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Fix HTML preview rendering in Tracy panel #48

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zraly wants to merge 4 commits into from
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Fix HTML preview rendering in Tracy panel #48

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4cc19b6
fixed html preview rendering
zraly Feb 11, 2026
10f0f88
fixed php 8.5 reflection warning
zraly Feb 12, 2026
7575200
fixed html preview loading
zraly Apr 9, 2026
2339ef6
fixed base tag handling
zraly Apr 9, 2026
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24 changes: 2 additions & 22 deletions src/MailPanel.body.latte
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Original file line number Diff line number Diff line change
@@ -1,22 +1,2 @@
{* Little magic here. Create iframe and then render message into it (needed because HTML messages) *}
{if $message->getHtmlBody() !== ''}
{$message->getHtmlBody()|noescape}
{else}
<!doctype html>
<meta charset="utf-8">
<style>
html, body {
margin: 0;
padding: 0;
border: none;
font-family: sans-serif;
font-size: 12px;
white-space: pre;
}

body {
padding: 10px;
}
</style>
<body>{$message|plainText}</body>
{/if}
{* Render a standalone HTML preview document or fragment. *}
{$message|previewHtml|noescape}
17 changes: 6 additions & 11 deletions src/MailPanel.latte
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Original file line number Diff line number Diff line change
Expand Up @@ -108,8 +108,7 @@
</tr>

<tr class="nextras-mail-panel-preview-html tracy-collapsed">
{capture $htmlPreview}{include MailPanel.body.latte, message => $message}{/capture}
<td colspan="2" data-content="{$htmlPreview}"></td>
<td colspan="2" data-src="{link('preview', ['message-id' => $messageId])}"></td>
</tr>
</table>
{/foreach}
Expand All @@ -130,22 +129,18 @@
var iframe = document.createElement('iframe');
preview.appendChild(iframe);

iframe.contentWindow.document.write(preview.dataset.content);
iframe.contentWindow.document.close();
delete preview.dataset.content;

var baseTag = iframe.contentWindow.document.createElement('base');
baseTag.target = '_parent';
iframe.contentWindow.document.body.appendChild(baseTag);

var fixHeight = function (ev) {
var iframeDocument = iframe.contentWindow.document;
var iframeBody = iframeDocument.body || iframeDocument.documentElement;
iframe.style.height = 0;
iframe.style.height = iframe.contentWindow.document.body.scrollHeight + 'px';
iframe.style.height = iframeBody.scrollHeight + 'px';
iframe.contentWindow.removeEventListener(ev.type, fixHeight);
};

iframe.contentWindow.addEventListener('load', fixHeight);
iframe.contentWindow.addEventListener('resize', fixHeight);
iframe.src = preview.dataset.src;
delete preview.dataset.src;
actions.removeEventListener('tracy-toggle', initHtmlPreview);
actions.removeEventListener('click', initHtmlPreview);
};
Expand Down
148 changes: 132 additions & 16 deletions src/MailPanel.php
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
use Nette;
use Nette\Http;
use Nette\Mail\Mailer;
use Nette\Mail\Message;
use Nette\Mail\MimePart;
use Nette\Utils\Strings;
use Tracy\Debugger;
Expand Down Expand Up @@ -43,6 +44,9 @@ class MailPanel implements IBarPanel
/** @var Latte\Engine|NULL */
private $latte;

/** @var \ReflectionProperty|NULL */
private $mimePartPartsProperty;


public function __construct(?string $tempDir, Http\IRequest $request, Mailer $mailer, int $messagesLimit = self::DEFAULT_COUNT)
{
Expand Down Expand Up @@ -135,29 +139,97 @@ private function getLatte(): Latte\Engine
});

$this->latte->addFilter('plainText', function (MimePart $part) {
$ref = new \ReflectionProperty('Nette\Mail\MimePart', 'parts');

$queue = [$part];
for ($i = 0; $i < count($queue); $i++) {
/** @var MimePart $subPart */
foreach ($ref->getValue($queue[$i]) as $subPart) {
$contentType = $subPart->getHeader('Content-Type');
if (Strings::startsWith($contentType, 'text/plain') && $subPart->getHeader('Content-Transfer-Encoding') !== 'base64') { // Take first available plain text
return $subPart->getBody();
} elseif (Strings::startsWith($contentType, 'multipart/alternative')) {
$queue[] = $subPart;
}
}
$plainText = $this->findBodyByContentType($part, 'text/plain');
if ($plainText !== null) {
return $plainText;
}

return $this->decodeBody($part);
});

$this->latte->addFilter('previewHtml', function (MimePart $part): string {
$htmlBody = $this->extractHtmlBody($part);
if ($htmlBody !== '') {
return $htmlBody;
}

return $part->getBody();
$plainText = $this->findBodyByContentType($part, 'text/plain') ?? $this->decodeBody($part);
return '<!doctype html>'
. '<meta charset="utf-8">'
. '<style>html,body{margin:0;padding:0;border:none;font-family:sans-serif;font-size:12px;white-space:pre;}body{padding:10px;}</style>'
. '<body>' . htmlspecialchars($plainText, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8') . '</body>';
});
}

return $this->latte;
}


private function extractHtmlBody(MimePart $part): string
{
if ($part instanceof Message && $part->getHtmlBody() !== '') {
return $part->getHtmlBody();
}

return $this->findBodyByContentType($part, 'text/html') ?? '';
}


private function findBodyByContentType(MimePart $part, string $contentTypePrefix): ?string
{
$queue = [$part];
for ($i = 0; $i < count($queue); $i++) {
$currentPart = $queue[$i];
$contentType = $currentPart->getHeader('Content-Type');
if (is_string($contentType) && Strings::startsWith(strtolower($contentType), $contentTypePrefix)) {
return $this->decodeBody($currentPart);
}

/** @var MimePart $subPart */
foreach ($this->getMimePartParts($currentPart) as $subPart) {
$queue[] = $subPart;
}
}

return null;
}


/**
* @return MimePart[]
*/
private function getMimePartParts(MimePart $part): array
{
if ($this->mimePartPartsProperty === null) {
$this->mimePartPartsProperty = new \ReflectionProperty(MimePart::class, 'parts');
if (PHP_VERSION_ID < 80100) {
$this->mimePartPartsProperty->setAccessible(true);
}
}

$parts = $this->mimePartPartsProperty->getValue($part);
return is_array($parts) ? $parts : [];
}


private function decodeBody(MimePart $part): string
{
$body = $part->getBody();
$transferEncoding = strtolower((string) $part->getHeader('Content-Transfer-Encoding'));

if ($transferEncoding === MimePart::EncodingQuotedPrintable) {
return quoted_printable_decode($body);
}

if ($transferEncoding === MimePart::EncodingBase64) {
$decodedBody = base64_decode($body, true);
return is_string($decodedBody) ? $decodedBody : $body;
}

return $body;
}


private function tryHandleRequest(): void
{
if (Debugger::$productionMode !== false) {
Expand All @@ -168,7 +240,10 @@ private function tryHandleRequest(): void
$messageId = $this->request->getQuery('nextras-mail-panel-message-id');
$attachmentId = $this->request->getQuery('nextras-mail-panel-attachment-id');

if ($action === 'detail' && is_string($messageId)) {
if ($action === 'preview' && is_string($messageId)) {
$this->handlePreview($messageId);

} elseif ($action === 'detail' && is_string($messageId)) {
$this->handleDetail($messageId);

} elseif ($action === 'source' && is_string($messageId)) {
Expand All @@ -192,7 +267,18 @@ private function handleDetail(string $messageId): void
$message = $this->mailer->getMessage($messageId);

header('Content-Type: text/html');
$this->getLatte()->render(__DIR__ . '/MailPanel.body.latte', ['message' => $message]);
echo $this->renderMessagePreview($message);
exit;
}


private function handlePreview(string $messageId): void
{
assert($this->mailer !== null);
$message = $this->mailer->getMessage($messageId);

header('Content-Type: text/html');
echo $this->addParentBaseTarget($this->renderMessagePreview($message));
exit;
}

Expand All @@ -208,6 +294,36 @@ private function handleSource(string $messageId): void
}


private function renderMessagePreview(MimePart $message): string
{
return $this->getLatte()->renderToString(__DIR__ . '/MailPanel.body.latte', ['message' => $message]);
}


private function addParentBaseTarget(string $html): string
{
$baseTag = '<base target="_parent">';

if (preg_match('~<base(?:\s[^>]*)?>~i', $html) === 1) {
return $html;
}

if (preg_match('~<head(?:\s[^>]*)?>~i', $html, $match, PREG_OFFSET_CAPTURE) === 1) {
$headTag = $match[0][0];
$position = $match[0][1] + strlen($headTag);
return substr($html, 0, $position) . $baseTag . substr($html, $position);
}

if (preg_match('~<html(?:\s[^>]*)?>~i', $html, $match, PREG_OFFSET_CAPTURE) === 1) {
$htmlTag = $match[0][0];
$position = $match[0][1] + strlen($htmlTag);
return substr($html, 0, $position) . '<head>' . $baseTag . '</head>' . substr($html, $position);
}

return '<!doctype html><html><head>' . $baseTag . '</head><body>' . $html . '</body></html>';
}


private function handleAttachment(string $messageId, int $attachmentId): void
{
assert($this->mailer !== null);
Expand Down
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