Add support for Lottie animations to respect offsetMillis

Author: geoff-powell

paparazzi/src/main/java/app/cash/paparazzi/PaparazziSdk.kt

@@ -323,6 +323,12 @@ public class PaparazziSdk @JvmOverloads constructor(
 
         // If we have pendingTasks run recomposer to ensure we get the correct frame.
         var hasPendingWork = false
+
+        if (startNanos > 0) {
+          // Initialize the choreographer at time=1 to initialize non sdk animations that rely on lastFrameTimeNanos=0 logic to track animation progress
+          withTime(1) {}
+        }
+
         withTime(nowNanos) {
           val result = renderSession.render(true)
           if (result.status == ERROR_UNKNOWN) {

sample/src/test/java/app/cash/paparazzi/sample/LottieTest.kt

@@ -3,21 +3,38 @@ package app.cash.paparazzi.sample
 import app.cash.paparazzi.Paparazzi
 import com.airbnb.lottie.LottieAnimationView
 import com.airbnb.lottie.LottieCompositionFactory
+import com.airbnb.lottie.LottieTask
+import org.junit.Before
 import org.junit.Rule
 import org.junit.Test
+import java.util.concurrent.Executor
 
 class LottieTest {
   @get:Rule
   var paparazzi = Paparazzi()
 
+
+  @Before
+  fun setup() {
+    LottieTask.EXECUTOR = Executor(Runnable::run)
+  }
+
   @Test
   fun lottie() {
     val composition = LottieCompositionFactory.fromRawResSync(paparazzi.context, R.raw.lottie_logo)
       .value!!
     val view = LottieAnimationView(paparazzi.context)
     view.setComposition(composition)
-//    view.progress = 1.0f
-//    paparazzi.snapshot(view, "lottie logo")
+
+    view.playAnimation()
+    paparazzi.snapshot(view, name = "start", offsetMillis = 0L)
+    paparazzi.snapshot(view, name = "middle", offsetMillis = 2500L)
+    paparazzi.snapshot(view, name = "end", offsetMillis = 5000L)
+    view.cancelAnimation()
+
+    view.progress = 1.0f
+    paparazzi.snapshot(view, "lottie logo")
+
     view.playAnimation()
     paparazzi.gif(view, "lottie logo", start = 0L, end = 5000L, fps = 60)
   }
@@ -27,15 +44,16 @@ class LottieTest {
     val composition = LottieCompositionFactory.fromRawResSync(paparazzi.context, R.raw.masks).value!!
     val view = LottieAnimationView(paparazzi.context)
     view.setComposition(composition)
+    view.progress = 0.0f
+    paparazzi.snapshot(view, "masks0")
+
+    view.progress = 0.5f
+    paparazzi.snapshot(view, "masks1")
+
+    view.progress = 1.0f
+    paparazzi.snapshot(view, "masks2")
+
     view.playAnimation()
-//    view.progress = 0.0f
-//    paparazzi.snapshot(view, "masks0")
-//
-//    view.progress = 0.5f
-//    paparazzi.snapshot(view, "masks1")
-//
-//    view.progress = 1.0f
-//    paparazzi.snapshot(view, "masks2")
     paparazzi.gif(view, "masks", start = 0L, end = 5000L, fps = 60)
   }
 }