在Ubuntu上用sane api实现通用扫描功能
最近由于工作需要,要写一套扫描相关的接口。
在这里记录一下,实现还有有点复杂的。
目录
依赖
主要功能
初始化
获取当前扫描仪列表
打开扫描仪
sane_open
设置扫描选项
sane_control_option
扫描
关闭设备
结束使用
参考资料
依赖
sudo apt install libsane-dev sane-utils
主要功能
初始化
我们在操作扫描仪之前需要初始化才能正常使用。
初始化使用的是sane里的sane_init。
void scanner_init()
{
printf("[%s] Start\n", __FUNCTION__);
SANE_Int version_code = 0;
sane_init(&version_code, auth_callback);
printf("SANE version code: %d\n", version_code);
}
static void
auth_callback(SANE_String_Const resource,
SANE_Char *username, SANE_Char *password)
{
}
初始化成功则version_code为SANE_STATUS_GOOD(0)。
获取当前扫描仪列表
核心是sane_get_devices函数。
先通过sane_get_devices获取扫描仪列表,然后申请一个二维数组,将扫描仪列表放入二维数组中返回。
const char **scanner_get_available_list()
{
printf("[%s] Start\n", __FUNCTION__);
SANE_Status status;
SANE_Int num_devices = 0;
const SANE_Device **device_list;
//获取扫描仪列表
status = sane_get_devices(&device_list, SANE_FALSE);
if (status != SANE_STATUS_GOOD)
{
printf("Error getting device list: %s\n", sane_strstatus(status));
return NULL;
}
// 获取当前设备数量
while (device_list[num_devices])
num_devices++;
// 如果设备列表为空,返回
if (num_devices == 0)
{
printf("No scanners found.\n");
sane_exit();
return NULL;
}
// 分配内存
const char **scanner_list = malloc(sizeof(SANE_Device *) * (num_devices + 1));
if (!scanner_list)
{
printf("Failed to allocate memory.\n");
sane_exit();
return NULL;
}
// 继续分配内存
for (int i = 0; i < num_devices; i++)
{
scanner_list[i] = strdup(device_list[i]->name);
if (!scanner_list[i])
{
printf("Failed to allocate memory.\n");
for (int j = 0; j < i; j++)
{
free(scanner_list[j]);
}
free(scanner_list);
sane_exit();
return NULL;
}
}
scanner_list[num_devices] = NULL;
// 返回设备列表
return scanner_list;
}
我们再把获取到的设备列表循环打印一下。
const char **scanner_list = scanner_get_available_list();
if (scanner_list != NULL)
{
for (int num_devices = 0; scanner_list[num_devices]; ++num_devices)
{
if (scanner_list[num_devices] != NULL) // 添加一个检查
{
printf("Device %d: name=%s \n",
num_devices, scanner_list[num_devices]);
}
}
}
else
{
return;
}
打开扫描仪
sane_open
这里介绍一下sane_open,第一个参数是扫描仪的名称,第二个参数是一个空的句柄,打开后通过句柄进行后续操作。
extern SANE_Status sane_open (SANE_String_Const devicename,
SANE_Handle * handle);
函数的具体实现如下:
static SANE_Handle sane_handle = NULL; // 扫描仪设备句柄,全局变量
int scanner_open_device(char *scanner_name)
{
printf("[%s] Start\n", __FUNCTION__);
SANE_Status sane_status = 0;
if (sane_status = sane_open(scanner_name, &sane_handle))
{
printf("sane_open status: %s\n", sane_strstatus(sane_status));
}
if (sane_status != SANE_STATUS_GOOD)
sane_handle = NULL;
return sane_status;
}
这里的入参scanner_name是扫描仪列表的scanner_list,如果要打开第一个扫描仪的话是scanner_list[0]。
如果函数的返回值不是SANE_STATUS_GOOD,表示打开失败了。
设置扫描选项
sane_control_option
扫描的所有参数都是通过sane_control_option实现的,每个参数的功能详见备注。
extern SANE_Status sane_control_option (SANE_Handle handle, //sane_open的句柄
SANE_Int option, //要设置选项的序号,2是颜色,3是分辨率
SANE_Action action, //操作的类型,给选项赋值或者获取当前值
void *value, //value的实际值
SANE_Int *info); //没发现有什么用
操作的类型一共有以下三种,我们这里只用到第二种。
typedef enum
{
SANE_ACTION_GET_VALUE = 0,
SANE_ACTION_SET_VALUE,
SANE_ACTION_SET_AUTO
}
SANE_Action;
我这里设置了颜色,扫描的分辨率和纸张大小,还有很多可以设置的选项,可以自行探索。
static SANE_Handle sane_handle = NULL; // 扫描仪设备句柄,全局变量
// 设置指定扫描仪颜色,通过传入参数val_color进行设置扫描设备的颜色
int scanner_set_color(SANE_String val_color)
{
printf("[%s] Start!\n", __FUNCTION__);
SANE_Status status;
status = sane_control_option(sane_handle, 2,
SANE_ACTION_SET_VALUE, val_color, NULL);
if (status != SANE_STATUS_GOOD)
{
printf("Option did not set, desc = %s\n", sane_strstatus(status));
return status;
}
printf("set color option success!\n");
return status;
}
// 设置指定扫描仪扫描的分辨率(清晰程度,分辨率越大越清晰)
int scanner_set_resolutions(SANE_Int val_resolution)
{
printf("[%s] Start!\n", __FUNCTION__);
SANE_Status status;
status = sane_control_option(sane_handle, 3, SANE_ACTION_SET_VALUE, &val_resolution, NULL);
if (status != SANE_STATUS_GOOD)
{
printf("Option did not set, desc = %s\n", sane_strstatus(status));
return status;
}
printf("set resolution option success!\n");
return status;
}
设置纸张大小有点复杂,因为纸张大小没有对应的option。因此曲线救国,通过设置扫描的纸张的长和宽来实现。长和宽的option序号分别是9和10。
enum sizes_type
{
A2 = 1,
A3,
A4,
A5,
A6
};
static double g_saneSizeA4BrY = 297;
int scanner_set_size(SANE_String size)
{
printf("[%s] Start!\n", __FUNCTION__);
SANE_Status status = SANE_STATUS_GOOD;
int type;
if (!strcmp("A2", size))
{
type = A2;
}
else if (!strcmp("A3", size))
{
type = A3;
}
else if (!strcmp("A4", size))
{
type = A4;
}
else if (!strcmp("A5", size))
{
type = A5;
}
else if (!strcmp("A6", size))
{
type = A6;
}
else
{
type = 0;
}
switch (type)
{
case A2:
status = kdk_scanner_set_size_real(sane_handle, 420, 594);
break;
case A3:
status = kdk_scanner_set_size_real(sane_handle, 297, 420);
break;
case A4:
status = kdk_scanner_set_size_real(sane_handle, 210, g_saneSizeA4BrY);
break;
case A5:
status = kdk_scanner_set_size_real(sane_handle, 148, 210);
break;
case A6:
status = kdk_scanner_set_size_real(sane_handle, 105, 144);
break;
default:
status = SANE_STATUS_UNSUPPORTED;
}
return status;
}
/**
* @brief scanner_set_size_real 统一设置扫描设备尺寸
*
* @param sane_handle 扫描句柄
*
* @param val_size_br_x 扫描设备右下角的x坐标
*
* @param val_size_br_y 扫描设备右下角的y坐标
*
* @return 返回扫描设备设置尺寸的情况
*/
SANE_Status scanner_set_size_real(SANE_Handle sane_handle, SANE_Int val_size_br_x,
SANE_Int val_size_br_y)
{
printf("[%s] Start!\n", __FUNCTION__);
SANE_Status status = SANE_STATUS_GOOD;
SANE_Word x = SANE_FIX(val_size_br_x);
SANE_Word y = SANE_FIX(val_size_br_y);
SANE_Word zero = SANE_FIX(0.0);
status = sane_control_option(sane_handle, 7, SANE_ACTION_SET_VALUE, &zero, NULL);
if (status != SANE_STATUS_GOOD)
{
return status;
}
status = sane_control_option(sane_handle, 8, SANE_ACTION_SET_VALUE, &zero, NULL);
if (status != SANE_STATUS_GOOD)
{
return status;
}
status = sane_control_option(sane_handle, 9,
SANE_ACTION_SET_VALUE, &x, NULL);
if (status != SANE_STATUS_GOOD)
{
printf("Option x did not set, desc = %s\n", sane_strstatus(status));
return status;
}
status = sane_control_option(sane_handle, 10,
SANE_ACTION_SET_VALUE, &y, NULL);
if (status != SANE_STATUS_GOOD)
{
printf("Option y did not set, desc = %s\n", sane_strstatus(status));
return status;
}
return status;
}
和前面一样,如果函数的返回值不是SANE_STATUS_GOOD,表示失败了。
扫描
扫描我分成两类,分为单页单面扫描和多页双面扫描。
单页和多页也是一种可以设置的扫描属性,单页和多页的主要是这个这个属性的区别,别的部分都差不多。
//设置扫描是单页还是多页
int scanner_set_page_type(SANE_Int type)
{
printf("[%s] Start!\n", __FUNCTION__);
SANE_Status status;
//对应的option序号为4
status = sane_control_option(sane_handle, 4,
SANE_ACTION_SET_VALUE, &type, NULL);
if (status != SANE_STATUS_GOOD)
{
printf("Option did not set, desc = %s\n", sane_strstatus(status));
return status;
}
printf("set page type option success!\n");
return status;
}
单页单面扫描,就是不管有多少页都只扫描第一页的第一面。
/**
* @brief 指定扫描仪进行扫描(统一按照多页,双面处理)
*
* @param fileName:保存扫描文件的文件名,比如传test的话,扫描后的文件会是test_1,test_2之类的形式
*
* @param type:扫描类型 0:单面单面扫描,1:多页双面扫描
*
* @return 操作的返回值,0或者7为成功,其他为失败
*/
int scanner_start_scan(SANE_String_Const fileName, int type)
{
printf("[%s] Start\n", __FUNCTION__);
SANE_Status sane_status = 0;
switch (type)
{
case 0:
return do_scan_one(fileName);
case 1:
return do_scan_all(fileName);
default:
return do_scan_all(fileName);
}
}
这是扫描单页的接口
// 单页扫描
SANE_Status do_scan_one(const char *fileName)
{
printf("[%s] Start\n", __FUNCTION__);
del_old_pic();//扫描之前删掉上一次的内容
SANE_Status status;
FILE *ofp = NULL;
char path[PATH_MAX];
char part_path[PATH_MAX];
buffer_size = (32 * 1024);
buffer = (SANE_Byte *)malloc(buffer_size);
int i = 1;
// 设置打印机单页进纸张
status = kdk_scanner_set_page_type(1);
if (status != SANE_STATUS_GOOD)
{
printf("set page type fail:%s\n", sane_strstatus(status));
return status;
}
do
{
// 设置保存路径
sprintf(path, "/tmp/%s-%d.pnm", fileName, i); // 格式化PNM文件路径
strcpy(part_path, path);
strcat(part_path, ".part");
printf("picture name: %s\n", path);
// 开始扫描
status = sane_start(sane_handle);
if (status != SANE_STATUS_GOOD)
{
break;
}
if (NULL == (ofp = fopen(part_path, "w")))
{
status = SANE_STATUS_ACCESS_DENIED;
break;
}
// 保存扫描数据
status = scan_it(ofp);
switch (status)
{
case SANE_STATUS_GOOD:
case SANE_STATUS_EOF:
{
status = SANE_STATUS_GOOD;
if (!ofp || 0 != fclose(ofp))
{
status = SANE_STATUS_ACCESS_DENIED;
break;
}
else
{
ofp = NULL;
if (rename(part_path, path))
{
status = SANE_STATUS_ACCESS_DENIED;
break;
}
}
}
break;
default:
break;
}
} while (0);
if (ofp)
{
fclose(ofp);
ofp = NULL;
}
if (buffer)
{
free(buffer);
buffer = NULL;
}
return status;
}
// 删除上一次扫描的文件
void del_old_pic()
{
DIR *dir;
struct dirent *entry;
char path[] = "/tmp/";
char ext[] = ".pnm";
dir = opendir(path);
if (dir == NULL)
{
perror("Unable to open directory");
exit(EXIT_FAILURE);
}
while ((entry = readdir(dir)) != NULL)
{
// Check if the entry is a file and ends with .pnm
if (entry->d_type == DT_REG &&
strstr(entry->d_name, ext) != NULL &&
strcmp(entry->d_name + strlen(entry->d_name) - strlen(ext), ext) == 0)
{
char full_path[512];
sprintf(full_path, "%s%s", path, entry->d_name);
if (remove(full_path) == 0)
{
printf("Deleted %s\n", full_path);
}
else
{
perror("Unable to delete file");
}
}
}
closedir(dir);
}
// sane 设置扫描方式
int kdk_scanner_set_page_type(SANE_Int type)
{
printf("[%s] Start!\n", __FUNCTION__);
SANE_Status status;
status = sane_control_option(sane_handle, 4,
SANE_ACTION_SET_VALUE, &type, NULL);
if (status != SANE_STATUS_GOOD)
{
printf("Option did not set, desc = %s\n", sane_strstatus(status));
return status;
}
printf("set page type option success!\n");
return status;
}
保存图片,这一部分细节很多,我也没仔细研究,直接用就行。
static SANE_Status scan_it(FILE *ofp)
{
int i, len, first_frame = 1, offset = 0, must_buffer = 0, hundred_percent;
SANE_Byte min = 0xff, max = 0;
SANE_Parameters parm;
SANE_Status status;
Image image = {0, 0, 0, 0, 0};
static const char *format_name[] = {"gray", "RGB", "red", "green", "blue"};
SANE_Word total_bytes = 0, expected_bytes;
SANE_Int hang_over = -1;
do
{
if (!first_frame)
{
status = sane_start(sane_handle);
if (status != SANE_STATUS_GOOD)
{
goto cleanup;
}
}
status = sane_get_parameters(sane_handle, &parm);
if (status != SANE_STATUS_GOOD)
{
goto cleanup;
}
if (first_frame)
{
switch (parm.format)
{
case SANE_FRAME_RED:
case SANE_FRAME_GREEN:
case SANE_FRAME_BLUE:
assert(parm.depth == 8);
must_buffer = 1;
offset = parm.format - SANE_FRAME_RED;
break;
case SANE_FRAME_RGB:
assert((parm.depth == 8) || (parm.depth == 16));
case SANE_FRAME_GRAY:
assert((parm.depth == 1) || (parm.depth == 8) || (parm.depth == 16));
if (parm.lines < 0)
{
must_buffer = 1;
offset = 0;
}
else
{
write_pnm_header(parm.format, parm.pixels_per_line, parm.lines, parm.depth, ofp);
}
break;
default:
break;
}
if (must_buffer)
{
image.width = parm.bytes_per_line;
if (parm.lines >= 0)
image.height = parm.lines - STRIP_HEIGHT + 1;
else
image.height = 0;
image.x = image.width - 1;
image.y = -1;
if (!advance(&image))
{
status = SANE_STATUS_NO_MEM;
goto cleanup;
}
}
}
else
{
assert(parm.format >= SANE_FRAME_RED && parm.format <= SANE_FRAME_BLUE);
offset = parm.format - SANE_FRAME_RED;
image.x = image.y = 0;
}
hundred_percent = parm.bytes_per_line * parm.lines * ((parm.format == SANE_FRAME_RGB || parm.format == SANE_FRAME_GRAY) ? 1 : 3);
// 这段是写图片数据
while (1)
{
double progr;
status = sane_read(sane_handle, buffer, buffer_size, &len);
total_bytes += (SANE_Word)len;
progr = ((total_bytes * 100.) / (double)hundred_percent);
if (progr > 100.)
progr = 100.;
if (status != SANE_STATUS_GOOD)
{
if (status != SANE_STATUS_EOF)
{
return status;
}
break;
}
if (must_buffer)
{
switch (parm.format)
{
case SANE_FRAME_RED:
case SANE_FRAME_GREEN:
case SANE_FRAME_BLUE:
for (i = 0; i < len; ++i)
{
image.data[offset + 3 * i] = buffer[i];
if (!advance(&image))
{
status = SANE_STATUS_NO_MEM;
goto cleanup;
}
}
offset += 3 * len;
break;
case SANE_FRAME_RGB:
for (i = 0; i < len; ++i)
{
image.data[offset + i] = buffer[i];
if (!advance(&image))
{
status = SANE_STATUS_NO_MEM;
goto cleanup;
}
}
offset += len;
break;
case SANE_FRAME_GRAY:
for (i = 0; i < len; ++i)
{
image.data[offset + i] = buffer[i];
if (!advance(&image))
{
status = SANE_STATUS_NO_MEM;
goto cleanup;
}
}
offset += len;
break;
default:
break;
}
}
else /* ! must_buffer */
{
if ((parm.depth != 16))
fwrite(buffer, 1, len, ofp);
else
{
#if !defined(WORDS_BIGENDIAN)
int i, start = 0;
/* check if we have saved one byte from the last sane_read */
if (hang_over > -1)
{
if (len > 0)
{
fwrite(buffer, 1, 1, ofp);
buffer[0] = (SANE_Byte)hang_over;
hang_over = -1;
start = 1;
}
}
/* now do the byte-swapping */
for (i = start; i < (len - 1); i += 2)
{
unsigned char LSB;
LSB = buffer[i];
buffer[i] = buffer[i + 1];
buffer[i + 1] = LSB;
}
/* check if we have an odd number of bytes */
if (((len - start) % 2) != 0)
{
hang_over = buffer[len - 1];
len--;
}
#endif
fwrite(buffer, 1, len, ofp);
}
}
if (verbose && parm.depth == 8)
{
for (i = 0; i < len; ++i)
if (buffer[i] >= max)
max = buffer[i];
else if (buffer[i] < min)
min = buffer[i];
}
}
first_frame = 0;
} while (!parm.last_frame);
if (must_buffer)
{
image.height = image.y;
write_pnm_header(parm.format, parm.pixels_per_line, image.height, parm.depth, ofp);
#if !defined(WORDS_BIGENDIAN)
if (parm.depth == 16)
{
int i;
for (i = 0; i < image.height * image.width; i += 2)
{
unsigned char LSB;
LSB = image.data[i];
image.data[i] = image.data[i + 1];
image.data[i + 1] = LSB;
}
}
#endif
fwrite(image.data, 1, image.height * image.width, ofp);
}
fflush(ofp);
cleanup:
if (image.data)
free(image.data);
return status;
}
void write_pnm_header(SANE_Frame format, int width, int height, int depth, FILE *ofp)
{
printf("[%s] Start\n", __FUNCTION__);
switch (format)
{
case SANE_FRAME_RED:
case SANE_FRAME_GREEN:
case SANE_FRAME_BLUE:
case SANE_FRAME_RGB:
fprintf(ofp, "P6\n# SANE data follows\n%d %d\n%d\n", width, height, (depth <= 8) ? 255 : 65535);
break;
default:
if (depth == 1)
fprintf(ofp, "P4\n# SANE data follows\n%d %d\n", width, height);
else
fprintf(ofp, "P5\n# SANE data follows\n%d %d\n%d\n", width, height, (depth <= 8) ? 255 : 65535);
break;
}
}
static void *
advance(Image *image)
{
if (++image->x >= image->width)
{
image->x = 0;
if (++image->y >= image->height || !image->data)
{
size_t old_size = 0, new_size;
if (image->data)
old_size = image->height * image->width;
image->height += STRIP_HEIGHT;
new_size = image->height * image->width;
if (image->data)
image->data = realloc(image->data, new_size);
else
image->data = malloc(new_size);
if (image->data)
memset(image->data + old_size, 0, new_size - old_size);
}
}
if (!image->data)
fprintf(stderr, "can't allocate image buffer (%dx%d)\n",
image->width, image->height);
return image->data;
}
双页扫描,用do_scan_all替换do_scan_one,其他的函数都一样。
// 双面扫描全部文件+保存为PNM图像格式
SANE_Status do_scan_all(const char *fileName)
{
printf("[%s] Start\n", __FUNCTION__);
SANE_Status status; // 返回状态
FILE *ofp = NULL; // 输出文件指针
char path[PATH_MAX]; // PNM文件路径
char part_path[PATH_MAX]; // 临时PNN文件路径
buffer_size = (32 * 1024); // 缓冲区大小
buffer = malloc(buffer_size); // 动态分配缓冲区
int i = 1;
del_old_pic();
//设置打印机多页进纸张
status = kdk_scanner_set_page_type(0);
if (status != SANE_STATUS_GOOD)
{
printf("set page type fail:%s\n", sane_strstatus(status));
return status;
}
do
{
sprintf(path, "/tmp/%s-%d.pnm", fileName, i); // 格式化PNM文件路径
strcpy(part_path, path); // 复制PNM文件路径到临时文件路径
strcat(part_path, ".part"); // 在临时文件路径后添加扩展名".part"
// 启动扫描过程
status = sane_start(sane_handle);
if (status != SANE_STATUS_GOOD)
{
break;
}
// 创建临时文件
if (NULL == (ofp = fopen(part_path, "w")))
{
status = SANE_STATUS_ACCESS_DENIED;
break;
}
// 进行扫描,并将结果写入到临时文件中
status = scan_it(ofp);
switch (status)
{
case SANE_STATUS_GOOD:
case SANE_STATUS_EOF:
{
// 扫描成功或结束
status = SANE_STATUS_GOOD;
// 关闭临时文件,并检查是否成功关闭
if (!ofp || 0 != fclose(ofp))
{
status = SANE_STATUS_ACCESS_DENIED;
break;
}
else
{
ofp = NULL; // 将文件指针设置为NULL,避免重复关闭
// 将临时文件重命名为正式的PNM文件
if (rename(part_path, path))
{
status = SANE_STATUS_ACCESS_DENIED;
break;
}
}
}
break;
default:
break;
}
i++;
} while (status == SANE_STATUS_GOOD);
// 如果出现错误,则取消扫描进程
if (SANE_STATUS_GOOD != status)
{
sane_cancel(sane_handle);
}
// 关闭输出文件
if (ofp)
{
fclose(ofp);
ofp = NULL;
}
// 释放缓冲区内存
if (buffer)
{
free(buffer);
buffer = NULL;
}
if ((status == SANE_STATUS_NO_DOCS) && (i > 1))
status = SANE_STATUS_GOOD;
return status; // 返回状态
}
扫描完成会会在tmp下生成扫描文件。
关闭设备
void scanner_close_device()
{
printf("[%s] Start\n", __FUNCTION__);
if (sane_handle != NULL)
{
sane_close(sane_handle);
}
sane_handle = NULL;
}
结束使用
void scanner_exit()
{
printf("[%s] Start\n", __FUNCTION__);
sane_exit();
}
参考资料
Linux下通用扫描仪API——SANE( Scanner Access Now Easy)_linux sane-CSDN博客