The IDirectFBDisplayLayer::GetSurface function's docs they that it is intended
to only be used when the display layer cooperative level is DLSCL_EXCLUSIVE.
However, the implementation appears to be designed for it to be used also
(potentially if needed) when the level is also DLSCL_ADMINISTRATIVE. It also
currently even allows usage when it is DLSCL_SHARED.
1. What's the intent for this function long term? Should the documentation be
updated to state that DLSCL_ADMINISTRATIVE is also allowed?
2. Why is DLSCL_SHARED being allowed temporarily and should it be kept that
way?
In the current implementation, I believe the following fix in
src/display/idirectfbdisplaylayer.c's IDirectFBDisplayLayer_GetSurface function
is needed to change the logic of when dfb_layer_region_flip_update is called
for a single buffered display layer to be first made visible AND to not always
perform a clear/background rendering if the GetSurface function is called
multiple times.
if (region->config.buffermode == DLBM_FRONTONLY &&
data->level != DLSCL_SHARED &&
D_FLAGS_IS_SET( region->state, CLRSF_FROZEN ))
{
if (data->level == DLSCL_EXCLUSIVE)
{
// Is this still needed if dfb_windowstack_repaint_all is
// called below? Probably just in case there is legacy
// code depending upon it and the surface buffer memory is
// not cleared when it is allocated.
surface->Clear( surface, 0, 0, 0, 0 );
}
// If a window stack is available, give it the opportunity to
// render the background (optionally based on configuration) and
// flip the display layer so it is visible. Otherwise, just
// directly flip the display make and make it visible.
if (region->context->stack)
{
dfb_windowstack_repaint_all( region->context->stack );
}
else
{
dfb_layer_region_flip_update( region, NULL, DSFLIP_NONE );
}
}
Thoughts?
Best Regards,
Timothy
--
Timothy Strelchun
CE Software Engineering
Digital Home Group
Intel Corporation
The views expressed above are my own and not those of Intel
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