRect: NSRect) {
        let font = NSFont.boldSystemFont(ofSize: 18)
        let textRect = CGRect(x: 5, y: 5, width: image.size.width - 5, height: image.size.height - 5)
        image.draw(in: dirtyRect)
        text.draw(in: textRect, withAttributes: [.font: font, .foregroundColor: NSColor.white])
    }

    var outputImage : NSImage  {
        let imageRep = bitmapImageRepForCachingDisplay(in: frame)!
        cacheDisplay(in: frame, to:imageRep)
        let tiffData = imageRep.tiffRepresentation!
        return NSImage(data : tiffData)!
    }
}

To use it, initialize a view

let image = ... // get some image
let view = ImageView(image: image, text: "Sample Text")

and get the new image

let imageWithText = view.outputImage

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Note:

The paragraph style is not used at all, but if you want to create a mutable paragraph style just write

let textStyle = NSMutableParagraphStyle()