From 93d39efdb1f8c8c4b848122b8c8ad986690fe9ba Mon Sep 17 00:00:00 2001
From: Hans Verkuil <hverkuil@xs4all.nl>
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 <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
---
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 d3f1450c4b088..51112badb804f 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
==========================
--
2.30.2