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authorTomasz Stanislawski <t.stanislaws@samsung.com>2011-12-09 13:45:47 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2012-01-10 23:19:57 -0200
commitaa73ab96bebb6fb9e0ee4429f78bfa3ef8c5b6b6 (patch)
tree19d65e4896c351fc356363c47fae51f3b6a79e38 /Documentation
parent392d9e1d02edcbe9bc94bc292dd364339556f8ec (diff)
downloadlinux-linaro-stable-aa73ab96bebb6fb9e0ee4429f78bfa3ef8c5b6b6.tar.gz
[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>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/DocBook/media/v4l/selection-api.xml30
1 files changed, 12 insertions, 18 deletions
diff --git a/Documentation/DocBook/media/v4l/selection-api.xml b/Documentation/DocBook/media/v4l/selection-api.xml
index 46cb47ab8e3b..2f0bdb4d5551 100644
--- a/Documentation/DocBook/media/v4l/selection-api.xml
+++ b/Documentation/DocBook/media/v4l/selection-api.xml
@@ -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>