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[media] V4L: Improve the selection API documentation 

Make the VIDIOC_G/S_SELECTION ioctls documentation more consistent
with the rest of media Docbook, use capital letters where necessary
and correct few minor errors.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Sylwester Nawrocki 2012-03-09 06:46:28 -03:00 committed by Mauro Carvalho Chehab
parent 1d53160111
commit 9080d5d3fa
3 changed files with 76 additions and 68 deletions
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8
Documentation/DocBook/media/v4l/selection-api.xml
View File

@ -52,6 +52,10 @@ cropping and composing rectangles have the same size.</para>
</textobject> </textobject>
</mediaobject> </mediaobject>
</figure> </figure>
For complete list of the available selection targets see table <xref
linkend="v4l2-sel-target"/>
</section> </section>
<section> <section>
@ -186,7 +190,7 @@ V4L2_SEL_TGT_COMPOSE_ACTIVE </constant> target.</para>
<section> <section>
<title>Scaling control.</title> <title>Scaling control</title>
<para>An application can detect if scaling is performed by comparing the width <para>An application can detect if scaling is performed by comparing the width
and the height of rectangles obtained using <constant> V4L2_SEL_TGT_CROP_ACTIVE and the height of rectangles obtained using <constant> V4L2_SEL_TGT_CROP_ACTIVE
@ -200,7 +204,7 @@ the scaling ratios using these values.</para>
<section> <section>
<title>Comparison with old cropping API.</title> <title>Comparison with old cropping API</title>
<para>The selection API was introduced to cope with deficiencies of previous <para>The selection API was introduced to cope with deficiencies of previous
<link linkend="crop"> API </link>, that was designed to control simple capture <link linkend="crop"> API </link>, that was designed to control simple capture

106
Documentation/DocBook/media/v4l/vidioc-g-selection.xml
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@ -58,43 +58,43 @@
<para>The ioctls are used to query and configure selection rectangles.</para> <para>The ioctls are used to query and configure selection rectangles.</para>
<para> To query the cropping (composing) rectangle set <structfield> <para> To query the cropping (composing) rectangle set &v4l2-selection;
&v4l2-selection;::type </structfield> to the respective buffer type. Do not <structfield> type </structfield> field to the respective buffer type.
use multiplanar buffers. Use <constant> V4L2_BUF_TYPE_VIDEO_CAPTURE Do not use multiplanar buffers. Use <constant> V4L2_BUF_TYPE_VIDEO_CAPTURE
</constant> instead of <constant> V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE </constant> instead of <constant> V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
</constant>. Use <constant> V4L2_BUF_TYPE_VIDEO_OUTPUT </constant> instead of </constant>. Use <constant> V4L2_BUF_TYPE_VIDEO_OUTPUT </constant> instead of
<constant> V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE </constant>. The next step is <constant> V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE </constant>. The next step is
setting <structfield> &v4l2-selection;::target </structfield> to value setting the value of &v4l2-selection; <structfield>target</structfield> field
<constant> V4L2_SEL_TGT_CROP_ACTIVE </constant> (<constant> to <constant> V4L2_SEL_TGT_CROP_ACTIVE </constant> (<constant>
V4L2_SEL_TGT_COMPOSE_ACTIVE </constant>). Please refer to table <xref V4L2_SEL_TGT_COMPOSE_ACTIVE </constant>). Please refer to table <xref
linkend="v4l2-sel-target" /> or <xref linkend="selection-api" /> for additional linkend="v4l2-sel-target" /> or <xref linkend="selection-api" /> for additional
targets. Fields <structfield> &v4l2-selection;::flags </structfield> and targets. The <structfield>flags</structfield> and <structfield>reserved
<structfield> &v4l2-selection;::reserved </structfield> are ignored and they </structfield> fields of &v4l2-selection; are ignored and they must be filled
must be filled with zeros. The driver fills the rest of the structure or with zeros. The driver fills the rest of the structure or
returns &EINVAL; if incorrect buffer type or target was used. If cropping returns &EINVAL; if incorrect buffer type or target was used. If cropping
(composing) is not supported then the active rectangle is not mutable and it is (composing) is not supported then the active rectangle is not mutable and it is
always equal to the bounds rectangle. Finally, structure <structfield> always equal to the bounds rectangle. Finally, the &v4l2-rect;
&v4l2-selection;::r </structfield> is filled with the current cropping <structfield>r</structfield> rectangle is filled with the current cropping
(composing) coordinates. The coordinates are expressed in driver-dependent (composing) coordinates. The coordinates are expressed in driver-dependent
units. The only exception are rectangles for images in raw formats, whose units. The only exception are rectangles for images in raw formats, whose
coordinates are always expressed in pixels. </para> coordinates are always expressed in pixels. </para>
<para> To change the cropping (composing) rectangle set <structfield> <para> To change the cropping (composing) rectangle set the &v4l2-selection;
&v4l2-selection;::type </structfield> to the respective buffer type. Do not <structfield>type</structfield> field to the respective buffer type. Do not
use multiplanar buffers. Use <constant> V4L2_BUF_TYPE_VIDEO_CAPTURE use multiplanar buffers. Use <constant> V4L2_BUF_TYPE_VIDEO_CAPTURE
</constant> instead of <constant> V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE </constant> instead of <constant> V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
</constant>. Use <constant> V4L2_BUF_TYPE_VIDEO_OUTPUT </constant> instead of </constant>. Use <constant> V4L2_BUF_TYPE_VIDEO_OUTPUT </constant> instead of
<constant> V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE </constant>. The next step is <constant> V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE </constant>. The next step is
setting <structfield> &v4l2-selection;::target </structfield> to value setting the value of &v4l2-selection; <structfield>target</structfield> to
<constant> V4L2_SEL_TGT_CROP_ACTIVE </constant> (<constant> <constant>V4L2_SEL_TGT_CROP_ACTIVE</constant> (<constant>
V4L2_SEL_TGT_COMPOSE_ACTIVE </constant>). Please refer to table <xref V4L2_SEL_TGT_COMPOSE_ACTIVE </constant>). Please refer to table <xref
linkend="v4l2-sel-target" /> or <xref linkend="selection-api" /> for additional linkend="v4l2-sel-target" /> or <xref linkend="selection-api" /> for additional
targets. Set desired active area into the field <structfield> targets. The &v4l2-rect; <structfield>r</structfield> rectangle need to be
&v4l2-selection;::r </structfield>. Field <structfield> set to the desired active area. Field &v4l2-selection; <structfield> reserved
&v4l2-selection;::reserved </structfield> is ignored and must be filled with </structfield> is ignored and must be filled with zeros. The driver may adjust
zeros. The driver may adjust the rectangle coordinates. An application may coordinates of the requested rectangle. An application may
introduce constraints to control rounding behaviour. Set the field introduce constraints to control rounding behaviour. The &v4l2-selection;
<structfield> &v4l2-selection;::flags </structfield> to one of values: <structfield>flags</structfield> field must be set to one of the following:
<itemizedlist> <itemizedlist>
<listitem> <listitem>
@ -129,7 +129,7 @@ and vertical offset and sizes are chosen according to following priority:
<orderedlist> <orderedlist>
<listitem> <listitem>
<para>Satisfy constraints from <structfield>&v4l2-selection;::flags</structfield>.</para> <para>Satisfy constraints from &v4l2-selection; <structfield>flags</structfield>.</para>
</listitem> </listitem>
<listitem> <listitem>
<para>Adjust width, height, left, and top to hardware limits and alignments.</para> <para>Adjust width, height, left, and top to hardware limits and alignments.</para>
@ -145,7 +145,7 @@ and vertical offset and sizes are chosen according to following priority:
</listitem> </listitem>
</orderedlist> </orderedlist>
On success the field <structfield> &v4l2-selection;::r </structfield> contains On success the &v4l2-rect; <structfield>r</structfield> field contains
the adjusted rectangle. When the parameters are unsuitable the application may the adjusted rectangle. When the parameters are unsuitable the application may
modify the cropping (composing) or image parameters and repeat the cycle until modify the cropping (composing) or image parameters and repeat the cycle until
satisfactory parameters have been negotiated. If constraints flags have to be satisfactory parameters have been negotiated. If constraints flags have to be
@ -162,38 +162,38 @@ exist no rectangle </emphasis> that satisfies the constraints.</para>
<tbody valign="top"> <tbody valign="top">
<row> <row>
<entry><constant>V4L2_SEL_TGT_CROP_ACTIVE</constant></entry> <entry><constant>V4L2_SEL_TGT_CROP_ACTIVE</constant></entry>
<entry>0</entry> <entry>0x0000</entry>
<entry>area that is currently cropped by hardware</entry> <entry>The area that is currently cropped by hardware.</entry>
</row> </row>
<row> <row>
<entry><constant>V4L2_SEL_TGT_CROP_DEFAULT</constant></entry> <entry><constant>V4L2_SEL_TGT_CROP_DEFAULT</constant></entry>
<entry>1</entry> <entry>0x0001</entry>
<entry>suggested cropping rectangle that covers the "whole picture"</entry> <entry>Suggested cropping rectangle that covers the "whole picture".</entry>
</row> </row>
<row> <row>
<entry><constant>V4L2_SEL_TGT_CROP_BOUNDS</constant></entry> <entry><constant>V4L2_SEL_TGT_CROP_BOUNDS</constant></entry>
<entry>2</entry> <entry>0x0002</entry>
<entry>limits for the cropping rectangle</entry> <entry>Limits for the cropping rectangle.</entry>
</row> </row>
<row> <row>
<entry><constant>V4L2_SEL_TGT_COMPOSE_ACTIVE</constant></entry> <entry><constant>V4L2_SEL_TGT_COMPOSE_ACTIVE</constant></entry>
<entry>256</entry> <entry>0x0100</entry>
<entry>area to which data are composed by hardware</entry> <entry>The area to which data is composed by hardware.</entry>
</row> </row>
<row> <row>
<entry><constant>V4L2_SEL_TGT_COMPOSE_DEFAULT</constant></entry> <entry><constant>V4L2_SEL_TGT_COMPOSE_DEFAULT</constant></entry>
<entry>257</entry> <entry>0x0101</entry>
<entry>suggested composing rectangle that covers the "whole picture"</entry> <entry>Suggested composing rectangle that covers the "whole picture".</entry>
</row> </row>
<row> <row>
<entry><constant>V4L2_SEL_TGT_COMPOSE_BOUNDS</constant></entry> <entry><constant>V4L2_SEL_TGT_COMPOSE_BOUNDS</constant></entry>
<entry>258</entry> <entry>0x0102</entry>
<entry>limits for the composing rectangle</entry> <entry>Limits for the composing rectangle.</entry>
</row> </row>
<row> <row>
<entry><constant>V4L2_SEL_TGT_COMPOSE_PADDED</constant></entry> <entry><constant>V4L2_SEL_TGT_COMPOSE_PADDED</constant></entry>
<entry>259</entry> <entry>0x0103</entry>
<entry>the active area and all padding pixels that are inserted or modified by the hardware</entry> <entry>The active area and all padding pixels that are inserted or modified by hardware.</entry>
</row> </row>
</tbody> </tbody>
</tgroup> </tgroup>
@ -209,12 +209,14 @@ exist no rectangle </emphasis> that satisfies the constraints.</para>
<row> <row>
<entry><constant>V4L2_SEL_FLAG_GE</constant></entry> <entry><constant>V4L2_SEL_FLAG_GE</constant></entry>
<entry>0x00000001</entry> <entry>0x00000001</entry>
<entry>indicate that adjusted rectangle must contain a rectangle from <structfield>&v4l2-selection;::r</structfield></entry> <entry>Indicates that the adjusted rectangle must contain the original
&v4l2-selection; <structfield>r</structfield> rectangle.</entry>
</row> </row>
<row> <row>
<entry><constant>V4L2_SEL_FLAG_LE</constant></entry> <entry><constant>V4L2_SEL_FLAG_LE</constant></entry>
<entry>0x00000002</entry> <entry>0x00000002</entry>
<entry>indicate that adjusted rectangle must be inside a rectangle from <structfield>&v4l2-selection;::r</structfield></entry> <entry>Indicates that the adjusted rectangle must be inside the original
&v4l2-rect; <structfield>r</structfield> rectangle.</entry>
</row> </row>
</tbody> </tbody>
</tgroup> </tgroup>
@ -245,27 +247,29 @@ exist no rectangle </emphasis> that satisfies the constraints.</para>
<row> <row>
<entry>__u32</entry> <entry>__u32</entry>
<entry><structfield>type</structfield></entry> <entry><structfield>type</structfield></entry>
<entry>Type of the buffer (from &v4l2-buf-type;)</entry> <entry>Type of the buffer (from &v4l2-buf-type;).</entry>
</row> </row>
<row> <row>
<entry>__u32</entry> <entry>__u32</entry>
<entry><structfield>target</structfield></entry> <entry><structfield>target</structfield></entry>
<entry>used to select between <link linkend="v4l2-sel-target"> cropping and composing rectangles </link></entry> <entry>Used to select between <link linkend="v4l2-sel-target"> cropping
and composing rectangles</link>.</entry>
</row> </row>
<row> <row>
<entry>__u32</entry> <entry>__u32</entry>
<entry><structfield>flags</structfield></entry> <entry><structfield>flags</structfield></entry>
<entry>control over coordinates adjustments, refer to <link linkend="v4l2-sel-flags">selection flags</link></entry> <entry>Flags controlling the selection rectangle adjustments, refer to
<link linkend="v4l2-sel-flags">selection flags</link>.</entry>
</row> </row>
<row> <row>
<entry>&v4l2-rect;</entry> <entry>&v4l2-rect;</entry>
<entry><structfield>r</structfield></entry> <entry><structfield>r</structfield></entry>
<entry>selection rectangle</entry> <entry>The selection rectangle.</entry>
</row> </row>
<row> <row>
<entry>__u32</entry> <entry>__u32</entry>
<entry><structfield>reserved[9]</structfield></entry> <entry><structfield>reserved[9]</structfield></entry>
<entry>Reserved fields for future use</entry> <entry>Reserved fields for future use.</entry>
</row> </row>
</tbody> </tbody>
</tgroup> </tgroup>
@ -278,24 +282,24 @@ exist no rectangle </emphasis> that satisfies the constraints.</para>
<varlistentry> <varlistentry>
<term><errorcode>EINVAL</errorcode></term> <term><errorcode>EINVAL</errorcode></term>
<listitem> <listitem>
<para>The buffer <structfield> &v4l2-selection;::type </structfield> <para>Given buffer type <structfield>type</structfield> or
or <structfield> &v4l2-selection;::target </structfield> is not supported, or the selection target <structfield>target</structfield> is not supported,
the <structfield> &v4l2-selection;::flags </structfield> are invalid.</para> or the <structfield>flags</structfield> argument is not valid.</para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><errorcode>ERANGE</errorcode></term> <term><errorcode>ERANGE</errorcode></term>
<listitem> <listitem>
<para>it is not possible to adjust a rectangle <structfield> <para>It is not possible to adjust &v4l2-rect; <structfield>
&v4l2-selection;::r </structfield> that satisfies all contraints from r</structfield> rectangle to satisfy all contraints given in the
<structfield> &v4l2-selection;::flags </structfield>.</para> <structfield>flags</structfield> argument.</para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><errorcode>EBUSY</errorcode></term> <term><errorcode>EBUSY</errorcode></term>
<listitem> <listitem>
<para>it is not possible to apply change of selection rectangle at the moment. <para>It is not possible to apply change of the selection rectangle
Usually because streaming is in progress.</para> at the moment. Usually because streaming is in progress.</para>
</listitem> </listitem>
</varlistentry> </varlistentry>
</variablelist> </variablelist>

30
include/linux/videodev2.h
View File

@ -762,20 +762,20 @@ struct v4l2_crop {
/* Selection targets */ /* Selection targets */
/* current cropping area */ /* Current cropping area */
#define V4L2_SEL_TGT_CROP_ACTIVE 0 #define V4L2_SEL_TGT_CROP_ACTIVE 0x0000
/* default cropping area */ /* Default cropping area */
#define V4L2_SEL_TGT_CROP_DEFAULT 1 #define V4L2_SEL_TGT_CROP_DEFAULT 0x0001
/* cropping bounds */ /* Cropping bounds */
#define V4L2_SEL_TGT_CROP_BOUNDS 2 #define V4L2_SEL_TGT_CROP_BOUNDS 0x0002
/* current composing area */ /* Current composing area */
#define V4L2_SEL_TGT_COMPOSE_ACTIVE 256 #define V4L2_SEL_TGT_COMPOSE_ACTIVE 0x0100
/* default composing area */ /* Default composing area */
#define V4L2_SEL_TGT_COMPOSE_DEFAULT 257 #define V4L2_SEL_TGT_COMPOSE_DEFAULT 0x0101
/* composing bounds */ /* Composing bounds */
#define V4L2_SEL_TGT_COMPOSE_BOUNDS 258 #define V4L2_SEL_TGT_COMPOSE_BOUNDS 0x0102
/* current composing area plus all padding pixels */ /* Current composing area plus all padding pixels */
#define V4L2_SEL_TGT_COMPOSE_PADDED 259 #define V4L2_SEL_TGT_COMPOSE_PADDED 0x0103
/** /**
* struct v4l2_selection - selection info * struct v4l2_selection - selection info
@ -785,7 +785,7 @@ struct v4l2_crop {
* @r: coordinates of selection window * @r: coordinates of selection window
* @reserved: for future use, rounds structure size to 64 bytes, set to zero * @reserved: for future use, rounds structure size to 64 bytes, set to zero
* *
* Hardware may use multiple helper window to process a video stream. * Hardware may use multiple helper windows to process a video stream.
* The structure is used to exchange this selection areas between * The structure is used to exchange this selection areas between
* an application and a driver. * an application and a driver.
*/ */