[Pixman] [PATCH v14 08/22] pixman-filter: rename "scale" to "size" when it is 1/scale

Bill Spitzak spitzak at gmail.com
Fri Mar 25 01:30:27 UTC 2016


Would using "iscale" (for inverse scale) work? Another is "tscale" because
it is the scale from the transform matrix.

I really would like to use two different names for these variables as it is
really confusing using the same one.


On Fri, Mar 18, 2016 at 8:24 AM, Bill Spitzak <spitzak at gmail.com> wrote:

>
>
> On Thu, Mar 17, 2016 at 10:06 PM, Søren Sandmann <soren.sandmann at gmail.com
> > wrote:
>
>> I suppose it's a little illogical that scale_x and scale_y really are the
>> reciprocal values of how much the source image should be scaled. I don't
>> remember exactly what I was thinking, but it might have something like
>> "this allows you to just pass t[0][0] and t[1][1] if you have a pure
>> scaling, which avoids a division". There is also kind of precedence in the
>> Pixman API since the transformation given as in the dst->source direction.
>>
>> I don't really like "size" either though. It's not really the size of the
>> filter that we are specifying; it just happens to be proportional to it.
>>
>> If it comes down to "size" and "scale", I prefer "scale".
>>
>
> I tried "width" but it is not actually the filter width. How about "dx"
> and "dy" since it is almost always the derivative of the x and y in the
> input (or du,dv or dtx dtx)
>
>>
>>
>> Søren
>>
>>
>> On Sun, Mar 6, 2016 at 8:06 PM, <spitzak at gmail.com> wrote:
>>
>>> From: Bill Spitzak <spitzak at gmail.com>
>>>
>>> This is to remove some confusion when reading the code. "scale" gets
>>> larger
>>> as the picture gets larger, while "size" (ie the size of the filter) gets
>>> smaller.
>>>
>>> v14: Removed changes to integral function
>>>
>>> Signed-off-by: Bill Spitzak <spitzak at gmail.com>
>>> Reviewed-by: Oded Gabbay <oded.gabbay at gmail.com>
>>> ---
>>>  pixman/pixman-filter.c | 18 +++++++++---------
>>>  pixman/pixman.h        |  6 +++---
>>>  2 files changed, 12 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/pixman/pixman-filter.c b/pixman/pixman-filter.c
>>> index a29116a..c03a7f6 100644
>>> --- a/pixman/pixman-filter.c
>>> +++ b/pixman/pixman-filter.c
>>> @@ -221,7 +221,7 @@ static void
>>>  create_1d_filter (int              width,
>>>                   pixman_kernel_t  reconstruct,
>>>                   pixman_kernel_t  sample,
>>> -                 double           scale,
>>> +                 double           size,
>>>                   int              n_phases,
>>>                   pixman_fixed_t *p)
>>>  {
>>> @@ -251,8 +251,8 @@ create_1d_filter (int              width,
>>>             double pos = x + 0.5 - frac;
>>>             double rlow = - filters[reconstruct].width / 2.0;
>>>             double rhigh = rlow + filters[reconstruct].width;
>>> -           double slow = pos - scale * filters[sample].width / 2.0;
>>> -           double shigh = slow + scale * filters[sample].width;
>>> +           double slow = pos - size * filters[sample].width / 2.0;
>>> +           double shigh = slow + size * filters[sample].width;
>>>             double c = 0.0;
>>>             double ilow, ihigh;
>>>
>>> @@ -262,7 +262,7 @@ create_1d_filter (int              width,
>>>                 ihigh = MIN (shigh, rhigh);
>>>
>>>                 c = integral (reconstruct, ilow,
>>> -                             sample, 1.0 / scale, ilow - pos,
>>> +                             sample, 1.0 / size, ilow - pos,
>>>                               ihigh - ilow);
>>>             }
>>>
>>> @@ -335,12 +335,12 @@ filter_width (pixman_kernel_t reconstruct,
>>> pixman_kernel_t sample, double size)
>>>  }
>>>
>>>  /* Create the parameter list for a SEPARABLE_CONVOLUTION filter
>>> - * with the given kernels and scale parameters
>>> + * with the given kernels and size parameters
>>>   */
>>>  PIXMAN_EXPORT pixman_fixed_t *
>>>  pixman_filter_create_separable_convolution (int             *n_values,
>>> -                                           pixman_fixed_t   scale_x,
>>> -                                           pixman_fixed_t   scale_y,
>>> +                                           pixman_fixed_t   size_x,
>>> +                                           pixman_fixed_t   size_y,
>>>                                             pixman_kernel_t
>>> reconstruct_x,
>>>                                             pixman_kernel_t
>>> reconstruct_y,
>>>                                             pixman_kernel_t  sample_x,
>>> @@ -348,8 +348,8 @@ pixman_filter_create_separable_convolution (int
>>>        *n_values,
>>>                                             int
>>> subsample_bits_x,
>>>                                             int
>>> subsample_bits_y)
>>>  {
>>> -    double sx = fabs (pixman_fixed_to_double (scale_x));
>>> -    double sy = fabs (pixman_fixed_to_double (scale_y));
>>> +    double sx = fabs (pixman_fixed_to_double (size_x));
>>> +    double sy = fabs (pixman_fixed_to_double (size_y));
>>>      pixman_fixed_t *params;
>>>      int subsample_x, subsample_y;
>>>      int width, height;
>>> diff --git a/pixman/pixman.h b/pixman/pixman.h
>>> index 509ba5e..b012a33 100644
>>> --- a/pixman/pixman.h
>>> +++ b/pixman/pixman.h
>>> @@ -845,12 +845,12 @@ typedef enum
>>>  } pixman_kernel_t;
>>>
>>>  /* Create the parameter list for a SEPARABLE_CONVOLUTION filter
>>> - * with the given kernels and scale parameters.
>>> + * with the given kernels and size parameters.
>>>   */
>>>  pixman_fixed_t *
>>>  pixman_filter_create_separable_convolution (int             *n_values,
>>> -                                           pixman_fixed_t   scale_x,
>>> -                                           pixman_fixed_t   scale_y,
>>> +                                           pixman_fixed_t   size_x,
>>> +                                           pixman_fixed_t   size_y,
>>>                                             pixman_kernel_t
>>> reconstruct_x,
>>>                                             pixman_kernel_t
>>> reconstruct_y,
>>>                                             pixman_kernel_t  sample_x,
>>> --
>>> 1.9.1
>>>
>>> _______________________________________________
>>> Pixman mailing list
>>> Pixman at lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/pixman
>>>
>>
>>
>
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