Решаем проблему с полупрозрачностью PNG в Internet Explorer
Как известно, Internet Explorer младше 7-й версии не умеет отображать альфа-канал в файлах PNG. Существует несколько вариантов решений проблемы на клиентском коде, но на Symfony есть возможность соорудить серверную логику и подключать ее в каждом проекте.
На есть http://www.symfony-project.org/ готовый снипет, его и используем.
для начала вот такой код:
class pngAlphaFilter extends sfFilter
{
public function execute ($filterChain)
{
$filterChain->execute();
}
public function executeBeforeRendering ($filterChain)
{
$response = $this->getContext()->getResponse();
$content = $response->getContent();
$newContent = $this->replacePngTags($content, '/images/');
$response->setContent($newContent);
$filterChain->execute();
}
/**
* KOIVI PNG Alpha IMG Tag Replacer for PHP (C) 2004 Justin Koivisto
* Version 2.0.12
* Last Modified: 12/30/2005
*
* Modifies IMG and INPUT tags for MSIE5+ browsers to ensure that PNG-24
* transparencies are displayed correctly. Replaces original SRC attribute
* with a binary transparent PNG file (spacer.png) that is located in the same
* directory as the orignal image, and adds the STYLE attribute needed to for
* the browser. (Matching is case-insensitive. However, the width attribute
* should come before height.
*
* Also replaces code for PNG images specified as backgrounds via:
* background-image: url(image.png); or background-image: url('image.png');
* When using PNG images in the background, there is no need to use a spacer.png
* image. (Only supports inline CSS at this point.)
*
* @param string $x String containing the content to search and replace in.
* @param string $img_path The path to the directory with the spacer image relative to
* the DOCUMENT_ROOT. If none os supplied, the spacer.png image
* should be in the same directory as PNG-24 image.
* @param string $sizeMeth String containing the sizingMethod to be used in the
* Microsoft.AlphaImageLoader call. Possible values are:
* crop - Clips the image to fit the dimensions of the object.
* image - Enlarges or reduces the border of the object to fit
* the dimensions of the image.
* scale - Default. Stretches or shrinks the image to fill the borders
* of the object.
* @param bool $inScript Boolean flag indicating whether or not to replace IMG tags that
* appear within SCRIPT tags in the passed content. If used, may cause
* javascript parse errors when the IMG tags is defined in a javascript
* string. (Which is why the options was added.)
* @return string
*/
public function replacePngTags($x,$img_path='',$sizeMeth='scale',$inScript=FALSE){
$arr2=array();
// make sure that we are only replacing for the Windows versions of Internet
// Explorer 5.5+
$msie='/msie\s(5\.[5-9]|[6]\.[0-9]*).*(win)/i';
if( !isset($_SERVER['HTTP_USER_AGENT']) ||
!preg_match($msie,$_SERVER['HTTP_USER_AGENT']) ||
preg_match('/opera/i',$_SERVER['HTTP_USER_AGENT']))
return $x;
if($inScript){
// first, I want to remove all scripts from the page…
$saved_scripts=array();
$placeholders=array();
preg_match_all('<script[^>]*>(.*)</script>isU',$x,$scripts);
for($i=0;$i<count($scripts[0]);$i++){
$x=str_replace($scripts[0][$i],'replacePngTags_ScriptTag-'.$i,$x);
$saved_scripts[]=$scripts[0][$i];
$placeholders[]='replacePngTags_ScriptTag-'.$i;
}
}
// find all the png images in backgrounds
preg_match_all('/background-image:\s*url\(([\\"\\\']?)([^\)]+\.png)\1\);/Uis',$x,$background);
for($i=0;$i<count($background[0]);$i++){
// simply replace:
// "background-image: url('image.png');"
// with:
// "filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(
// enabled=true, sizingMethod=scale, src='image.png');"
// I don't think that the background-repeat styles will work with this…
$x=str_replace($background[0][$i],'filter:progid:DXImageTransform.'.
'Microsoft.AlphaImageLoader(enabled=true, sizingMethod='.$sizeMeth.
', src=\''.$background[2][$i].'\');',$x);
}
// find all the IMG tags with ".png" in them
$pattern='/<(input|img)[^>]*src=([\\"\\\']?)([^>]*\.png)\2[^>]*>/i';
preg_match_all($pattern,$x,$images);
for($num_images=0;$num_images<count($images[0]);$num_images++){
// for each found image pattern
$original=$images[0][$num_images];
$quote=$images[2][$num_images];
$atts=''; $width=0; $height=0; $modified=$original;
// We do this so that we can put our spacer.png image in the same
// directory as the image - if a path wasn't passed to the function
if(empty($img_path)){
$tmp=split('[\\/]',$images[3][$num_images]);
$this_img=array_pop($tmp);
$img_path=join('/',$tmp);
if(empty($img_path)){
// this was a relative URI, image should be in this directory
$tmp=split('[\\/]',$_SERVER['SCRIPT_NAME']);
array_pop($tmp); // trash the script name, we only want the directory name
$img_path=join('/',$tmp).'/';
}else{
$img_path.='/';
}
}else if(substr($img_path,-1)!='/'){
// in case the supplied path didn't end with a /
$img_path.='/';
}
// If the size is defined by styles, find them
preg_match_all(
'/style=([\\"\\\']).*(\s?width:\s?([0-9]+(px|%));).*'.
'(\s?height:\s?([0-9]+(px|%));).*\\1/Ui',
$images[0][$num_images],$arr2);
if(is_array($arr2) && count($arr2[0])){
// size was defined by styles, get values
$width=$arr2[3][0];
$height=$arr2[6][0];
// remove the width and height from the style
$stripper=str_replace(' ','\s','/('.$arr2[2][0].'|'.$arr2[5][0].')/');
// Also remove any empty style tags
$modified=preg_replace(
'`style='.$arr2[1][0].$arr2[1][0].'`i',
'',
preg_replace($stripper,'',$modified));
}else{
// size was not defined by styles, get values from attributes
preg_match_all('/width=([\\"\\\']?)([0-9%]+)\\1/i',$images[0][$num_images],$arr2);
if(is_array($arr2) && count($arr2[0])){
$width=$arr2[2][0];
if(is_numeric($width))
$width.='px';
// remove width from the tag
$modified=str_replace($arr2[0][0],'',$modified);
}
preg_match_all('/height=([\\"\\\']?)([0-9%]+)\\1/i',$images[0][$num_images],$arr2);
if(is_array($arr2) && count($arr2[0])){
$height=$arr2[2][0];
if(is_numeric($height))
$height.='px';
// remove height from the tag
$modified=str_replace($arr2[0][0],'',$modified);
}
}
if($width==0 || $height==0){
// width and height not defined in HTML attributes or css style, try to get
// them from the image itself
// this does not work in all conditions… It is best to define width and
// height in your img tag or with inline styles..
if(file_exists($_SERVER['DOCUMENT_ROOT'].$img_path.$images[3][$num_images])){
// image is on this filesystem, get width & height
$size=getimagesize($_SERVER['DOCUMENT_ROOT'].$img_path.$images[3][$num_images]);
$width=$size[0].'px';
$height=$size[1].'px';
}else if(file_exists($_SERVER['DOCUMENT_ROOT'].$images[3][$num_images])){
// image is on this filesystem, get width & height
$size=getimagesize($_SERVER['DOCUMENT_ROOT'].$images[3][$num_images]);
$width=$size[0].'px';
$height=$size[1].'px';
}
}
// end quote is already supplied by originial src attribute
$replace_src_with=$quote.$img_path.'spacer.png'.$quote.' style="width: '.$width.
'; height: '.$height.'; filter: progid:DXImageTransform.'.
'Microsoft.AlphaImageLoader(src=\''.$images[3][$num_images].'\', sizingMethod='.
$sizeMeth.');"';
// now create the new tag from the old
$new_tag=str_replace($quote.$images[3][$num_images].$quote,$replace_src_with,
str_replace(' ',' ',$modified));
// now place the new tag into the content
$x=str_replace($original,$new_tag,$x);
}
if($inScript){
// before the return, put the script tags back in. (I was having problems when there was
// javascript that had image tags for PNGs in it when using this function…
$x=str_replace($placeholders,$saved_scripts,$x);
}
return $x;
}
}
Этот код пишем в файл pngAlphaFilter.class.php и кладем его в директорию lib нашего приложения.
Далее активируем фильтр в файле filters.yml
pngAlphaFilter: class: pngAlphaFilter
Далее кладем прозрачный PNG spacer.png в директорию с изображениями (web/images). Файл можно взять здесь http://koivi.com/ie-png-transparency/spacer.png
Теперь полупрозрачность в нашем приложении будет работать. Никаких изменений в шаблонах или CSS делать не нужно
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