diff options
| author | Jan-Marek Glogowski <glogow@fbihome.de> | 2021-10-12 10:33:36 +0200 |
|---|---|---|
| committer | Mark Hung <marklh9@gmail.com> | 2021-10-17 15:33:45 +0200 |
| commit | a2adb7fa926c2b9ed053c65e130a9da336cc98b0 (patch) | |
| tree | dd95b1817f5c2a12b70fefc0db6b874a55576642 /vcl | |
| parent | 23cded985ba0131f85ee445492c04871fbfb6351 (diff) | |
WIN release SalPrinter's SalGraphics borrowed HDC
Regression from commit d27187b158d7e3f92180b1f2ab79b048dc5318a5
("vcl:use unique_ptr<SalWinGraphics> in WinSalPrinter").
Would need something like Rust's Borrowing semantics to prevent.
Ideas on IRC to make this bug more unlikely were some extra HDC +
SalGraphics struct to pass around or something like unique_ptr
reference passing and moving the value into a local copy.
For now just add some additional comments.
Change-Id: I472ee9acb4a4c02177c27ecd1c1277dfc812cadf
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/123440
Tested-by: Jenkins
Reviewed-by: Mark Hung <marklh9@gmail.com>
Diffstat (limited to 'vcl')
| -rw-r--r-- | vcl/inc/win/salgdi.h | 8 | ||||
| -rw-r--r-- | vcl/win/gdi/salprn.cxx | 3 |
2 files changed, 11 insertions, 0 deletions
diff --git a/vcl/inc/win/salgdi.h b/vcl/inc/win/salgdi.h index 9555cc158b75..974c58ae81ad 100644 --- a/vcl/inc/win/salgdi.h +++ b/vcl/inc/win/salgdi.h @@ -141,6 +141,13 @@ public: void fill(sal_uInt32 color); }; +/** + * WinSalGraphics never owns the HDC it uses to draw, because the HDC can have + * various origins with different ways to correctly free it. And WinSalGraphics + * stores all default values (mhDef*) of the HDC, which must be restored when + * the HDC changes (setHDC) or the SalGraphics is destructed. So think of the + * HDC in terms of Rust's Borrowing semantics. + */ class WinSalGraphics : public SalGraphics { friend class WinSalGraphicsImpl; @@ -177,6 +184,7 @@ public: HFONT ImplDoSetFont(vcl::font::FontSelectPattern const & i_rFont, const vcl::font::PhysicalFontFace * i_pFontFace, HFONT& o_rOldFont); HDC getHDC() const { return mhLocalDC; } + // NOTE: this doesn't transfer ownership! See class comment. void setHDC(HDC aNew); HPALETTE getDefPal() const; diff --git a/vcl/win/gdi/salprn.cxx b/vcl/win/gdi/salprn.cxx index 86e1e616a57f..332c7a8dfaae 100644 --- a/vcl/win/gdi/salprn.cxx +++ b/vcl/win/gdi/salprn.cxx @@ -1373,6 +1373,9 @@ WinSalPrinter::~WinSalPrinter() HDC hDC = mhDC; if ( hDC ) { + // explicitly reset(), so the mxGraphics's borrowed HDC defaults are + // restored and WinSalGraphics's destructor won't work on a deleted HDC. + mxGraphics.reset(); DeleteDC( hDC ); } |