Show BlurHash previews of attachments

Pachyderm/Model/Attachment.swift

@@ -17,6 +17,7 @@ public class Attachment: Codable {
     public let textURL: URL?
     public let meta: Metadata?
     public let description: String?
+    public let blurHash: String?
     
     public static func update(_ attachment: Attachment, focus: (Float, Float)?, description: String?) -> Request<Attachment> {
         return Request<Attachment>(method: .put, path: "/api/v1/media/\(attachment.id)", body: .formData([
@@ -35,6 +36,7 @@ public class Attachment: Codable {
         self.textURL = try? container.decode(URL?.self, forKey: .textURL)
         self.meta = try? container.decode(Metadata?.self, forKey: .meta)
         self.description = try? container.decode(String?.self, forKey: .description)
+        self.blurHash = try? container.decode(String?.self, forKey: .blurHash)
     }
     
     private enum CodingKeys: String, CodingKey {
@@ -46,6 +48,7 @@ public class Attachment: Codable {
         case textURL = "text_url"
         case meta
         case description
+        case blurHash = "blurhash"
     }
 }
 
@@ -60,7 +63,7 @@ extension Attachment {
 }
 
 extension Attachment {
-    public class Metadata: Codable {
+    public struct Metadata: Codable {
         public let length: String?
         public let duration: Float?
         public let audioEncoding: String?
@@ -91,7 +94,7 @@ extension Attachment {
         }
     }
     
-    public class ImageMetadata: Codable {
+    public struct ImageMetadata: Codable {
         public let width: Int?
         public let height: Int?
         public let size: String?

Tusker.xcodeproj/project.pbxproj

@@ -169,6 +169,7 @@
 		D67895BC24671E6D00D4CD9E /* PKDrawing+Render.swift in Sources */ = {isa = PBXBuildFile; fileRef = D67895BB24671E6D00D4CD9E /* PKDrawing+Render.swift */; };
 		D67895C0246870DE00D4CD9E /* LocalAccountAvatarView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D67895BF246870DE00D4CD9E /* LocalAccountAvatarView.swift */; };
 		D679C09F215850EF00DA27FE /* XCBActions.swift in Sources */ = {isa = PBXBuildFile; fileRef = D679C09E215850EF00DA27FE /* XCBActions.swift */; };
+		D67B506D250B291200FAECFB /* BlurHashDecode.swift in Sources */ = {isa = PBXBuildFile; fileRef = D67B506C250B291200FAECFB /* BlurHashDecode.swift */; };
 		D67C57AD21E265FC00C3118B /* LargeAccountDetailView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D67C57AC21E265FC00C3118B /* LargeAccountDetailView.swift */; };
 		D67C57AF21E28EAD00C3118B /* Array+Uniques.swift in Sources */ = {isa = PBXBuildFile; fileRef = D67C57AE21E28EAD00C3118B /* Array+Uniques.swift */; };
 		D67C57B221E28FAD00C3118B /* ComposeStatusReplyView.xib in Resources */ = {isa = PBXBuildFile; fileRef = D67C57B121E28FAD00C3118B /* ComposeStatusReplyView.xib */; };
@@ -494,6 +495,7 @@
 		D67895BB24671E6D00D4CD9E /* PKDrawing+Render.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "PKDrawing+Render.swift"; sourceTree = "<group>"; };
 		D67895BF246870DE00D4CD9E /* LocalAccountAvatarView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LocalAccountAvatarView.swift; sourceTree = "<group>"; };
 		D679C09E215850EF00DA27FE /* XCBActions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = XCBActions.swift; sourceTree = "<group>"; };
+		D67B506C250B291200FAECFB /* BlurHashDecode.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BlurHashDecode.swift; sourceTree = "<group>"; };
 		D67C57AC21E265FC00C3118B /* LargeAccountDetailView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LargeAccountDetailView.swift; sourceTree = "<group>"; };
 		D67C57AE21E28EAD00C3118B /* Array+Uniques.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Array+Uniques.swift"; sourceTree = "<group>"; };
 		D67C57B121E28FAD00C3118B /* ComposeStatusReplyView.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = ComposeStatusReplyView.xib; sourceTree = "<group>"; };
@@ -1119,6 +1121,14 @@
 			path = XCallbackURL;
 			sourceTree = "<group>";
 		};
+		D67B506B250B28FF00FAECFB /* Vendor */ = {
+			isa = PBXGroup;
+			children = (
+				D67B506C250B291200FAECFB /* BlurHashDecode.swift */,
+			);
+			path = Vendor;
+			sourceTree = "<group>";
+		};
 		D67C57A721E2649B00C3118B /* Account Detail */ = {
 			isa = PBXGroup;
 			children = (
@@ -1337,6 +1347,7 @@
 				D64D8CA82463B494006B0BAA /* CachedDictionary.swift */,
 				D60E2F2B24423EAD005F8713 /* LazilyDecoding.swift */,
 				D6CA6A91249FAD8900AD45C1 /* AudioSessionHelper.swift */,
+				D67B506B250B28FF00FAECFB /* Vendor */,
 				D6F1F84E2193B9BE00F5FE67 /* Caching */,
 				D6757A7A2157E00100721E32 /* XCallbackURL */,
 				D62D241E217AA46B005076CC /* Shortcuts */,
@@ -1800,6 +1811,7 @@
 				D6B4A4FF2506B81A000C81C1 /* AccountDisplayNameLabel.swift in Sources */,
 				D67C57B421E2910700C3118B /* ComposeStatusReplyView.swift in Sources */,
 				D6B053A623BD2D0C00A066FA /* AssetCollectionViewController.swift in Sources */,
+				D67B506D250B291200FAECFB /* BlurHashDecode.swift in Sources */,
 				D62275A024F1677200B82A16 /* ComposeHostingController.swift in Sources */,
 				04DACE8E212CC7CC009840C4 /* ImageCache.swift in Sources */,
 				D627FF7B217E951500CC0648 /* DraftsTableViewController.swift in Sources */,

Tusker/Screens/Attachment Gallery/GalleryViewController.swift

@@ -77,6 +77,7 @@ class GalleryViewController: UIPageViewController, UIPageViewControllerDataSourc
             case .image:
                 let vc = LoadingLargeImageViewController(attachment: attachment)
                 vc.shrinkGestureEnabled = false
+                vc.animationSourceView = sourceViews[index]
                 return vc
             case .video, .audio:
                 let vc = GalleryPlayerViewController()

Tusker/Screens/Large Image/LargeImageViewController.swift

@@ -31,7 +31,12 @@ class LargeImageViewController: UIViewController, UIScrollViewDelegate, LargeIma
     @IBOutlet weak var bottomControlsView: UIView!
     @IBOutlet weak var descriptionLabel: UILabel!
     
-    var contentView: ContentView
+    var contentView: ContentView {
+        didSet {
+            oldValue.removeFromSuperview()
+            setupContentView()
+        }
+    }
     var contentViewLeadingConstraint: NSLayoutConstraint!
     var contentViewTopConstraint: NSLayoutConstraint!
 
@@ -76,14 +81,7 @@ class LargeImageViewController: UIViewController, UIScrollViewDelegate, LargeIma
     override func viewDidLoad() {
         super.viewDidLoad()
 
-        contentView.translatesAutoresizingMaskIntoConstraints = false
+        setupContentView()
-        scrollView.addSubview(contentView)
-        contentViewLeadingConstraint = contentView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor)
-        contentViewTopConstraint = contentView.topAnchor.constraint(equalTo: scrollView.topAnchor)
-        NSLayoutConstraint.activate([
-            contentViewLeadingConstraint,
-            contentViewTopConstraint,
-        ])
 
         setControlsVisible(initialControlsVisible, animated: false)
         shareButton.isEnabled = !contentView.activityItemsForSharing.isEmpty
@@ -107,6 +105,17 @@ class LargeImageViewController: UIViewController, UIScrollViewDelegate, LargeIma
         view.addGestureRecognizer(doubleTap)
     }
     
+    private func setupContentView() {
+        contentView.translatesAutoresizingMaskIntoConstraints = false
+        scrollView.addSubview(contentView)
+        contentViewLeadingConstraint = contentView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor)
+        contentViewTopConstraint = contentView.topAnchor.constraint(equalTo: scrollView.topAnchor)
+        NSLayoutConstraint.activate([
+            contentViewLeadingConstraint,
+            contentViewTopConstraint,
+        ])
+    }
+
     override func viewDidLayoutSubviews() {
         super.viewDidLayoutSubviews()
         

Tusker/Screens/Large Image/LoadingLargeImageViewController.swift

@@ -10,14 +10,16 @@ import Pachyderm
 
 class LoadingLargeImageViewController: UIViewController, LargeImageAnimatableViewController {
 
+    private var attachment: Attachment?
     let url: URL
     let cache: ImageCache
     let imageDescription: String?
 
-    var largeImageVC: LargeImageViewController?
+    private(set) var loaded = false
-    var loadingVC: LoadingViewController?
+    private(set) var largeImageVC: LargeImageViewController?
+    private var loadingVC: LoadingViewController?
     
-    var imageRequest: ImageCache.Request?
+    private var imageRequest: ImageCache.Request?
     
     private var initialControlsVisible: Bool = true
     var controlsVisible: Bool {
@@ -70,6 +72,7 @@ class LoadingLargeImageViewController: UIViewController, LargeImageAnimatableVie
     
     convenience init(attachment: Attachment) {
         self.init(url: attachment.url, cache: .attachments, imageDescription: attachment.description)
+        self.attachment = attachment
     }
     
     required init?(coder: NSCoder) {
@@ -85,6 +88,8 @@ class LoadingLargeImageViewController: UIViewController, LargeImageAnimatableVie
         if let data = cache.get(url) {
             createLargeImage(data: data)
         } else {
+            createPreview()
+            
             loadingVC = LoadingViewController()
             embedChild(loadingVC!)
             imageRequest = cache.get(url) { [weak self] (data) in
@@ -110,15 +115,32 @@ class LoadingLargeImageViewController: UIViewController, LargeImageAnimatableVie
         }
     }
     
-    func createLargeImage(data: Data) {
+    private func createLargeImage(data: Data) {
+        guard !loaded else { return }
+        loaded = true
         guard let image = UIImage(data: data) else { return }
         let gifData = url.pathExtension == "gif" ? data : nil
+        createLargeImage(image: image, gifData: gifData)
+    }
+    
+    private func createLargeImage(image: UIImage, gifData: Data?) {
         let imageView = LargeImageImageContentView(image: image, gifData: gifData)
         
+        if let existing = largeImageVC {
+            existing.contentView = imageView
+        } else {
             largeImageVC = LargeImageViewController(contentView: imageView, description: imageDescription, sourceView: animationSourceView)
             largeImageVC!.initialControlsVisible = initialControlsVisible
             largeImageVC!.shrinkGestureEnabled = false
             embedChild(largeImageVC!)
         }
+    }
+    
+    private func createPreview() {
+        guard !self.loaded,
+              let image = animationSourceView?.image else { return }
+        
+        self.createLargeImage(image: image, gifData: nil)
+    }
     
 }

Tusker/Vendor/BlurHashDecode.swift

@@ -0,0 +1,148 @@
+/// BlurHash reference decoder implementation.
+/// From https://github.com/woltapp/blurhash/blob/b23214ddcab803fe1ec9a3e6b20558caf33a23a5/Swift/BlurHashDecode.swift
+import UIKit
+
+extension UIImage {
+    public convenience init?(blurHash: String, size: CGSize, punch: Float = 1) {
+        guard blurHash.count >= 6 else { return nil }
+
+        let sizeFlag = String(blurHash[0]).decode83()
+        let numY = (sizeFlag / 9) + 1
+        let numX = (sizeFlag % 9) + 1
+
+        let quantisedMaximumValue = String(blurHash[1]).decode83()
+        let maximumValue = Float(quantisedMaximumValue + 1) / 166
+
+        guard blurHash.count == 4 + 2 * numX * numY else { return nil }
+
+        let colours: [(Float, Float, Float)] = (0 ..< numX * numY).map { i in
+            if i == 0 {
+                let value = String(blurHash[2 ..< 6]).decode83()
+                return decodeDC(value)
+            } else {
+                let value = String(blurHash[4 + i * 2 ..< 4 + i * 2 + 2]).decode83()
+                return decodeAC(value, maximumValue: maximumValue * punch)
+            }
+        }
+
+        let width = Int(size.width)
+        let height = Int(size.height)
+        let bytesPerRow = width * 3
+        guard let data = CFDataCreateMutable(kCFAllocatorDefault, bytesPerRow * height) else { return nil }
+        CFDataSetLength(data, bytesPerRow * height)
+        guard let pixels = CFDataGetMutableBytePtr(data) else { return nil }
+
+        for y in 0 ..< height {
+            for x in 0 ..< width {
+                var r: Float = 0
+                var g: Float = 0
+                var b: Float = 0
+
+                for j in 0 ..< numY {
+                    for i in 0 ..< numX {
+                        let basis = cos(Float.pi * Float(x) * Float(i) / Float(width)) * cos(Float.pi * Float(y) * Float(j) / Float(height))
+                        let colour = colours[i + j * numX]
+                        r += colour.0 * basis
+                        g += colour.1 * basis
+                        b += colour.2 * basis
+                    }
+                }
+
+                let intR = UInt8(linearTosRGB(r))
+                let intG = UInt8(linearTosRGB(g))
+                let intB = UInt8(linearTosRGB(b))
+
+                pixels[3 * x + 0 + y * bytesPerRow] = intR
+                pixels[3 * x + 1 + y * bytesPerRow] = intG
+                pixels[3 * x + 2 + y * bytesPerRow] = intB
+            }
+        }
+
+        let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.none.rawValue)
+
+        guard let provider = CGDataProvider(data: data) else { return nil }
+        guard let cgImage = CGImage(width: width, height: height, bitsPerComponent: 8, bitsPerPixel: 24, bytesPerRow: bytesPerRow,
+        space: CGColorSpaceCreateDeviceRGB(), bitmapInfo: bitmapInfo, provider: provider, decode: nil, shouldInterpolate: true, intent: .defaultIntent) else { return nil }
+
+        self.init(cgImage: cgImage)
+    }
+}
+
+private func decodeDC(_ value: Int) -> (Float, Float, Float) {
+    let intR = value >> 16
+    let intG = (value >> 8) & 255
+    let intB = value & 255
+    return (sRGBToLinear(intR), sRGBToLinear(intG), sRGBToLinear(intB))
+}
+
+private func decodeAC(_ value: Int, maximumValue: Float) -> (Float, Float, Float) {
+    let quantR = value / (19 * 19)
+    let quantG = (value / 19) % 19
+    let quantB = value % 19
+
+    let rgb = (
+        signPow((Float(quantR) - 9) / 9, 2) * maximumValue,
+        signPow((Float(quantG) - 9) / 9, 2) * maximumValue,
+        signPow((Float(quantB) - 9) / 9, 2) * maximumValue
+    )
+
+    return rgb
+}
+
+private func signPow(_ value: Float, _ exp: Float) -> Float {
+    return copysign(pow(abs(value), exp), value)
+}
+
+private func linearTosRGB(_ value: Float) -> Int {
+    let v = max(0, min(1, value))
+    if v <= 0.0031308 { return Int(v * 12.92 * 255 + 0.5) }
+    else { return Int((1.055 * pow(v, 1 / 2.4) - 0.055) * 255 + 0.5) }
+}
+
+private func sRGBToLinear<Type: BinaryInteger>(_ value: Type) -> Float {
+    let v = Float(Int64(value)) / 255
+    if v <= 0.04045 { return v / 12.92 }
+    else { return pow((v + 0.055) / 1.055, 2.4) }
+}
+
+private let encodeCharacters: [String] = {
+    return "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz#$%*+,-.:;=?@[]^_{|}~".map { String($0) }
+}()
+
+private let decodeCharacters: [String: Int] = {
+    var dict: [String: Int] = [:]
+    for (index, character) in encodeCharacters.enumerated() {
+        dict[character] = index
+    }
+    return dict
+}()
+
+private extension String {
+    func decode83() -> Int {
+        var value: Int = 0
+        for character in self {
+            if let digit = decodeCharacters[String(character)] {
+                value = value * 83 + digit
+            }
+        }
+        return value
+    }
+}
+
+private extension String {
+    subscript (offset: Int) -> Character {
+        return self[index(startIndex, offsetBy: offset)]
+    }
+
+    subscript (bounds: CountableClosedRange<Int>) -> Substring {
+        let start = index(startIndex, offsetBy: bounds.lowerBound)
+        let end = index(startIndex, offsetBy: bounds.upperBound)
+        return self[start...end]
+    }
+
+    subscript (bounds: CountableRange<Int>) -> Substring {
+        let start = index(startIndex, offsetBy: bounds.lowerBound)
+        let end = index(startIndex, offsetBy: bounds.upperBound)
+        return self[start..<end]
+    }
+}

Tusker/Views/Attachments/AttachmentView.swift

@@ -25,6 +25,7 @@ class AttachmentView: UIImageView, GIFAnimatable {
     
     var attachment: Attachment!
     var index: Int!
+    var expectedSize: CGSize!
     
     private var attachmentRequest: ImageCache.Request?
     
@@ -35,12 +36,13 @@ class AttachmentView: UIImageView, GIFAnimatable {
 
     public lazy var animator: Animator? = Animator(withDelegate: self)
 
-    init(attachment: Attachment, index: Int) {
+    init(attachment: Attachment, index: Int, expectedSize: CGSize) {
         super.init(image: nil)
         commonInit()
         
         self.attachment = attachment
         self.index = index
+        self.expectedSize = expectedSize
         loadAttachment()
     }
     
@@ -90,6 +92,31 @@ class AttachmentView: UIImageView, GIFAnimatable {
         guard AttachmentsContainerView.supportedAttachmentTypes.contains(attachment.kind) else {
             preconditionFailure("invalid attachment type")
         }
+        
+        if let hash = attachment.blurHash {
+            DispatchQueue.global(qos: .default).async { [weak self] in
+                guard let self = self else { return }
+                let size: CGSize
+                if let meta = self.attachment.meta,
+                   let width = meta.width, let height = meta.height {
+                    size = CGSize(width: width, height: height)
+                } else if let orig = self.attachment.meta?.original,
+                          let width = orig.width, let height = orig.height {
+                    size = CGSize(width: width, height: height)
+                } else {
+                    size = self.expectedSize
+                }
+                if let preview = UIImage(blurHash: hash, size: size) {
+                    DispatchQueue.main.async { [weak self] in
+                        guard let self = self else { return }
+                        if self.image == nil {
+                            self.image = preview
+                        }
+                    }
+                }
+            }
+        }
+        
         switch attachment.kind {
         case .image:
             loadImage()

Tusker/Views/Attachments/AttachmentsContainerView.swift

@@ -65,18 +65,18 @@ class AttachmentsContainerView: UIView {
 
             switch attachments.count {
             case 1:
-                let attachmentView = createAttachmentView(index: 0)
+                let attachmentView = createAttachmentView(index: 0, hSize: .full, vSize: .full)
                 attachmentView.layer.cornerRadius = 5
                 attachmentView.layer.masksToBounds = true
                 fillView(attachmentView)
                 sendSubviewToBack(attachmentView)
                 accessibilityElements.append(attachmentView)
             case 2:
-                let left = createAttachmentView(index: 0)
+                let left = createAttachmentView(index: 0, hSize: .half, vSize: .full)
                 left.layer.cornerRadius = 5
                 left.layer.maskedCorners = [.layerMinXMinYCorner, .layerMinXMaxYCorner]
                 left.layer.masksToBounds = true
-                let right = createAttachmentView(index: 1)
+                let right = createAttachmentView(index: 1, hSize: .half, vSize: .full)
                 right.layer.cornerRadius = 5
                 right.layer.maskedCorners = [.layerMaxXMinYCorner, .layerMaxXMaxYCorner]
                 right.layer.masksToBounds = true
@@ -92,15 +92,15 @@ class AttachmentsContainerView: UIView {
                 accessibilityElements.append(left)
                 accessibilityElements.append(right)
             case 3:
-                let left = createAttachmentView(index: 0)
+                let left = createAttachmentView(index: 0, hSize: .half, vSize: .full)
                 left.layer.cornerRadius = 5
                 left.layer.maskedCorners = [.layerMinXMinYCorner, .layerMinXMaxYCorner]
                 left.layer.masksToBounds = true
-                let topRight = createAttachmentView(index: 1)
+                let topRight = createAttachmentView(index: 1, hSize: .half, vSize: .half)
                 topRight.layer.cornerRadius = 5
                 topRight.layer.maskedCorners = .layerMaxXMinYCorner
                 topRight.layer.masksToBounds = true
-                let bottomRight = createAttachmentView(index: 2)
+                let bottomRight = createAttachmentView(index: 2, hSize: .half, vSize: .half)
                 bottomRight.layer.cornerRadius = 5
                 bottomRight.layer.maskedCorners = .layerMaxXMaxYCorner
                 bottomRight.layer.masksToBounds = true
@@ -121,11 +121,11 @@ class AttachmentsContainerView: UIView {
                 accessibilityElements.append(topRight)
                 accessibilityElements.append(bottomRight)
             case 4:
-                let topLeft = createAttachmentView(index: 0)
+                let topLeft = createAttachmentView(index: 0, hSize: .half, vSize: .half)
                 topLeft.layer.cornerRadius = 5
                 topLeft.layer.maskedCorners = .layerMinXMinYCorner
                 topLeft.layer.masksToBounds = true
-                let bottomLeft = createAttachmentView(index: 2)
+                let bottomLeft = createAttachmentView(index: 2, hSize: .half, vSize: .half)
                 bottomLeft.layer.cornerRadius = 5
                 bottomLeft.layer.maskedCorners = .layerMinXMaxYCorner
                 bottomLeft.layer.masksToBounds = true
@@ -133,11 +133,11 @@ class AttachmentsContainerView: UIView {
                     topLeft,
                     bottomLeft
                 ])
-                let topRight = createAttachmentView(index: 1)
+                let topRight = createAttachmentView(index: 1, hSize: .half, vSize: .half)
                 topRight.layer.cornerRadius = 5
                 topRight.layer.maskedCorners = .layerMaxXMinYCorner
                 topRight.layer.masksToBounds = true
-                let bottomRight = createAttachmentView(index: 3)
+                let bottomRight = createAttachmentView(index: 3, hSize: .half, vSize: .half)
                 bottomRight.layer.cornerRadius = 5
                 bottomRight.layer.maskedCorners = .layerMaxXMaxYCorner
                 bottomRight.layer.masksToBounds = true
@@ -177,11 +177,11 @@ class AttachmentsContainerView: UIView {
                 moreView.addSubview(moreLabel)
                 moreView.accessibilityLabel = moreLabel.text
 
-                let topLeft = createAttachmentView(index: 0)
+                let topLeft = createAttachmentView(index: 0, hSize: .half, vSize: .half)
                 topLeft.layer.cornerRadius = 5
                 topLeft.layer.maskedCorners = .layerMinXMinYCorner
                 topLeft.layer.masksToBounds = true
-                let bottomLeft = createAttachmentView(index: 2)
+                let bottomLeft = createAttachmentView(index: 2, hSize: .half, vSize: .half)
                 bottomLeft.layer.cornerRadius = 5
                 bottomLeft.layer.maskedCorners = .layerMinXMaxYCorner
                 bottomLeft.layer.masksToBounds = true
@@ -189,7 +189,7 @@ class AttachmentsContainerView: UIView {
                     topLeft,
                     bottomLeft
                 ])
-                let topRight = createAttachmentView(index: 1)
+                let topRight = createAttachmentView(index: 1, hSize: .half, vSize: .half)
                 topRight.layer.cornerRadius = 5
                 topRight.layer.maskedCorners = .layerMaxXMinYCorner
                 topRight.layer.masksToBounds = true
@@ -225,8 +225,24 @@ class AttachmentsContainerView: UIView {
         contentHidden = Preferences.shared.blurAllMedia || status.sensitive
     }
     
-    private func createAttachmentView(index: Int) -> AttachmentView {
+    private func createAttachmentView(index: Int, hSize: RelativeSize, vSize: RelativeSize) -> AttachmentView {
-        let attachmentView = AttachmentView(attachment: attachments[index], index: index)
+        let width: CGFloat
+        switch hSize {
+        case .full:
+            width = bounds.width
+        case .half:
+            width = (bounds.width - 4) / 2
+        }
+        let height: CGFloat
+        switch vSize {
+        case .full:
+            height = bounds.height
+        case .half:
+            height = (bounds.height - 4) / 2
+        }
+        let size = CGSize(width: width, height: height)
+        
+        let attachmentView = AttachmentView(attachment: attachments[index], index: index, expectedSize: size)
         attachmentView.delegate = delegate
         attachmentView.translatesAutoresizingMaskIntoConstraints = false
         attachmentView.isAccessibilityElement = true
@@ -376,8 +392,7 @@ class AttachmentsContainerView: UIView {
 
 }
 
-fileprivate extension UIView {
+fileprivate enum RelativeSize {
-    enum RelativeSize {
     case full, half
     
     var multiplier: CGFloat {
@@ -390,6 +405,7 @@ fileprivate extension UIView {
     }
 }
 
+fileprivate extension UIView {
     func halfWidth(spacing: CGFloat = 4) -> NSLayoutConstraint {
         return widthAnchor.constraint(equalTo: superview!.widthAnchor, multiplier: 0.5, constant: -spacing / 2)
     }