Expose API to get original value from animation (#1559)

Fixes #1547

Lottie.xcodeproj/project.pbxproj

@@ -545,6 +545,7 @@
 		2EAF5B0427A0798700E00531 /* AnimationFontProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2EAF59F227A0798700E00531 /* AnimationFontProvider.swift */; };
 		2EAF5B0527A0798700E00531 /* AnimationFontProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2EAF59F227A0798700E00531 /* AnimationFontProvider.swift */; };
 		2EAF5B0627A0798700E00531 /* AnimationFontProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2EAF59F227A0798700E00531 /* AnimationFontProvider.swift */; };
+		6DB3BDB628243FA5002A276D /* ValueProvidersTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6DB3BDB528243FA5002A276D /* ValueProvidersTests.swift */; };
 		A1D5BAAC27C731A500777D06 /* DataURLTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = A1D5BAAB27C731A500777D06 /* DataURLTests.swift */; };
 /* End PBXBuildFile section */
 
@@ -749,6 +750,7 @@
 		2EAF59EF27A0798700E00531 /* GradientValueProvider.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = GradientValueProvider.swift; sourceTree = "<group>"; };
 		2EAF59F027A0798700E00531 /* PointValueProvider.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = PointValueProvider.swift; sourceTree = "<group>"; };
 		2EAF59F227A0798700E00531 /* AnimationFontProvider.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AnimationFontProvider.swift; sourceTree = "<group>"; };
+		6DB3BDB528243FA5002A276D /* ValueProvidersTests.swift */ = {isa = PBXFileReference; indentWidth = 2; lastKnownFileType = sourcecode.swift; path = ValueProvidersTests.swift; sourceTree = "<group>"; tabWidth = 2; };
 		A1D5BAAB27C731A500777D06 /* DataURLTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DataURLTests.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
@@ -818,6 +820,7 @@
 				A1D5BAAB27C731A500777D06 /* DataURLTests.swift */,
 				2E8040BD27A07343006E74CB /* Utils */,
 				2E044E262820536800FA773B /* AutomaticEngineTests.swift */,
+				6DB3BDB528243FA5002A276D /* ValueProvidersTests.swift */,
 			);
 			path = Tests;
 			sourceTree = "<group>";
@@ -1809,6 +1812,7 @@
 				2EAF59A727A076BC00E00531 /* Bundle+Module.swift in Sources */,
 				2E8044AE27A07347006E74CB /* Snapshotting+presentationLayer.swift in Sources */,
 				2E72128527BB32DB0027BC56 /* PerformanceTests.swift in Sources */,
+				6DB3BDB628243FA5002A276D /* ValueProvidersTests.swift in Sources */,
 				2E72128327BB329C0027BC56 /* AnimationKeypathTests.swift in Sources */,
 				2E044E272820536800FA773B /* AutomaticEngineTests.swift in Sources */,
 			);

Sources/Private/CoreAnimation/CoreAnimationLayer.swift

@@ -395,6 +395,13 @@ extension CoreAnimationLayer: RootAnimationLayer {
     return nil
   }
 
+  func getOriginalValue(for _: AnimationKeypath, atFrame _: AnimationFrameTime?) -> Any? {
+    LottieLogger.shared.assertionFailure("""
+      The Core Animation rendering engine doesn't support querying values for individual frames
+      """)
+    return nil
+  }
+
   func layer(for _: AnimationKeypath) -> CALayer? {
     LottieLogger.shared.assertionFailure("`AnimationKeypath`s are currently unsupported")
     return nil

Sources/Private/MainThread/LayerContainers/MainThreadAnimationLayer.swift

@@ -216,6 +216,18 @@ final class MainThreadAnimationLayer: CALayer, RootAnimationLayer {
     return nil
   }
 
+  func getOriginalValue(for keypath: AnimationKeypath, atFrame: AnimationFrameTime?) -> Any? {
+    for layer in animationLayers {
+      if
+        let foundProperties = layer.nodeProperties(for: keypath),
+        let first = foundProperties.first
+      {
+        return first.originalValueProvider.value(frame: atFrame ?? currentFrame)
+      }
+    }
+    return nil
+  }
+
   func layer(for keypath: AnimationKeypath) -> CALayer? {
     for layer in animationLayers {
       if let foundLayer = layer.layer(for: keypath) {

Sources/Private/MainThread/NodeRenderSystem/NodeProperties/NodeProperty.swift

@@ -15,13 +15,15 @@ class NodeProperty<T>: AnyNodeProperty {
 
   init(provider: AnyValueProvider) {
     valueProvider = provider
+    originalValueProvider = valueProvider
     typedContainer = ValueContainer<T>(provider.value(frame: 0) as! T)
     typedContainer.setNeedsUpdate()
   }
 
   // MARK: Internal
 
   var valueProvider: AnyValueProvider
+  var originalValueProvider: AnyValueProvider
 
   var valueType: Any.Type { T.self }
 

Sources/Private/MainThread/NodeRenderSystem/NodeProperties/Protocols/AnyNodeProperty.swift

@@ -25,6 +25,9 @@ protocol AnyNodeProperty {
   /// The value provider for the property
   var valueProvider: AnyValueProvider { get }
 
+  /// The original value provider for the property
+  var originalValueProvider: AnyValueProvider { get }
+
   /// The Type of the value provider
   var valueType: Any.Type { get }
 

Sources/Private/RootAnimationLayer.swift

@@ -30,6 +30,7 @@ protocol RootAnimationLayer: CALayer {
 
   func setValueProvider(_ valueProvider: AnyValueProvider, keypath: AnimationKeypath)
   func getValue(for keypath: AnimationKeypath, atFrame: AnimationFrameTime?) -> Any?
+  func getOriginalValue(for keypath: AnimationKeypath, atFrame: AnimationFrameTime?) -> Any?
 
   func layer(for keypath: AnimationKeypath) -> CALayer?
   func animatorNodes(for keypath: AnimationKeypath) -> [AnimatorNode]?

Sources/Public/Animation/AnimationView.swift

@@ -534,6 +534,16 @@ final public class AnimationView: AnimationViewBase {
     animationLayer?.getValue(for: keypath, atFrame: atFrame)
   }
 
+  /// Reads the original value of a property specified by the Keypath.
+  /// This will ignore any value providers and can be useful when implementing a value providers that makes change to the original value from the animation.
+  /// Returns nil if no property is found.
+  ///
+  /// - Parameter for: The keypath used to search for the property.
+  /// - Parameter atFrame: The Frame Time of the value to query. If nil then the current frame is used.
+  public func getOriginalValue(for keypath: AnimationKeypath, atFrame: AnimationFrameTime?) -> Any? {
+    animationLayer?.getOriginalValue(for: keypath, atFrame: atFrame)
+  }
+
   /// Logs all child keypaths.
   public func logHierarchyKeypaths() {
     animationLayer?.logHierarchyKeypaths()

Tests/ValueProvidersTests.swift

@@ -0,0 +1,27 @@
+//
+//  ValueProvidersTests.swift
+//  LottieTests
+//
+//  Created by Marcelo Fabri on 5/5/22.
+//
+
+import Lottie
+import XCTest
+
+final class ValueProvidersTests: XCTestCase {
+
+  func testGetValue() throws {
+    let animationView = try XCTUnwrap(SnapshotConfiguration.makeAnimationView(
+      for: "HamburgerArrow",
+      configuration: .init(renderingEngine: .mainThread)))
+
+    let keypath = AnimationKeypath(keypath: "A1.Shape 1.Stroke 1.Color")
+    animationView.setValueProvider(ColorValueProvider(.red), keypath: keypath)
+    let updatedColor = try XCTUnwrap(animationView.getValue(for: keypath, atFrame: 0) as? Color)
+    XCTAssertEqual(updatedColor, .red)
+
+    let originalColor = try XCTUnwrap(animationView.getOriginalValue(for: keypath, atFrame: 0) as? Color)
+    XCTAssertEqual(originalColor, Color(r: 0.4, g: 0.16, b: 0.7, a: 1))
+  }
+
+}