Maintain annotation aspect ratio in Swift

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//
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//  Copyright © 2016-2026 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 AspectRatioConservingResizingExample: Example {
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    override init() {
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        super.init()
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        title = "Aspect Ratio Conserving Example"
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        contentDescription = "Shows how to implement resizing that always preserves the annotation aspect ratio."
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        category = .viewCustomization
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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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        // Add free text
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        let freeText = FreeTextAnnotation()
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        freeText.fontSize = 30
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        freeText.contents = "Example text. Drag me!"
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        freeText.boundingBox = CGRect(x: 50, y: 50, width: 300, height: 300)
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        freeText.sizeToFit()
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        freeText.color = UIColor.blue
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        freeText.absolutePageIndex = 0
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        document.add(annotations: [freeText])
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        let pdfController = PDFViewController(document: document, delegate: self) {
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            $0.overrideClass(ResizableView.self, with: AspectResizableView.self)
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        }
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        return pdfController
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    }
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    // MARK: Resizable view customization
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    private class AspectResizableView: ResizableView {
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        // MARK: Lifecycle
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        override init(frame: CGRect) {
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            super.init(frame: frame)
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            customize()
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        }
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        required init?(coder aDecoder: NSCoder) {
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            super.init(coder: aDecoder)
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            customize()
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        }
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        // MARK: Knob customization
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        private func customize() {
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            // Always snap to guide.
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            guideSnapAllowance = PSPDFGuideSnapAllowanceAlways
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            // Remove all knobs but the bottom right one.
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            let range = ResizableView.OuterKnob.topLeft.rawValue...ResizableView.OuterKnob.bottomRight.rawValue
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            let knobTypes = range.compactMap { ResizableView.OuterKnob(rawValue: $0) }
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            for knobType in knobTypes {
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                outerKnob(ofType: knobType)?.removeFromSuperview()
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            }
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        }
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    }
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}
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// MARK: PDFViewControllerDelegate
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extension AspectRatioConservingResizingExample: PDFViewControllerDelegate {
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    internal func pdfViewController(_ pdfController: PDFViewController, didConfigurePageView pageView: PDFPageView, forPageAt pageIndex: Int) {
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        if pageView.pageIndex == 0 {
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            pageView.selectedAnnotations = pdfController.document?.annotations(at: 0, type: FreeTextAnnotation.self)
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        }
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    }
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}