86 lines
3.1 KiB
Swift
86 lines
3.1 KiB
Swift
//
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// AttributedStringBuilder.swift
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// ElementX
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//
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// Created by Stefan Ceriu on 22/03/2022.
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// Copyright © 2022 Element. All rights reserved.
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//
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import Foundation
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import DTCoreText
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struct AttributedStringBuilder: AttributedStringBuilderProtocol {
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private var defaultCSS: String {
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AttributedStringBuilderUtils.cssToMarkBlockquotes() +
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"""
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pre,code {
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background-color: #F5F7FA;
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display: inline;
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font-family: monospace;
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white-space: pre;
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-coretext-fontname: Menlo-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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// Do not use the default HTML renderer of NSAttributedString because this method
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// runs on the UI thread which we want to avoid because renderHTMLString is called
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// most of the time from a background thread.
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// Use DTCoreText HTML renderer instead.
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// Using DTCoreText, which renders static string, helps to avoid code injection attacks
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// that could happen with the default HTML renderer of NSAttributedString which is a
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// webview.
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func fromHTML(_ htmlString: String?) -> AttributedString? {
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guard let htmlString = htmlString,
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let data = htmlString.data(using: .utf8) 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 defaultColor = UIColor.black
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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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DTDefaultTextColor: defaultColor,
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DTDefaultLinkDecoration: false,
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DTDefaultStyleSheet: DTCSSStylesheet(styleBlock: self.defaultCSS) as Any
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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 var nsAttributedString = builder.generatedAttributedString() else {
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return nil
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}
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nsAttributedString = AttributedStringBuilderUtils.removeDTCoreTextArtifacts(nsAttributedString)
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nsAttributedString = AttributedStringBuilderUtils.removeMarkedBlockquotesArtifacts(nsAttributedString)
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return try? AttributedString(nsAttributedString, including: \.elementX)
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}
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func blockquoteCoalescedComponentsFrom(_ attributedString: AttributedString?) -> [AttributedStringBuilderComponent]? {
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guard let attributedString = attributedString else {
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return nil
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}
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return attributedString.runs[\.blockquote].map { (value, range) in
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AttributedStringBuilderComponent(attributedString: AttributedString(attributedString[range]),
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isBlockquote: value != nil)
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}
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}
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}
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