[Win32] Use PrintWindow() with PW_RENDERFULLCONTENT flag

[sratz]

Resolves #373.

I came up with this solution with some google research. It seems to work well, but I'm quite clueless about those Win32 APIs, so would be great if a Win32 expert could help out here.

[github-actions]

Test Results

   502 files     502 suites   8m 7s ⏱️
 4 334 tests  4 320 ✅  14 💤 0 ❌
16 575 runs  16 466 ✅ 109 💤 0 ❌

Results for commit 1816af4.

♻️ This comment has been updated with latest results.

[DenisUngemach]

Hi, the undocumented flag PW_RENDERFULLCONTENT seems to be necessary for printWindow.
Also chromium does not really know why:
https://chromium.googlesource.com/chromium/src.git/+/62.0.3178.1/ui/snapshot/snapshot_win.cc

Without that flag PrintWindow may not correctly capture what's actually onscreen.

[sratz]

This appears to be working well.

Nobody in Platform is actually calling Control.print (GC), so it's hard to test that more intensively.

My proposal would be to get that in in M1 and hope for (no negative) feedback from downstream consumers elsewhere.

[HeikoKlare]

The change sounds reasonable, in particular also considering the Chromium implementation, but I am no expert on this either. We also do not make any use of the print method in our product, so I cannot assist with any testing.

My proposal would be to get that in in M1 and hope for (no negative) feedback from downstream consumers elsewhere.

I agree. Let's try to fix this as early as possible in a release cycle. What about explicitly pinging the people involved in #373 to test the fix and give feedback? Otherwise I think we might not get any (negative) feedback simply because of the lack of testing.

[HeikoKlare]

Let's give it a try.