Denis Oliver Kropp wrote:
> Daniel Laird wrote:
>>> 1) Find out why the background is cleared at all, because
>>> layers != PRIMARY should have no background color set,
>>> or maybe it's black. The background mode for these layers
>>> should be DLBM_DONTCARE to solve the issue.
>>>
>>> 2) Not create a window stack when the layer has a certain
>>> capability, maybe add DLCAPS_NOWINDOWSTACK.
>>>
>>> 3) Allocate a dummy line of pixels in your surface pool and
>>> keep the pitch at 0 :-)
>>>
>> Option 3 is probably the best but not the cleanest. I had a quick go with
>> option 2.
>
> Option 3 is at least the one with the least impact or risks.
>
>> I modified dfb_layer_context_init in layer_context.c.
>> I added
>> /* Create the window stack if the layer supports it. */
>> if (!D_FLAGS_IS_SET( shared->description.caps, DLCAPS_NOWINDOWSTACK ))
>> {
>> context->stack = dfb_windowstack_create( context );
>> if (!context->stack) {
>> dfb_layer_context_unref( context );
>> return D_OOSHM();
>> }
>>
>> /* Tell the window stack about its size. */
>> dfb_windowstack_resize( context->stack,
>> context->config.width,
>> context->config.height );
>> }
>> This seemed to do the job rather nicely. Can you see any drawbacks? know of
>> any hidden issues I might encounter.
>
>
> The issues could be wherever context->stack is assumed to be non-NULL,
> which should cause failing assertions, but some sites might just cause
> a segmentation fault.
>
> So option 1 would be quite clean and somewhat safe, but at any time a
> user might request to create a window or render to the layer surface
> directly...
>
> I think I'd go for Option 1+3 which avoids filling the dummy line
> multiple (height) times, but still has a fallback in case there's
> another access.
Ideally, option 2 would be the best, of course, but it also requires
the biggest effort and caution :-)
Denis
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