source-code

source-code/ALTs/AltStore/Components/CollapsingTextView.swift

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+//
+//  CollapsingTextView.swift
+//  AltStore
+//
+//  Created by Riley Testut on 7/23/19.
+//  Copyright © 2019 Riley Testut. All rights reserved.
+//
+
+import UIKit
+
+class CollapsingTextView: UITextView
+{
+    var isCollapsed = true {
+        didSet {
+            self.setNeedsLayout()
+        }
+    }
+    
+    var maximumNumberOfLines = 2 {
+        didSet {
+            self.setNeedsLayout()
+        }
+    }
+    
+    var lineSpacing: CGFloat = 2 {
+        didSet {
+            self.setNeedsLayout()
+        }
+    }
+    
+    let moreButton = UIButton(type: .system)
+    
+    override func awakeFromNib()
+    {
+        super.awakeFromNib()
+        
+        self.layoutManager.delegate = self
+        
+        self.textContainerInset = .zero
+        self.textContainer.lineFragmentPadding = 0
+        self.textContainer.lineBreakMode = .byTruncatingTail
+        self.textContainer.heightTracksTextView = true
+        self.textContainer.widthTracksTextView = true
+        
+        self.moreButton.setTitle(NSLocalizedString("More", comment: ""), for: .normal)
+        self.moreButton.addTarget(self, action: #selector(CollapsingTextView.toggleCollapsed(_:)), for: .primaryActionTriggered)
+        self.addSubview(self.moreButton)
+        
+        self.setNeedsLayout()
+    }
+    
+    override func layoutSubviews()
+    {
+        super.layoutSubviews()
+        
+        guard let font = self.font else { return }
+        
+        let buttonFont = UIFont.systemFont(ofSize: font.pointSize, weight: .medium)
+        self.moreButton.titleLabel?.font = buttonFont
+        
+        let buttonY = (font.lineHeight + self.lineSpacing) * CGFloat(self.maximumNumberOfLines - 1)
+        let size = self.moreButton.sizeThatFits(CGSize(width: 1000, height: 1000))
+        
+        let moreButtonFrame = CGRect(x: self.bounds.width - self.moreButton.bounds.width,
+                                     y: buttonY,
+                                     width: size.width,
+                                     height: font.lineHeight)
+        self.moreButton.frame = moreButtonFrame
+        
+        if self.isCollapsed
+        {
+            self.textContainer.maximumNumberOfLines = self.maximumNumberOfLines
+            
+            let maximumCollapsedHeight = font.lineHeight * CGFloat(self.maximumNumberOfLines)
+            if self.intrinsicContentSize.height > maximumCollapsedHeight
+            {
+                var exclusionFrame = moreButtonFrame
+                exclusionFrame.origin.y += self.moreButton.bounds.midY
+                exclusionFrame.size.width = self.bounds.width // Extra wide to make sure it wraps to next line.
+                self.textContainer.exclusionPaths = [UIBezierPath(rect: exclusionFrame)]
+                
+                self.moreButton.isHidden = false
+            }
+            else
+            {
+                self.textContainer.exclusionPaths = []
+                
+                self.moreButton.isHidden = true
+            }
+        }
+        else
+        {
+            self.textContainer.maximumNumberOfLines = 0
+            self.textContainer.exclusionPaths = []
+            
+            self.moreButton.isHidden = true
+        }
+        
+        self.invalidateIntrinsicContentSize()
+    }
+}
+
+private extension CollapsingTextView
+{
+    @objc func toggleCollapsed(_ sender: UIButton)
+    {
+        self.isCollapsed.toggle()
+    }
+}
+
+extension CollapsingTextView: NSLayoutManagerDelegate
+{
+    func layoutManager(_ layoutManager: NSLayoutManager, lineSpacingAfterGlyphAt glyphIndex: Int, withProposedLineFragmentRect rect: CGRect) -> CGFloat
+    {
+        return self.lineSpacing
+    }
+}