Add BlurEffect support

Example/Example.xcodeproj/project.pbxproj

@@ -39,6 +39,13 @@
 			remoteGlobalIDString = 275751E22DEE1441003E467C;
 			remoteInfo = TestingHost;
 		};
+		27DC9A772F2017EA00F8F371 /* PBXContainerItemProxy */ = {
+			isa = PBXContainerItemProxy;
+			containerPortal = 27CD0B412AFC8D37003665EB /* Project object */;
+			proxyType = 1;
+			remoteGlobalIDString = 27D49DF72BA604FB00F6E2E2;
+			remoteInfo = HostingExample;
+		};
 /* End PBXContainerItemProxy section */
 
 /* Begin PBXFileReference section */
@@ -233,6 +240,7 @@
 			);
 			dependencies = (
 				279080A42E8E600A0082B5B6 /* PBXTargetDependency */,
+				27DC9A782F2017EA00F8F371 /* PBXTargetDependency */,
 			);
 			fileSystemSynchronizedGroups = (
 				275751F62DEE1456003E467C /* OpenSwiftUIUITests */,
@@ -310,7 +318,7 @@
 					};
 					279283B82DFF11CE00234D64 = {
 						CreatedOnToolsVersion = 16.3;
-						TestTargetID = 275751E22DEE1441003E467C;
+						TestTargetID = 27D49DF72BA604FB00F6E2E2;
 					};
 					27CD0B482AFC8D37003665EB = {
 						CreatedOnToolsVersion = 15.0;
@@ -414,6 +422,11 @@
 			target = 275751E22DEE1441003E467C /* TestingHost */;
 			targetProxy = 279080A32E8E600A0082B5B6 /* PBXContainerItemProxy */;
 		};
+		27DC9A782F2017EA00F8F371 /* PBXTargetDependency */ = {
+			isa = PBXTargetDependency;
+			target = 27D49DF72BA604FB00F6E2E2 /* HostingExample */;
+			targetProxy = 27DC9A772F2017EA00F8F371 /* PBXContainerItemProxy */;
+		};
 /* End PBXTargetDependency section */
 
 /* Begin XCBuildConfiguration section */
@@ -1103,7 +1116,7 @@
 				SUPPORTS_MACCATALYST = NO;
 				SWIFT_EMIT_LOC_STRINGS = NO;
 				TARGETED_DEVICE_FAMILY = "1,2,7";
-				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/TestingHost.app/$(BUNDLE_EXECUTABLE_FOLDER_PATH)/TestingHost";
+				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/HostingExample.app/$(BUNDLE_EXECUTABLE_FOLDER_PATH)/HostingExample";
 			};
 			name = SwiftUIDebug;
 		};
@@ -1125,7 +1138,7 @@
 				SUPPORTS_MACCATALYST = NO;
 				SWIFT_EMIT_LOC_STRINGS = NO;
 				TARGETED_DEVICE_FAMILY = "1,2,7";
-				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/TestingHost.app/$(BUNDLE_EXECUTABLE_FOLDER_PATH)/TestingHost";
+				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/HostingExample.app/$(BUNDLE_EXECUTABLE_FOLDER_PATH)/HostingExample";
 			};
 			name = SwiftUIRelease;
 		};
@@ -1147,7 +1160,7 @@
 				SUPPORTS_MACCATALYST = NO;
 				SWIFT_EMIT_LOC_STRINGS = NO;
 				TARGETED_DEVICE_FAMILY = "1,2,7";
-				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/TestingHost.app/$(BUNDLE_EXECUTABLE_FOLDER_PATH)/TestingHost";
+				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/HostingExample.app/$(BUNDLE_EXECUTABLE_FOLDER_PATH)/HostingExample";
 			};
 			name = OpenSwiftUIDebug;
 		};
@@ -1169,7 +1182,7 @@
 				SUPPORTS_MACCATALYST = NO;
 				SWIFT_EMIT_LOC_STRINGS = NO;
 				TARGETED_DEVICE_FAMILY = "1,2,7";
-				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/TestingHost.app/$(BUNDLE_EXECUTABLE_FOLDER_PATH)/TestingHost";
+				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/HostingExample.app/$(BUNDLE_EXECUTABLE_FOLDER_PATH)/HostingExample";
 			};
 			name = OpenSwiftUIRelease;
 		};

Example/OpenSwiftUIUITests/Render/RendererEffect/BlurEffectUITests.swift

@@ -0,0 +1,25 @@
+//
+//  BlurEffectUITests.swift
+//  OpenSwiftUIUITests
+
+import Testing
+import SnapshotTesting
+
+@MainActor
+@Suite(.snapshots(record: .never, diffTool: diffTool))
+struct BlurEffectUITests {
+    @Test
+    func blurColor() {
+        struct ContentView: View {
+            var body: some View {
+                Color.blue
+                    .frame(width: 100, height: 100)
+                    .blur(radius: 10)
+                    .background(Color.red)
+            }
+        }
+        openSwiftUIAssertSnapshot(of: ContentView(), drawHierarchyInKeyWindow: true)
+    }
+
+    // TODO: blur image test when named image is supported
+}

Example/OpenSwiftUIUITests/UITests/SnapshotTesting+Testing.swift

@@ -38,6 +38,7 @@ let defaultSize = CGSize(width: 200, height: 200)
 
 func openSwiftUIAssertSnapshot<V: View>(
     of value: @autoclosure () -> V,
+    drawHierarchyInKeyWindow: Bool = false,
     perceptualPrecision: Float = 1,
     size: CGSize = defaultSize,
     named name: String? = nil,
@@ -51,7 +52,7 @@ func openSwiftUIAssertSnapshot<V: View>(
 ) {
     openSwiftUIAssertSnapshot(
         of: PlatformHostingController(rootView: value()),
-        as: .image(perceptualPrecision: perceptualPrecision, size: size),
+        as: .image(drawHierarchyInKeyWindow: drawHierarchyInKeyWindow, perceptualPrecision: perceptualPrecision, size: size),
         named: (name.map { ".\($0)" } ?? "") + "\(Int(size.width))x\(Int(size.height))",
         record: recording,
         timeout: timeout,

Example/TestingHost/TestingHostApp.swift

@@ -2,6 +2,9 @@
 //  TestingHostApp.swift
 //  TestingHost
 
+// FIXME: OpenSwiftUI does not set up key window correctly
+// -> use HostingExample as OpenSwiftUIUITests's host temporary to add drawHierarchyInKeyWindow support
+
 #if OPENSWIFTUI
 import OpenSwiftUI
 #else
@@ -16,6 +19,7 @@ import UIKit
 
 @main
 struct TestingHostApp: App {
+    // FIXME: OpenSwiftUI does not support ApplicationDelegateAdaptor yet
     #if !OPENSWIFTUI
     #if canImport(AppKit)
     @NSApplicationDelegateAdaptor(AppDelegate.self) var appDelegate

Sources/OpenSwiftUICore/Render/RendererEffect/BlurEffect.swift

@@ -0,0 +1,87 @@
+//
+//  BlurEffect.swift
+//  OpenSwiftUICore
+//
+//  Audited for 6.5.4
+//  Status: Complete
+
+public import Foundation
+
+// MARK: - _BlurEffect
+
+/// A blur effect applied to a view.
+@available(OpenSwiftUI_v1_0, *)
+@frozen
+public struct _BlurEffect: RendererEffect, Equatable {
+
+    public var radius: CGFloat
+
+    public var isOpaque: Bool
+
+    @inlinable
+    public init(radius: CGFloat, opaque: Bool) {
+        self.radius = radius
+        self.isOpaque = opaque
+    }
+
+    public var animatableData: CGFloat {
+        get { radius }
+        set { radius = newValue }
+    }
+
+    package var descriptionAttributes: [(name: String, value: String)] {
+        var attributes: [(name: String, value: String)] = []
+        attributes.append(("radius", radius.description))
+        attributes.append(("isOpaque", isOpaque ? "true" : "false"))
+        return attributes
+    }
+
+    package func effectValue(size: CGSize) -> DisplayList.Effect {
+        .filter(.blur(BlurStyle(radius: radius, isOpaque: isOpaque)))
+    }
+
+    nonisolated public static func == (a: _BlurEffect, b: _BlurEffect) -> Swift.Bool {
+        a.radius == b.radius && a.isOpaque == b.isOpaque
+    }
+}
+
+// MARK: - View + blur
+
+@available(OpenSwiftUI_v1_0, *)
+extension View {
+
+    /// Applies a Gaussian blur to this view.
+    ///
+    /// Use `blur(radius:opaque:)` to apply a gaussian blur effect to the
+    /// rendering of this view.
+    ///
+    /// The example below shows two ``Text`` views, the first with no blur
+    /// effects, the second with `blur(radius:opaque:)` applied with the
+    /// `radius` set to `2`. The larger the radius, the more diffuse the
+    /// effect.
+    ///
+    ///     struct Blur: View {
+    ///         var body: some View {
+    ///             VStack {
+    ///                 Text("This is some text.")
+    ///                     .padding()
+    ///                 Text("This is some blurry text.")
+    ///                     .blur(radius: 2.0)
+    ///             }
+    ///         }
+    ///     }
+    ///
+    /// ![A screenshot showing the effect of applying gaussian blur effect to
+    /// the rendering of a view.](OpenSwiftUI-View-blurRadius.png)
+    ///
+    /// - Parameters:
+    ///   - radius: The radial size of the blur. A blur is more diffuse when its
+    ///     radius is large.
+    ///   - opaque: A Boolean value that indicates whether the blur renderer
+    ///     permits transparency in the blur output. Set to `true` to create an
+    ///     opaque blur, or set to `false` to permit transparency.
+    @inlinable
+    nonisolated public func blur(radius: CGFloat, opaque: Bool = false) -> some View {
+        return modifier(_BlurEffect(radius: radius, opaque: opaque))
+    }
+}