Fix pb with imagick

htdocs/core/lib/files.lib.php

@@ -1565,12 +1565,14 @@ function dol_remove_file_process($filenb,$donotupdatesession=0,$donotdeletefile=
  *  @param	string	$fileinput  Input file name
  *  @param  string	$ext        Format of target file (It is also extension added to file if fileoutput is not provided).
  *  @param	string	$fileoutput	Output filename
- *  @return	int					<0 if KO, >0 if OK
+ *  @return	int					<0 if KO, 0=Nothing done, >0 if OK
  */
 function dol_convert_file($fileinput,$ext='png',$fileoutput='')
 {
 	global $langs;
 
+	if (class_exists('Imagick'))
+	{
 		$image=new Imagick();
 		$ret = $image->readImage($fileinput);
 		if ($ret)
@@ -1595,6 +1597,11 @@ function dol_convert_file($fileinput,$ext='png',$fileoutput='')
 			return -1;
 		}
 	}
+	else
+	{
+		return 0;
+	}
+}
 
 
 /**

htdocs/core/lib/functions.lib.php

@@ -1235,10 +1235,13 @@ function dol_banner_tab($object, $paramid, $morehtml='', $shownav=1, $fieldid='r
                         if ( (! file_exists($fileimage) || (filemtime($fileimage) < filemtime($file)))
                           && (! file_exists($fileimagebis) || (filemtime($fileimagebis) < filemtime($file)))
                            )
+                        {
+                        	if (empty($conf->global->MAIN_DISABLE_PDF_THUMBS))		// If you experienc trouble with pdf thumb generation and imagick, you can disable here.
                         	{
                             	$ret = dol_convert_file($file, 'png', $fileimage);
                             	if ($ret < 0) $error++;
                         	}
+                        }
 
                         $heightforphotref=70;
                         if (! empty($conf->dol_optimize_smallscreen)) $heightforphotref=60;