Re: [pygame] software filter for camera

[Nirav Patel <olpc@xxxxxxxxxxxxxx>]

Just to clarify,  I think the get_hw_capabilities function is very
useful and will merge it in soon, but I'm not sure about automatic
software flipping.

Nirav

On Sun, May 10, 2009 at 11:22 AM, Nirav Patel <olpc@xxxxxxxxxxxxxx> wrote:
> This is certainly a good idea.  The issue is that controls are often
> very poorly implemented in camera drivers.  Some drivers do support
> hardware flipping but don't respond to VIDIOC_QUERYCTRL, while some
> return true to a VIDIOC_S_CTRL while not actually doing the flip that
> they were told to do.  I have yet to come across a case of responding
> false to VIDIO_S_CTRL while still doing the flip, but it is not
> unfathomable.  I think having automatic software flipping could cause
> as many problems as it fixes.
>
> The solution I was hoping people would go for would be for pygame
> apps/games that use the camera to have options somewhere, commandline,
> keyboard, or otherwise, that would allow the user to say whether or
> not to flip it in software, as seeing the image is the only way to
> guarantee the correct behavior.
>
> That is just my opinion though, what does everyone else think?
>
> Nirav
>
> On Sun, May 10, 2009 at 9:31 AM,  <don@xxxxxxxxxxxxxxxxx> wrote:
>> Hi,
>>
>> I was testing the camera module and was a bit disappointed to find that my camera
>> doesn't support flipping via Camera.set_controls().
>> I thought that it would be a good idea if these basic settings should work whether
>> the camera supports them or not. So I set out to write a patch which implements
>> this.
>>
>> The patch does three things:
>>  1) it exposes a C-API for transform.flip()
>>  2) it adds a new field "filter" to the camera object. When the user calls
>> set_controls() and the camera doesn't support h/vflip then it sets a flag in the
>> filter variable. when Camera.get_image() is called and the flag is set the surface
>> returned from the camera is passed through transform.flip() to get the desired
>> result.
>>  3) adds a new public method Camera.get_hw_capabilities() which returns a tuple
>> (hflip, vflip) containing booleans so signal if the camera device supports flipping.
>>
>> caveat:
>>  the transform.flip() function doesn't perform the flip in-place but rather
>> returns a new surface. therefor the software filter so far only works when creating
>> a new surface in the get_image() call (i.e. "new_surf = cam.get_image()" and not
>> "cam.get_image(screen)")
>>
>> I tried to design this in an extensible way so that one can use the "filter"
>> variable to later add other filters like color inversion.
>>
>>
>> regards,
>> Lorenz
>>
>