Use event classes for better flexibility and type hinting

src/Decoder.php

@@ -1,6 +1,7 @@
 <?php
 namespace GIFEndec;
 
+use GIFEndec\Events\FrameDecodedEvent;
 use GIFEndec\Geometry\Point;
 use GIFEndec\Geometry\Rectangle;
 use GIFEndec\IO\PhpStream;
@@ -96,7 +97,11 @@ public function decode(callable $onFrameDecoded)
                         break;
                     case 0x2C:
                         $this->readImageDescriptor();
-                        $onFrameDecoded($this->currentFrame, $frameIndex++);
+
+                        $event = new FrameDecodedEvent();
+                        $event->frameIndex = $frameIndex++;
+                        $event->decodedFrame = $this->currentFrame;
+                        $onFrameDecoded($event);
                         break;
                     case 0x3B:
                         $cycle = false;

src/Events/FrameDecodedEvent.php

@@ -0,0 +1,17 @@
+<?php
+namespace GIFEndec\Events;
+
+use GIFEndec\Frame;
+
+class FrameDecodedEvent
+{
+    /**
+     * @var int
+     */
+    public $frameIndex;
+
+    /**
+     * @var Frame
+     */
+    public $decodedFrame;
+}

src/Events/FrameRenderedEvent.php

@@ -0,0 +1,22 @@
+<?php
+namespace GIFEndec\Events;
+
+use GIFEndec\Frame;
+
+class FrameRenderedEvent
+{
+    /**
+     * @var int
+     */
+    public $frameIndex;
+
+    /**
+     * @var Frame
+     */
+    public $decodedFrame;
+
+    /**
+     * @var resource
+     */
+    public $renderedFrame;
+}

src/Renderer.php

@@ -1,6 +1,9 @@
 <?php
 namespace GIFEndec;
 
+use GIFEndec\Events\FrameDecodedEvent;
+use GIFEndec\Events\FrameRenderedEvent;
+
 class Renderer
 {
     /**
@@ -26,8 +29,12 @@ public function __construct(Decoder $decoder)
      */
     public function start(callable $onFrameRendered)
     {
-        $this->decoder->decode(function (Frame $frame, $index) use ($onFrameRendered) {
-            $onFrameRendered($this->render($frame, $index), $index);
+        $this->decoder->decode(function (FrameDecodedEvent $e) use ($onFrameRendered) {
+            $event = new FrameRenderedEvent();
+            $event->frameIndex = $e->frameIndex;
+            $event->decodedFrame = $e->decodedFrame;
+            $event->renderedFrame = $this->render($e->decodedFrame, $e->frameIndex);
+            $onFrameRendered($event);
         });
     }