Added method resizeToBestFit

Added a method to resize an image to best fit a given set of dimensions
while keeping the original aspect ratio.

Author: Droeftoeter

README.md

@@ -64,6 +64,13 @@ $image->resizeToWidth(300);
 $image->save('image2.jpg');
 ```
 
+To resize an image to best fit a given set of dimensions (keeping aspet ratio):
+```php
+$image = new ImageResize('image.jpg');
+$image->resizeToBestFit(500, 300);
+$image->save('image2.jpg');
+```
+
 To to crop an image:
 
 ```php

src/ImageResize.php

@@ -251,6 +251,32 @@ public function resizeToWidth($width, $allow_enlarge = false)
         return $this;
     }
 
+    /**
+     * Resizes image to best fit inside the given dimensions
+     *
+     * @param integer $max_width
+     * @param integer $max_height
+     * @param boolean $allow_enlarge
+     * @return \static
+     */
+    public function resizeToBestFit($max_width, $max_height, $allow_enlarge = false)
+    {
+        if($this->getSourceWidth() <= $max_width && $this->getSourceHeight() <= $max_height && $allow_enlarge === false){
+            return $this;
+        }
+
+        $ratio  = $this->getSourceHeight() / $this->getSourceWidth();
+        $width = $max_width;
+        $height = $width * $ratio;
+
+        if($height > $max_height){
+            $height = $max_height;
+            $width = $height / $ratio;
+        }
+
+        return $this->resize($width, $height, true);
+    }
+
     /**
      * Resizes image according to given scale (proportionally)
      *

test/Test.php

@@ -139,6 +139,28 @@ public function testResizeToWidth()
         $this->assertEquals(50, $resize->getDestHeight());
     }
 
+    public function testResizeToBestFit()
+    {
+        $image = $this->createImage(200, 500, 'png');
+        $resize = new ImageResize($image);
+
+        $resize->resizeToBestFit(100, 100);
+
+        $this->assertEquals(40, $resize->getDestWidth());
+        $this->assertEquals(100, $resize->getDestHeight());
+    }
+
+    public function testResizeToBestFitNoEnlarge()
+    {
+        $image = $this->createImage(200, 100, 'png');
+        $resize = new ImageResize($image);
+
+        $resize->resizeToBestFit(250, 250);
+
+        $this->assertEquals(200, $resize->getDestWidth());
+        $this->assertEquals(100, $resize->getDestHeight());
+    }
+
     public function testScale()
     {
         $image = $this->createImage(200, 100, 'png');
@@ -172,7 +194,6 @@ public function testResizeLargerNotAllowed()
         $this->assertEquals(100, $resize->getDestHeight());
     }
 
-
     /**
      * Crop tests
      */