#4096 - Added voice message decoding, timeline cell and playback UI.

Riot/Modules/Room/VoiceMessages/VoiceMessageWaveformView.swift

@@ -0,0 +1,112 @@
+//
+// Copyright 2021 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import UIKit
+
+class VoiceMessageWaveformView: UIView {
+
+    private let lineWidth: CGFloat = 2.0
+    private let primarylineColor = UIColor.lightGray
+    private let secondaryLineColor = UIColor.darkGray
+    private let linePadding: CGFloat = 2.0
+
+    private var samples: [Float] = []
+    private var barViews: [CALayer] = []
+    
+    var progress = 0.0 {
+        didSet {
+            updateBarViews()
+        }
+    }
+
+    var requiredNumberOfSamples: Int {
+        return barViews.count
+    }
+    
+    override init(frame: CGRect) {
+        super.init(frame: frame)
+        setupBarViews()
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError()
+    }
+
+    override func layoutSubviews() {
+        super.layoutSubviews()
+        setupBarViews()
+    }
+    
+    func setSamples(_ samples: [Float]) {
+        self.samples = samples
+        updateBarViews()
+    }
+
+    func addSample(_ sample: Float) {
+        samples.append(sample)
+        updateBarViews()
+    }
+
+    // MARK: - Private
+
+    private func setupBarViews() {
+        for layer in barViews {
+            layer.removeFromSuperlayer()
+        }
+
+        var barViews: [CALayer] = []
+
+        var xOffset: CGFloat = lineWidth / 2
+
+        while xOffset < bounds.width - lineWidth {
+            let layer = CALayer()
+            layer.backgroundColor = primarylineColor.cgColor
+            layer.cornerRadius = lineWidth / 2
+            layer.masksToBounds = true
+            layer.anchorPoint = CGPoint(x: 0, y: 0.5)
+            layer.frame = CGRect(x: xOffset, y: bounds.midY - lineWidth / 2, width: lineWidth, height: lineWidth)
+
+            self.layer.addSublayer(layer)
+
+            barViews.append(layer)
+
+            xOffset += lineWidth + linePadding
+        }
+
+        self.barViews = barViews
+
+        updateBarViews()
+    }
+
+    private func updateBarViews() {
+        let drawMappingFactor = bounds.size.height
+        let minimumGraphAmplitude: CGFloat = lineWidth
+        
+        let progressPosition = Int(floor(progress * Double(barViews.count)))
+        
+        for (index, layer) in barViews.enumerated() {
+            let sample = CGFloat(index >= samples.count ? 1 : samples[index])
+            
+            let invertedDbSample = 1 - sample // sample is in dB, linearly normalized to [0, 1] (1 -> -50 dB)
+            let drawingAmplitude = max(minimumGraphAmplitude, invertedDbSample * drawMappingFactor)
+            
+            layer.frame.origin.y = bounds.midY - drawingAmplitude / 2
+            layer.frame.size.height = drawingAmplitude
+            
+            layer.backgroundColor = (index < progressPosition ? secondaryLineColor.cgColor : primarylineColor.cgColor)   
+        }
+    }
+}