Merge in from trunk r64802 - r68625

[wxWidgets.git] / src / dfb / dcscreen.cpp

diff --git a/src/dfb/dcscreen.cpp b/src/dfb/dcscreen.cpp
index 730903e87ffa5c052bcd941c4a3c190f8cb807bd..db19dc53a1f20563d99fd46adec38f651aa599ca 100644 (file)
--- a/src/dfb/dcscreen.cpp
+++ b/src/dfb/dcscreen.cpp
@@ -31,8 +31,33 @@
 // wxScreenDC
 //-----------------------------------------------------------------------------
 
 // wxScreenDC
 //-----------------------------------------------------------------------------
 

-#warning "FIXME: this doesn't work (neither single app nor multiapp core)
-// FIXME: maybe use a subsurface as well?
+// FIXME: Currently, wxScreenDC doesn't work at all in non-exclusive mode
+//        (DFSCL_NORMAL). In this mode, requesting primary surface results
+//        in one of the following actions, depending on directfbrc
+//        configuration:
+//
+//        (1) if force-desktop, a surface is created and used as *background*
+//            for the windows managed by DFB WM
+//
+//        (2) otherwise, a dummy surface of the right size and format is
+//            created, but isn't shown on the screen
+//
+//        (3) furthermore, if autoflip-window option is not used and primary
+//            surface is requested as single-buffered (which is needed to
+//            implement wxScreenDC semantics), a warning is issued in addition
+//            to 2); if autoflip-window is used, then a helper thread is
+//            created and does periodic flipping, which is even worse
+//
+//        2) and 3) are obviously unsatisfactory. 1) isn't suitable either,
+//        because wxScreenDC has to render *on top* of windows.
+//
+//        In conclusion, wxScreenDC as currently implemented is only usable
+//        for measuring things (e.g. font sizes). For this task, however, it
+//        is quite expensive to create in DFSCL_NORMAL mode, because it
+//        involves creation of a new surface as big as the screen.
+//
+//        The surface, as obtained from GetPrimarySurface(), is double-buffered
+//        for the sole purpose of silencing the warning from 3) above.

 
 IMPLEMENT_ABSTRACT_CLASS(wxScreenDCImpl, wxDFBDCImpl)
 
 
 IMPLEMENT_ABSTRACT_CLASS(wxScreenDCImpl, wxDFBDCImpl)
 


@@ -41,5 +66,3 @@ wxScreenDCImpl::wxScreenDCImpl(wxScreenDC *owner)
 {
     DFBInit(wxIDirectFB::Get()->GetPrimarySurface());
 }
 {
     DFBInit(wxIDirectFB::Get()->GetPrimarySurface());
 }

-
-#warning "FIXME: does wxScreenDC need Flip call in dtor?"