Improve spritesheet file search for Aseprite import

Now searches directory of .json too if the file given in .json metadata can't be found.
Also, modifies affected test.

src/de/gurkenlabs/litiengine/graphics/animation/AsepriteHandler.java

@@ -4,13 +4,16 @@
 import java.io.FileReader;
 import java.io.FileNotFoundException;
 import java.io.IOException;
+import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.awt.Dimension;
 import java.awt.Image;
 import java.awt.image.BufferedImage;
 import java.util.Set;
 import java.util.Map;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Arrays;
 import javax.imageio.ImageIO;
 
 import com.google.gson.Gson;
@@ -43,7 +46,6 @@ public ImportAnimationException(String message) {
 
   /** 
    * Imports an Aseprite animation (.json + sprite sheet).
-   * Note: searches for sprite sheet path through .json metadata, specifically 'image' element. This should be an absolute path in system.
    *
    * @param jsonPath path (including filename) to Aseprite JSON.
    * 
@@ -57,11 +59,11 @@ public static Animation importAnimation(String jsonPath) throws IOException, Fil
       throw new FileNotFoundException("FileNotFoundException: Could not find .json file " + jsonPath);
     }
 
-    String spriteSheetPath = getSpriteSheetPath(rootElement);
-    File spriteSheetFile = new File(spriteSheetPath);
-    if(!spriteSheetFile.exists()) {
+    File spriteSheetFile = null;
+    try { spriteSheetFile = getSpriteSheetFile(rootElement, jsonPath); }
+    catch(FileNotFoundException e) {
       throw new FileNotFoundException("FileNotFoundException: Could not find sprite sheet file. " +
-                                      "Expected location is 'image' in .json metadata, which evaluates to: " + spriteSheetPath);
+                                      "Expected location is 'image' in .json metadata, or same folder as .json file.");
     }
 
     Dimension keyFrameDimensions = getKeyFrameDimensions(rootElement);
@@ -74,7 +76,7 @@ public static Animation importAnimation(String jsonPath) throws IOException, Fil
       }
 
       Spritesheet spriteSheet = new Spritesheet(image,
-                                                spriteSheetPath,
+                                                spriteSheetFile.getPath().toString(),
                                                 (int)keyFrameDimensions.getWidth(),
                                                 (int)keyFrameDimensions.getHeight());
 
@@ -100,6 +102,51 @@ private static JsonElement getRootJsonElement(String jsonPath) throws FileNotFou
     catch(FileNotFoundException e) { throw e; }
   }
 
+  /**
+   * Searches for sprite sheet path through .json metadata, or same folder as .json file.
+   * @param rootElement root element of JSON data.
+   * @param jsonPath path (including filename) to .json Aseprite file.
+   *
+   * @return sprite sheet file if it can be found, else an exception is thrown.
+   * */
+  private static File getSpriteSheetFile(JsonElement rootElement, String jsonPath) throws FileNotFoundException {
+
+    //try searching path supplied in .json data
+    JsonElement metaData = rootElement.getAsJsonObject().get("meta");
+    String spriteSheetPath = metaData.getAsJsonObject().get("image").getAsString();
+
+    File spriteSheetFile = new File(spriteSheetPath);
+
+    if(spriteSheetFile.exists())
+      return spriteSheetFile;
+
+    //try searching local directory
+    Path jsonFilePath = Paths.get(jsonPath);
+    String dirPath = jsonFilePath.getParent().toString();
+    String fileName1 = jsonFilePath.getFileName().toString();
+    String alternative1 = fileName1.substring(0, fileName1.lastIndexOf(".")); //same file name as .json
+
+    Path spriteSheetFilePath = Paths.get(spriteSheetPath);
+    String fileName2 = spriteSheetFilePath.getFileName().toString();
+    String alternative2 = fileName2.substring(0, fileName2.lastIndexOf(".")); //same file name as 'image' element
+
+    List<String> suffixes = Arrays.asList(".png", ".jpg", ".jpeg");
+    for(String suffix : suffixes) {
+
+      String alternativeFile1 = dirPath + "/" + alternative1 + suffix;
+      spriteSheetFile = new File(alternativeFile1);
+      if(spriteSheetFile.exists())
+        return spriteSheetFile;
+
+      String alternativeFile2 = dirPath + "/" + alternative2 + suffix;
+      spriteSheetFile = new File(alternativeFile2);
+      if(spriteSheetFile.exists())
+        return spriteSheetFile;
+    }
+
+    throw new FileNotFoundException();
+  }
+
   /**
    * @param rootElement root element of JSON data.
    *
@@ -370,4 +417,4 @@ public Layer(String name, int opacity, String blendMode){
         }
 
     } 
-}
+}

tests/de/gurkenlabs/litiengine/graphics/animation/AsepriteHandlerTests.java

@@ -74,7 +74,7 @@ public void FileNotFoundExceptionTest(){
     Throwable exception_withoutJsonFile = assertThrows(FileNotFoundException.class, () -> AsepriteHandler.importAnimation("tests/de/gurkenlabs/litiengine/graphics/animation/aseprite_test_animations/Sprite-0003.json"));
     assertEquals("FileNotFoundException: Could not find .json file tests/de/gurkenlabs/litiengine/graphics/animation/aseprite_test_animations/Sprite-0003.json", exception_withoutJsonFile.getMessage());
     Throwable exception_withoutSpriteSheet = assertThrows(FileNotFoundException.class, () -> AsepriteHandler.importAnimation("tests/de/gurkenlabs/litiengine/graphics/animation/aseprite_test_animations/Sprite-0004.json"));
-    assertEquals("FileNotFoundException: Could not find sprite sheet file. Expected location is 'image' in .json metadata, which evaluates to: tests/de/gurkenlabs/litiengine/graphics/animation/aseprite_test_animations/Sprite-0002-sheet.png", exception_withoutSpriteSheet.getMessage());
+    assertEquals("FileNotFoundException: Could not find sprite sheet file. Expected location is 'image' in .json metadata, or same folder as .json file.", exception_withoutSpriteSheet.getMessage());
   }
 
   /**