Fixed invalid extraction of image dimensions for HEIF files w/ multiple images

Source/com/drew/metadata/heif/boxes/ImageRotationBox.java

@@ -22,6 +22,14 @@ public ImageRotationBox(SequentialReader reader, Box box) throws IOException
 
     public void addMetadata(HeifDirectory directory)
     {
+        // There may be several images in the HEIF file, what we'd like to return is the rotation
+        // of the "main" image. We assume that if there are several images, they all have the same
+        // rotation (and as such we can just take the first rotation that we encounter).
+        // That is a bold assumption, but should be right most of the time.
+        // In the wild, the rotation attribute is mainly used for efficiency on cameras, as it avoids
+        // having to rotate the whole framebuffer (the camera just records the wanted rotation). There
+        // is no reason a priori to expect the camera to not use this optimization for each image in the
+        // HEIF file.
         if (!directory.containsTag(HeifDirectory.TAG_IMAGE_ROTATION)) {
             directory.setInt(HeifDirectory.TAG_IMAGE_ROTATION, angle);
         }

Source/com/drew/metadata/heif/boxes/ImageSpatialExtentsProperty.java

@@ -21,6 +21,7 @@
 package com.drew.metadata.heif.boxes;
 
 import com.drew.lang.SequentialReader;
+import com.drew.metadata.MetadataException;
 import com.drew.metadata.heif.HeifDirectory;
 
 import java.io.IOException;
@@ -43,7 +44,28 @@ public ImageSpatialExtentsProperty(SequentialReader reader, Box box) throws IOEx
 
     public void addMetadata(HeifDirectory directory)
     {
-        if (!directory.containsTag(HeifDirectory.TAG_IMAGE_WIDTH) && !directory.containsTag(HeifDirectory.TAG_IMAGE_HEIGHT)) {
+        if (directory.containsTag(HeifDirectory.TAG_IMAGE_WIDTH) && directory.containsTag(HeifDirectory.TAG_IMAGE_HEIGHT)) {
+            // There may be several images in the HEIF file, what we'd like to return is the width and height
+            // of the "main" image.
+            // We assume that the main image is the biggest image, so we want to take the max width & height.
+            // While it is not guaranteed to be correct, this is a pretty safe bet and seems to be validated
+            // by actual images found in the wild (additional images in practice are often thumbnails or overlays,
+            // that are going to be smaller that the main image).
+            // Note that here we also assume that if width is bigger than the preexisting value, so is height.
+            try {
+                directory.setLong(
+                    HeifDirectory.TAG_IMAGE_WIDTH,
+                    Math.max(directory.getInt(HeifDirectory.TAG_IMAGE_WIDTH), width)
+                );
+                directory.setLong(
+                    HeifDirectory.TAG_IMAGE_HEIGHT,
+                    Math.max(directory.getInt(HeifDirectory.TAG_IMAGE_HEIGHT), height)
+                );
+            } catch(MetadataException ex) {
+                // We could not read width and height tags as int values (unexpected type ?).
+                // We just ignore this. It should never ever happen given that we always set those to int values.
+            }
+        } else {
             directory.setLong(HeifDirectory.TAG_IMAGE_WIDTH, width);
             directory.setLong(HeifDirectory.TAG_IMAGE_HEIGHT, height);
         }