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| // | ||
| // AsyncImageLoad.swift | ||
| // Down | ||
| // | ||
| // Created by Mikhail Ivanov on 03.06.2021. | ||
| // Copyright © 2021 Down. All rights reserved. | ||
| // | ||
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| #if canImport(UIKit) | ||
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| import UIKit | ||
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| #elseif canImport(AppKit) | ||
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| import AppKit | ||
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| #endif | ||
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| public protocol AsyncImageLoadDelegate | ||
| { | ||
| func textAttachmentDidLoadImage(textAttachment: AsyncImageLoad, displaySizeChanged: Bool) | ||
| } | ||
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| final public class AsyncImageLoad: NSTextAttachment | ||
| { | ||
| public var imageURL: URL? | ||
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There was a problem hiding this comment. Does this need to be optional? |
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| public var displaySize: CGSize? | ||
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| public var maximumDisplayWidth: CGFloat? | ||
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| public var delegate: AsyncImageLoadDelegate? | ||
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There was a problem hiding this comment. Shouldn't this delegate be �� |
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| weak var textContainer: NSTextContainer? | ||
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| private var originalImageSize: CGSize? | ||
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| public init(imageURL: URL? = nil, delegate: AsyncImageLoadDelegate? = nil) | ||
| { | ||
| self.imageURL = imageURL | ||
| self.delegate = delegate | ||
| super.init(data: nil, ofType: nil) | ||
| } | ||
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| required public init?(coder aDecoder: NSCoder) { | ||
| fatalError("init(coder:) has not been implemented") | ||
| } | ||
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| #if os(macOS) | ||
| override public var image: NSImage? { | ||
| didSet { | ||
| originalImageSize = image?.size | ||
| } | ||
| } | ||
| #else | ||
| override public var image: UIImage? { | ||
| didSet { | ||
| originalImageSize = image?.size | ||
| } | ||
| } | ||
| #endif | ||
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| // MARK: - Function | ||
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| private func startAsyncImageDownload() | ||
| { | ||
| guard let imageURL = imageURL, | ||
| contents == nil | ||
| else { | ||
| return | ||
| } | ||
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| URLSession.shared.dataTask(with: imageURL) { (data, response, error) in | ||
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| guard let data = data, | ||
| error == nil else { | ||
| print(error?.localizedDescription as Any) | ||
| return | ||
| } | ||
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| var displaySizeChanged = false | ||
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| self.contents = data | ||
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| #if os(macOS) | ||
| if let image = NSImage(data: data) | ||
| { | ||
| let imageSize = image.size | ||
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| if self.displaySize == nil | ||
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There was a problem hiding this comment. Is the purpose of |
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| { | ||
| displaySizeChanged = true | ||
| } | ||
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| self.originalImageSize = imageSize | ||
| } | ||
| #else | ||
| if let image = UIImage(data: data) | ||
| { | ||
| let imageSize = image.size | ||
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| if self.displaySize == nil | ||
| { | ||
| displaySizeChanged = true | ||
| } | ||
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| self.originalImageSize = imageSize | ||
| } | ||
| #endif | ||
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| DispatchQueue.main.async { | ||
| if displaySizeChanged | ||
| { | ||
| self.textContainer?.layoutManager?.setNeedsLayout(forAttachment: self) | ||
| } | ||
| else | ||
| { | ||
| self.textContainer?.layoutManager?.setNeedsDisplay(forAttachment: self) | ||
| } | ||
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| // notify the optional delegate | ||
| self.delegate?.textAttachmentDidLoadImage(textAttachment: self, displaySizeChanged: displaySizeChanged) | ||
| } | ||
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| }.resume() | ||
| } | ||
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| #if os(macOS) | ||
| public override func image(forBounds imageBounds: CGRect, textContainer: NSTextContainer?, characterIndex charIndex: Int) -> NSImage? | ||
| { | ||
| if let image = image { return image } | ||
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| guard let contents = contents, let image = NSImage(data: contents) else | ||
| { | ||
| self.textContainer = textContainer | ||
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| startAsyncImageDownload() | ||
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| return nil | ||
| } | ||
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| return image | ||
| } | ||
| #else | ||
| public override func image(forBounds imageBounds: CGRect, textContainer: NSTextContainer?, characterIndex charIndex: Int) -> UIImage? | ||
| { | ||
| if let image = image { return image } | ||
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| guard let contents = contents, let image = UIImage(data: contents) else | ||
| { | ||
| self.textContainer = textContainer | ||
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| startAsyncImageDownload() | ||
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| return nil | ||
| } | ||
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| return image | ||
| } | ||
| #endif | ||
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| public override func attachmentBounds(for textContainer: NSTextContainer?, proposedLineFragment lineFrag: CGRect, glyphPosition position: CGPoint, characterIndex charIndex: Int) -> CGRect | ||
| { | ||
| if let displaySize = displaySize | ||
| { | ||
| return CGRect(origin: CGPoint.zero, size: displaySize) | ||
| } | ||
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| if let imageSize = originalImageSize | ||
| { | ||
| let maxWidth = maximumDisplayWidth ?? lineFrag.size.width | ||
| let factor = maxWidth / imageSize.width | ||
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| return CGRect(origin: CGPoint.zero, size:CGSize(width: Int(imageSize.width * factor), height: Int(imageSize.height * factor))) | ||
| } | ||
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| return CGRect.zero | ||
| } | ||
| } | ||
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| extension NSLayoutManager | ||
| { | ||
| /// Determine the character ranges for an attachment | ||
| private func rangesForAttachment(attachment: NSTextAttachment) -> [NSRange]? | ||
| { | ||
| guard let attributedString = self.textStorage else | ||
| { | ||
| return nil | ||
| } | ||
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| // find character range for this attachment | ||
| let range = NSRange(location: 0, length: attributedString.length) | ||
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| var refreshRanges = [NSRange]() | ||
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There was a problem hiding this comment. Would we ever expect to find more than one range for a single attachment? |
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| attributedString.enumerateAttribute(NSAttributedString.Key.attachment, in: range, options: []) { (value, effectiveRange, nil) in | ||
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| guard let foundAttachment = value as? NSTextAttachment, foundAttachment == attachment else | ||
| { | ||
| return | ||
| } | ||
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| // add this range to the refresh ranges | ||
| refreshRanges.append(effectiveRange) | ||
| } | ||
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| if refreshRanges.count == 0 | ||
| { | ||
| return nil | ||
| } | ||
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| return refreshRanges | ||
| } | ||
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| /// Trigger a relayout for an attachment | ||
| public func setNeedsLayout(forAttachment attachment: NSTextAttachment) | ||
|
There was a problem hiding this comment. Does this need to be public? |
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| { | ||
| guard let ranges = rangesForAttachment(attachment: attachment) else | ||
| { | ||
| return | ||
| } | ||
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| // invalidate the display for the corresponding ranges | ||
| for range in ranges.reversed() { | ||
| self.invalidateLayout(forCharacterRange: range, actualCharacterRange: nil) | ||
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| // also need to trigger re-display or already visible images might not get updated | ||
| self.invalidateDisplay(forCharacterRange: range) | ||
| } | ||
| } | ||
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| /// Trigger a re-display for an attachment | ||
| public func setNeedsDisplay(forAttachment attachment: NSTextAttachment) | ||
| { | ||
| guard let ranges = rangesForAttachment(attachment: attachment) else | ||
| { | ||
| return | ||
| } | ||
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| // invalidate the display for the corresponding ranges | ||
| for range in ranges.reversed() { | ||
| self.invalidateDisplay(forCharacterRange: range) | ||
| } | ||
| } | ||
| } | ||
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Does this need to be public?
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Name suggestion:
AsyncImageAttachment