Stephan Bergmann
4521cb0c40
Inspired by <https://gcc.gnu.org/pipermail/gcc-patches/2022-November/607102.html> "[PATCH] doc: -Wdelete-non-virtual-dtor supersedes -Wnon-virtual-dtor", drop explicitly enabling -Wnon-virtual-dtor in favor of -Wdelete-non-virtual-dtor, which is already enabled by -Wall. (-Wdelete-non-virtual-dtor first appeared in Clang 3.0, <https://github.com/llvm/llvm-project/commit/8bd428574c717e68a8274739d2ba0f6dc16fd0fb> "Add new warning that warns when invoking 'delete' on a polymorphic, non-final, class without a virtual destructor", and GCC 4.7, <https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=014ab419efc12a59efebd2720d79e1c055675c85> "invoke.texi: Document -Wdelete-non-virtual-dtor. [...]") Dropping the explicit setting of -Wnon-virtual-dtor (and nowhere setting it implicitly via -Weffc++) means we can get rid of lots of places that either set -Wno-non-virtual-dtor or use some pragma to ignore -Wnon-virtual-dtor. (In various places across extensions/source/activex/ and winaccessibility/, the commitsf26996bd33"Silence -Werror,-Wnon-virtual-dtor in generated so_activex.h (clang-cl)" andc6086ca653"Silence -Werror,-Wnon-virtual-dtor in generated UAccCOM.h (clang-cl)" had singled out some includes to wrap them in pragmas. Now that those pragmas are gone again, move those includes back to where they had been prior to being singled out. And the -Wno-non-virtual-dtor in external/firebird/macos-arm64.patch.0 appeared first inccd0e5f445"Make firebird build for macOS on arm64", which, though it doesn't state it explicitly, apparently created that patch's builds/posix/prefix.darwin_arm64 as a copy of firebird's already existing builds/posix/prefix.* files, which routinely include that warning option too, so keep it there too even if it is probably irrelevant throughout.) Change-Id: I7e4fa9f2c07e267b2ed15607905027f6b78142f3 Reviewed-on: https://gerrit.libreoffice.org/c/core/+/143182 Tested-by: Jenkins Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Windows Accessibility Bridge
This code provides a bridge between our internal Accessibility
interfaces (implemented on all visible 'things' in the suite: eg.
windows, buttons, entry boxes etc.) - and the Windows MSAA /
IAccessible2 COM interfaces that are familiar to windows users and
Accessible Technologies (ATs) such as the NVDA screen reader.
The code breaks into three bits:
-
source/service/- the UNO service providing the accessibility bridge. It essentially listens to events from the LibreOffice core and creates and synchronises COM peers for our internal accessibility objects when events arrive.
-
source/UAccCom/- COM implementations of the
MSAA/IAccessible2interfaces to provide native peers for the accessibility code.
- COM implementations of the
-
source/UAccCOMIDL/- COM Interface Definition Language (IDL) for UAccCom.
Here is one way of visualising the code / control flow
VCL <-> UNO toolkit <-> UNO a11y <-> win a11y <-> COM / IAccessible2
vcl/ <-> toolkit/ <-> accessibility/ <-> winaccessibility/ <-> UAccCom/
Threading
It's possible that the UNO components are called from threads other
than the main thread, so they have to be synchronized. It would be nice
to put the component into a UNO apartment (and the COM components into STA)
but UNO would spawn a new thread for it so it's not possible.
The COM components also call into the same global AccObjectWinManager
as the UNO components do so both have to be synchronized in the same way.
So we use the SolarMutex for all synchronization since anything else
would be rather difficult to make work. Unfortunately there is a
pre-existing problem in vcl with Win32 Window creation and destruction
on non-main threads where a synchronous SendMessage is used while
the SolarMutex is locked that can cause deadlocks if the main thread is
waiting on the SolarMutex itself at that time and thus not handing the
Win32 message; this is easy to trigger with JunitTests but hopefully
not by actual end users.
Debugging / Playing with winaccessibility
If NVDA is running when soffice starts, IA2 should be automatically enabled and work as expected. In order to use 'accprobe' to debug it is necessary to override the check for whether an AT (like NVDA) is running; to do that use:
SAL_FORCE_IACCESSIBLE2=1 soffice.exe -writer
Then you can use accprobe to introspect the accessibility hierarchy remotely, checkout:
http://accessibility.linuxfoundation.org/a11yweb/util/accprobe/
But often it's more useful to look at NVDA's text output window.