hdr image viewer
update xcode project use existing asset fetch pinch zoom fix xcode debug scaling
This commit is contained in:
mertalev
@@ -0,0 +1,219 @@
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import Flutter
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import UIKit
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import Photos
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// TODO: the bounds this uses for scaling can change with the hero animation,
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// so it doesn't display the image correctly until swiping to the next asset and back
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class NativeImageView: NSObject, FlutterPlatformView {
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private var _containerView: UIView
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private var _scrollView: UIScrollView
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private var _imageView: UIImageView
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private var _image: UIImage?
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private var _hasSetupZoom = false
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private static let imageManager = PHImageManager.default()
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private static let fetchOptions = {
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let fetchOptions = PHFetchOptions()
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fetchOptions.fetchLimit = 1
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fetchOptions.wantsIncrementalChangeDetails = false
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return fetchOptions
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}()
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private static let requestOptions = {
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let requestOptions = PHImageRequestOptions()
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requestOptions.isNetworkAccessAllowed = true
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requestOptions.deliveryMode = .opportunistic
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requestOptions.resizeMode = .none
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requestOptions.isSynchronous = false
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requestOptions.version = .current
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return requestOptions
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}()
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init(
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frame: CGRect,
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viewIdentifier viewId: Int64,
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arguments args: Any?,
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binaryMessenger messenger: FlutterBinaryMessenger
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) {
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_containerView = UIView(frame: frame)
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_scrollView = UIScrollView()
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_imageView = UIImageView()
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super.init()
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setupViews()
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guard let arguments = args as? [String: Any],
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let assetId = arguments["assetId"] as? String else {
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print("Asset ID not provided")
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return
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}
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guard let asset = ThumbnailApiImpl.requestAsset(assetId: assetId) else {
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print("Asset not found for identifier: \(assetId)")
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return
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}
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loadImage(from: asset)
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}
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func view() -> UIView {
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return _containerView
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}
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private func setupViews() {
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// Configure image view
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_imageView.contentMode = .scaleAspectFit
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_imageView.preferredImageDynamicRange = .high
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if #available(iOS 17.0, *) {
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_imageView.layer.wantsExtendedDynamicRangeContent = true
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_imageView.layer.contentsFormat = .RGBA16Float
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}
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// Configure scroll view
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_scrollView.delegate = self
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_scrollView.showsVerticalScrollIndicator = false
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_scrollView.showsHorizontalScrollIndicator = false
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_scrollView.bouncesZoom = true
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_scrollView.decelerationRate = .fast
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_scrollView.contentInsetAdjustmentBehavior = .never
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_scrollView.backgroundColor = .clear
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// Add double tap gesture
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let doubleTapGesture = UITapGestureRecognizer(target: self, action: #selector(handleDoubleTap(_:)))
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doubleTapGesture.numberOfTapsRequired = 2
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_scrollView.addGestureRecognizer(doubleTapGesture)
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// Setup view hierarchy
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_scrollView.addSubview(_imageView)
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_containerView.addSubview(_scrollView)
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// Setup constraints
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_scrollView.translatesAutoresizingMaskIntoConstraints = false
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NSLayoutConstraint.activate([
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_scrollView.topAnchor.constraint(equalTo: _containerView.topAnchor),
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_scrollView.leadingAnchor.constraint(equalTo: _containerView.leadingAnchor),
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_scrollView.trailingAnchor.constraint(equalTo: _containerView.trailingAnchor),
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_scrollView.bottomAnchor.constraint(equalTo: _containerView.bottomAnchor)
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])
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// Observe bounds changes
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_containerView.addObserver(self, forKeyPath: "bounds", options: [.new], context: nil)
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}
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override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
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if keyPath == "bounds", let image = _image {
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DispatchQueue.main.async { [weak self] in
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self?.setupZoomScale(for: image)
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}
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}
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}
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deinit {
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_containerView.removeObserver(self, forKeyPath: "bounds")
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}
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private func loadImage(from asset: PHAsset) {
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Self.imageManager.requestImageDataAndOrientation(
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for: asset,
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options: Self.requestOptions
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) { [weak self] data, uti, orientation, info in
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guard let data = data else { return }
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if #available(iOS 17.0, *) {
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var config = UIImageReader.Configuration()
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config.prefersHighDynamicRange = true
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let imageReader = UIImageReader(configuration: config)
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guard let image = imageReader.image(data: data) else { return }
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DispatchQueue.main.async {
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self?.setImage(image)
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}
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} else {
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guard let image = UIImage(data: data) else { return }
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DispatchQueue.main.async {
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self?.setImage(image)
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}
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}
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}
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}
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private func setImage(_ image: UIImage) {
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_image = image
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_imageView.image = image
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// Wait for next run loop to ensure layout is complete
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DispatchQueue.main.async { [weak self] in
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self?.setupZoomScale(for: image)
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}
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}
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private func setupZoomScale(for image: UIImage) {
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guard _scrollView.bounds.size.width > 0, _scrollView.bounds.size.height > 0 else {
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// View not laid out yet
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return
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}
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// Set image view size to match image
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_imageView.frame = CGRect(origin: .zero, size: image.size)
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_scrollView.contentSize = image.size
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// Calculate zoom scales
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let scrollViewSize = _scrollView.bounds.size
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let widthScale = scrollViewSize.width / image.size.width
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let heightScale = scrollViewSize.height / image.size.height
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let minScale = min(widthScale, heightScale)
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_scrollView.minimumZoomScale = minScale
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_scrollView.maximumZoomScale = max(2.0, minScale * 5.0)
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_scrollView.zoomScale = minScale
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centerImageView()
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_hasSetupZoom = true
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}
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private func centerImageView() {
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let scrollViewSize = _scrollView.bounds.size
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let imageViewSize = _imageView.frame.size
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let horizontalInset = max(0, (scrollViewSize.width - imageViewSize.width) / 2)
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let verticalInset = max(0, (scrollViewSize.height - imageViewSize.height) / 2)
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_scrollView.contentInset = UIEdgeInsets(
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top: verticalInset,
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left: horizontalInset,
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bottom: verticalInset,
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right: horizontalInset
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)
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}
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@objc private func handleDoubleTap(_ gesture: UITapGestureRecognizer) {
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guard _hasSetupZoom else { return }
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if _scrollView.zoomScale > _scrollView.minimumZoomScale {
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_scrollView.setZoomScale(_scrollView.minimumZoomScale, animated: true)
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} else {
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let tapLocation = gesture.location(in: _imageView)
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let zoomScale = min(_scrollView.maximumZoomScale, _scrollView.minimumZoomScale * 3.0)
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let zoomRect = zoomRectForScale(zoomScale, center: tapLocation)
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_scrollView.zoom(to: zoomRect, animated: true)
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}
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}
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private func zoomRectForScale(_ scale: CGFloat, center: CGPoint) -> CGRect {
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var zoomRect = CGRect.zero
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zoomRect.size.width = _scrollView.frame.size.width / scale
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zoomRect.size.height = _scrollView.frame.size.height / scale
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zoomRect.origin.x = center.x - (zoomRect.size.width / 2.0)
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zoomRect.origin.y = center.y - (zoomRect.size.height / 2.0)
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return zoomRect
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}
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}
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// MARK: - UIScrollViewDelegate
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extension NativeImageView: UIScrollViewDelegate {
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func viewForZooming(in scrollView: UIScrollView) -> UIView? {
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return _imageView
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}
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func scrollViewDidZoom(_ scrollView: UIScrollView) {
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centerImageView()
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}
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}
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