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https://github.com/Novaloop-AG/element-x-ios.git
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Add an initial version of the V2 AttributedStringBuilder
This commit is contained in:
Stefan Ceriu
Doug
@@ -6,17 +6,16 @@
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//
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import Compound
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import DTCoreText
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import LRUCache
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import MatrixRustSDK
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import SwiftSoup
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import UIKit
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struct AttributedStringBuilderV2: AttributedStringBuilderProtocol {
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private let cacheKey: String
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private let temporaryBlockquoteMarkingColor = UIColor.magenta
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private let temporaryCodeBlockMarkingColor = UIColor.cyan
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private let mentionBuilder: MentionBuilderProtocol
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private static let attributeMSC4286 = "data-msc4286-external-payment-details"
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private static let cacheDispatchQueue = DispatchQueue(label: "io.element.elementx.attributed_string_builder_v2_cache")
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private static var caches: [String: LRUCache<String, AttributedString>] = [:]
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@@ -39,7 +38,6 @@ struct AttributedStringBuilderV2: AttributedStringBuilderProtocol {
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}
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let mutableAttributedString = NSMutableAttributedString(string: string)
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removeDefaultForegroundColors(mutableAttributedString)
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addLinksAndMentions(mutableAttributedString)
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addMatrixEntityPermalinkAttributesTo(mutableAttributedString)
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@@ -67,41 +65,16 @@ struct AttributedStringBuilderV2: AttributedStringBuilderProtocol {
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let htmlString = originalHTMLString.replacingHtmlBreaksOccurrences()
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guard let data = htmlString.data(using: .utf8) else {
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let doc = try? SwiftSoup.parseBodyFragment(htmlString)
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guard let body = doc?.body() else {
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return nil
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}
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let defaultFont = UIFont.preferredFont(forTextStyle: .body)
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let parsingOptions: [String: Any] = [
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DTUseiOS6Attributes: true,
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DTDefaultFontFamily: defaultFont.familyName,
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DTDefaultFontName: defaultFont.fontName,
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DTDefaultFontSize: defaultFont.pointSize,
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DTDefaultStyleSheet: DTCSSStylesheet(styleBlock: defaultCSS) as Any,
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DTDefaultLinkDecoration: false
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]
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guard let builder = DTHTMLAttributedStringBuilder(html: data, options: parsingOptions, documentAttributes: nil) else {
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return nil
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}
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builder.willFlushCallback = { element in
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element?.sanitize(font: defaultFont)
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}
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guard let attributedString = builder.generatedAttributedString() else {
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return nil
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}
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let mutableAttributedString = NSMutableAttributedString(attributedString: attributedString)
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removeDefaultForegroundColors(mutableAttributedString)
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let mutableAttributedString = attributedString(from: body, preserveFormatting: false)
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detectPhishingAttempts(mutableAttributedString)
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addLinksAndMentions(mutableAttributedString)
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replaceMarkedBlockquotes(mutableAttributedString)
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replaceMarkedCodeBlocks(mutableAttributedString)
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addMatrixEntityPermalinkAttributesTo(mutableAttributedString)
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removeDTCoreTextArtifacts(mutableAttributedString)
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let result = try? AttributedString(mutableAttributedString, including: \.elementX)
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Self.cacheValue(result, forKey: htmlString, cacheKey: cacheKey)
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@@ -111,6 +84,105 @@ struct AttributedStringBuilderV2: AttributedStringBuilderProtocol {
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// MARK: - Private
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func attributedString(from element: Element, preserveFormatting: Bool) -> NSMutableAttributedString {
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let result = NSMutableAttributedString()
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for node in element.getChildNodes() {
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if let textNode = node as? TextNode {
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var text = preserveFormatting ? textNode.getWholeText() : textNode.text()
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// There seem to be sibling TextNodes following every </br> tag that
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// contain one single space character which we don't want as it
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// breaks line head indents.
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if (node.previousSibling() as? Element)?.tagName() == "br" {
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text.trimPrefix(" ")
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}
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result.append(NSAttributedString(string: text))
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continue
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}
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guard let childElement = node as? Element else {
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continue
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}
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let tag = childElement.tagName().lowercased()
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var content = NSMutableAttributedString()
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switch tag {
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case "h1", "h2", "h3", "h4", "h5", "h6":
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let level = Int(String(tag.dropFirst())) ?? 1
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let size: CGFloat = UIFont.systemFontSize + CGFloat(6 - level) * 2
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content = attributedString(from: childElement, preserveFormatting: preserveFormatting)
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content.setFontPreservingSymbolicTraits(UIFont.boldSystemFont(ofSize: size))
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case "p", "div":
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content = attributedString(from: childElement, preserveFormatting: preserveFormatting)
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content.append(NSAttributedString(string: "\n"))
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case "br":
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content = NSMutableAttributedString(string: "\n")
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case "b", "strong":
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content = attributedString(from: childElement, preserveFormatting: preserveFormatting)
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content.setFontPreservingSymbolicTraits(UIFont.boldSystemFont(ofSize: UIFont.systemFontSize))
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case "i", "em":
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content = attributedString(from: childElement, preserveFormatting: preserveFormatting)
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content.setFontPreservingSymbolicTraits(UIFont.italicSystemFont(ofSize: UIFont.systemFontSize))
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case "u":
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content = attributedString(from: childElement, preserveFormatting: preserveFormatting)
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content.addAttribute(.underlineStyle, value: NSUnderlineStyle.single.rawValue, range: NSRange(location: 0, length: content.length))
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case "s", "del":
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content = attributedString(from: childElement, preserveFormatting: preserveFormatting)
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content.addAttribute(.strikethroughStyle, value: NSUnderlineStyle.single.rawValue, range: NSRange(location: 0, length: content.length))
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case "sup":
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content = attributedString(from: childElement, preserveFormatting: preserveFormatting)
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content.addAttribute(.baselineOffset, value: 6, range: NSRange(location: 0, length: content.length))
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content.setFontPreservingSymbolicTraits(UIFont.systemFont(ofSize: UIFont.systemFontSize * 0.7))
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case "sub":
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content = attributedString(from: childElement, preserveFormatting: preserveFormatting)
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content.addAttribute(.baselineOffset, value: -4, range: NSRange(location: 0, length: content.length))
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content.setFontPreservingSymbolicTraits(UIFont.systemFont(ofSize: UIFont.systemFontSize * 0.7))
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case "blockquote":
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content = attributedString(from: childElement, preserveFormatting: preserveFormatting)
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content.addAttribute(.MatrixBlockquote, value: true, range: NSRange(location: 0, length: content.length))
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case "code", "pre":
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let preserveFormatting = preserveFormatting || tag == "pre"
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content = attributedString(from: childElement, preserveFormatting: preserveFormatting)
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content.setFontPreservingSymbolicTraits(UIFont.monospacedSystemFont(ofSize: UIFont.systemFontSize, weight: .regular))
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content.addAttribute(.backgroundColor, value: UIColor.compound._bgCodeBlock as Any, range: NSRange(location: 0, length: content.length))
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case "hr":
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content = NSMutableAttributedString(string: "\n")
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case "a":
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content = attributedString(from: childElement, preserveFormatting: preserveFormatting)
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if let href = try? childElement.attr("href") {
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content.addAttribute(.link, value: href, range: NSRange(location: 0, length: content.length))
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}
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case "span":
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if (try? childElement.attr(Self.attributeMSC4286)) ?? nil != nil {
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content = attributedString(from: childElement, preserveFormatting: preserveFormatting)
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}
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default:
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content = attributedString(from: childElement, preserveFormatting: preserveFormatting)
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}
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result.append(content)
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}
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return result
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}
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private static func cacheValue(_ value: AttributedString?, forKey key: String, cacheKey: String) {
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cacheDispatchQueue.sync {
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if caches[cacheKey] == nil {
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@@ -130,11 +202,6 @@ struct AttributedStringBuilderV2: AttributedStringBuilderProtocol {
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return result
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}
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private func removeDefaultForegroundColors(_ attributedString: NSMutableAttributedString) {
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attributedString.removeAttribute(.foregroundColor, range: .init(location: 0, length: attributedString.length))
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}
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// swiftlint:disable:next cyclomatic_complexity
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private func addLinksAndMentions(_ attributedString: NSMutableAttributedString) {
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let string = attributedString.string
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@@ -201,12 +268,7 @@ struct AttributedStringBuilderV2: AttributedStringBuilderProtocol {
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if hasLink {
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return
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}
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// Don't add any extra attributes within codeblocks
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if attributedString.attribute(.backgroundColor, at: match.range.location, effectiveRange: nil) as? UIColor == temporaryCodeBlockMarkingColor {
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return
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}
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switch match.type {
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case .atRoom:
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attributedString.addAttribute(.MatrixAllUsersMention, value: true, range: match.range)
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@@ -227,41 +289,6 @@ struct AttributedStringBuilderV2: AttributedStringBuilderProtocol {
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}
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}
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private func replaceMarkedBlockquotes(_ attributedString: NSMutableAttributedString) {
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// According to blockquotes in the string, DTCoreText can apply 2 policies:
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// - define a `DTTextBlocksAttribute` attribute on a <blockquote> block
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// - or, just define a `NSBackgroundColorAttributeName` attribute
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attributedString.enumerateAttribute(.DTTextBlocks, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
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guard let value = value as? NSArray,
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let dtTextBlock = value.firstObject as? DTTextBlock,
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dtTextBlock.backgroundColor == temporaryBlockquoteMarkingColor else {
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return
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}
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attributedString.addAttribute(.MatrixBlockquote, value: true, range: range)
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}
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attributedString.enumerateAttribute(.backgroundColor, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
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guard let value = value as? UIColor,
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value == temporaryBlockquoteMarkingColor else {
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return
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}
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attributedString.removeAttribute(.backgroundColor, range: range)
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attributedString.addAttribute(.MatrixBlockquote, value: true, range: range)
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}
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}
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private func replaceMarkedCodeBlocks(_ attributedString: NSMutableAttributedString) {
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attributedString.enumerateAttribute(.backgroundColor, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
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if let value = value as? UIColor,
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value == temporaryCodeBlockMarkingColor {
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attributedString.addAttribute(.backgroundColor, value: UIColor.compound._bgCodeBlock as Any, range: range)
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attributedString.removeAttribute(.link, range: range)
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}
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}
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}
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func addMatrixEntityPermalinkAttributesTo(_ attributedString: NSMutableAttributedString) {
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attributedString.enumerateAttribute(.link, in: .init(location: 0, length: attributedString.length), options: []) { value, range, _ in
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if value != nil {
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@@ -324,53 +351,6 @@ struct AttributedStringBuilderV2: AttributedStringBuilderProtocol {
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attributedString.addAttribute(.link, value: finalURL, range: range)
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}
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private func removeDTCoreTextArtifacts(_ attributedString: NSMutableAttributedString) {
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guard attributedString.length > 0 else {
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return
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}
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// DTCoreText adds a newline at the end of plain text ( https://github.com/Cocoanetics/DTCoreText/issues/779 )
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// or after a blockquote section.
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// Trim trailing whitespace and newlines in the string content
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while (attributedString.string as NSString).hasSuffixCharacter(from: .whitespacesAndNewlines) {
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attributedString.deleteCharacters(in: .init(location: attributedString.length - 1, length: 1))
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}
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}
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private var defaultCSS: String {
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"""
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blockquote {
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background: \(temporaryBlockquoteMarkingColor.toHexString());
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display: block;
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}
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pre,code {
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background-color: \(temporaryCodeBlockMarkingColor.toHexString());
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display: inline;
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white-space: pre;
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font-size: 0.9em;
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-coretext-fontname: .AppleSystemUIFontMonospaced-Regular;
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}
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h1,h2,h3 {
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font-size: 1.2em;
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}
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"""
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}
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}
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private extension UIColor {
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func toHexString() -> String {
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var red: CGFloat = 0.0
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var green: CGFloat = 0.0
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var blue: CGFloat = 0.0
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var alpha: CGFloat = 0.0
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getRed(&red, green: &green, blue: &blue, alpha: &alpha)
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let rgb = Int(red * 255) << 16 | Int(green * 255) << 8 | Int(blue * 255) << 0
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return NSString(format: "#%06x", rgb) as String
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}
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}
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private struct TextParsingMatch {
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@@ -396,3 +376,23 @@ private struct TextParsingMatch {
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}
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}
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}
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private extension NSMutableAttributedString {
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func setFontPreservingSymbolicTraits(_ newFont: UIFont) {
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enumerateAttribute(.font, in: NSRange(location: 0, length: length)) { value, range, _ in
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if let oldFont = value as? UIFont {
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// keep the traits (bold, italic, etc.)
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let traits = oldFont.fontDescriptor.symbolicTraits
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if let descriptor = newFont.fontDescriptor.withSymbolicTraits(traits) {
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let updatedFont = UIFont(descriptor: descriptor, size: newFont.pointSize)
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addAttribute(.font, value: updatedFont, range: range)
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} else {
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// fallback if traits can't be applied
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addAttribute(.font, value: newFont, range: range)
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}
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} else {
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addAttribute(.font, value: newFont, range: range)
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}
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}
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}
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}
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