[Performance] Skip unchanged UIKit image requests

AsyncImageView/AsyncImageView.swift

@@ -77,13 +77,17 @@ open class AsyncImageView<
 
 	open override var frame: CGRect {
 		didSet {
-			self.requestNewImageIfReady()
+			if self.frame.size != oldValue.size {
+				self.requestNewImageIfReady()
+			}
 		}
 	}
 
 	open override var bounds: CGRect {
 		didSet {
-			self.requestNewImageIfReady()
+			if self.bounds.size != oldValue.size {
+				self.requestNewImageIfReady()
+			}
 		}
 	}
 

AsyncImageViewTests/AsyncImageViewRequestSpec.swift

@@ -0,0 +1,84 @@
+import Quick
+import Nimble
+import UIKit
+
+import ReactiveSwift
+
+import AsyncImageView
+
+class AsyncImageViewRequestSpec: QuickSpec {
+	override class func spec() {
+		describe("AsyncImageView requests") {
+			var counter: Atomic<Int>!
+			var view: AsyncImageView<
+				RequestTestRenderData,
+				RequestTestViewData,
+				RequestTestRenderer,
+				RequestTestRenderer
+			>!
+			var window: UIWindow!
+
+			beforeEach {
+				counter = Atomic(0)
+				view = AsyncImageView<
+					RequestTestRenderData,
+					RequestTestViewData,
+					RequestTestRenderer,
+					RequestTestRenderer
+				>(
+					initialFrame: CGRect(origin: .zero, size: CGSize(width: 10, height: 10)),
+					renderer: RequestTestRenderer(),
+					placeholderRenderer: nil,
+					uiScheduler: ImmediateScheduler(),
+					imageCreationScheduler: ImmediateScheduler()
+				)
+				window = UIWindow()
+				window.addSubview(view)
+				view.data = RequestTestViewData(counter: counter)
+			}
+
+			it("does not create render data for frame origin changes") {
+				for offset in 1...10 {
+					view.frame.origin.x = CGFloat(offset)
+				}
+
+				expect(counter.value) == 1
+			}
+
+			it("does not create render data for bounds origin changes") {
+				for offset in 1...10 {
+					view.bounds.origin.x = CGFloat(offset)
+				}
+
+				expect(counter.value) == 1
+			}
+
+			it("creates render data for size changes") {
+				view.frame.size = CGSize(width: 20, height: 20)
+				view.bounds.size = CGSize(width: 30, height: 30)
+
+				expect(counter.value) == 3
+			}
+		}
+	}
+}
+
+private struct RequestTestViewData: ImageViewDataType {
+	let counter: Atomic<Int>
+
+	func renderDataWithSize(_ size: CGSize) -> RequestTestRenderData {
+		self.counter.modify { $0 += 1 }
+
+		return RequestTestRenderData(size: size)
+	}
+}
+
+private struct RequestTestRenderData: RenderDataType {
+	let size: CGSize
+}
+
+private final class RequestTestRenderer: RendererType {
+	func renderImageWithData(_ data: RequestTestRenderData) -> SignalProducer<UIImage, Never> {
+		return SignalProducer(value: UIImage())
+	}
+}