Re: [Gnash-dev] What to do when a dynamic cast fail in librender?

[Sandro Santilli]

While I also see a static_cast being probably safe I still like
the auto-testing feature of dynamic_cast. In this specific case
you could obtain the same effect of the explicit check and throw
by dynamically casting to a reference rather than to an object:

 const bitmap_info_cairo& binfo = dynamic_cast<
 const bitmap_info_cairo& >(*bm); // will throw bad_cast on failure

For testing them, see MovieTester::initTestingRenderers() in
testsuite/MovieTester.cpp. Right now only the first renderer
is used. A TODO comment envisions a multi-renderer testing but
mentions it'd take many changes (pre-rendered objects are stored
in parse state, which would basically trigger bad_cast exceptions
right where you're looking); still you might want to try setting
the order (or single renderer being tested) with some environment
variable or something like that.

--strk;

On Sun, Apr 20, 2014 at 02:46:11PM +0200, Bastiaan Jacques wrote:
> So far as I can tell, all CachedBitmap objects are created by the
> renderer (in createCachedBitmap()), and because that function always
> returns a bitmap_info_cairo, a dynamic_cast does not seem to be
> required.  You can just replace it with a static_cast instead of
> checking the dynamic_cast.
> 
> Bastiaan
> 
> On Sun, 20 Apr 2014, Petter Reinholdtsen wrote:
> 
> >diff --git a/librender/cairo/Renderer_cairo.cpp 
> >b/librender/cairo/Renderer_cairo.cpp
> >index c597dd4..2e95686 100644
> >--- a/librender/cairo/Renderer_cairo.cpp
> >+++ b/librender/cairo/Renderer_cairo.cpp
> >@@ -299,6 +299,9 @@ struct StyleHandler : 
> >boost::static_visitor<cairo_pattern_t*>
> >
> >        const bitmap_info_cairo* binfo =
> >            dynamic_cast<const bitmap_info_cairo*>(bm);
> >+       if (NULL == binfo) { // CID 1154657, binfo used below
> >+           throw std::bad_cast();
> >+       }
> >
> >        cairo_matrix_t mat;
> >        init_cairo_matrix(&mat, m);
> 
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