飞凌嵌入式ElfBoard-LCD显示图片（bmp）编程示例之显示bmp图片代码示例

fread(row, sizeof(uint8_t), row_size, bmp_file);

for (int x = 0; x < width; x++) {

int pixel_index = x * 3; // 每个像素 3 字节

uint8_t blue = row[pixel_index];

uint8_t green = row[pixel_index + 1];

uint8_t red = row[pixel_index + 2];

// 计算帧缓冲区位置

long location = (vinfo->yres_virtual - 1 - y) * vinfo->xres_virtual * (vinfo->bits_per_pixel / 8) +

x * (vinfo->bits_per_pixel / 8);

fb_ptr[location] = blue;        // 蓝色分量

fb_ptr[location + 1] = green;   // 绿色分量

fb_ptr[location + 2] = red;      // 红色分量

}

}

#include <stdlib.h>

#include <string.h>

#include <fcntl.h>

#include <unistd.h>

#include <linux/fb.h>

#include <sys/ioctl.h>

#include <sys/mman.h>

#include <stdint.h>

#pragma pack(push, 1)

typedef struct {

uint16_t bfType;      // BMP 文件类型

uint32_t bfSize;      // 文件大小

uint16_t bfReserved1; // 保留字段

uint16_t bfReserved2; // 保留字段

uint32_t bfOffBits;   // 图像数据的偏移量

} BMPFileHeader;

typedef struct {

uint32_t biSize;          // 信息头的大小

int32_t  biWidth;         // 图像宽度

int32_t  biHeight;        // 图像高度

uint16_t biPlanes;        // 颜色平面数

uint16_t biBitCount;      // 每个像素的位数

uint32_t biCompression;   // 压缩类型

uint32_t biSizeImage;     // 图像大小

int32_t  biXPelsPerMeter;  // 水平分辨率

int32_t  biYPelsPerMeter;  // 垂直分辨率

uint32_t biClrUsed;       // 使用的颜色数

uint32_t biClrImportant;   // 重要的颜色数

} BMPInfoHeader;

#pragma pack(pop)

void draw_bmp(const char *filename, int fb_fd, struct fb_var_screeninfo *vinfo) {

FILE *bmp_file = fopen(filename, "rb");

if (!bmp_file) {

perror("Failed to open BMP file");

exit(1);

}

BMPFileHeader file_header;

BMPInfoHeader info_header;

fread(&file_header, sizeof(BMPFileHeader), 1, bmp_file);

fread(&info_header, sizeof(BMPInfoHeader), 1, bmp_file);

// 检查 BMP 文件格式

if (file_header.bfType != 0x4D42) {

fprintf(stderr, "Not a valid BMP file\n");

fclose(bmp_file);

return;

}

// BMP 文件宽度和高度

int width = info_header.biWidth;

int height = info_header.biHeight;

// 每行字节对齐到 4 字节

int row_size = (width * 3 + 3) & ~3;

// 分配内存并读取像素数据

uint8_t *row = malloc(row_size);

if (!row) {

perror("Failed to allocate memory");

fclose(bmp_file);

return;

}

// 映射帧缓冲区

size_t screensize = vinfo->yres_virtual * vinfo->xres_virtual * (vinfo->bits_per_pixel / 8);

uint8_t *fb_ptr = (uint8_t *)mmap(NULL, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fb_fd, 0);

if (fb_ptr == MAP_FAILED) {

perror("Failed to map framebuffer device to memory");

free(row);

fclose(bmp_file);

return;

}

// 清空帧缓冲

memset(fb_ptr, 0, screensize);

// 绘制 BMP 图像到帧缓冲区

for (int y = 0; y < height; y++) {

fread(row, sizeof(uint8_t), row_size, bmp_file);

for (int x = 0; x < width; x++) {

int pixel_index = x * 3; // 每个像素 3 字节

uint8_t blue = row[pixel_index];

uint8_t green = row[pixel_index + 1];

uint8_t red = row[pixel_index + 2];

// 计算帧缓冲区位置

long location = (vinfo->yres_virtual - 1 - y) * vinfo->xres_virtual * (vinfo->bits_per_pixel / 8) +

x * (vinfo->bits_per_pixel / 8);

fb_ptr[location] = blue;        // 蓝色分量

fb_ptr[location + 1] = green;   // 绿色分量

fb_ptr[location + 2] = red;      // 红色分量

}

}

// 清理

munmap(fb_ptr, screensize);

free(row);

fclose(bmp_file);

}

int main(int argc, char *argv[]) {

if (argc != 3) {

fprintf(stderr, "Usage: %s <framebuffer_device> <image_file>\n", argv[0]);

return 1;

}

const char *fb_device = argv[1];

const char *image_file = argv[2];

// 打开帧缓冲设备

int fb_fd = open(fb_device, O_RDWR);

if (fb_fd == -1) {

perror("Error opening framebuffer device");

return 1;

}

// 获取屏幕信息

struct fb_var_screeninfo vinfo;

if (ioctl(fb_fd, FBIOGET_VSCREENINFO, &vinfo)) {

perror("Error reading variable information");

close(fb_fd);

return 1;

}

printf(".xres=%d, .yres=%d, .bit=%d\r\n", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel);

printf(".xres_virtual=%d, .yres_virtual=%d\r\n", vinfo.xres_virtual, vinfo.yres_virtual);

// 显示 BMP 图片

draw_bmp(image_file, fb_fd, &vinfo);

close(fb_fd);

return 0;

}