[Interest] How to render small Images decently on non retina displays with QtQuick?

Shawn Rutledge Shawn.Rutledge at qt.io
Thu Mar 15 16:14:14 CET 2018

> On 15 Mar 2018, at 15:58, Nikolai Tasev <nikolai at nand.bg> wrote:
> On 3/15/2018 4:26 PM, Shawn Rutledge wrote:
>> In the future I think it will make sense to use PDF for vector icons too (in color, even). (Some frameworks already can do this.) Then instead of an icon font, you could have one PDF file with all the icons for your app, one icon per “page”. I hope to eventually support using a PDF file with an ordinary Image in QML, but we have to add API for selecting the page, and there are other issues with caching and so on. I had patches to get it mostly working a couple of years ago, it just wasn’t 100% ready for integration.
> The PDF format specification is even more complex than the SVG one аs it is used also to control printing output. The good PDF RIPs are all proprietary. I had quite a lot difficulties using Ghostscript and Poppler until I switched to  a library with a paid license. So it will be again limited to a subset of the specification and maybe slow.
QtPDF is using pdfium.  http://code.qt.io/cgit/qt-labs/qtpdf.git  It is complex third-party code (but open source), and the rendering is again done in software, but it seems fast enough.  I haven’t tried to compare rendering times: the same drawing in SVG vs. PDF.

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