Drawing Text to a CGContext for Quartz PDF not working - swift

Question

This is for Swift 5 on macOS
I am trying to write some text to a generated PDF.
I am able to load a background image onto the pages, but when I call my drawText method, it is not making it onto either of the pages.
I tried drawing an NSString to the context via the .draw() method and that would not work either. I hoping to get this to work so I can add more text, including text boxes, etc.
What am I doing wrong? Thanks for any pointers.
import Cocoa
import CoreText
import Quartz
extension NSImage {
/*
Converts an NSImage to a CGImage for rendering in a CGContext
Credit - Xue Yu
- https://gist.github.com/KrisYu/83d7d97cae35a0b10fd238e5c86d288f
*/
var toCGImage: CGImage {
var imageRect = NSRect(x: 0, y: 0, width: pageWidth, height: pageHeight)
guard let image = cgImage(forProposedRect: &imageRect, context: nil, hints: nil) else {
abort()
}
return image
}
}
class PDFText {
/*
Create a non-nil CGContext
Credit - hmali - 3/15/2019
https://stackoverflow.com/questions/41100895/empty-cgcontext
*/
var pdfContext = CGContext(data: nil,
width: 0,
height: 0,
bitsPerComponent: 1,
bytesPerRow: 1,
space: CGColorSpace.init(name: CGColorSpace.sRGB)!,
bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue)
let textRect = CGRect(x: 295, y: 350, width: 100, height: 100)
func createPDF() {
let filePath = "/Users/Shared/Text.pdf"
let fileURL = NSURL(fileURLWithPath: filePath)
pdfContext = CGContext(fileURL, mediaBox: &backgroundRect, nil)
pdfContext!.beginPDFPage(nil)
drawBackground()
drawText("This is page 1")
pdfContext!.endPDFPage()
pdfContext!.beginPDFPage(nil)
drawBackground()
drawText("This is page 1")
pdfContext!.endPDFPage()
pdfContext!.closePDF()
}
func drawBackground() {
let cgImage = NSImage(contentsOfFile: "/Users/Shared/background.png")?.toCGImage
pdfContext?.draw(cgImage!, in: CGRect(x: 0, y: 0, width: Int(72*8.5), height: Int(72*11)))
}
func drawText(_ text:String) {
let style = NSMutableParagraphStyle()
style.alignment = .center
let attr = [NSAttributedString.Key.font: NSFont(name: "Helvetica", size: 16.0),
NSAttributedString.Key.foregroundColor: NSColor.purple,
NSAttributedString.Key.backgroundColor: NSColor.clear,
NSAttributedString.Key.paragraphStyle: style]
let attrText = NSAttributedString(string: text, attributes: attr as [NSAttributedString.Key : Any])
pdfContext?.saveGState()
pdfContext?.translateBy(x: attrText.size().width, y: attrText.size().height)
attrText.draw(with: textRect)
pdfContext?.restoreGState()
}
}

Answer 1

Closing an open question that I got worked out (complete code).
Swift 5.4 on macOS
import Cocoa
import CoreText
import Quartz
var pageWidth: CGFloat = 72*8.5
var pageHeight: CGFloat = 72*11.0
var pageRect: CGRect = CGRect(x:0, y:0, width: pageWidth, height: pageHeight)
extension NSImage {
/*
Converts an NSImage to a CGImage for rendering in a CGContext
Credit - Xue Yu
- https://gist.github.com/KrisYu/83d7d97cae35a0b10fd238e5c86d288f
*/
var toCGImage: CGImage {
var imageRect = NSRect(x: 0, y: 0, width: pageWidth, height: pageHeight)
guard let image = cgImage(forProposedRect: &imageRect, context: nil, hints: nil) else {
abort()
}
return image
}
}
class PDFText {
/*
Create a non-nil empty CGContext
Credit - hmali - 3/15/2019
https://stackoverflow.com/questions/41100895/empty-cgcontext
*/
var pdfContext = CGContext(data: nil,
width: 0,
height: 0,
bitsPerComponent: 1,
bytesPerRow: 1,
space: CGColorSpace.init(name: CGColorSpace.sRGB)!,
bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue)
// Set a rectangle to be in the center of the page
let textRect = CGRect(x: pageRect.midX-50, y: pageRect.midY-50, width: 100, height: 100)
func createPDF() {
let filePath = "/Users/Shared/Text.pdf"
let fileURL = NSURL(fileURLWithPath: filePath)
pdfContext = CGContext(fileURL, mediaBox: &pageRect, nil)
// This must be called to begin a page in a PDF document
pdfContext!.beginPDFPage(nil)
drawBackground()
drawText(text: "This is page 1")
// This has to be called prior to writing another page to the PDF document
pdfContext!.endPDFPage()
pdfContext!.beginPDFPage(nil)
drawBackground()
drawText(text: "This is page 2")
// Call this or before closing the document.
pdfContext!.endPDFPage()
pdfContext!.closePDF()
}
func drawBackground() {
// Draws an image into the graphics context.
// NOTE: If the image is not sized for the specified rectangle it will be
// scaled (up/down) automatically to fit within the rectangle.
let cgImage = NSImage(contentsOfFile: "/Users/Shared/background.png")?.toCGImage
pdfContext?.draw(cgImage!, in: pageRect)
}
func drawText(text:String) {
// Credit: Nutchaphon Rewik, https://github.com/nRewik/SimplePDF
// Create a paragraph style to be used with the atributed string
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = .center
// Set up the sttributes to be applied to the attributed text
let stringAttributes = [NSAttributedString.Key.font: NSFont(name: "Helvetica", size: 16.0),
NSAttributedString.Key.foregroundColor: NSColor.purple,
NSAttributedString.Key.backgroundColor: NSColor.clear,
NSAttributedString.Key.paragraphStyle: paragraphStyle]
// Create the attributed string
let attributedString = NSAttributedString(string: text, attributes: stringAttributes as [NSAttributedString.Key : Any])
// Set up a CoreText frame that encloses the attributed string
let frameSetter = CTFramesetterCreateWithAttributedString(attributedString)
// Get the frame size for the attributed string
let frameSize = CTFramesetterSuggestFrameSizeWithConstraints(frameSetter, CFRangeMake(0, attributedString.string.count), nil, textRect.size, nil)
// Save the Graphics state of the context
pdfContext!.saveGState()
// Put the text matrix into a known state. This ensures that no old scaling
// factors are left in place.
pdfContext!.textMatrix = CGAffineTransform.identity
// Create a path object to enclose the text.
let framePath = CGPath(rect: CGRect(x: textRect.minX, y: textRect.midY-frameSize.height/2, width: textRect.width, height: frameSize.height), transform: nil)
// Get the frame that will do the rendering. The currentRange variable specifies
// only the starting point. The framesetter lays out as much text as will fit into
// the frame or until it runs out of text.
let frameRef = CTFramesetterCreateFrame(frameSetter, CFRange(location: 0, length: 0), framePath, nil)
// Draw the CoreText frame (that includes the text) into the graphics context.
CTFrameDraw(frameRef, pdfContext!)
// Restore the previous Graphics state.
pdfContext?.restoreGState()
}
}
let pdf = PDFText()
pdf.createPDF()