Implement printing.

We support printing only for certain file types, currently: `.gif`,
`.jpg`, `.md`, `.pdf`, `.png`, `.rtf`, `.txt`. For all other formats,
open them in their corresponding applications first and print from
there.

qlview.xcodeproj/xcuserdata/robin.xcuserdatad/xcschemes/xcschememanagement.plist

@@ -12,12 +12,12 @@
 		<key>qlview-adhoc.xcscheme_^#shared#^_</key>
 		<dict>
 			<key>orderHint</key>
-			<integer>1</integer>
+			<integer>0</integer>
 		</dict>
 		<key>qlview-signed.xcscheme_^#shared#^_</key>
 		<dict>
 			<key>orderHint</key>
-			<integer>0</integer>
+			<integer>1</integer>
 		</dict>
 		<key>qlview.xcscheme_^#shared#^_</key>
 		<dict>

qlview/app.swift

@@ -20,9 +20,15 @@ extension FocusedValues {
 struct qlviewApp: App {
     @Environment(\.dismiss) private var dismiss
     @NSApplicationDelegateAdaptor(AppDelegate.self) var appDelegate
-    @FocusedBinding(\.document) var document
+    @FocusedBinding(\.document) var document_binding
+
+    var document : Document? {
+        guard let document = document_binding else { return nil }
+        return document
+    }
+
     @State private var showAbout = false
-        
+
     var body: some Scene {
         WindowGroup(for: Document.self) { $doc in
             ContentView(doc: doc)
@@ -50,7 +56,6 @@ struct qlviewApp: App {
 
                 Button("Open in App") {
                     guard let document = document else { return }
-                    guard let document = document else { return }
 
                     document.open()
                     NSApplication.shared.keyWindow?.close()
@@ -59,7 +64,6 @@ struct qlviewApp: App {
 
                 Button("Move To ...") {
                     guard let document = document else { return }
-                    guard let document = document else { return }
 
                     if document.move() {
                         NSApplication.shared.keyWindow?.close()
@@ -72,11 +76,11 @@ struct qlviewApp: App {
 
                 Button("Print ...") {
                     guard let document = document else { return }
-                    guard let document = document else { return }
 
                     document.print()
                 }
                 .keyboardShortcut("p", modifiers: .command)
+                .disabled(document == nil || !document!.canPrint())
             })
         }
     }

qlview/document.swift

@@ -1,4 +1,6 @@
 import SwiftUI
+import PDFKit
+import WebKit
 
 struct Document: Identifiable, Codable, Hashable {
     var url: URL
@@ -37,22 +39,142 @@ struct Document: Identifiable, Codable, Hashable {
                 }
             }
         }
-            return false
+        return false
     }
-
 
-    func print() {
-        showAlert(msg: "Error", sub: "Printing not yet implemented.", style: .critical)
-//        let nsview = view.makeNSView(context: nil)
-//
-//        let view = QLView(url: url, qlview: nsview)
-//        let renderer = ImageRenderer(content: AnyView(view) )
-//        let nsview = view.makeNSView(context: nil)
-//        let printInfo = NSPrintInfo()
-//        let printOperation = NSPrintOperation(view: view)
-//        printOperation.showsPrintPanel = true
-//        printOperation.showsProgressPanel = true
-//        printOperation.run()
+    // Printing
+
+    func isHTML() -> Bool {
+        return url.pathExtension == "html"
+    }
+
+    func isImage() -> Bool {
+        return url.pathExtension == "png" || url.pathExtension == "gif" || url.pathExtension == "jpg" || url.pathExtension == "jpeg";
+    }
+
+    func isMarkdown() -> Bool {
+        return url.pathExtension == "md"
+    }
+
+    func isPDF() -> Bool {
+        return url.pathExtension == "pdf"
+    }
+
+    func isTxt() -> NSAttributedString.DocumentType? {
+        if url.pathExtension == "txt" {
+            return .plain
+        }
+
+        if url.pathExtension == "rtf" {
+            return .rtf
+        }
+
+        return nil
+    }
+
+    func canPrint() -> Bool {
+        return isPDF() || isMarkdown() || isImage() || isTxt() != nil // TODO: isHTML() currently no working
     }
+
+    func print() {
+        guard canPrint() else { return }
+
+        let info = NSPrintInfo.shared
+        let paper_size = NSRect(x: 0, y: 0, width: info.paperSize.width, height: info.paperSize.height)
+
+        info.horizontalPagination = .automatic
+        info.verticalPagination = .automatic
+        info.verticalPagination = .fit
+        info.horizontalPagination = .fit
+        info.orientation = .portrait
+        info.isHorizontallyCentered = false
+        info.isVerticallyCentered = false
+
+        var op : NSPrintOperation?
+
+        if isHTML() {
+            // TODO: This doesn't work, printed docoument is always empty.
+            // We currently don't get here.
+            assert(false)
+
+            // let html = WKWebView(frame: paper_size)
+            // html.loadFileURL(url, allowingReadAccessTo: url.deletingLastPathComponent())
+            // html.bounds = paper_size
+            //
+            // // op = html.printOperation(with: printInfo)
+            // op = NSPrintOperation(view: html)
+        }
+
+        else if ( isImage() ) {
+            guard let image = NSImage(contentsOf: url) else { return }
+            let imageView = NSImageView(image: image)
+            imageView.frame = NSRect(x: 0, y: 0, width: image.size.width, height: image.size.height)
+            imageView.imageScaling = .scaleProportionallyDown
+
+            info.isHorizontallyCentered = false
+            info.isVerticallyCentered = false
+            op = NSPrintOperation(view: imageView)
+        }
+
+        else if isMarkdown() {
+            do {
+                let txt = try NSMutableAttributedString(markdown: "Hello, **World**!")
+
+                let view = NSTextView()
+                view.frame = paper_size
+                view.textStorage?.setAttributedString(txt)
+                op = NSPrintOperation(view: view, printInfo: info)
+            }
+            catch {
+                showAlert(msg: "Printing Error", sub: "Cannot load markdown document.")
+            }
+        }
+
+        else if isPDF() {
+            let pdf = PDFDocument(url: self.url)
+            let scale: PDFPrintScalingMode = .pageScaleNone
+            op = pdf?.printOperation(for: info, scalingMode: scale, autoRotate: true)
+        }
+
+        else if let type = isTxt() {
+            do {
+                let txt = try NSMutableAttributedString(url: url, options:
+                                                            [.documentType: type,
+                                                             .characterEncoding: String.Encoding.utf8.rawValue,
+                                                             .baseURL: url, // not really used
+                                                             .readAccessURL: url.deletingLastPathComponent() // not really used
+                                                            ], documentAttributes: nil)
+
+                let style = NSMutableParagraphStyle()
+                style.lineBreakMode = .byCharWrapping
+
+                txt.setAttributes([
+                    .font: NSFont.monospacedSystemFont(ofSize: 10, weight: .regular),
+                    .paragraphStyle: style
+                ], range: NSMakeRange(0, txt.length))
+
+
+                let view = NSTextView()
+                view.frame = paper_size
+                view.textStorage?.setAttributedString(txt)
+                op = NSPrintOperation(view: view, printInfo: info)
+            }
+            catch {
+                showAlert(msg: "Printing Error", sub: "Cannot load text document.")
+            }
+        }
+
+        if op == nil {
+            showAlert(msg: "Print failure", sub: "Cannot print document type")
+            return
+        }
+
+        op?.jobTitle = url.lastPathComponent
+        op?.showsPrintPanel = true
+        op?.showsProgressPanel = true
 
+        DispatchQueue.main.async {
+            op?.run()
+        }
+    }
 }

qlview/view.swift

@@ -101,10 +101,12 @@ struct ContentView: View {
 
                     Button(action: { doc.print() }) {
                         Image(systemName: "printer")
-                    }.help("Print")
+                    }
+                    .disabled(!doc.canPrint())
+                    .help("Print")
 
                     ShareLink(item: doc.url)
-                        .help("Share ...")
+                    .help("Share ...")
                 }
 
                 ToolbarItemGroup(placement: .automatic) {