i have a function to implement that returns a pointer to an array of
pixels representing the
pixels in the specified row , or else returns NULL if an error occurred. If
successful, the returned
array pointer may point to a temporary buffer or directly into the frame
buffer.
(The latter is usually desirable, if possible.)
On Thu, Dec 23, 2010 at 2:42 PM, Chris Bore <chris_b...@yahoo.co.uk> wrote:
> Although it is used in DirectFB, I do not recommend using the Lock/Unlock
> functions. They bypass the API, and raise other issues that can be
> problematic. I do not think there is ever a case where using Lock to gain
> direct access to the encapsulated pixel data is really necessary - it can
> always be done using the standard API. If you explain what you are trying to
> do then perhaps I can suggest another way to do it.
>
> ==================================
> Chris Bore
> Training Director
> BORES Signal Processing
> ch...@bores.com
> www.bores.com
> +44 (0)1483 740138
>
>
> ------------------------------
> *From:* ravi <ravi...@gmail.com>
> *To:* Sriram Neelakandan <sriram.neelakan...@gmail.com>
> *Cc:* directfb-users@directfb.org
> *Sent:* Thu, 23 December, 2010 4:58:32
> *Subject:* Re: [directfb-users] accessing the row
>
>
> If i unlock the surface first then how can i return the pointer to the
> caller? I'm unlocking the surface in a different function that caller will
> call after this function.
> On Thu, Dec 23, 2010 at 10:02 AM, Sriram Neelakandan <
> sriram.neelakan...@gmail.com> wrote:
>
>> well that means the surface is already locked .. u must unlock each Lock
>> after usage
>>
>> 1. Lock
>> 2. use the pointer
>> 3. UnLock
>>
>>
>> On Wed, Dec 22, 2010 at 4:31 PM, ravi <ravi...@gmail.com> wrote:
>>
>>> Hell,
>>> i have a function to implement that returns a pointer to an
>>> array of pixels representing the
>>> pixels in the specified row of the surface columns from x (inclusive) to
>>> x + w
>>> (exclusive), I implemented it like this......
>>>
>>> { void *data;
>>> int pitch;
>>> surface->Lock(surface, DSLF_READ, &data, &pitch );
>>>
>>> return (pointer *)data + pitch*row;
>>>
>>> }
>>>
>>> running this function is aborting the program with this message......
>>>
>>> DirectFBError [>surface->Lock( surface, (DFBSurfaceLockFlags)(DSLF_READ
>>> | DSLF_WRITE), &data, &pitch )]: Resource is locked!
>>>
>>>
>>>
>>> --
>>> Regards
>>>
>>> Ravi Swami
>>> EnMedia Software Technologies
>>> Ph +91-974-264-3747
>>>
>>> _______________________________________________
>>> directfb-users mailing list
>>> directfb-users@directfb.org
>>> http://mail.directfb.org/cgi-bin/mailman/listinfo/directfb-users
>>>
>>>
>>
>>
>> --
>> Sriram Neelakandan
>> Author - Embedded Linux System Design And Development (
>> http://tinyurl.com/2doosu)
>>
>
>
>
> --
> Regards
>
> Ravi Swami
> EnMedia Software Technologies
> Ph +91-974-264-3747
>
--
Regards
Ravi Swami
EnMedia Software Technologies
Ph +91-974-264-3747
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