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Merge pull request #25212 from nextcloud/enh/preview-markdown 

Enhance markdown file preview rendering
This commit is contained in:
Morris Jobke 2021-01-20 15:02:41 +01:00 committed by GitHub
parent 6129a85187 01f013661a
commit 4c81f5c4ad
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 110 additions and 0 deletions
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110
lib/private/Preview/MarkDown.php
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@ -24,6 +24,9 @@
namespace OC\Preview;
use OCP\Files\File;
use OCP\IImage;
class MarkDown extends TXT {
/**
* {@inheritDoc}
@ -31,4 +34,111 @@ class MarkDown extends TXT {
public function getMimeType(): string {
return '/text\/(x-)?markdown/';
}
public function getThumbnail(File $file, int $maxX, int $maxY): ?IImage {
$content = $file->fopen('r');
if ($content === false) {
return null;
}
$content = stream_get_contents($content,3000);
//don't create previews of empty text files
if (trim($content) === '') {
return null;
}
// Merge text paragraph lines that might belong together
$content = preg_replace('/^(\s*)\*\s/mU', '$1- ', $content);
$content = preg_replace('/((?!^(\s*-|#)).*)(\w|\\|\.)(\r\n|\n|\r)(\w|\*)/mU', '$1 $3', $content);
// Remove markdown symbols that we cannot easily represent in rendered text in the preview
$content = preg_replace('/\*\*(.*)\*\*/U', '$1', $content);
$content = preg_replace('/\*(.*)\*/U', '$1', $content);
$content = preg_replace('/\_\_(.*)\_\_/U', '$1', $content);
$content = preg_replace('/\_(.*)\_/U', '$1', $content);
$content = preg_replace('/\~\~(.*)\~\~/U', '$1', $content);
$content = preg_replace('/\!?\[((.|\n)*)\]\((.*)\)/mU', '$1 ($3)', $content);
$content = preg_replace('/\n\n+/', "\n", $content);
$content = preg_replace('/[\x{10000}-\x{10FFFF}]/u', '', $content);
$lines = preg_split("/\r\n|\n|\r/", $content);
// Define text size of text file preview
$fontSize = $maxX ? (int) ((1 / ($maxX >= 512 ? 60 : 40) * $maxX)) : 10;
$image = imagecreate($maxX, $maxY);
imagecolorallocate($image, 255, 255, 255);
$textColor = imagecolorallocate($image, 0, 0, 0);
$fontFile = __DIR__ . '/../../../core/fonts/NotoSans-Regular.ttf';
$fontFileBold = __DIR__ . '/../../../core/fonts/NotoSans-Bold.ttf';
$canUseTTF = function_exists('imagettftext');
$textOffset = (int)min($maxX * 0.05, $maxY * 0.05);
$nextLineStart = 0;
$y = $textOffset;
foreach ($lines as $line) {
$actualFontSize = $fontSize;
if (mb_strpos($line, '# ') === 0) {
$actualFontSize *= 2;
}
if (mb_strpos($line, '## ') === 0) {
$actualFontSize *= 1.8;
}
if (mb_strpos($line, '### ') === 0) {
$actualFontSize *= 1.6;
}
if (mb_strpos($line, '#### ') === 0) {
$actualFontSize *= 1.4;
}
if (mb_strpos($line, '##### ') === 0) {
$actualFontSize *= 1.2;
}
if (mb_strpos($line, '###### ') === 0) {
$actualFontSize *= 1.1;
}
// Add spacing before headlines
if ($actualFontSize !== $fontSize && $y !== $textOffset) {
$y += (int)($actualFontSize * 2);
}
$x = $textOffset;
$y += (int)($nextLineStart + $actualFontSize);
if ($canUseTTF === true) {
$wordWrap = (int)((1 / $actualFontSize * 1.3) * $maxX);
// Get rid of markdown symbols that we still needed for the font size
$line = preg_replace('/^#*\s/', '', $line);
$wrappedText = wordwrap($line, $wordWrap,"\n");
$linesWrapped = count(explode("\n", $wrappedText));
imagettftext($image, $actualFontSize, 0, $x, $y, $textColor, $actualFontSize === $fontSize ? $fontFile : $fontFileBold, $wrappedText);
$nextLineStart = (int)($linesWrapped * ceil($actualFontSize * 2));
if ($actualFontSize !== $fontSize && $y !== $textOffset) {
$nextLineStart -= $actualFontSize;
}
} else {
$y -= (int)$fontSize;
imagestring($image, 1, $x, $y, $line, $textColor);
$nextLineStart = $fontSize;
}
if ($y >= $maxY) {
break;
}
}
$imageObject = new \OC_Image();
$imageObject->setResource($image);
return $imageObject->valid() ? $imageObject : null;
}
}