[Printing] Image export fails on iOS

[mbeckem]

Environment: Safari / Chrome on iOS (iPad)

Reproduction

• Trigger map print (as png) by using the Printing UI Component

Expected

• A png image can be downloaded or opened

Actual

• Safari: Offers choice between "load" and "view". "view" does not work.
• Chrome: Does not work at all

Notes

• PDF export works as expected (implemented in jspdf)
• The link.click() (with download attribute) seems to be problematic here (in PrintingController)
  • The download attribute should be well supported (https://caniuse.com/download)
  • One workaround might be to switch to window.open(pngData, _blank) instead when iOS is detected
  • Before implementing any workaround, check if the download html attribute is available on the link in the tested environment
• Related:
  • https://stackoverflow.com/questions/55760169/alternative-for-download-attribute-in-safari-ios
  • https://stackoverflow.com/questions/46690722/download-attribute-not-working-in-safari/54479139
  • https://github.com/rndme/download/blob/09d6492f47ef18feca39c3d748960dce44f93a89/download.js#L124