[media] control.rst: improve the queryctrl code examples (93d39efd) · Commits · 戴 / test

Documentation/media/uapi/v4l/control.rst

+55 −33

Original line number	Diff line number	Diff line
		@@ -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
		==========================

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