[media] control.rst: improve the queryctrl code examples
The code examples on how to enumerate controls were really long in the tooth. Update them. Using FLAG_NEXT_CTRL is preferred these days, so give that example first. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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@ -312,21 +312,20 @@ more menu type controls.
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.. _enum_all_controls:
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.. _enum_all_controls:
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Example: Enumerating all user controls
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Example: Enumerating all controls
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======================================
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=================================
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.. code-block:: c
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.. code-block:: c
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struct v4l2_queryctrl queryctrl;
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struct v4l2_queryctrl queryctrl;
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struct v4l2_querymenu querymenu;
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struct v4l2_querymenu querymenu;
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static void enumerate_menu(void)
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static void enumerate_menu(__u32 id)
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{
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{
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printf(" Menu items:\\n");
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printf(" Menu items:\\n");
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memset(&querymenu, 0, sizeof(querymenu));
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memset(&querymenu, 0, sizeof(querymenu));
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querymenu.id = queryctrl.id;
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querymenu.id = id;
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for (querymenu.index = queryctrl.minimum;
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for (querymenu.index = queryctrl.minimum;
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querymenu.index <= queryctrl.maximum;
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querymenu.index <= queryctrl.maximum;
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@ -337,6 +336,55 @@ Example: Enumerating all user controls
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}
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}
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}
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}
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memset(&queryctrl, 0, sizeof(queryctrl));
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queryctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL;
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while (0 == ioctl(fd, VIDIOC_QUERYCTRL, &queryctrl)) {
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if (!(queryctrl.flags & V4L2_CTRL_FLAG_DISABLED)) {
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printf("Control %s\\n", queryctrl.name);
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if (queryctrl.type == V4L2_CTRL_TYPE_MENU)
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enumerate_menu(queryctrl.id);
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}
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queryctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
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}
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if (errno != EINVAL) {
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perror("VIDIOC_QUERYCTRL");
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exit(EXIT_FAILURE);
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}
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Example: Enumerating all controls including compound controls
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=============================================================
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.. code-block:: c
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struct v4l2_query_ext_ctrl query_ext_ctrl;
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memset(&query_ext_ctrl, 0, sizeof(query_ext_ctrl));
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query_ext_ctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL | V4L2_CTRL_FLAG_NEXT_COMPOUND;
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while (0 == ioctl(fd, VIDIOC_QUERY_EXT_CTRL, &query_ext_ctrl)) {
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if (!(query_ext_ctrl.flags & V4L2_CTRL_FLAG_DISABLED)) {
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printf("Control %s\\n", query_ext_ctrl.name);
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if (query_ext_ctrl.type == V4L2_CTRL_TYPE_MENU)
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enumerate_menu(query_ext_ctrl.id);
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}
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query_ext_ctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL | V4L2_CTRL_FLAG_NEXT_COMPOUND;
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}
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if (errno != EINVAL) {
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perror("VIDIOC_QUERY_EXT_CTRL");
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exit(EXIT_FAILURE);
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}
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Example: Enumerating all user controls (old style)
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==================================================
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.. code-block:: c
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memset(&queryctrl, 0, sizeof(queryctrl));
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memset(&queryctrl, 0, sizeof(queryctrl));
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for (queryctrl.id = V4L2_CID_BASE;
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for (queryctrl.id = V4L2_CID_BASE;
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@ -349,7 +397,7 @@ Example: Enumerating all user controls
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printf("Control %s\\n", queryctrl.name);
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printf("Control %s\\n", queryctrl.name);
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if (queryctrl.type == V4L2_CTRL_TYPE_MENU)
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if (queryctrl.type == V4L2_CTRL_TYPE_MENU)
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enumerate_menu();
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enumerate_menu(queryctrl.id);
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} else {
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} else {
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if (errno == EINVAL)
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if (errno == EINVAL)
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continue;
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continue;
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@ -368,7 +416,7 @@ Example: Enumerating all user controls
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printf("Control %s\\n", queryctrl.name);
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printf("Control %s\\n", queryctrl.name);
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if (queryctrl.type == V4L2_CTRL_TYPE_MENU)
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if (queryctrl.type == V4L2_CTRL_TYPE_MENU)
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enumerate_menu();
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enumerate_menu(queryctrl.id);
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} else {
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} else {
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if (errno == EINVAL)
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if (errno == EINVAL)
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break;
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break;
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@ -379,32 +427,6 @@ Example: Enumerating all user controls
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}
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}
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Example: Enumerating all user controls (alternative)
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====================================================
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.. code-block:: c
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memset(&queryctrl, 0, sizeof(queryctrl));
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queryctrl.id = V4L2_CTRL_CLASS_USER | V4L2_CTRL_FLAG_NEXT_CTRL;
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while (0 == ioctl(fd, VIDIOC_QUERYCTRL, &queryctrl)) {
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if (V4L2_CTRL_ID2CLASS(queryctrl.id) != V4L2_CTRL_CLASS_USER)
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break;
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if (queryctrl.flags & V4L2_CTRL_FLAG_DISABLED)
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continue;
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printf("Control %s\\n", queryctrl.name);
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if (queryctrl.type == V4L2_CTRL_TYPE_MENU)
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enumerate_menu();
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queryctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
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}
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if (errno != EINVAL) {
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perror("VIDIOC_QUERYCTRL");
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exit(EXIT_FAILURE);
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}
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Example: Changing controls
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Example: Changing controls
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==========================
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==========================
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