tdf#93839 - Encourage vdevs to pick up new GL Contexts when they go invalid.

Change-Id: I21726d0dd052fdc87e8dd36ff7122518325f6313
Reviewed-on: https://gerrit.libreoffice.org/18242Reviewed-by: Jan Holesovsky <kendy@collabora.com>
Tested-by: Jan Holesovsky <kendy@collabora.com>

vcl/inc/openglgdiimpl.hxx

@@ -154,6 +154,8 @@ public:
 
     virtual void Init() SAL_OVERRIDE;
 
+    virtual void DeInit() SAL_OVERRIDE;
+
     virtual void freeResources() SAL_OVERRIDE;
 
     const vcl::Region& getClipRegion() const;

vcl/inc/salgdiimpl.hxx

@@ -46,6 +46,8 @@ public:
 
     virtual void Init() = 0;
 
+    virtual void DeInit() {}
+
     virtual void freeResources() = 0;
 
     virtual bool setClipRegion( const vcl::Region& ) = 0;

vcl/opengl/gdiimpl.cxx

@@ -149,6 +149,19 @@ void OpenGLSalGraphicsImpl::Init()
     }
 }
 
+// Currently only used to get windows ordering right.
+void OpenGLSalGraphicsImpl::DeInit()
+{
+    // tdf#93839:
+    // Our window handles and resources are being free underneath us.
+    // These can be bound into a context, which relies on them. So
+    // let it know. Other eg. VirtualDevice contexts which have
+    // references on and rely on this context continuing to work will
+    // get a shiny new context in AcquireContext:: next PreDraw.
+    if( mpContext && !IsOffscreen() )
+        mpContext->reset();
+}
+
 void OpenGLSalGraphicsImpl::PreDraw()
 {
     OpenGLZone::enter();

vcl/source/opengl/OpenGLContext.cxx

@@ -1253,6 +1253,9 @@ void OpenGLContext::reset()
 
     OpenGLZone aZone;
 
+    // don't reset a context in the middle of stack frames rendering to it
+    assert( mnPainting == 0 );
+
     // reset the clip region
     maClipRegion.SetEmpty();
 

vcl/win/source/gdi/salgdi.cxx

@@ -502,6 +502,8 @@ void WinSalGraphics::DeInitGraphics()
         SelectBrush( getHDC(), mhDefBrush );
     if ( mhDefFont )
         SelectFont( getHDC(), mhDefFont );
+
+    mpImpl->DeInit();
 }
 
 HDC ImplGetCachedDC( sal_uLong nID, HBITMAP hBmp )

vcl/win/source/gdi/salvd.cxx

@@ -181,7 +181,7 @@ WinSalVirtualDevice::~WinSalVirtualDevice()
     // destroy saved DC
     if( mpGraphics->getDefPal() )
         SelectPalette( mpGraphics->getHDC(), mpGraphics->getDefPal(), TRUE );
-    mpGraphics->InitGraphics();
+    mpGraphics->DeInitGraphics();
     if( mhDefBmp )
         SelectBitmap( mpGraphics->getHDC(), mhDefBmp );
     if( !mbForeignDC )