gif snapshot handler

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

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2020 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package app.cash.paparazzi
+
+import app.cash.paparazzi.SnapshotHandler.FrameHandler
+import app.cash.paparazzi.internal.ImageUtils
+import java.awt.image.BufferedImage
+import java.io.File
+import javax.imageio.ImageIO
+
+class GifSnapshotHandler @JvmOverloads constructor(
+  private val maxPercentDifference: Double = 0.1,
+  rootDirectory: File = File(System.getProperty("paparazzi.snapshot.dir"))
+) : SnapshotHandler {
+  private val imagesDirectory: File = File(rootDirectory, "images")
+  private val videosDirectory: File = File(rootDirectory, "videos")
+
+  init {
+    imagesDirectory.mkdirs()
+    videosDirectory.mkdirs()
+  }
+
+  override fun newFrameHandler(
+    snapshot: Snapshot,
+    frameCount: Int,
+    fps: Int
+  ): FrameHandler {
+    return object : FrameHandler {
+      override fun handle(
+        image: BufferedImage,
+        frameIndex: Int?,
+      ) {
+        // handle() gets called with each image when gif() is used
+        val expected = File(
+          imagesDirectory,
+          snapshot.toFileName(
+            extension = "png",
+            frameIndex = frameIndex
+          )
+        )
+        if (!expected.exists()) {
+          throw AssertionError("File $expected does not exist")
+        }
+        val goldenImage = ImageIO.read(expected)
+        ImageUtils.assertImageSimilar(
+          relativePath = expected.path,
+          image = image,
+          goldenImage = goldenImage,
+          maxPercentDifferent = maxPercentDifference
+        )
+      }
+
+      override fun close() = Unit
+    }
+  }
+
+  override fun close() = Unit
+}

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

@@ -91,7 +91,7 @@ class HtmlReportWriter @JvmOverloads constructor(
     return object : FrameHandler {
       val hashes = mutableListOf<String>()
 
-      override fun handle(image: BufferedImage) {
+      override fun handle(image: BufferedImage, frameIndex: Int?) {
         hashes += writeImage(image)
       }
 
@@ -111,7 +111,8 @@ class HtmlReportWriter @JvmOverloads constructor(
           if (isRecording) {
             for ((index, frameHash) in hashes.withIndex()) {
               val originalFrame = File(imagesDirectory, "$frameHash.png")
-              val frameSnapshot = snapshot.copy(name = "${snapshot.name} $index")
+              val name = snapshot.name?.let { "$it $index" } ?: "$index"
+              val frameSnapshot = snapshot.copy(name = name)
               val goldenFile = File(goldenImagesDirectory, frameSnapshot.toFileName("_", "png"))
               if (!goldenFile.exists()) {
                 originalFrame.copyTo(goldenFile)

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

@@ -323,7 +323,7 @@ class Paparazzi @JvmOverloads constructor(
               }
               validateLayoutAccessibility(modifiedView, image)
             }
-            frameHandler.handle(scaleImage(frameImage(image)))
+            frameHandler.handle(scaleImage(frameImage(image)), frame)
           }
         }
       } finally {
@@ -659,5 +659,12 @@ class Paparazzi @JvmOverloads constructor(
       } else {
         HtmlReportWriter()
       }
+
+    fun determineGifHandler(maxPercentDifference: Double = 0.1): SnapshotHandler =
+      if (isVerifying) {
+        GifSnapshotHandler(maxPercentDifference)
+      } else {
+        HtmlReportWriter()
+      }
   }
 }

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

@@ -30,12 +30,18 @@ data class Snapshot(
 
 internal fun Snapshot.toFileName(
   delimiter: String = "_",
-  extension: String
+  extension: String,
+  frameIndex: Int? = null,
 ): String {
   val formattedLabel = if (name != null) {
     "$delimiter${name.toLowerCase(Locale.US).replace("\\s".toRegex(), delimiter)}"
   } else {
     ""
   }
-  return "${testName.packageName}${delimiter}${testName.className}${delimiter}${testName.methodName}$formattedLabel.$extension"
+  return if (frameIndex != null) {
+    "${testName.packageName}${delimiter}${testName.className}${delimiter}${testName.methodName}_$frameIndex.$extension"
+  } else {
+    "${testName.packageName}${delimiter}${testName.className}${delimiter}${testName.methodName}$formattedLabel.$extension"
+  }
+
 }

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

@@ -26,6 +26,6 @@ interface SnapshotHandler : Closeable {
   ): FrameHandler
 
   interface FrameHandler : Closeable {
-    fun handle(image: BufferedImage)
+    fun handle(image: BufferedImage, frameIndex: Int? = null)
   }
 }

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

@@ -39,7 +39,7 @@ class SnapshotVerifier @JvmOverloads constructor(
     fps: Int
   ): FrameHandler {
     return object : FrameHandler {
-      override fun handle(image: BufferedImage) {
+      override fun handle(image: BufferedImage, frameIndex: Int?) {
         // Note: does not handle videos or its frames at the moment
         val expected = File(imagesDirectory, snapshot.toFileName(extension = "png"))
         if (!expected.exists()) {