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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
Mauro Carvalho Chehab
parent
1d53160111
commit
9080d5d3fa
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@ -52,6 +52,10 @@ cropping and composing rectangles have the same size.</para>
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</textobject>
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</mediaobject>
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</figure>
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For complete list of the available selection targets see table <xref
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linkend="v4l2-sel-target"/>
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</section>
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<section>
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@ -186,7 +190,7 @@ V4L2_SEL_TGT_COMPOSE_ACTIVE </constant> target.</para>
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<section>
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<title>Scaling control.</title>
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<title>Scaling control</title>
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<para>An application can detect if scaling is performed by comparing the width
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and the height of rectangles obtained using <constant> V4L2_SEL_TGT_CROP_ACTIVE
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@ -200,7 +204,7 @@ the scaling ratios using these values.</para>
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<section>
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<title>Comparison with old cropping API.</title>
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<title>Comparison with old cropping API</title>
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<para>The selection API was introduced to cope with deficiencies of previous
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<link linkend="crop"> API </link>, that was designed to control simple capture
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@ -58,43 +58,43 @@
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<para>The ioctls are used to query and configure selection rectangles.</para>
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<para> To query the cropping (composing) rectangle set <structfield>
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&v4l2-selection;::type </structfield> to the respective buffer type. Do not
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use multiplanar buffers. Use <constant> V4L2_BUF_TYPE_VIDEO_CAPTURE
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<para> To query the cropping (composing) rectangle set &v4l2-selection;
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<structfield> type </structfield> field to the respective buffer type.
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Do not use multiplanar buffers. Use <constant> V4L2_BUF_TYPE_VIDEO_CAPTURE
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</constant> instead of <constant> V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
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</constant>. Use <constant> V4L2_BUF_TYPE_VIDEO_OUTPUT </constant> instead of
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<constant> V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE </constant>. The next step is
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setting <structfield> &v4l2-selection;::target </structfield> to value
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<constant> V4L2_SEL_TGT_CROP_ACTIVE </constant> (<constant>
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setting the value of &v4l2-selection; <structfield>target</structfield> field
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to <constant> V4L2_SEL_TGT_CROP_ACTIVE </constant> (<constant>
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V4L2_SEL_TGT_COMPOSE_ACTIVE </constant>). Please refer to table <xref
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linkend="v4l2-sel-target" /> or <xref linkend="selection-api" /> for additional
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targets. Fields <structfield> &v4l2-selection;::flags </structfield> and
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<structfield> &v4l2-selection;::reserved </structfield> are ignored and they
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must be filled with zeros. The driver fills the rest of the structure or
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targets. The <structfield>flags</structfield> and <structfield>reserved
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</structfield> fields of &v4l2-selection; are ignored and they must be filled
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with zeros. The driver fills the rest of the structure or
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returns &EINVAL; if incorrect buffer type or target was used. If cropping
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(composing) is not supported then the active rectangle is not mutable and it is
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always equal to the bounds rectangle. Finally, structure <structfield>
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&v4l2-selection;::r </structfield> is filled with the current cropping
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always equal to the bounds rectangle. Finally, the &v4l2-rect;
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<structfield>r</structfield> rectangle is filled with the current cropping
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(composing) coordinates. The coordinates are expressed in driver-dependent
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units. The only exception are rectangles for images in raw formats, whose
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coordinates are always expressed in pixels. </para>
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<para> To change the cropping (composing) rectangle set <structfield>
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&v4l2-selection;::type </structfield> to the respective buffer type. Do not
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<para> To change the cropping (composing) rectangle set the &v4l2-selection;
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<structfield>type</structfield> field to the respective buffer type. Do not
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use multiplanar buffers. Use <constant> V4L2_BUF_TYPE_VIDEO_CAPTURE
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</constant> instead of <constant> V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
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</constant>. Use <constant> V4L2_BUF_TYPE_VIDEO_OUTPUT </constant> instead of
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<constant> V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE </constant>. The next step is
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setting <structfield> &v4l2-selection;::target </structfield> to value
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<constant> V4L2_SEL_TGT_CROP_ACTIVE </constant> (<constant>
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setting the value of &v4l2-selection; <structfield>target</structfield> to
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<constant>V4L2_SEL_TGT_CROP_ACTIVE</constant> (<constant>
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V4L2_SEL_TGT_COMPOSE_ACTIVE </constant>). Please refer to table <xref
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linkend="v4l2-sel-target" /> or <xref linkend="selection-api" /> for additional
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targets. Set desired active area into the field <structfield>
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&v4l2-selection;::r </structfield>. Field <structfield>
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&v4l2-selection;::reserved </structfield> is ignored and must be filled with
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zeros. The driver may adjust the rectangle coordinates. An application may
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introduce constraints to control rounding behaviour. Set the field
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<structfield> &v4l2-selection;::flags </structfield> to one of values:
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targets. The &v4l2-rect; <structfield>r</structfield> rectangle need to be
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set to the desired active area. Field &v4l2-selection; <structfield> reserved
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</structfield> is ignored and must be filled with zeros. The driver may adjust
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coordinates of the requested rectangle. An application may
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introduce constraints to control rounding behaviour. The &v4l2-selection;
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<structfield>flags</structfield> field must be set to one of the following:
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<itemizedlist>
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<listitem>
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@ -129,7 +129,7 @@ and vertical offset and sizes are chosen according to following priority:
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<orderedlist>
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<listitem>
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<para>Satisfy constraints from <structfield>&v4l2-selection;::flags</structfield>.</para>
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<para>Satisfy constraints from &v4l2-selection; <structfield>flags</structfield>.</para>
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</listitem>
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<listitem>
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<para>Adjust width, height, left, and top to hardware limits and alignments.</para>
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@ -145,7 +145,7 @@ and vertical offset and sizes are chosen according to following priority:
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</listitem>
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</orderedlist>
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On success the field <structfield> &v4l2-selection;::r </structfield> contains
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On success the &v4l2-rect; <structfield>r</structfield> field contains
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the adjusted rectangle. When the parameters are unsuitable the application may
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modify the cropping (composing) or image parameters and repeat the cycle until
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satisfactory parameters have been negotiated. If constraints flags have to be
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@ -162,38 +162,38 @@ exist no rectangle </emphasis> that satisfies the constraints.</para>
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<tbody valign="top">
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<row>
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<entry><constant>V4L2_SEL_TGT_CROP_ACTIVE</constant></entry>
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<entry>0</entry>
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<entry>area that is currently cropped by hardware</entry>
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<entry>0x0000</entry>
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<entry>The area that is currently cropped by hardware.</entry>
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</row>
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<row>
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<entry><constant>V4L2_SEL_TGT_CROP_DEFAULT</constant></entry>
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<entry>1</entry>
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<entry>suggested cropping rectangle that covers the "whole picture"</entry>
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<entry>0x0001</entry>
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<entry>Suggested cropping rectangle that covers the "whole picture".</entry>
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</row>
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<row>
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<entry><constant>V4L2_SEL_TGT_CROP_BOUNDS</constant></entry>
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<entry>2</entry>
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<entry>limits for the cropping rectangle</entry>
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<entry>0x0002</entry>
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<entry>Limits for the cropping rectangle.</entry>
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</row>
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<row>
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<entry><constant>V4L2_SEL_TGT_COMPOSE_ACTIVE</constant></entry>
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<entry>256</entry>
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<entry>area to which data are composed by hardware</entry>
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<entry>0x0100</entry>
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<entry>The area to which data is composed by hardware.</entry>
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</row>
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<row>
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<entry><constant>V4L2_SEL_TGT_COMPOSE_DEFAULT</constant></entry>
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<entry>257</entry>
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<entry>suggested composing rectangle that covers the "whole picture"</entry>
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<entry>0x0101</entry>
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<entry>Suggested composing rectangle that covers the "whole picture".</entry>
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</row>
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<row>
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<entry><constant>V4L2_SEL_TGT_COMPOSE_BOUNDS</constant></entry>
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<entry>258</entry>
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<entry>limits for the composing rectangle</entry>
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<entry>0x0102</entry>
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<entry>Limits for the composing rectangle.</entry>
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</row>
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<row>
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<entry><constant>V4L2_SEL_TGT_COMPOSE_PADDED</constant></entry>
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<entry>259</entry>
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<entry>the active area and all padding pixels that are inserted or modified by the hardware</entry>
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<entry>0x0103</entry>
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<entry>The active area and all padding pixels that are inserted or modified by hardware.</entry>
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</row>
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</tbody>
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</tgroup>
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@ -209,12 +209,14 @@ exist no rectangle </emphasis> that satisfies the constraints.</para>
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<row>
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<entry><constant>V4L2_SEL_FLAG_GE</constant></entry>
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<entry>0x00000001</entry>
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<entry>indicate that adjusted rectangle must contain a rectangle from <structfield>&v4l2-selection;::r</structfield></entry>
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<entry>Indicates that the adjusted rectangle must contain the original
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&v4l2-selection; <structfield>r</structfield> rectangle.</entry>
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</row>
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<row>
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<entry><constant>V4L2_SEL_FLAG_LE</constant></entry>
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<entry>0x00000002</entry>
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<entry>indicate that adjusted rectangle must be inside a rectangle from <structfield>&v4l2-selection;::r</structfield></entry>
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<entry>Indicates that the adjusted rectangle must be inside the original
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&v4l2-rect; <structfield>r</structfield> rectangle.</entry>
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</row>
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</tbody>
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</tgroup>
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@ -245,27 +247,29 @@ exist no rectangle </emphasis> that satisfies the constraints.</para>
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<row>
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<entry>__u32</entry>
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<entry><structfield>type</structfield></entry>
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<entry>Type of the buffer (from &v4l2-buf-type;)</entry>
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<entry>Type of the buffer (from &v4l2-buf-type;).</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>target</structfield></entry>
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<entry>used to select between <link linkend="v4l2-sel-target"> cropping and composing rectangles </link></entry>
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<entry>Used to select between <link linkend="v4l2-sel-target"> cropping
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and composing rectangles</link>.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>flags</structfield></entry>
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<entry>control over coordinates adjustments, refer to <link linkend="v4l2-sel-flags">selection flags</link></entry>
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<entry>Flags controlling the selection rectangle adjustments, refer to
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<link linkend="v4l2-sel-flags">selection flags</link>.</entry>
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</row>
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<row>
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<entry>&v4l2-rect;</entry>
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<entry><structfield>r</structfield></entry>
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<entry>selection rectangle</entry>
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<entry>The selection rectangle.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>reserved[9]</structfield></entry>
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<entry>Reserved fields for future use</entry>
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<entry>Reserved fields for future use.</entry>
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</row>
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</tbody>
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</tgroup>
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@ -278,24 +282,24 @@ exist no rectangle </emphasis> that satisfies the constraints.</para>
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<varlistentry>
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<term><errorcode>EINVAL</errorcode></term>
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<listitem>
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<para>The buffer <structfield> &v4l2-selection;::type </structfield>
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or <structfield> &v4l2-selection;::target </structfield> is not supported, or
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the <structfield> &v4l2-selection;::flags </structfield> are invalid.</para>
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<para>Given buffer type <structfield>type</structfield> or
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the selection target <structfield>target</structfield> is not supported,
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or the <structfield>flags</structfield> argument is not valid.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><errorcode>ERANGE</errorcode></term>
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<listitem>
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<para>it is not possible to adjust a rectangle <structfield>
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&v4l2-selection;::r </structfield> that satisfies all contraints from
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<structfield> &v4l2-selection;::flags </structfield>.</para>
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<para>It is not possible to adjust &v4l2-rect; <structfield>
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r</structfield> rectangle to satisfy all contraints given in the
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<structfield>flags</structfield> argument.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><errorcode>EBUSY</errorcode></term>
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<listitem>
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<para>it is not possible to apply change of selection rectangle at the moment.
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Usually because streaming is in progress.</para>
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<para>It is not possible to apply change of the selection rectangle
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at the moment. Usually because streaming is in progress.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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@ -762,20 +762,20 @@ struct v4l2_crop {
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/* Selection targets */
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/* current cropping area */
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#define V4L2_SEL_TGT_CROP_ACTIVE 0
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/* default cropping area */
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#define V4L2_SEL_TGT_CROP_DEFAULT 1
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/* cropping bounds */
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#define V4L2_SEL_TGT_CROP_BOUNDS 2
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/* current composing area */
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#define V4L2_SEL_TGT_COMPOSE_ACTIVE 256
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/* default composing area */
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#define V4L2_SEL_TGT_COMPOSE_DEFAULT 257
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/* composing bounds */
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#define V4L2_SEL_TGT_COMPOSE_BOUNDS 258
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/* current composing area plus all padding pixels */
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#define V4L2_SEL_TGT_COMPOSE_PADDED 259
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/* Current cropping area */
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#define V4L2_SEL_TGT_CROP_ACTIVE 0x0000
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/* Default cropping area */
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#define V4L2_SEL_TGT_CROP_DEFAULT 0x0001
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/* Cropping bounds */
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#define V4L2_SEL_TGT_CROP_BOUNDS 0x0002
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/* Current composing area */
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#define V4L2_SEL_TGT_COMPOSE_ACTIVE 0x0100
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/* Default composing area */
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#define V4L2_SEL_TGT_COMPOSE_DEFAULT 0x0101
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/* Composing bounds */
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#define V4L2_SEL_TGT_COMPOSE_BOUNDS 0x0102
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/* Current composing area plus all padding pixels */
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#define V4L2_SEL_TGT_COMPOSE_PADDED 0x0103
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/**
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* struct v4l2_selection - selection info
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@ -785,7 +785,7 @@ struct v4l2_crop {
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* @r: coordinates of selection window
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* @reserved: for future use, rounds structure size to 64 bytes, set to zero
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*
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* Hardware may use multiple helper window to process a video stream.
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* Hardware may use multiple helper windows to process a video stream.
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* The structure is used to exchange this selection areas between
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* an application and a driver.
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*/
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