From 3351a363e810f11e1cc20b402a0174b3eb12aba9 Mon Sep 17 00:00:00 2001
From: Brion Vibber <brion@users.mediawiki.org>
Date: Thu, 23 Aug 2007 18:28:21 +0000
Subject: [PATCH] * Resizing transparent GIF images with GD now retains
 transparency by skipping   resampling

---
 RELEASE-NOTES             |  7 +++++--
 includes/media/Bitmap.php | 29 +++++++++++++++++++----------
 2 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/RELEASE-NOTES b/RELEASE-NOTES
index 12ba6a70be..978eb26938 100644
--- a/RELEASE-NOTES
+++ b/RELEASE-NOTES
@@ -398,8 +398,8 @@ it from source control: http://www.mediawiki.org/wiki/Download_from_SVN
 * (bug 8737) Fix warnings caused by incorrect use of `/dev/null` when piping
   process error output under Windows
 * (bug 7890) Don't list redirects to special pages in Special:BrokenRedirects
-* (bug 10783) Resizing PNG-24 images causes all alpha channel transparency to be
-  lost and transparent pixels to be turned black
+* (bug 10783) Resizing PNG-24 images with GD no longer causes all alpha
+  channel transparency to be lost and transparent pixels to be turned black
 * (bug 9339) General error pages were transforming messages and their parameters
   in the wrong order
 * (bug 9026) Incorrect heading numbering when viewing Special:Statistics with
@@ -407,6 +407,9 @@ it from source control: http://www.mediawiki.org/wiki/Download_from_SVN
 * Fixed invalid XHTML in Special:Upload
 * (bug 11013) Make sure dl() is available before attempting to use it to check
   available databases in installer
+* Resizing transparent GIF images with GD now retains transparency by skipping
+  resampling
+
 
 == API changes since 1.10 ==
 
diff --git a/includes/media/Bitmap.php b/includes/media/Bitmap.php
index c43e571c1a..245abb8ccc 100644
--- a/includes/media/Bitmap.php
+++ b/includes/media/Bitmap.php
@@ -157,7 +157,7 @@ class BitmapHandler extends ImageHandler {
 				wfDebug( "$err\n" );
 				return new MediaTransformError( 'thumbnail_error', $clientWidth, $clientHeight, $err );
 			}
-			list( $loader, /* $colorStyle */, $saveType ) = $typemap[$mimeType];
+			list( $loader, $colorStyle, $saveType ) = $typemap[$mimeType];
 
 			if( !function_exists( $loader ) ) {
 				$err = "Incomplete GD library configuration: missing function $loader";
@@ -168,16 +168,25 @@ class BitmapHandler extends ImageHandler {
 			$src_image = call_user_func( $loader, $srcPath );
 			$dst_image = imagecreatetruecolor( $physicalWidth, $physicalHeight );
 			
-			//PNG-24 Alpha Trans  
-			$background = imagecolorallocate($dst_image, 0, 0, 0);  //Make $dst_image all black 
-			ImageColorTransparent($dst_image, $background);         //Make $dst_image transparent 
-			imagealphablending($dst_image, false); 
-
-			imagecopyresampled( $dst_image, $src_image,
-						0,0,0,0,
-						$physicalWidth, $physicalHeight, imagesx( $src_image ), imagesy( $src_image ) );
+			// Initialise the destination image to transparent instead of
+			// the default solid black, to support PNG and GIF transparency nicely
+			$background = imagecolorallocate( $dst_image, 0, 0, 0 );
+			imagecolortransparent( $dst_image, $background );
+			imagealphablending( $dst_image, false ); 
+
+			if( $colorStyle == 'palette' ) {
+				// Don't resample for paletted GIF images.
+				// It may just uglify them, and completely breaks transparency.
+				imagecopyresized( $dst_image, $src_image,
+					0,0,0,0,
+					$physicalWidth, $physicalHeight, imagesx( $src_image ), imagesy( $src_image ) );
+			} else {
+				imagecopyresampled( $dst_image, $src_image,
+					0,0,0,0,
+					$physicalWidth, $physicalHeight, imagesx( $src_image ), imagesy( $src_image ) );
+			}
 
-			imagesavealpha($dst_image, true);
+			imagesavealpha( $dst_image, true );
 			
 			call_user_func( $saveType, $dst_image, $dstPath );
 			imagedestroy( $dst_image );
-- 
2.20.1