MDL-8855 - Wrote additional GD code to support alpha transparency in …

…PNG files.

mod/data/field/picture/field.class.php

@@ -234,6 +234,12 @@ function update_thumbnail($content) {
             } else {
                 $im1 = ImageCreate($thumbwidth,$thumbheight);
             }
+
+            // Prevent alpha blending for PNG images
+            if ($image->type == 3) {
+                imagealphablending($im1, false);
+            }
+
             $cx = $image->width  / 2;
             $cy = $image->height / 2;
 
@@ -243,12 +249,22 @@ function update_thumbnail($content) {
 
             ImageCopyBicubic($im1, $im, 0, 0, $cx-$halfwidth, $cy-$halfheight,
                              $thumbwidth, $thumbheight, $halfwidth*2, $halfheight*2);
-
-            if (function_exists('ImageJpeg')) {
+
+            // Save alpha transparency for PNG images
+            if ($image->type == 3) {
+                imagesavealpha($im1, true);
+            }
+
+            if (function_exists('ImageJpeg') && $image->type != 3) {
                 @touch($thumbnaillocation);  // Helps in Safe mode
                 if (ImageJpeg($im1, $thumbnaillocation, 90)) {
                     @chmod($thumbnaillocation, 0666);
                 }
+            } elseif (function_exists('ImagePng') && $image->type == 3) {
+                @touch($thumbnaillocation);  // Helps in Safe mode
+                if (ImagePng($im1, $thumbnaillocation, 9)) {
+                    @chmod($thumbnaillocation, 0666);
+                } 
             }
 
         } else { // Try and remove the thumbnail - we don't want thumbnailing active