Dactyloidae iOS initial commit

mobile/ios/Shared/Extensions/UIImageExtensions.swift

@@ -0,0 +1,83 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+import Foundation
+import UIKit
+import SDWebImage
+
+private let imageLock = NSLock()
+
+extension UIImage {
+    /// Despite docs that say otherwise, UIImage(data: NSData) isn't thread-safe (see bug 1223132).
+    /// As a workaround, synchronize access to this initializer.
+    /// This fix requires that you *always* use this over UIImage(data: NSData)!
+    public static func imageFromDataThreadSafe(_ data: Data) -> UIImage? {
+        imageLock.lock()
+        let image = UIImage(data: data)
+        imageLock.unlock()
+        return image
+    }
+
+    /// Generates a UIImage from GIF data by calling out to SDWebImage. The latter in turn uses UIImage(data: NSData)
+    /// in certain cases so we have to synchronize calls (see bug 1223132).
+    public static func imageFromGIFDataThreadSafe(_ data: Data) -> UIImage? {
+        imageLock.lock()
+        let image = UIImage.sd_animatedGIF(with: data)
+        imageLock.unlock()
+        return image
+    }
+
+    public static func dataIsGIF(_ data: Data) -> Bool {
+        guard data.count > 3 else {
+            return false
+        }
+
+        // Look for "GIF" header to identify GIF images
+        var header = [UInt8](repeating: 0, count: 3)
+        data.copyBytes(to: &header, count: 3 * MemoryLayout<UInt8>.size)
+        return header == [0x47, 0x49, 0x46]
+    }
+
+    public static func createWithColor(_ size: CGSize, color: UIColor) -> UIImage {
+        UIGraphicsBeginImageContextWithOptions(size, false, 0.0)
+        let context = UIGraphicsGetCurrentContext()
+        let rect = CGRect(origin: CGPoint.zero, size: size)
+        color.setFill()
+        context!.fill(rect)
+        let image = UIGraphicsGetImageFromCurrentImageContext()
+        UIGraphicsEndImageContext()
+        return image!
+    }
+
+    public func createScaled(_ size: CGSize) -> UIImage {
+        UIGraphicsBeginImageContextWithOptions(size, false, 0)
+        draw(in: CGRect(origin: CGPoint(x: 0, y: 0), size: size))
+        let scaledImage = UIGraphicsGetImageFromCurrentImageContext()
+        UIGraphicsEndImageContext()
+        return scaledImage!
+    }
+
+    public static func templateImageNamed(_ name: String) -> UIImage? {
+        return UIImage(named: name)?.withRenderingMode(.alwaysTemplate)
+    }
+
+    // TESTING ONLY: not for use in release/production code.
+    // PNG comparison can return false negatives, be very careful using for non-equal comparison.
+    // PNG comparison requires UIImages to be constructed the same way in order for the metadata block to match,
+    // this function ensures that.
+    //
+    // This can be verified with this code:
+    //    let image = UIImage(named: "fxLogo")!
+    //    let data = UIImagePNGRepresentation(image)!
+    //    assert(data != UIImagePNGRepresentation(UIImage(data: data)!))
+    @available(*, deprecated, message: "use only in testing code")
+    public func isStrictlyEqual(to other: UIImage) -> Bool {
+        // Must use same constructor for PNG metadata block to be the same.
+        let imageA = UIImage(data: UIImagePNGRepresentation(self)!)!
+        let imageB = UIImage(data: UIImagePNGRepresentation(other)!)!
+        let dataA = UIImagePNGRepresentation(imageA)!
+        let dataB = UIImagePNGRepresentation(imageB)!
+        return dataA == dataB
+    }
+}