Capture RCO image data (PNG) for the renderer

RCO IMG entries hold PNG images (magic 89 50 4E 47), decodable directly
by ImageIO/JavaFX. RcoFile now reads pImgData and stores raw image
bytes in ImageObject; the CLI reports the first image's magic.

cli/src/main/java/dev/quoije/umd/cli/Main.java

@@ -409,6 +409,14 @@ public final class Main {
             System.out.printf("%s: valid=%b compression=%d objects=%d images=%d%n",
                     rcoPath, rco.isValid(), rco.compression(), rco.objects().size(), rco.images().size());
 
+            for (Map.Entry<Integer, dev.quoije.umd.rco.object.ImageObject> img : rco.images().entrySet()) {
+                byte[] imgData = img.getValue().getData();
+                System.out.printf("  image 0x%X: %d bytes, magic=%s%n",
+                        img.getKey(), imgData == null ? 0 : imgData.length,
+                        imgData == null ? "null" : hexPrefix(imgData, 8));
+                break;
+            }
+
             System.out.printf("events (%d):%n", rco.events().size());
             for (Map.Entry<Integer, String> event : rco.events().entrySet()) {
                 System.out.printf("  [%3d] %s%n", event.getKey(), event.getValue());

core/src/main/java/dev/quoije/umd/rco/RcoFile.java

@@ -80,6 +80,8 @@ public final class RcoFile {
     private int lTextData;
     private int pLabelData;
     private int lLabelData;
+    private int pImgData;
+    private int lImgData;
     private int pMainTable;
     private int pEventData;
     private int lEventData;
@@ -186,8 +188,12 @@ public final class RcoFile {
         pEventData = read32();
         lEventData = read32();
 
-        // Remaining pointer/data tables (18 ints) plus 3 trailing 0xFFFFFFFF.
-        skip(21 * 4);
+        // Remaining pointer/data tables: 12 pointer ints, then image data,
+        // sound data, model data, and 3 trailing 0xFFFFFFFF.
+        skip(4 * 12);
+        pImgData = read32();
+        lImgData = read32();
+        skip(4 * 7);
     }
 
     private void readEvents() {
@@ -245,12 +251,13 @@ public final class RcoFile {
                 if (entry.type == 1) {
                     skip(2); // format
                     int comp = read16();
-                    skip(4); // sizePacked
-                    skip(4); // offset
+                    int sizePacked = read32();
+                    int imgOffset = read32();
                     if (comp != COMPRESSION_NONE) {
                         skip(4); // sizeUnpacked
                     }
-                    images.put(entryOffset, new ImageObject(null));
+                    byte[] imgData = readImageData(imgOffset, sizePacked);
+                    images.put(entryOffset, new ImageObject(imgData));
                 }
             }
             case TABLE_MODEL -> {
@@ -327,6 +334,15 @@ public final class RcoFile {
         return entry;
     }
 
+    private byte[] readImageData(int imgOffset, int length) {
+        if (imgOffset == RCO_NULL_PTR || length <= 0 || pImgData + imgOffset + length > buffer.length) {
+            return null;
+        }
+        byte[] data = new byte[length];
+        System.arraycopy(buffer, pImgData + imgOffset, data, 0, length);
+        return data;
+    }
+
     private String readLabel(int labelOffset) {
         int current = tell();
         seek(pLabelData + labelOffset);