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[media] doc: v4l: selection: choose pixels as units for selection rectangles 

Pixels were preferred units for selection rectangles over driver-dependent
units for almost all use cases. Therefore the units were fixed to pixels.

Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
hifive-unleashed-5.1
Tomasz Stanislawski 2011-12-09 13:45:47 -03:00 committed by Mauro Carvalho Chehab
parent 392d9e1d02
commit aa73ab96be
1 changed files with 12 additions and 18 deletions
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30
Documentation/DocBook/media/v4l/selection-api.xml
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@ -84,9 +84,7 @@ configure the cropping targets before to the composing targets.</para>
areas that can be sampled is given by the <constant> V4L2_SEL_TGT_CROP_BOUNDS
</constant> target. It is recommended for the driver developers to put the
top/left corner at position <constant> (0,0) </constant>. The rectangle's
coordinates are expressed in driver dependant units, although the coordinate
system guarantees that if sizes of the active cropping and the active composing
rectangles are equal then no scaling is performed. </para>
coordinates are expressed in pixels.</para>
<para>The top left corner, width and height of the source rectangle, that is
the area actually sampled, is given by the <constant> V4L2_SEL_TGT_CROP_ACTIVE
@ -103,10 +101,10 @@ not later.</para>
<para>The composing targets refer to a memory buffer. The limits of composing
coordinates are obtained using <constant> V4L2_SEL_TGT_COMPOSE_BOUNDS
</constant>. All coordinates are expressed in natural unit for given formats.
Pixels are highly recommended. The rectangle's top/left corner must be located
at position <constant> (0,0) </constant>. The width and height are equal to the
image size set by <constant> VIDIOC_S_FMT </constant>.</para>
</constant>. All coordinates are expressed in pixels. The rectangle's top/left
corner must be located at position <constant> (0,0) </constant>. The width and
height are equal to the image size set by <constant> VIDIOC_S_FMT </constant>.
</para>
<para>The part of a buffer into which the image is inserted by the hardware is
controlled by the <constant> V4L2_SEL_TGT_COMPOSE_ACTIVE </constant> target.
@ -145,10 +143,9 @@ the cropping targets.</para>
<para>The cropping targets refer to the memory buffer that contains an image to
be inserted into a video signal or graphical screen. The limits of cropping
coordinates are obtained using <constant> V4L2_SEL_TGT_CROP_BOUNDS </constant>.
All coordinates are expressed in natural units for a given format. Pixels are
highly recommended. The top/left corner is always point <constant> (0,0)
</constant>. The width and height is equal to the image size specified using
<constant> VIDIOC_S_FMT </constant> ioctl.</para>
All coordinates are expressed in pixels. The top/left corner is always point
<constant> (0,0) </constant>. The width and height is equal to the image size
specified using <constant> VIDIOC_S_FMT </constant> ioctl.</para>
<para>The top left corner, width and height of the source rectangle, that is
the area from which image date are processed by the hardware, is given by the
@ -163,13 +160,10 @@ limitations.</para>
bounding rectangle.</para>
<para>The part of a video signal or graphics display where the image is
inserted by the hardware is controlled by <constant> V4L2_SEL_TGT_COMPOSE_ACTIVE
</constant> target. The rectangle's coordinates are expressed in driver
dependant units. The only exception are digital outputs where the units are
pixels. For other types of devices, the coordinate system guarantees that if
sizes of the active cropping and the active composing rectangles are equal then
no scaling is performed. The composing rectangle must lie completely inside
the bounds rectangle. The driver must adjust the area to fit to the bounding
inserted by the hardware is controlled by <constant>
V4L2_SEL_TGT_COMPOSE_ACTIVE </constant> target. The rectangle's coordinates
are expressed in pixels. The composing rectangle must lie completely inside the
bounds rectangle. The driver must adjust the area to fit to the bounding
limits. Moreover, the driver can perform other adjustments according to
hardware limitations. </para>