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一、涉及的知识点：

1、bmp的显示

2、双向循环链表实现图片的轮播

3、触摸屏的滑动算法实现图片的切换

4、目录操作用以检索bmp图片文件

5、项目的优化方向

（1）可以实现不同图片大小的显示

（2）图片轮播的时候可以点击屏幕以实现暂停，返回，等的操作。

程序代码：（有待完善优化）

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/input.h>   
#include <sys/mman.h>
#include <dirent.h>
#include <strings.h>
#include <string.h>
#include <stdlib.h>// 双链表设计
struct node
{char path[1024];struct node *next;struct node *prev;
};// bmp文件头结构体-》占用14个字节
struct bitmap_header
{int16_t type;int32_t size;          // 图像文件大小int16_t reserved1;int16_t reserved2;int32_t offbits;       // bmp图像数据偏移量
} __attribute__((packed));// bmp位图信息头结构体 -》占用40个字节
struct bitmap_info
{int32_t size;          // 本结构大小int32_t width;         // 图像宽int32_t height;        // 图像高int16_t planes;int16_t bit_count;     // 色深int32_t compression;int32_t size_img;      // bmp数据大小，必须是4的整数倍int32_t X_pel;int32_t Y_pel;int32_t clrused;int32_t clrImportant;
} __attribute__((packed));extern int open_lcd(void);
extern void close_lcd(void);
extern int show_bmp24(char *bmp_path);
extern void filter_bmp(char *dir_path);
extern int open_ts(void);
extern void close_ts(void);
extern void func_photo(void);
extern void Acq_xy(int *X, int *Y);
extern void insert_node(struct node *head, char *path);
extern void show_phone_list_next(void);
extern void show_phone_list_pre(void);int lcd_fd;
int pox_X, pox_Y;
int T_fd;
int i_bmp;	               //bmp文件数量
char bmp_list[10][50];	   //bmp文件列表int (*lcd)[800] = NULL;
int touch_x, touch_y;      // 记录按下的坐标int main()
{open_lcd();open_ts();show_bmp24("/CJH/ui/ui_main.bmp");while (1){Acq_xy(&pox_X, &pox_Y);printf("(%d, %d)\n", pox_X, pox_Y);//点击左上角进入相册功能if(pox_X>=0 && pox_X<150 && pox_Y>=0 && pox_Y<100){printf("点击屏幕左上角->进入相册\n");func_photo();}}close_ts();close_lcd();return 0;}//打开触摸屏
int open_ts(void)
{//打开触摸屏设备文件T_fd = open("/dev/input/event0", O_RDWR);if (T_fd <= 0){perror("打开触摸屏失败\n");return -1;}
}//关闭触摸屏
void close_ts(void)
{//关闭触摸屏设备文件 close(T_fd);
}void Acq_xy(int *X, int *Y)
{while (1){struct input_event ev;read(T_fd, &ev, sizeof(ev));if (ev.type == EV_ABS && ev.code == ABS_X){*X = ev.value*800/1024;}if (ev.type == EV_ABS &&  ev.code == ABS_Y){*Y = ev.value*480/600;}// printf("x=%d, y=%d\n", X, Y);if (ev.type == EV_KEY &&  ev.code == BTN_TOUCH){if (ev.value > 0){printf("按下 x=%d y=%d\n", *X, *Y);touch_x = *X;touch_y = *Y;}else{printf("松开 x=%d y=%d\n",*X, *Y);break;}}}
}void func_photo(void)
{filter_bmp("/CJH/phone");int k;for (k = 0; k < i_bmp; k++)printf("%d: %s\n", k+1, bmp_list[k]);show_bmp24("/CJH/phone/11.bmp");int i = -1;while (1){Acq_xy(&pox_X, &pox_Y);// 计算坐标x差值if (touch_x - pox_X < -30){printf("右滑动\n");i++;if (i>i_bmp-1)i=1;show_bmp24(bmp_list[i]);}if (touch_x - pox_X > 30){printf("左滑动\n");i--;if(i<0)i=i_bmp-1;show_bmp24(bmp_list[i]);}if (pox_X>=0 && pox_X<150 && pox_Y>=0 && pox_Y<100){printf("点击屏幕左上角->返回主界面\n");show_bmp24("/CJH/ui/ui_main.bmp");break;}if (touch_y - pox_Y > 45){printf("下滑动->前续遍历\n");show_phone_list_pre();show_bmp24("/CJH/ui/ui_main.bmp");break;}if (touch_y - pox_Y < -45){printf("下滑动->后续遍历\n");show_phone_list_next();show_bmp24("/CJH/ui/ui_main.bmp");break; }}}//筛选检索bmp
void filter_bmp(char *dir_path)
{i_bmp = 0;bzero(bmp_list, sizeof(bmp_list));// 1.打开目录DIR *dp = opendir(dir_path);// 2.读取目录项（包括文件名）struct dirent *temp;while(1){temp = readdir(dp);if(temp == NULL)	break;//成功读取到// printf("%s\n", temp->d_name);int len = strlen(temp->d_name);if(len>4 &&temp->d_name[len-4] == '.' &&temp->d_name[len-3] == 'b' &&temp->d_name[len-2] == 'm' &&temp->d_name[len-1] == 'p'){// printf("yes: %s\n", temp->d_name);char temp_path[50] = {0};//将文件名与完整路径拼接起来sprintf(temp_path, "%s/%s", dir_path, temp->d_name);strncpy(bmp_list[i_bmp], temp_path, sizeof(bmp_list[i_bmp]));i_bmp++;}}// 3.关闭目录closedir(dp);
}int open_lcd(void)
{lcd_fd = open("/dev/fb0", O_RDWR);if (lcd_fd < 0){printf("LCD设备打开失败\n");return -1;}// 映射LCD设备lcd = mmap(NULL, 800 * 480 * 4, PROT_READ | PROT_WRITE, MAP_SHARED, lcd_fd, 0);if (lcd == MAP_FAILED){printf("映射失败\n");return -1;}else{printf("映射成功\n");}
}//关闭lcd
void close_lcd(void)
{close(lcd_fd);// 解除映射munmap(lcd, 800 * 4 * 480);
}// 显示24位的BMP图片
int show_bmp24(char *bmp_path)
{// 1.打开图片文件int bmp_fd = open(bmp_path, O_RDWR);if (bmp_fd < 0){printf("打开图片失败\n");return -1;}// 2.读取14个字节头数据struct bitmap_header head;read(bmp_fd, &head, 14);struct bitmap_info info;read(bmp_fd, &info, 40);int widht = info.width;int height = info.height;int bbp = info.bit_count;printf("%s 大小 %d 宽度 %d 高度 %d 色深 %d\n", bmp_path, head.size, widht, height, bbp);// 像素缓存区char rgb[widht * 3 * height];read(bmp_fd, rgb, sizeof(rgb));// 3.把rgb的数据转换为argb数据char argb[800 * 4 * 480];for (int i = 0; i < 800 * 480; i++){argb[0 + i * 4] = rgb[0 + i * 3];argb[1 + i * 4] = rgb[1 + i * 3];argb[2 + i * 4] = rgb[2 + i * 3];argb[3 + i * 4] = 0;}// 4.把一维数组转换为二维数组显示正向图片int(*color)[800] = (void *)argb;for (int y = 0; y < 480; y++){for (int x = 0; x < 800; x++){lcd[y][x] = color[479 - y][x];}}// 关闭图片close(bmp_fd);
}// 插入节点
void insert_node(struct node *head, char *path)
{// 1.新建节点struct node *xnew = malloc(sizeof(struct node));// 2.初始化数据域strcpy(xnew->path, path);// 初始化地址域xnew->next = xnew;xnew->prev = xnew;// 3.插入节点到链表中xnew->prev = head->prev;xnew->next = head;head->prev->next = xnew;head->prev = xnew;
}void show_phone_list_next(void)
{// 1.创建一个头结点struct node *head = malloc(sizeof(struct node));// 2.初始化头结点strcpy(head->path, "NULL");head->next = head;head->prev = head;filter_bmp("/CJH/phone");int k;for (k = 0; k < i_bmp; k++){   printf("%d: %s\n", k+1, bmp_list[k]);insert_node(head, bmp_list[k]);}// 指向头结点struct node *pos = head; while (1){if (strcmp(pos->path, "NULL") != 0){show_bmp24(pos->path);}sleep(1);pos = pos->next;if (pos == head){break;}}
}void show_phone_list_pre(void)
{// 1.创建一个头结点struct node *head = malloc(sizeof(struct node));// 2.初始化头结点strcpy(head->path, "NULL");head->next = head;head->prev = head;filter_bmp("/CJH/phone");int k;for (k = 0; k < i_bmp; k++){   printf("%d: %s\n", k+1, bmp_list[k]);insert_node(head, bmp_list[k]);}// 指向头结点struct node *pos = head; while (1){if (strcmp(pos->path, "NULL") != 0){show_bmp24(pos->path);}sleep(1);pos = pos->prev;if (pos == head){break;}}
}

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