Add support to TextProviders for CoreAnimation

Sources/Private/CoreAnimation/CoreAnimationLayer.swift

@@ -98,13 +98,17 @@ final class CoreAnimationLayer: BaseAnimationLayer {
   /// The `AnimationTextProvider` that `TextLayer`'s use to retrieve texts,
   /// that they should use to render their text context
   var textProvider: AnimationTextProvider {
-    didSet { reloadTexts() }
+    didSet {
+      // We need to rebuild the current animation after registering a value provider,
+      // since any existing `CAAnimation`s could now be out of date.
+      rebuildCurrentAnimation()
+    }
   }
 
   /// The `FontProvider` that `TextLayer`s use to retrieve the `CTFont`
   /// that they should use to render their text content
   var fontProvider: AnimationFontProvider {
-    didSet { reloadTexts() }
+    didSet { reloadFonts() }
   }
 
   /// Queues the animation with the given timing configuration
@@ -404,8 +408,8 @@ extension CoreAnimationLayer: RootAnimationLayer {
     }
   }
 
-  func reloadTexts() {
-    // When the text (or font) provider changes, we have to update all `TextLayer`s
+  func reloadFonts() {
+    // When the text provider changes, we have to update all `TextLayer`s
     // so they can query the most up-to-date font from the new font provider.
     for sublayer in allSublayers {
       if let textLayer = sublayer as? TextLayer {

Sources/Private/CoreAnimation/Layers/TextLayer.swift

@@ -26,10 +26,11 @@ final class TextLayer: BaseCompositionLayer {
   override func setupAnimations(context: LayerAnimationContext) throws {
     try super.setupAnimations(context: context)
 
-    // Question 1: Which keypath to pass?
     _ = try context.currentKeypath.keys.map { key in
-      // Question 2: Where do we get the text layer text?
-      let customText = context.textProvider.textFor(keypathName: key, sourceText: "text layer text")
+      // Question 2.1: Should we get from somewhere source text? What if the user has custom name?
+      let customText = context.textProvider.textFor(keypathName: context.currentKeypath.fullPath, sourceText: "text layer text")
+      // Question 2.2: If we don't have this .isEmpty check, then how do we decide when to set our custom text, and when to
+      // set the result of the `exactlyOneKeyFrame()`?
       if customText.isEmpty {
         renderLayer.text = customText
       } else {
@@ -73,7 +74,6 @@ final class TextLayer: BaseCompositionLayer {
         """)
     }
 
-    renderLayer.text = text.text
     renderLayer.font = context.fontProvider.fontFor(family: text.fontFamily, size: CGFloat(text.fontSize))
 
     renderLayer.alignment = text.justification.textAlignment

Tests/SnapshotConfiguration.swift

@@ -23,7 +23,7 @@ struct SnapshotConfiguration {
   var customImageProvider: AnimationImageProvider?
 
   /// A custom `AnimationTextProvider` to use when rendering this animatino
-    var customTextProvider: AnimationTextProvider?
+  var customTextProvider: AnimationTextProvider?
 
   /// A custom `AnimationFontProvider` to use when rendering this animation
   var customFontProvider: AnimationFontProvider?
@@ -74,7 +74,7 @@ extension SnapshotConfiguration {
     "Nonanimating/_dog": .customImageProvider(HardcodedImageProvider(imageName: "Samples/Images/dog.png")),
 
     // Test cases for `AnimatedTextProvider`
-      "": .customTextProvider(HardcodedTextProvider()),
+    "Issues/issue_1722": .customTextProvider(HardcodedTextProvider(text: "Bounce-bounce")),
 
     // Test cases for `AnimationFontProvider`
     "Nonanimating/Text_Glyph": .customFontProvider(HardcodedFontProvider(font: UIFont(name: "Chalkduster", size: 36)!)),

Tests/Utils/HardcodedTextProvider.swift

@@ -11,12 +11,13 @@ import UIKit
 
 /// An `AnimationTextProvider` that always returns a specific hardcoded text
 class HardcodedTextProvider: AnimationTextProvider {
-  // Question 4: What should we actually return here?
+  private let text: String
+
+  init(text: String) {
+    self.text = text
+  }
+
   func textFor(keypathName: String, sourceText: String) -> String {
-    #if os(iOS)
-    return "text layer text"
-    #else
-    return nil
-    #endif
+    text
   }
 }