Fix "Automatic Zoom" for landscape documents with very wide pages (issue 5398)

[Snuffleupagus]

Attempting to fix #5398.

[Snuffleupagus]

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[yurydelendik]

Thank you

[markusd1984]

I have a window 1920x880 in which the pdf gets scaled only to 1200x674px using the default Auto zoom

even though it's a widescreen 16x9 slide and the page fit is able to scale it up much bigger to make use of the available height rendering it at 1555 x 875 px.

How is the automatic zoom to be different to page fit and what's preventing it to make use of the full height in this case?

case 'auto':
            var isLandscape = (currentPage.width > currentPage.height);
            // For pages in landscape mode, fit the page height to the viewer
            // *unless* the page would thus become too wide to fit horizontally.
            var horizontalScale = isLandscape ?
            Math.min(pageHeightScale, pageWidthScale) : pageWidthScale;
            scale = Math.min(MAX_AUTO_SCALE, horizontalScale);