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开源相机管理库Aravis例程学习（六）——camera-features - paw5zx
source link: https://www.cnblogs.com/paw5zx/p/18168917
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开源相机管理库Aravis例程学习（六）——camera-features
本文针对官方例程中的：04-camera-features做简单的讲解。并介绍其中调用的arv_camera_get_integer，arv_camera_get_string。
aravis版本：0.8.31
操作系统：ubuntu-20.04
gcc版本：9.4.0
这段代码使用Aravis的API，获取相机的一些基本设置，如图像的宽度、高度和像素格式，主要操作步骤如下：
- 获取图像宽度，高度，像素格式等信息
/* SPDX-License-Identifier:Unlicense */ /* Aravis header */#include <arv.h> /* Standard headers */#include <stdlib.h>#include <stdio.h> /* * Connect to the first available camera, then display the current settings for image width and height, as well as the * pixel format, using the more generic ArvCamera feature API. */ int main (int argc, char **argv){ ArvCamera *camera; GError *error = NULL; //连接相机 camera = arv_camera_new (NULL, &error); if (ARV_IS_CAMERA (camera)) { int width; int height; const char *pixel_format; printf ("Found camera '%s'\n", arv_camera_get_model_name (camera, NULL)); /* Retrieve generally mandatory features for transmitters */ if (!error) width = arv_camera_get_integer (camera, "Width", &error); if (!error) height = arv_camera_get_integer (camera, "Height", &error); if (!error) pixel_format = arv_camera_get_string (camera, "PixelFormat", &error); if (error == NULL) { printf ("Width = %d\n", width); printf ("Height = %d\n", height); printf ("Pixel format = %s\n", pixel_format); } g_clear_object (&camera); } if (error != NULL) { /* En error happened, display the correspdonding message */ printf ("Error: %s\n", error->message); return EXIT_FAILURE; } return EXIT_SUCCESS;}
这个例程与03-camera-api实现的功能相似，但是不同的是本文的代码使用的是更为通用的API（arv_camera_get_integer和arv_camera_get_string）来获取的相机的参数。
我们查看03-camera-api中的arv_camera_get_region，arv_camera_get_pixel_format_as_string的函数定义可以发现，他们的底层其实就是通过调用arv_camera_get_integer和arv_camera_get_string来实现的相关功能：
//file: arvcamera.cvoid arv_camera_get_region (ArvCamera *camera, gint *x, gint *y, gint *width, gint *height, GError **error){ ArvCameraPrivate *priv = arv_camera_get_instance_private (camera); GError *local_error = NULL; g_return_if_fail (ARV_IS_CAMERA (camera)); if (x != NULL) *x = priv->has_region_offset ? arv_camera_get_integer (camera, "OffsetX", &local_error) : 0; if (y != NULL && local_error == NULL) *y = priv->has_region_offset ? arv_camera_get_integer (camera, "OffsetY", &local_error) : 0; if (width != NULL && local_error == NULL) *width = arv_camera_get_integer (camera, "Width", &local_error); if (height != NULL && local_error == NULL) *height = arv_camera_get_integer (camera, "Height", &local_error); if (local_error != NULL) g_propagate_error (error, local_error);} const char * arv_camera_get_pixel_format_as_string (ArvCamera *camera, GError **error){ return arv_camera_get_string (camera, "PixelFormat", error);}
运行结果：
arv_camera_get_integer
简介：获取已连接相机的一个整数型特性的值
gint64 arv_camera_get_integer ( ArvCamera* camera, const char* feature, GError** error)
Available since: 0.8.0
arv_camera_get_string
简介：获取已连接相机的一个字符串型特性的值
const char* arv_camera_get_string ( ArvCamera* camera, const char* feature, GError** error)
Available since: 0.8.0
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