简介

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

例程代码

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：

• 连接相机
• 获取图像宽度，高度，像素格式等信息
• 释放资源

/* 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.c
void 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：

函数说明

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