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TelegramCore/ResizeableTextInputView.swift

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+import Foundation
+import UIKit
+import Display
+
+class ResizeableTextInputViewImpl: UITextView {
+    override func setContentOffset(_ contentOffset: CGPoint, animated: Bool) {
+        super.setContentOffset(contentOffset, animated: false)
+    }
+}
+
+class ResizeableTextInputView: UIView, UITextViewDelegate {
+    let textView: ResizeableTextInputViewImpl
+    let shadowTextView: ResizeableTextInputViewImpl
+    let placeholderLabel: UILabel
+    var updateHeight: () -> Void = { }
+    var maxHeightForLines: CGFloat
+    var heightForSingleLine: CGFloat
+    let insets = UIEdgeInsets(top: 2.0, left: 0.0, bottom: 4.0, right: 0.0)
+    
+    var placeholder: String {
+        get {
+            return self.placeholderLabel.text ?? ""
+        } set(value) {
+            self.placeholderLabel.text = value
+            self.placeholderLabel.sizeToFit()
+            let placeholderSize = self.placeholderLabel.bounds.size
+            self.placeholderLabel.frame = CGRect(x: 2.0, y: self.insets.top, width: placeholderSize.width, height: placeholderSize.height)
+        }
+    }
+    
+    init() {
+        self.textView = ResizeableTextInputViewImpl()
+        self.textView.layoutManager.allowsNonContiguousLayout = true
+        self.textView.textContainerInset = UIEdgeInsets(top: 0.0, left: self.insets.left, bottom: 0.0, right: self.insets.right)
+        self.textView.backgroundColor = UIColor.clear
+        self.textView.textColor = UIColor.black
+        self.textView.isOpaque = false
+        self.textView.font = Font.regular(16.0)
+        
+        self.shadowTextView = ResizeableTextInputViewImpl()
+        self.shadowTextView.font = self.textView.font
+        self.shadowTextView.textContainerInset = self.textView.textContainerInset
+        self.shadowTextView.layoutManager.allowsNonContiguousLayout = true
+        self.shadowTextView.frame = CGRect(x: 0.0, y: 0.0, width: 100.0, height: CGFloat.greatestFiniteMagnitude)
+        
+        self.shadowTextView.text = "A"
+        self.shadowTextView.layoutManager.ensureLayout(for: shadowTextView.textContainer)
+        let singleLineHeight = ceil(shadowTextView.layoutManager.usedRect(for: shadowTextView.textContainer).size.height)
+        self.heightForSingleLine = singleLineHeight + 2.0 + self.insets.top + self.insets.bottom
+        
+        self.shadowTextView.text = "\n\n\n"
+        self.shadowTextView.layoutManager.ensureLayout(for: shadowTextView.textContainer)
+        let maxHeight = ceil(shadowTextView.layoutManager.usedRect(for: shadowTextView.textContainer).size.height)
+        self.maxHeightForLines = maxHeight + 2.0 + self.insets.top + self.insets.bottom
+        
+        self.placeholderLabel = UILabel()
+        
+        super.init(frame: CGRect())
+        
+        self.clipsToBounds = true
+        
+        self.textView.delegate = self
+        self.addSubview(textView)
+        
+        self.placeholderLabel.font = self.textView.font
+        self.placeholderLabel.textColor = UIColor(0xbebec0)
+        self.addSubview(self.placeholderLabel)
+    }
+
+    required init?(coder aDecoder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    private func maxHeight() -> CGFloat {
+        return self.maxHeightForLines ?? 0.0
+    }
+    
+    func calculateSizeThatFits(constrainedSize: CGSize) -> CGSize {
+        self.shadowTextView.frame = CGRect(x: 0.0, y: 0.0, width: constrainedSize.width + 4.0, height: CGFloat.greatestFiniteMagnitude)
+        self.shadowTextView.text = "\n"
+        //shadowTextView.layoutManager.ensureLayoutForTextContainer(shadowTextView.textContainer)
+        self.shadowTextView.text = textView.text
+        
+        shadowTextView.layoutManager.glyphRange(for: shadowTextView.textContainer)
+        let height = ceil(shadowTextView.layoutManager.usedRect(for: shadowTextView.textContainer).size.height)
+        
+        return CGSize(width: constrainedSize.width, height: min(height + 2.0 + self.insets.top + self.insets.bottom, self.maxHeight()))
+    }
+    
+    func textViewDidChange(_ textView: UITextView) {
+        self.placeholderLabel.isHidden = textView.text.startIndex != textView.text.endIndex
+        self.updateHeight()
+    }
+    
+    override var frame: CGRect {
+        get {
+            return super.frame
+        } set(value) {
+            super.frame = value
+            
+            let heightFix: CGFloat = 25.0
+            self.textView.frame = CGRect(x: -4.0, y: -0.5, width: value.size.width + 4.0, height: value.size.height + heightFix - self.insets.bottom)
+            let distance = -(self.maxHeight() - self.textView.frame.size.height)
+            self.clipsToBounds = distance > 0.0
+            self.textView.contentInset = UIEdgeInsets(top: 2.0 + self.insets.top, left: 0.0, bottom: max(0.0, distance) + self.insets.bottom, right: 0.0)
+            self.textView.scrollIndicatorInsets = UIEdgeInsets(top: 2.0 + self.insets.top, left: 0.0, bottom: max(0.0, distance) + self.insets.bottom, right: -2.0)
+            
+            let placeholderSize = self.placeholderLabel.bounds.size
+            self.placeholderLabel.frame = CGRect(x: 1.0, y: self.insets.top + 2.0, width: placeholderSize.width, height: placeholderSize.height)
+        }
+    }
+}