add [] for extract band

Author: jcupitt

Diff for: README.md

@@ -1,7 +1,6 @@
 # Experimental PHP binding for libvips 
 
-This is an experimental PHP binding for libvips. Not quite done yet, but 
-it does more or less work. 
+This is an experimental PHP binding for libvips. 
 
 ### Example
 
@@ -10,7 +9,7 @@ it does more or less work.
 <?php
 	include 'vips.php';
 
-	$image = VImage::new_from_file($argv[1]); 
+	$image = VImage::new_from_file($argv[1]);
 
 	echo "width = ", $image->width, "\n";
 
@@ -20,6 +19,25 @@ it does more or less work.
 ?>
 ```
 
+### Missing
+
+Some features that other vips bindings have are not yet implemented:
+
+* You can't assign to an array index to change an image band.
+
+* In-place operations, like `circle`, are not yet supported.
+
+* No phpDoc yet.
+
+* No exceptions yet.
+
+* No logging at the moment. 
+
+Some things will never be done:
+
+* You can't use `()` to get a pixel value, since php does not support multiple
+  arguments to `__invoke()`.
+
 ### How it works
 
 `vips.c` defines a simple but ugly route to call any libvips operation from PHP.
@@ -123,20 +141,6 @@ $ ./try1.php ~/pics/k2.jpg x.tif
 
 See `examples/`.
 
-### TODO
-
-* `[]` for band extract should be easy
-
-* can we overload `()` for `getpoint`? unclear
-
-* add phpDoc comments 
-
-  need comments for magic properties
-
-  extra phpDoc comments for all magic methods, use py to generate
-
-* exceptions? logging?
-
 ### links
 
 http://php.net/manual/en/internals2.php

Diff for: tests/041.phpt

@@ -0,0 +1,19 @@
+--TEST--
+VImage::[] works
+--SKIPIF--
+<?php if (!extension_loaded("vips")) print "skip"; ?>
+--FILE--
+<?php 
+  include 'vips.php';
+
+  $filename = dirname(__FILE__) . "/images/img_0076.jpg";
+  $image = VImage::new_from_file($filename);
+
+  $image = $image->invert()[1];
+
+  if ($image->bands == 1) {
+	echo "pass";
+  }
+?>
+--EXPECT--
+pass

Diff for: vips.php

@@ -8,7 +8,7 @@
 	dl('vips.' . PHP_SHLIB_SUFFIX);
 }
 
-class VImage 
+class VImage implements ArrayAccess
 {
 	/* The resource for the underlying VipsImage.
 	 */
@@ -218,6 +218,29 @@ public static function __callStatic($name, $arguments)
 		return self::call($name, NULL, $arguments); 
 	}
 
+	/* ArrayAccess interface ... we allow [] to get band.
+	 */
+
+	public function offsetExists($offset) 
+	{
+		return $offset >= 0 && $offset <= $this->bands - 1;
+	}
+
+	public function offsetGet($offset) 
+	{
+		return self::offsetExists($offset) ? self::extract_band($offset) : NULL;
+	}
+
+	public function offsetSet($offset, $value) 
+	{
+		echo "VImage::offsetSet: not implemented\n"; 
+	}
+
+	public function offsetUnset($offset) 
+	{
+		echo "VImage::offsetUnset: not implemented\n"; 
+	}
+
 	/* add/sub/mul/div with a constant argument can use linear for a huge
 	 * speedup.
 	 */