Customize Vertical Annotation Toolbar in Swift for iOS

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//
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//  Copyright © 2021-2025 PSPDFKit GmbH. All rights reserved.
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//
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//  The Nutrient sample applications are licensed with a modified BSD license.
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//  Please see License for details. This notice may not be removed from this file.
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//
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import PSPDFKit
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import PSPDFKitUI
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class CustomVerticalAnnotationToolbarExample: Example {
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    override init() {
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        super.init()
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        title = "Custom Vertical Always-Visible Annotation Toolbar"
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        contentDescription = "Reimplements a completely custom annotation toolbar"
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        category = .viewCustomization
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        priority = 30
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    }
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    override func invoke(with delegate: ExampleRunnerDelegate?) -> UIViewController? {
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        let document = AssetLoader.document(for: .annualReport)
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        let controller = VerticalAnnotationToolbarPDFViewController(document: document) {
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            // Remove the long-press annotation menu
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            $0.createAnnotationMenuGroups = []
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            $0.editableAnnotationTypes = [.ink, .freeText]
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        }
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        // Remove the default annotation bar button item
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        if let items = controller.navigationItem.rightBarButtonItems(for: .document)?
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            .filter({ $0 != controller.annotationButtonItem }) {
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            controller.navigationItem.setRightBarButtonItems(items, for: .document, animated: false)
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        }
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        return controller
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    }
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}
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final private class VerticalAnnotationToolbarPDFViewController: PDFViewController {
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    var verticalToolbar: CustomVerticalAnnotationToolbar?
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    override func viewDidLoad() {
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        super.viewDidLoad()
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        // Create the custom toolbar and anchor it on the trailing side of the PDF controller view.
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        let verticalToolbar = CustomVerticalAnnotationToolbar(annotationStateManager: annotationStateManager)
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        verticalToolbar.translatesAutoresizingMaskIntoConstraints = false
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        view.addSubview(verticalToolbar)
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        NSLayoutConstraint.activate([
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            verticalToolbar.centerYAnchor.constraint(equalTo: view.centerYAnchor),
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            verticalToolbar.trailingAnchor.constraint(equalTo: view.trailingAnchor),
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        ])
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        self.verticalToolbar = verticalToolbar
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    }
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    override func setViewMode(_ viewMode: ViewMode, animated: Bool) {
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        super.setViewMode(viewMode, animated: animated)
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        // Ensure custom annotation toolbar is hidden when thumbnails are shown
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        UIView.animate(withDuration: 0.25, delay: 0, options: .allowUserInteraction) {
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            self.verticalToolbar?.alpha = viewMode == .thumbnails ? 0 : 1
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        }
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    }
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}
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final private class CustomVerticalAnnotationToolbar: UIView {
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    let annotationStateManager: AnnotationStateManager
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    var drawButton: UIButton?
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    var freeTextButton: UIButton?
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    var undoButton: UIButton?
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    var redoButton: UIButton?
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    required init(annotationStateManager: AnnotationStateManager) {
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        self.annotationStateManager = annotationStateManager
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        super.init(frame: .zero)
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        annotationStateManager.add(self)
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        let editableAnnotationTypes = annotationStateManager.pdfController?.configuration.editableAnnotationTypes ?? []
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        if editableAnnotationTypes.contains(.ink) {
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            drawButton = button(withImageName: "ink", action: #selector(inkButtonPressed))
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        }
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        if editableAnnotationTypes.contains(.freeText) {
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            freeTextButton = button(withImageName: "freetext", action: #selector(freeTextButtonPressed))
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        }
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        undoButton = button(withImageName: "undo", action: #selector(undoButtonPressed))
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        undoButton?.isEnabled = false
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        redoButton = button(withImageName: "redo", action: #selector(redoButtonPressed))
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        redoButton?.isEnabled = false
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        let stackView = UIStackView(arrangedSubviews: [drawButton, freeTextButton, undoButton, redoButton].compactMap({ $0 }))
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        stackView.translatesAutoresizingMaskIntoConstraints = false
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        stackView.axis = .vertical
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        stackView.distribution = .fillEqually
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        addSubview(stackView)
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        let buttonLength: CGFloat = 44
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        NSLayoutConstraint.activate([
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            stackView.widthAnchor.constraint(equalToConstant: buttonLength),
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            stackView.heightAnchor.constraint(equalToConstant: buttonLength * CGFloat(stackView.arrangedSubviews.count)),
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            widthAnchor.constraint(equalTo: stackView.widthAnchor),
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            heightAnchor.constraint(equalTo: stackView.heightAnchor)
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        ])
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        backgroundColor = UIColor.psc_systemBackground
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    }
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    func button(withImageName imageName: String, action: Selector) -> UIButton {
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        let button = UIButton(type: .custom)
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        let image = SDK.imageNamed(imageName)!.withRenderingMode(.alwaysTemplate)
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        button.setImage(image, for: .normal)
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        button.addTarget(self, action: action, for: .touchUpInside)
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        button.translatesAutoresizingMaskIntoConstraints = false
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        return button
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    }
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    required init?(coder: NSCoder) {
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        fatalError("init(coder:) has not been implemented")
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    }
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    @objc func inkButtonPressed() {
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        annotationStateManager.toggleState(.ink)
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    }
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    @objc func freeTextButtonPressed() {
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        annotationStateManager.toggleState(.freeText)
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    }
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    @objc func undoButtonPressed() {
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        undoManager?.undo()
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    }
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    @objc func redoButtonPressed() {
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        undoManager?.redo()
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    }
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}
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extension CustomVerticalAnnotationToolbar: AnnotationStateManagerDelegate {
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    static let selectedColor = UIColor.psc_label.withAlphaComponent(0.2)
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    static let deselectedColor = UIColor.clear
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    func annotationStateManager(_ manager: AnnotationStateManager, didChangeState oldState: Annotation.Tool?, to newState: Annotation.Tool?, variant oldVariant: Annotation.Variant?, to newVariant: Annotation.Variant?) {
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        drawButton?.backgroundColor = newState == .ink ? CustomVerticalAnnotationToolbar.selectedColor : CustomVerticalAnnotationToolbar.deselectedColor
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        freeTextButton?.backgroundColor = newState == .freeText ? CustomVerticalAnnotationToolbar.selectedColor : CustomVerticalAnnotationToolbar.deselectedColor
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    }
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    func annotationStateManager(_ manager: AnnotationStateManager, didChangeUndoState undoEnabled: Bool, redoState redoEnabled: Bool) {
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        undoButton?.isEnabled = undoEnabled
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        redoButton?.isEnabled = redoEnabled
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    }
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}