How do I get a layer backed NSView to write to PDF in the clipboard - layer

Question

I am using a layer backed view with a CGImage and would like to use the NSView.writePDF(inside:to) API to copy the views image to the clipboard. The view has subviews that I would like included in the PDF.
I have created a Xcode playground to illustrate the problem.
//: A Cocoa based Playground to test NSView.writePDF()
import AppKit
import PlaygroundSupport
class BaseView: NSView {
var isSelected: Bool = false {
didSet {
self.needsDisplay = true
}
}
var fillColor = NSColor.yellow
var cgFillColor: CGColor {
return self.isSelected ? fillColor.cgColor : fillColor.withAlphaComponent(0.5).cgColor
}
var storeLayoutCGImageRef: CGImage? {
didSet {
self.layer?.contents = storeLayoutCGImageRef
}
}
override func draw(_ dirtyRect: NSRect) {
super.draw(dirtyRect)
guard let context = NSGraphicsContext.current?.cgContext else {
return
}
context.setFillColor(cgFillColor)
context.fill(dirtyRect)
}
override func mouseDown(with theEvent: NSEvent) {
self.isSelected = !self.isSelected
}
#objc func copyImage(_ sender: Any){
let pb = NSPasteboard.general
pb.declareTypes([.pdf], owner: self)
self.writePDF(inside: self.bounds, to: pb)
}
#objc func doNothing(_ sender: Any){
}
// Load image in the background
func loadImage(completion: #escaping ()->Void){
DispatchQueue.global().async {
if let image = NSImage(named: "B-019969.jpg") {
// Lets use double the size ?
var rect = CGRect(x: 0, y: 0, width: image.size.width*3.0, height: image.size.height*3.0)
let cgImage = image.cgImage(forProposedRect: &rect, context: nil, hints: nil)
DispatchQueue.main.async {
self.storeLayoutCGImageRef = cgImage
completion()
}
return
}
DispatchQueue.main.async {
//self.storeLayoutImage = nil
self.storeLayoutCGImageRef = nil
completion()
}
}
}
}
class ModuleView: BaseView {
let color = NSColor.purple
override init(frame frameRect: NSRect) {
super.init(frame: frameRect)
self.fillColor = color
}
required init?(coder decoder: NSCoder) {
super.init(coder: decoder)
self.fillColor = color
}
override func menu(for event: NSEvent) -> NSMenu? {
if !isSelected {
let menu = NSMenu()
menu.addItem(NSMenuItem(title: "Copy module", action: #selector(copyImage(_:)), keyEquivalent: ""))
return menu
} else {
// Display popup menu
let menu = NSMenu()
menu.addItem(NSMenuItem(title: "Copy module", action: #selector(copyImage(_:)), keyEquivalent: ""))
menu.addItem(NSMenuItem(title: "Do Something", action: #selector(doNothing(_:)), keyEquivalent: ""))
return menu
}
}
}
class ShelfView: BaseView {
let color = NSColor.yellow
override init(frame frameRect: NSRect) {
super.init(frame: frameRect)
self.fillColor = color
self.loadImage {
print("Image loaded")
}
}
required init?(coder decoder: NSCoder) {
super.init(coder: decoder)
self.fillColor = color
}
override func menu(for event: NSEvent) -> NSMenu? {
if !isSelected {
let menu = NSMenu()
menu.addItem(NSMenuItem(title: "Copy shelf", action: #selector(copyImage(_:)), keyEquivalent: ""))
return menu
} else {
// Display popup menu
let menu = NSMenu()
menu.addItem(NSMenuItem(title: "Copy shelf", action: #selector(copyImage(_:)), keyEquivalent: ""))
menu.addItem(NSMenuItem(title: "Do Something", action: #selector(doNothing(_:)), keyEquivalent: ""))
return menu
}
}
override var wantsUpdateLayer: Bool {
return true
}
override func updateLayer() {
self.layer?.backgroundColor = self.cgFillColor
self.layer?.contents = self.storeLayoutCGImageRef
}
}
class view: BaseView
{
var module: ModuleView?
let color = NSColor.cyan
override init(frame: NSRect)
{
super.init(frame: frame)
self.fillColor = color
self.addModules()
self.addShelves()
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func addModules(){
let module = ModuleView()
module.frame = NSRect(x: 10.0, y: 10.0, width: 180.0, height: 180.0)
self.module = module
self.addSubview(module)
}
func addShelves(){
let shelf = ShelfView()
shelf.frame = NSRect(x: 10.0, y: 10.0, width:160.0, height: 160.0)
self.module?.addSubview(shelf)
}
override func menu(for event: NSEvent) -> NSMenu? {
if !isSelected {
let menu = NSMenu()
menu.addItem(NSMenuItem(title: "Copy fixture", action: #selector(copyImage(_:)), keyEquivalent: ""))
return menu
} else {
// Display popup menu
let menu = NSMenu()
menu.addItem(NSMenuItem(title: "Copy fixture", action: #selector(copyImage(_:)), keyEquivalent: ""))
menu.addItem(NSMenuItem(title: "Do Something", action: #selector(doNothing(_:)), keyEquivalent: ""))
return menu
}
}
}
var v = view(frame: NSRect(x: 0, y: 0, width: 200, height: 200))
PlaygroundPage.current.liveView = v
Is there a way to make sure the layer gets included in the PDF output?

Answer 1

OK, I just figured it out - basically you have to implement the draw(_ dirtyRect) function which gets called during printing or when the NSView.writePDF() is called.
Note that the draw() function won't get called under certain conditions - e.g. selecting the item with the mouse will only result in the updateLayer() method being called.
Here is the updated playground, hope this saves someone else some time.
//: A Cocoa based Playground to test NSView.writePDF()
import AppKit
import PlaygroundSupport
class BaseView: NSView {
var isSelected: Bool = false {
didSet {
self.needsDisplay = true
}
}
var fillColor = NSColor.yellow
var cgFillColor: CGColor {
return self.isSelected ? fillColor.cgColor : fillColor.withAlphaComponent(0.5).cgColor
}
var storeLayoutCGImageRef: CGImage? {
didSet {
self.layer?.contents = storeLayoutCGImageRef
}
}
var image: CGImage?
override func draw(_ dirtyRect: NSRect) {
super.draw(dirtyRect)
guard let context = NSGraphicsContext.current?.cgContext else {
return
}
// NB THIS PART !!
self.layer?.render(in:context)
}
override func mouseDown(with theEvent: NSEvent) {
self.isSelected = !self.isSelected
}
#objc func copyImage(_ sender: Any){
let pb = NSPasteboard.general
pb.declareTypes([.pdf], owner: self)
self.writePDF(inside: self.bounds, to: pb)
}
#objc func doNothing(_ sender: Any){
}
// Load image in the background
func loadImage(completion: #escaping ()->Void){
DispatchQueue.global().async {
if let image = NSImage(named: "Sample Image.png") {
// Lets use double the size ?
var rect = CGRect(x: 0, y: 0, width: image.size.width*3.0, height: image.size.height*3.0)
let cgImage = image.cgImage(forProposedRect: &rect, context: nil, hints: nil)
DispatchQueue.main.async {
self.storeLayoutCGImageRef = cgImage
completion()
}
return
}
DispatchQueue.main.async {
//self.storeLayoutImage = nil
self.storeLayoutCGImageRef = nil
completion()
}
}
}
}
class ModuleView: BaseView {
let color = NSColor.purple
override init(frame frameRect: NSRect) {
super.init(frame: frameRect)
self.fillColor = color
}
required init?(coder decoder: NSCoder) {
super.init(coder: decoder)
self.fillColor = color
}
override func menu(for event: NSEvent) -> NSMenu? {
if !isSelected {
let menu = NSMenu()
menu.addItem(NSMenuItem(title: "Copy module", action: #selector(copyImage(_:)), keyEquivalent: ""))
return menu
} else {
// Display popup menu
let menu = NSMenu()
menu.addItem(NSMenuItem(title: "Copy module", action: #selector(copyImage(_:)), keyEquivalent: ""))
menu.addItem(NSMenuItem(title: "Do Something", action: #selector(doNothing(_:)), keyEquivalent: ""))
return menu
}
}
}
class ShelfView: BaseView {
let color = NSColor.green
override init(frame frameRect: NSRect) {
super.init(frame: frameRect)
self.fillColor = color
self.loadImage {
print("Image loaded")
}
}
required init?(coder decoder: NSCoder) {
super.init(coder: decoder)
self.fillColor = color
}
override func menu(for event: NSEvent) -> NSMenu? {
if !isSelected {
let menu = NSMenu()
menu.addItem(NSMenuItem(title: "Copy shelf", action: #selector(copyImage(_:)), keyEquivalent: ""))
return menu
} else {
// Display popup menu
let menu = NSMenu()
menu.addItem(NSMenuItem(title: "Copy shelf", action: #selector(copyImage(_:)), keyEquivalent: ""))
menu.addItem(NSMenuItem(title: "Do Something", action: #selector(doNothing(_:)), keyEquivalent: ""))
return menu
}
}
override func draw(_ dirtyRect: NSRect) {
print("ShelfView.draw() called")
super.draw(dirtyRect)
guard let context = NSGraphicsContext.current?.cgContext else {
return
}
if let image = self.storeLayoutCGImageRef {
context.draw(image, in: self.bounds)
}
}
override var wantsUpdateLayer: Bool {
return true
}
override func updateLayer() {
print("updateLayer() called")
self.layer?.backgroundColor = self.cgFillColor
self.layer?.contents = self.storeLayoutCGImageRef
}
}
class view: BaseView
{
var module: ModuleView?
let color = NSColor.cyan
override init(frame: NSRect)
{
super.init(frame: frame)
self.fillColor = color
self.addModules()
self.addShelves()
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func addModules(){
let module = ModuleView()
module.frame = NSRect(x: 10.0, y: 10.0, width: 180.0, height: 180.0)
self.module = module
self.addSubview(module)
}
func addShelves(){
let shelf = ShelfView()
shelf.frame = NSRect(x: 10.0, y: 10.0, width:160.0, height: 160.0)
self.module?.addSubview(shelf)
}
override func menu(for event: NSEvent) -> NSMenu? {
if !isSelected {
let menu = NSMenu()
menu.addItem(NSMenuItem(title: "Copy fixture", action: #selector(copyImage(_:)), keyEquivalent: ""))
return menu
} else {
// Display popup menu
let menu = NSMenu()
menu.addItem(NSMenuItem(title: "Copy fixture", action: #selector(copyImage(_:)), keyEquivalent: ""))
menu.addItem(NSMenuItem(title: "Do Something", action: #selector(doNothing(_:)), keyEquivalent: ""))
return menu
}
}
}
var v = view(frame: NSRect(x: 0, y: 0, width: 200, height: 200))
PlaygroundPage.current.liveView = v