Add animation extractor script

php/extract_animation.php

@@ -0,0 +1,58 @@
+<?php
+
+include_once("monoformat_schema.php");
+include_once("monoformat_structured.php");
+
+if (count($argv) != 4) {
+    fwrite(STDERR, "Usage: $argv[0] binfile index outprefix\n");
+    exit(1);
+}
+
+$binfile = $argv[1];
+$index = (int) $argv[2];
+$outprefix = $argv[3];
+
+$file = monoformat\parseFile(file_get_contents($binfile));
+$animations = [];
+foreach ($file->sections as $section) {
+    for ($i = 0; $i < $section->elementCount(); ++$i) {
+        $element = $section->elementAt($i);
+        if ($element->elementType() == monoformat\ElementType::Animation) {
+            array_push($animations, $element);
+        }
+    }
+}
+
+if ($index < 0 || $index >= count($animations)) {
+    $n = count($animations);
+    $nm1 = $n - 1;
+    fwrite(STDERR, "$argv[0]: the animation file contains $n animations, index $index is invalid (must be 0 .. $nm1)\n");
+    exit(2);
+}
+
+$animation = $animations[$index];
+$height = $animation->height();
+$width = $animation->width();
+
+$nFrames = $animation->numberOfFrames();
+for ($f = 0; $f < $nFrames; ++$f) {
+    $outfile = sprintf("%s_%04d.png", $outprefix, $f);
+    print("Writing $outfile...\n");
+    $input = $animation->image($f);
+    $image = imagecreatetruecolor($width, $height);
+    $bg = imagecolorallocate($image, 0, 0, 0);
+    $fg = imagecolorallocate($image, 255, 255, 255);
+    for ($y = 0; $y < $height; ++$y) {
+        for ($x = 0; $x < $width; ++$x) {
+            $i = $y * $width + $x;
+            if ($input[$i]) {
+                imagesetpixel($image, $x, $y, $fg);
+            } else {
+                imagesetpixel($image, $x, $y, $bg);
+            }
+        }
+    }
+    imagepng($image, $outfile);
+}
+
+?>