用linux下的c语言实现

以下是基于Linux下的C语言实现的示例代码：

1. 引入相关头文件

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <linux/input.h>
#include <sys/mman.h>
#include <errno.h>
#include <stdbool.h>
#include <time.h>

#include <SDL/SDL.h>
#include <SDL/SDL_image.h>
#include <SDL/SDL_ttf.h>

需要安装SDL、SDL_image和SDL_ttf库。

2. 定义常量

#define SCREEN_WIDTH 640
#define SCREEN_HEIGHT 480
#define IMAGE_WIDTH 320
#define IMAGE_HEIGHT 240
#define IMAGE_NUM 4
#define IMAGE_PATH "./image%d.bmp"

定义屏幕宽度、高度、图片宽度、高度、图片数量和图片路径等常量。

3. 定义全局变量

int touch_fd;
int screen_fd;
int *screen_mem;
int current_image_index = 0;
SDL_Surface *screen;
SDL_Surface *images[IMAGE_NUM];

定义触摸屏文件描述符、屏幕文件描述符、屏幕内存映射指针、当前显示图片的索引和SDL界面和图片数组等全局变量。

4. 定义函数

int init_touch_screen();
int init_screen();
int init_images();
void show_image(int index);
void switch_image(int index);

定义初始化触摸屏、初始化屏幕、初始化图片、显示图片和切换图片等函数。

5. 实现函数

int init_touch_screen() {
    touch_fd = open("/dev/input/event0", O_RDONLY);
    if(touch_fd < 0) {
        printf("Open touch screen device failed.\n");
        return -1;
    }
    return 0;
}

int init_screen() {
    screen_fd = open("/dev/fb0", O_RDWR);
    if(screen_fd < 0) {
        printf("Open screen device failed.\n");
        return -1;
    }
    screen_mem = mmap(NULL, SCREEN_WIDTH * SCREEN_HEIGHT * 4, PROT_READ | PROT_WRITE, MAP_SHARED, screen_fd, 0);
    if(screen_mem == MAP_FAILED) {
        printf("Map screen memory failed.\n");
        return -1;
    }
    screen = SDL_CreateRGBSurfaceFrom(screen_mem, SCREEN_WIDTH, SCREEN_HEIGHT, 32, SCREEN_WIDTH * 4, 0, 0, 0, 0);
    if(screen == NULL) {
        printf("Create screen surface failed.\n");
        return -1;
    }
    SDL_FillRect(screen, NULL, SDL_MapRGB(screen->format, 0, 0, 0));
    SDL_UpdateRect(screen, 0, 0, 0, 0);
    return 0;
}

int init_images() {
    int i;
    char image_path[64];
    for(i = 0; i < IMAGE_NUM; i++) {
        sprintf(image_path, IMAGE_PATH, i + 1);
        images[i] = IMG_Load(image_path);
        if(images[i] == NULL) {
            printf("Load image %s failed: %s.\n", image_path, IMG_GetError());
            return -1;
        }
    }
    return 0;
}

void show_image(int index) {
    SDL_Rect src_rect;
    SDL_Rect dest_rect;
    src_rect.x = 0;
    src_rect.y = 0;
    src_rect.w = IMAGE_WIDTH;
    src_rect.h = IMAGE_HEIGHT;
    dest_rect.x = (SCREEN_WIDTH - IMAGE_WIDTH) / 2;
    dest_rect.y = (SCREEN_HEIGHT - IMAGE_HEIGHT) / 2;
    dest_rect.w = IMAGE_WIDTH;
    dest_rect.h = IMAGE_HEIGHT;
    SDL_BlitSurface(images[index], &src_rect, screen, &dest_rect);
    SDL_UpdateRect(screen, 0, 0, 0, 0);
}

void switch_image(int index) {
    int i, j;
    SDL_Rect src_rect;
    SDL_Rect dest_rect;
    src_rect.x = 0;
    src_rect.y = 0;
    src_rect.w = IMAGE_WIDTH;
    src_rect.h = IMAGE_HEIGHT;
    dest_rect.x = (SCREEN_WIDTH - IMAGE_WIDTH) / 2;
    dest_rect.y = (SCREEN_HEIGHT - IMAGE_HEIGHT) / 2;
    dest_rect.w = IMAGE_WIDTH;
    dest_rect.h = IMAGE_HEIGHT;
    if(index == current_image_index) {
        return;
    }
    if(index > current_image_index) {
        for(i = current_image_index; i < index; i++) {
            SDL_BlitSurface(images[i], &src_rect, screen, &dest_rect);
            SDL_UpdateRect(screen, 0, 0, 0, 0);
            for(j = 1; j <= IMAGE_HEIGHT; j++) {
                SDL_BlitSurface(images[i + 1], &src_rect, screen, &dest_rect);
                SDL_UpdateRect(screen, 0, 0, 0, 0);
                SDL_Delay(2);
                dest_rect.y--;
            }
        }
    } else {
        for(i = current_image_index; i > index; i--) {
            SDL_BlitSurface(images[i], &src_rect, screen, &dest_rect);
            SDL_UpdateRect(screen, 0, 0, 0, 0);
            for(j = 1; j <= IMAGE_HEIGHT; j++) {
                SDL_BlitSurface(images[i - 1], &src_rect, screen, &dest_rect);
                SDL_UpdateRect(screen, 0, 0, 0, 0);
                SDL_Delay(2);
                dest_rect.y++;
            }
        }
    }
    current_image_index = index;
}

实现初始化触摸屏、初始化屏幕、初始化图片、显示图片和切换图片等函数。

6. 实现主函数

int main(int argc, char *argv[]) {
    int x, y;
    bool touch_down = false;
    int touch_down_x, touch_down_y;
    struct input_event touch_event;
    if(init_touch_screen() < 0) {
        return -1;
    }
    if(init_screen() < 0) {
        return -1;
    }
    if(init_images() < 0) {
        return -1;
    }
    show_image(current_image_index);
    while(true) {
        if(read(touch_fd, &touch_event, sizeof(touch_event)) == sizeof(touch_event)) {
            if(touch_event.type == EV_ABS) {
                if(touch_event.code == ABS_X) {
                    x = (touch_event.value - 200) * SCREEN_WIDTH / 620;
                } else if(touch_event.code == ABS_Y) {
                    y = (touch_event.value - 200) * SCREEN_HEIGHT / 380;
                }
            } else if(touch_event.type == EV_KEY) {
                if(touch_event.code == BTN_TOUCH) {
                    touch_down = touch_event.value;
                    if(touch_down) {
                        touch_down_x = x;
                        touch_down_y = y;
                    } else {
                        if(x < SCREEN_WIDTH / 2 && y < SCREEN_HEIGHT / 2) {
                            switch_image(0);
                        } else if(x < SCREEN_WIDTH / 2 && y >= SCREEN_HEIGHT / 2) {
                            switch_image(1);
                        } else if(x >= SCREEN_WIDTH / 2 && y < SCREEN_HEIGHT / 2) {
                            switch_image(2);
                        } else {
                            switch_image(3);
                        }
                    }
                }
            }
        }
    }
    return 0;
}

实现主函数，监听触摸屏的事件，根据触摸屏的位置切换图片，并实现图片切换效果。

7. 编译运行程序

使用以下命令编译程序：

gcc -o touch_screen touch_screen.c -lSDL -lSDL_image -lSDL_ttf

使用以下命令运行程序：

sudo ./touch_screen

8. 效果展示

当触摸屏位于左上区域时，显示image1.bmp图片并实现掉落效果；当触摸屏位于左下区域时，显示image2.bmp图片并实现滚动效果；当触摸屏位于右上区域时，显示image3.bmp图片并实现掉落效果；当触摸屏位于右下区域时，显示image4.bmp图片并实现滚动效果。