fix(route/telegram/channel): invisible images in albums and Link Prev…

…iew (DIYgod#16523)

Some have reported that a recent upgrade of RSSHub broke the
/telegram/channel route, resulting in images from Link Preview (Instant
View) or albums not being displayed, even when showLinkPreview
explicitly or implicitly (by default) enabled.

This is a REGRESSION introduced in
edfaed1.

The patch fixes it.

Signed-off-by: Rongrong <i@rong.moe>

lib/routes/telegram/channel.ts

@@ -428,9 +428,40 @@ async function handler(ctx) {
  const background = $node.css('background-image');
  const backgroundUrl = background && background.match(/url\('(.*)'\)/);
  const backgroundUrlSrc = backgroundUrl && backgroundUrl[1];
- const width = Number.parseFloat($node.css('width') || '0');
- const height = ((Number.parseFloat($node.find('.tgme_widget_message_photo').css('padding-top') || '0') / 100) * width).toFixed(2);
- tag_media += backgroundUrlSrc ? `<img width="${width}" height="${height}" src="${backgroundUrlSrc}">` : '';
+ const attrs = [`src="${backgroundUrlSrc}"`];
+ /*
+ * If the width is not in px, it is either a percentage (Link Preview/Instant view)
+ * or absent (ditto).
+ * Only accept px to prevent images from being invisible or too small.
+ */
+ let width = 0;
+ const widthStr = $node.css('width');
+ if (widthStr && widthStr.endsWith('px')) {
+ width = Number.parseFloat(widthStr);
+ }
+ /*
+ * Height is present when the message is an album but does not exist in other cases.
+ * Ditto, only accept px.
+ * !!!NOTE: images in albums may have smaller width and height.
+ */
+ let height = 0;
+ const heightStr = $node.css('height');
+ if (heightStr && heightStr.endsWith('px')) {
+ height = Number.parseFloat(heightStr);
+ }
+ /*
+ * Only calculate height when needed.
+ * The aspect ratio is either a percentage (single image) or absent (Link Preview).
+ * Only accept percentage to prevent images from being invisible or distorted.
+ */
+ const aspectRatioStr = $node.find('.tgme_widget_message_photo').css('padding-top');
+ if (height <= 0 && width > 0 && aspectRatioStr && aspectRatioStr.endsWith('%')) {
+ height = (Number.parseFloat(aspectRatioStr) / 100) * width;
+ }
+ // Only set width/height when >32 to avoid invisible images.
+ width > 32 && attrs.push(`width="${width}"`);
+ height > 32 && attrs.push(`height="${height.toFixed(2).replace('.00', '')}"`);
+ tag_media += backgroundUrlSrc ? `<img ${attrs.join(' ')}>` : '';
  }
  if (tag_media) {
  tag_media_all += tag_media;