EMF, JPEG XR and multi-page TIFF file support

[bananakid]

I'd like to leave a small enhancements request:

• add support for EMF vector files (Qt library)
• add support for JXR (JPEG XR) image files (sample, Qt library)
• currently opening a multi-page TIFF file returns an error and even the first page isn't displayed (sample), hopefully this can be addressed in the near future

Thank you for all the other improvements to qView!

[jdpurcell]

For JXR support in Windows, you can download nomacs-portable-win.zip from a nomacs prerelease, look inside the zip for their imageformats folder, and extract kimg_jxr.dll into qView's imageformats folder. qView already includes most of the KImageFormats plugins by the way, but they disable JXR by default for security reasons since the JXR code published by Microsoft is unmaintained. There is a maintained fork of jxrlib but it wouldn't integrate easily into the build system used by qView - most of the decoders are built via vcpkg and their jxrlib is the unmaintained Microsoft one.

I don't have much interest in expanding the format support, it's good enough for me. I just include whatever's in KImageFormats and enabled by default.

TIFF support comes from Qt itself and the error is because that file is a TIFF container containing compressed JPG data which Qt doesn't support currently. As for multi-page images in general, I don't intend to support those fully (i.e. ability to switch pages), but I did just commit a little fix related to that - if there are multiple images like multi-resolution icons, it will now at least pick the highest resolution version to display.

[jdpurcell]

It wasn't easy but I did figure out how to get JXR working in my KImageFormats build. It's using the forked JXR library with security updates. Newest qView build with the JXR plugin is here.

[bananakid]

Thank you for throughout explanation regarding JPEG XR & TIFF. I tested the build, it works well (I'm using builds from Actions), but I can't check if it works with HDR JPEG XL images as my Mac (with Windows 10 via Boot Camp) doesn't have HDR display (here're samples by Microsoft). Hopefully Qt will update TIFF file type to support multiple pages someday!

While I agree there's no need to add every file type that exists, I'd like to clarify that both JPEG XR and EMF (updated WMF) are core image formats used by Microsoft Office. For instance, I typically prepare images (logos, diagrams, charts, etc.) for my Word documents and export them to EMF to import in Word afterwards. EMF is SVG for Microsoft Office and other Windows enterprise-grade tools. So this request was to provide basic support for quite common file types (that are definitely more common than, say, BW or IM8).