From 93d39efdb1f8c8c4b848122b8c8ad986690fe9ba Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Wed, 9 Nov 2016 06:31:10 -0200 Subject: [PATCH] [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 Signed-off-by: Mauro Carvalho Chehab --- Documentation/media/uapi/v4l/control.rst | 88 +++++++++++++++--------- 1 file changed, 55 insertions(+), 33 deletions(-) diff --git a/Documentation/media/uapi/v4l/control.rst b/Documentation/media/uapi/v4l/control.rst index d3f1450c4b08..51112badb804 100644 --- a/Documentation/media/uapi/v4l/control.rst +++ b/Documentation/media/uapi/v4l/control.rst @@ -312,21 +312,20 @@ more menu type controls. .. _enum_all_controls: -Example: Enumerating all user controls -====================================== +Example: Enumerating all controls +================================= .. code-block:: c - struct v4l2_queryctrl queryctrl; struct v4l2_querymenu querymenu; - static void enumerate_menu(void) + static void enumerate_menu(__u32 id) { printf(" Menu items:\\n"); memset(&querymenu, 0, sizeof(querymenu)); - querymenu.id = queryctrl.id; + querymenu.id = id; for (querymenu.index = queryctrl.minimum; querymenu.index <= queryctrl.maximum; @@ -337,6 +336,55 @@ Example: Enumerating all user controls } } + memset(&queryctrl, 0, sizeof(queryctrl)); + + queryctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL; + while (0 == ioctl(fd, VIDIOC_QUERYCTRL, &queryctrl)) { + if (!(queryctrl.flags & V4L2_CTRL_FLAG_DISABLED)) { + printf("Control %s\\n", queryctrl.name); + + if (queryctrl.type == V4L2_CTRL_TYPE_MENU) + enumerate_menu(queryctrl.id); + } + + queryctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL; + } + if (errno != EINVAL) { + perror("VIDIOC_QUERYCTRL"); + exit(EXIT_FAILURE); + } + +Example: Enumerating all controls including compound controls +============================================================= + +.. code-block:: c + + struct v4l2_query_ext_ctrl query_ext_ctrl; + + memset(&query_ext_ctrl, 0, sizeof(query_ext_ctrl)); + + query_ext_ctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL | V4L2_CTRL_FLAG_NEXT_COMPOUND; + while (0 == ioctl(fd, VIDIOC_QUERY_EXT_CTRL, &query_ext_ctrl)) { + if (!(query_ext_ctrl.flags & V4L2_CTRL_FLAG_DISABLED)) { + printf("Control %s\\n", query_ext_ctrl.name); + + if (query_ext_ctrl.type == V4L2_CTRL_TYPE_MENU) + enumerate_menu(query_ext_ctrl.id); + } + + query_ext_ctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL | V4L2_CTRL_FLAG_NEXT_COMPOUND; + } + if (errno != EINVAL) { + perror("VIDIOC_QUERY_EXT_CTRL"); + exit(EXIT_FAILURE); + } + +Example: Enumerating all user controls (old style) +================================================== + +.. code-block:: c + + memset(&queryctrl, 0, sizeof(queryctrl)); for (queryctrl.id = V4L2_CID_BASE; @@ -349,7 +397,7 @@ Example: Enumerating all user controls printf("Control %s\\n", queryctrl.name); if (queryctrl.type == V4L2_CTRL_TYPE_MENU) - enumerate_menu(); + enumerate_menu(queryctrl.id); } else { if (errno == EINVAL) continue; @@ -368,7 +416,7 @@ Example: Enumerating all user controls printf("Control %s\\n", queryctrl.name); if (queryctrl.type == V4L2_CTRL_TYPE_MENU) - enumerate_menu(); + enumerate_menu(queryctrl.id); } else { if (errno == EINVAL) break; @@ -379,32 +427,6 @@ Example: Enumerating all user controls } -Example: Enumerating all user controls (alternative) -==================================================== - -.. code-block:: c - - memset(&queryctrl, 0, sizeof(queryctrl)); - - queryctrl.id = V4L2_CTRL_CLASS_USER | V4L2_CTRL_FLAG_NEXT_CTRL; - while (0 == ioctl(fd, VIDIOC_QUERYCTRL, &queryctrl)) { - if (V4L2_CTRL_ID2CLASS(queryctrl.id) != V4L2_CTRL_CLASS_USER) - break; - if (queryctrl.flags & V4L2_CTRL_FLAG_DISABLED) - continue; - - printf("Control %s\\n", queryctrl.name); - - if (queryctrl.type == V4L2_CTRL_TYPE_MENU) - enumerate_menu(); - - queryctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL; - } - if (errno != EINVAL) { - perror("VIDIOC_QUERYCTRL"); - exit(EXIT_FAILURE); - } - Example: Changing controls ========================== -- GitLab