Catch exception if failing to set the drag source

... or the drop target.

This is the "don't trust the comment or lose a day debugging WASM
AKA don't switch of your brain" commit.

The comment was "createInstance can throw any exception", so - no
more createInstance, no more exception! Nope, you're WRONG! While
the uno::Reference<...>::set(..., UNO_QUERY) might itself not
throw an exception, something else from the CreateDragSource or
CreateDropTarget call could.

The symptom was a caught exception when loading the initial Writer
document in SynchronousDispatch::dispatch.

While at it, also apply the clean-ups suggested by Mike Kaganski
in a comment to the original patch after the merge.

Regression from commit 031576105c21b2e0c2585a1236092487d5d193e2
("VCL move platform code from mouse.cxx into plugins").

Change-Id: If80a90a9a6c070d912584f85b9fd10382b98e29c
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/128175
Tested-by: Jenkins
Reviewed-by: Jan-Marek Glogowski <glogow@fbihome.de>

2 files changed, 20 insertions, 12 deletions

diff --git a/vcl/source/app/dndhelp.cxx b/vcl/source/app/dndhelp.cxx
index d4d6ea059f06..bf0e897dfc7f 100644
--- a/vcl/source/app/dndhelp.cxx
+++ b/vcl/source/app/dndhelp.cxx
@@ -143,25 +143,25 @@ void vcl::unohelper::DragAndDropWrapper::dropActionChanged( const css::datatrans
 }
 
 css::uno::Reference<css::uno::XInterface>
-vcl::OleDnDHelper(const css::uno::Reference<css::lang::XInitialization>& pDnD, const sal_IntPtr pWin, DragOrDrop eDoD)
+vcl::OleDnDHelper(const css::uno::Reference<css::lang::XInitialization>& xDnD, const sal_IntPtr pWin, DragOrDrop eDoD)
 {
-    if (pWin && pDnD)
+    if (pWin && xDnD)
     {
         if (eDoD == vcl::DragOrDrop::Drag)
-            pDnD->initialize({ uno::Any(), uno::Any(static_cast<sal_uInt64>(pWin)) });
+            xDnD->initialize({ uno::Any(), uno::Any(static_cast<sal_uInt64>(pWin)) });
         else
-            pDnD->initialize({ uno::Any(static_cast<sal_uInt64>(pWin)), uno::Any() });
+            xDnD->initialize({ uno::Any(static_cast<sal_uInt64>(pWin)), uno::Any() });
     }
-    return css::uno::Reference<css::uno::XInterface>(pDnD);
+    return xDnD;
 }
 
 css::uno::Reference<css::uno::XInterface>
-vcl::X11DnDHelper(const css::uno::Reference<css::lang::XInitialization>& pDnD, const sal_IntPtr pWin)
+vcl::X11DnDHelper(const css::uno::Reference<css::lang::XInitialization>& xDnD, const sal_IntPtr pWin)
 {
-    if (pWin && pDnD)
-        pDnD->initialize({ uno::Any(Application::GetDisplayConnection()),
+    if (pWin && xDnD)
+        xDnD->initialize({ uno::Any(Application::GetDisplayConnection()),
                            uno::Any(static_cast<sal_uInt64>(pWin)) });
-    return css::uno::Reference<css::uno::XInterface>(pDnD);
+    return xDnD;
 }
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/source/window/mouse.cxx b/vcl/source/window/mouse.cxx
index a25e226ed9fb..02f6c8a484b1 100644
--- a/vcl/source/window/mouse.cxx
+++ b/vcl/source/window/mouse.cxx
@@ -732,9 +732,17 @@ Reference< css::datatransfer::dnd::XDragSource > Window::GetDragSource()
     if (mpWindowImpl->mpFrameData->mxDragSource.is())
         return mpWindowImpl->mpFrameData->mxDragSource;
 
-    SalInstance* pInst = ImplGetSVData()->mpDefInst;
-    mpWindowImpl->mpFrameData->mxDragSource.set(pInst->CreateDragSource(pEnvData), UNO_QUERY);
-    mpWindowImpl->mpFrameData->mxDropTarget.set(pInst->CreateDropTarget(pEnvData), UNO_QUERY);
+    try
+    {
+        SalInstance* pInst = ImplGetSVData()->mpDefInst;
+        mpWindowImpl->mpFrameData->mxDragSource.set(pInst->CreateDragSource(pEnvData), UNO_QUERY);
+        mpWindowImpl->mpFrameData->mxDropTarget.set(pInst->CreateDropTarget(pEnvData), UNO_QUERY);
+    }
+    catch (const Exception&)
+    {
+        mpWindowImpl->mpFrameData->mxDropTarget.clear();
+        mpWindowImpl->mpFrameData->mxDragSource.clear();
+    }
     return mpWindowImpl->mpFrameData->mxDragSource;
 #else
     return Reference< css::datatransfer::dnd::XDragSource > ();