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TelegramUI/AudioWaveformNode.swift

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+import Foundation
+import Display
+import AsyncDisplayKit
+
+private final class AudioWaveformNodeParameters: NSObject {
+    let waveform: AudioWaveform?
+    let color: UIColor?
+    
+    init(waveform: AudioWaveform?, color: UIColor?) {
+        self.waveform = waveform
+        self.color = color
+        
+        super.init()
+    }
+}
+
+final class AudioWaveformNode: ASDisplayNode {
+    private var waveform: AudioWaveform?
+    private var color: UIColor?
+    
+    override init() {
+        super.init()
+        
+        self.isOpaque = false
+    }
+    
+    override var frame: CGRect {
+        get {
+            return super.frame
+        } set(value) {
+            let redraw = value.size != self.frame.size
+            super.frame = value
+            
+            if redraw {
+                self.setNeedsDisplay()
+            }
+        }
+    }
+    
+    func setup(color: UIColor, waveform: AudioWaveform?) {
+        if self.color == nil || !self.color!.isEqual(color) || self.waveform != waveform {
+            self.color = color
+            self.waveform = waveform
+            self.setNeedsDisplay()
+        }
+    }
+    
+    override func drawParameters(forAsyncLayer layer: _ASDisplayLayer) -> NSObjectProtocol? {
+        return AudioWaveformNodeParameters(waveform: self.waveform, color: self.color)
+    }
+    
+    @objc override class func draw(_ bounds: CGRect, withParameters parameters: NSObjectProtocol?, isCancelled: @escaping asdisplaynode_iscancelled_block_t, isRasterizing: Bool) {
+        
+        let context = UIGraphicsGetCurrentContext()!
+        
+        if !isRasterizing {
+            context.setBlendMode(.copy)
+            context.setFillColor(UIColor.clear.cgColor)
+            context.fill(bounds)
+        }
+        
+        if let parameters = parameters as? AudioWaveformNodeParameters {
+            let sampleWidth: CGFloat = 2.0
+            let halfSampleWidth: CGFloat = 1.0
+            let distance: CGFloat = 1.0
+            
+            let size = bounds.size
+            
+            if let color = parameters.color {
+                context.setFillColor(color.cgColor)
+            }
+            
+            if let waveform = parameters.waveform {
+                waveform.samples.withUnsafeBytes { (samples: UnsafePointer<UInt16>) -> Void in
+                    let peakHeight: CGFloat = 12.0
+                    let maxReadSamples = waveform.samples.count / 2
+                    
+                    var maxSample: UInt16 = 0
+                    for i in 0 ..< maxReadSamples {
+                        let sample = samples[i]
+                        if maxSample < sample {
+                            maxSample = sample
+                        }
+                    }
+                    
+                    let invScale = 1.0 / max(1.0, CGFloat(maxSample))
+                    let numSamples = Int(floor(size.width / (sampleWidth + distance)))
+                    
+                    let adjustedSamplesMemory = malloc(numSamples * 2)!
+                    let adjustedSamples = adjustedSamplesMemory.assumingMemoryBound(to: UInt16.self)
+                    defer {
+                        free(adjustedSamplesMemory)
+                    }
+                    memset(adjustedSamplesMemory, 0, numSamples * 2)
+                    
+                    for i in 0 ..< maxReadSamples {
+                        let index = i * numSamples / maxReadSamples
+                        let sample = samples[i]
+                        if adjustedSamples[index] < sample {
+                            adjustedSamples[index] = sample
+                        }
+                    }
+                    
+                    for i in 0 ..< numSamples {
+                        let offset = CGFloat(i) * (sampleWidth + distance)
+                        let peakSample = adjustedSamples[i]
+                        
+                        var sampleHeight = CGFloat(peakSample) * peakHeight * invScale
+                        if abs(sampleHeight) > peakHeight {
+                            sampleHeight = peakHeight
+                        }
+                        
+                        let adjustedSampleHeight = sampleHeight - sampleWidth
+                        if adjustedSampleHeight.isLessThanOrEqualTo(sampleWidth) {
+                            context.fillEllipse(in: CGRect(x: offset, y: size.height - sampleWidth, width: sampleWidth, height: sampleHeight))
+                            context.fill(CGRect(x: offset, y: size.height - halfSampleWidth, width: sampleWidth, height: halfSampleWidth))
+                        } else {
+                            let adjustedRect = CGRect(x: offset, y: size.height - adjustedSampleHeight, width: sampleWidth, height: adjustedSampleHeight)
+                            context.fill(adjustedRect)
+                            context.fillEllipse(in: CGRect(x: adjustedRect.minX, y: adjustedRect.minY - halfSampleWidth, width: sampleWidth, height: sampleWidth))
+                            context.fillEllipse(in: CGRect(x: adjustedRect.minX, y: adjustedRect.maxY - halfSampleWidth, width: sampleWidth, height: sampleHeight))
+                        }
+                    }
+                }
+            } else {
+                context.fill(CGRect(x: halfSampleWidth, y: size.height - sampleWidth, width: size.width - sampleWidth, height: sampleWidth))
+                context.fillEllipse(in: CGRect(x: 0.0, y: size.height - sampleWidth, width: sampleWidth, height: sampleWidth))
+                context.fillEllipse(in: CGRect(x: size.width - sampleWidth, y: size.height - sampleWidth, width: sampleWidth, height: sampleWidth))
+            }
+        }
+    }
+}