Try to detect the character encoding in PDFs and try to translate

the title from the PDF to UTF-8
This commit is contained in:
Tobi823 2018-09-19 12:30:26 +02:00
parent 8648f0c005
commit f80f16dfc8
1 changed files with 34 additions and 14 deletions

View File

@ -53,7 +53,7 @@ class ContentProxy
if ((empty($content) || false === $this->validateContent($content)) && false === $disableContentUpdate) {
$fetchedContent = $this->graby->fetchContent($url);
$fetchedContent['title'] = $this->sanitizeUTF8Text($fetchedContent['title']);
$fetchedContent['title'] = $this->sanitizeContentTitle($fetchedContent['title'], $fetchedContent['content_type']);
// when content is imported, we have information in $content
// in case fetching content goes bad, we'll keep the imported information instead of overriding them
@ -70,24 +70,44 @@ class ContentProxy
}
/**
* Remove invalid UTF-8 characters from the given string in following steps:
* - try to interpret the given string as ISO-8859-1, convert it to UTF-8 and return it (if its valid)
* - simply remove every invalid UTF-8 character and return the result (https://stackoverflow.com/a/1433665)
* Try to sanitize the title of the fetched content from wrong character encodings and invalid UTF-8 character.
* @param $title
* @param $contentType
* @return string
*/
private function sanitizeContentTitle($title, $contentType) {
if ('application/pdf' === $contentType) {
$convertedTitle = $this->convertPdfEncodingToUTF8($title);
return $this->sanitizeUTF8Text($convertedTitle);
}
return $this->sanitizeUTF8Text($title);
}
/**
* If the title from the fetched content comes from a PDF, then its very possible that the character encoding is not
* UTF-8. This methods tries to identify the character encoding and translate the title to UTF-8.
* @param $title
* @return string (maybe contains invalid UTF-8 character)
*/
private function convertPdfEncodingToUTF8($title) {
// first try UTF-16 (then UTF-8) because its easier to detect its present/absence
foreach (array('UTF-16BE', 'UTF-16LE', 'UTF-8', 'WINDOWS-1252') as $encoding) {
if (mb_check_encoding($title, $encoding)) {
return mb_convert_encoding($title, 'UTF-8', $encoding);
}
}
return $title;
}
/**
* Remove invalid UTF-8 characters from the given string.
* @param String $rawText
* @return string
*/
private function sanitizeUTF8Text($rawText) {
if (mb_check_encoding($rawText, 'utf-8')) {
return $rawText; // return because its valid utf-8 text
if (mb_check_encoding($rawText, 'UTF-8')) {
return $rawText;
}
// we assume that $text is encoded in ISO-8859-1 (and not the similar Windows-1252 or other encoding)
$convertedText = utf8_encode($rawText);
if (mb_check_encoding($convertedText, 'utf-8')) {
return $convertedText;
}
// last resort: simply remove invalid UTF-8 character because $rawText can have some every exotic encoding
return iconv("UTF-8", "UTF-8//IGNORE", $rawText);
}