On 08/01/2016 10:57 AM, Laurent Pinchart wrote:
> Hi Hans,
>
> Thank you for the patch.
>
> On Monday 01 Aug 2016 10:45:30 Hans Verkuil wrote:
>> Checking the selection constraint flags is often forgotten by drivers,
>> especially if the selection code just clamps the rectangle to the minimum
>> and maximum allowed rectangles.
>>
>> This patch adds a simple helper function that checks the adjusted rectangle
>> against the constraint flags and either returns -ERANGE if it doesn't fit,
>> or fills in the new rectangle and returns 0.
>>
>> It also adds a small helper function to v4l2-rect.h to check if one
>> rectangle fits inside another.
>>
>> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
>> ---
>> diff --git a/drivers/media/v4l2-core/v4l2-common.c
>> b/drivers/media/v4l2-core/v4l2-common.c index 5b80850..a2e5119 100644
>> --- a/drivers/media/v4l2-core/v4l2-common.c
>> +++ b/drivers/media/v4l2-core/v4l2-common.c
>> @@ -61,6 +61,7 @@
>> #include <media/v4l2-common.h>
>> #include <media/v4l2-device.h>
>> #include <media/v4l2-ctrls.h>
>> +#include <media/v4l2-rect.h>
>>
>> #include <linux/videodev2.h>
>>
>> @@ -371,6 +372,21 @@ void v4l_bound_align_image(u32 *w, unsigned int wmin,
>> unsigned int wmax, }
>> EXPORT_SYMBOL_GPL(v4l_bound_align_image);
>>
>> +int v4l2_s_selection(struct v4l2_selection *s, const struct v4l2_rect *r)
>> +{
>> + /* The original rect must lay inside the adjusted one */
>> + if ((s->flags & V4L2_SEL_FLAG_GE) &&
>> + !v4l2_rect_is_inside(&s->r, r))
>> + return -ERANGE;
>> + /* The adjusted rect must lay inside the original one */
>> + if ((s->flags & V4L2_SEL_FLAG_LE) &&
>> + !v4l2_rect_is_inside(r, &s->r))
>> + return -ERANGE;
>
> I'd like to see how this function is used in drivers.
See my comments here:
https://patchwork.linuxtv.org/patch/35794/
>
>> + s->r = *r;
>> + return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(v4l2_s_selection);
>> +
>> const struct v4l2_frmsize_discrete *v4l2_find_nearest_format(
>> const struct v4l2_discrete_probe *probe,
>> s32 width, s32 height)
>> diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h
>> index 350cbf9..cfa9cbf 100644
>> --- a/include/media/v4l2-common.h
>> +++ b/include/media/v4l2-common.h
>> @@ -246,6 +246,17 @@ void v4l_bound_align_image(unsigned int *w, unsigned
>> int wmin, unsigned int hmax, unsigned int halign,
>> unsigned int salign);
>>
>> +/**
>> + * v4l2_s_selection - Helper to check adjusted rectangle against constraint
>> flags
>> + *
>> + * @s: pointer to &struct v4l2_selection containing the original rectangle
>> + * @r: pointer to &struct v4l2_rect containing the adjusted rectangle.
>> + *
>> + * Returns -ERANGE if the adjusted rectangle doesn't fit the constraints
>> + * or 0 if it is fine. On success it sets @s->r to @r.
>> + */
>
> Part of the functions are documented in the header and part in the
> implementation. We need to pick one option, and I prefer the latter one (which
> is also more consistent with how functions are documented in most subsystems).
I'll move it.
>
>> +int v4l2_s_selection(struct v4l2_selection *s, const struct v4l2_rect *r);
>> +
>> struct v4l2_discrete_probe {
>> const struct v4l2_frmsize_discrete *sizes;
>> int num_sizes;
>> diff --git a/include/media/v4l2-rect.h b/include/media/v4l2-rect.h
>> index d2125f0..858c8cb 100644
>> --- a/include/media/v4l2-rect.h
>> +++ b/include/media/v4l2-rect.h
>> @@ -95,6 +95,21 @@ static inline bool v4l2_rect_same_size(const struct
>> v4l2_rect *r1, }
>>
>> /**
>> + * v4l2_rect_is_inside() - return true if r1 is inside r2
>> + * @r1: rectangle.
>> + * @r2: rectangle.
>> + *
>> + * Return true if r1 fits inside r2.
>> + */
>> +static inline bool v4l2_rect_is_inside(const struct v4l2_rect *r1,
>> + const struct v4l2_rect *r2)
>
> How about calling the arguments inner and outer to make the purpose of each
> argument more explicit from the function prototype ?
Much better, thanks.
> Also, I would name the function v4l2_rect_is_contained(), or possibly
> v4l2_rect_contains() in which case the arguments should be switched. It should
> also be noted that C doesn't provide support for function overloading so we
> can't have
>
> /* Rectangle contains rectangle */
> bool v4l2_rect_contains(const struct v4l2_rect *outer,
> const struct v4l2_rect *inner);
> /* Rectangle contains point */
> bool v4l2_rect_contains(const struct v4l2_rect *rect,
> unsigned int x, unsigned int y);
>
> Maybe we should thus name the function v4l2_rect_contains_rect() in prevision
> for a future v4l2_rect_contains_point() ?
I prefer is_inside. The name implies that one rect is inside another
whereas 'contains' just suggests that some object is contained by a rect.
Also, the 'inside' terminology is already used in v4l2-rect.h.
>
>> +{
>> + return r1->left >= r2->left && r1->top >= r2->top &&
>> + r1->left + r1->width <= r2->left + r2->width &&
>> + r1->top + r1->height <= r2->top + r2->height;
>
> Isn't that's a big long for an inline function ?
I don't think so.
>
>> +}
>> +
>> +/**
>> * v4l2_rect_intersect() - calculate the intersection of two rects.
>> * @r: intersection of @r1 and @r2.
>> * @r1: rectangle.
>
Regards,
Hans
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