#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <string.h>
#include <linux/fb.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <arpa/inet.h>
#include <errno.h>
//14byte文件头
typedef struct
{
char cfType[2];//文件类型，"BM"(0x4D42)
int cfSize;//文件大小（字节）
int cfReserved;//保留，值为0
int cfoffBits;//数据区相对于文件头的偏移量（字节）
}__attribute__((packed)) BITMAPFILEHEADER;
//__attribute__((packed))的作用是告诉编译器取消结构在编译过程中的优化对齐
//40byte信息头
typedef struct
{
char ciSize[4];//BITMAPFILEHEADER所占的字节数
int ciWidth;//宽度
int ciHeight;//高度
char ciPlanes[2];//目标设备的位平面数，值为1
int ciBitCount;//每个像素的位数
char ciCompress[4];//压缩说明
char ciSizeImage[4];//用字节表示的图像大小，该数据必须是4的倍数
char ciXPelsPerMeter[4];//目标设备的水平像素数/米
char ciYPelsPerMeter[4];//目标设备的垂直像素数/米
char ciClrUsed[4]; //位图使用调色板的颜色数
char ciClrImportant[4]; //指定重要的颜色数，当该域的值等于颜色数时（或者等于0时），表示所有颜色都一样重要
}__attribute__((packed)) BITMAPINFOHEADER;
typedef struct
{
unsigned char blue;
unsigned char green;
unsigned char red;
unsigned char reserved;
}__attribute__((packed)) PIXEL;//颜色模式RGB
BITMAPFILEHEADER FileHead;
BITMAPINFOHEADER InfoHead;
static char *fbp = 0;
static int xres = 0;
static int yres = 0;
static int bits_per_pixel = 0;
int width, height;
int show_bmp();
int fbfd = 0;
static void fb_update(struct fb_var_screeninfo *vi) //将要渲染的图形缓冲区的内容绘制到设备显示屏来
{
vi->yoffset = 1;
ioctl(fbfd, FBIOPUT_VSCREENINFO, vi);
vi->yoffset = 0;
ioctl(fbfd, FBIOPUT_VSCREENINFO, vi);
}
static int cursor_bitmap_format_convert(char *dst,char *src)//由于倒叙，也就是当前buffer的最后一行是新buffer的第一行
{
int i ,j ;
char *psrc = src ;
char *pdst = dst;
char *p = psrc;
/* 由于bmp存储是从后面往前面，所以需要倒序进行转换 */
pdst += (width * height * 3);
for(i=0;i<height;i++){
p = psrc + (i+1) * width * 3;
for(j=0;j<width;j++){
pdst -= 3;
p -= 3;
pdst[0] = p[0];
pdst[1] = p[1];
pdst[2] = p[2];
}
}
return 0;
}
int show_bmp(char *path)
{
int i;
FILE *fp;
int rc;
int line_x, line_y;
long int location = 0, BytesPerLine = 0;
char *bmp_buf = NULL;
char *bmp_buf_dst = NULL;
char * buf = NULL;
int flen = 0;
int ret = -1;
int total_length = 0;
printf("into show_bmp function\n");
if(path == NULL)
{
printf("path Error,return\n");
return -1;
}
printf("path = %s\n", path);
fp = fopen( path, "rb" );
if(fp == NULL){
printf("load cursor file open failed\n");
return -1;
}
/* 求解文件长度 */
fseek(fp,0,SEEK_SET);
fseek(fp,0,SEEK_END);
flen = ftell(fp);
printf("flen is %d\n",flen);
bmp_buf = (char*)calloc(1,flen - 54);
if(bmp_buf == NULL){
printf("load > malloc bmp out of memory!\n");
return -1;
}
/* 再移位到文件头部 */
fseek(fp,0,SEEK_SET);
rc = fread(&FileHead, sizeof(BITMAPFILEHEADER),1, fp);
if ( rc != 1)
{
printf("read header error!\n");
fclose( fp );
return( -2 );
}
//检测是否是bmp图像
if (memcmp(FileHead.cfType, "BM", 2) != 0)
{
printf("it's not a BMP file\n");
fclose( fp );
return( -3 );
}
rc = fread( (char *)&InfoHead, sizeof(BITMAPINFOHEADER),1, fp );
if ( rc != 1)
{
printf("read infoheader error!\n");
fclose( fp );
return( -4 );
}
width = InfoHead.ciWidth;
height = InfoHead.ciHeight;
//位图数据记录了位图的每一个像素值，记录顺序是在扫描行内是从左到右，扫描行之间是从下到上。位图的一个像素值所占的字节数：
//当biBitCount=24时，1个像素占3个字节,按顺序分别为B,G,R；
//biSizeImage = ((((bi.biWidth * bi.biBitCount) + 31) & ~31) / 8) * bi.biHeight;
printf("FileHead.cfSize =%d byte\n",FileHead.cfSize);
printf("flen = %d\n", flen);
printf("width = %d, height = %d\n", width, height);
total_length = width * height *3;
printf("total_length = %d\n", total_length);
//跳转的数据区
fseek(fp, FileHead.cfoffBits, SEEK_SET);
printf(" FileHead.cfoffBits = %d\n", FileHead.cfoffBits);
printf(" InfoHead.ciBitCount = %d\n", InfoHead.ciBitCount);
//每行字节数
buf = bmp_buf;
while ((ret = fread(buf,1,total_length,fp)) >= 0) {
if (ret == 0) {
usleep(100);
continue;
}
printf("total_length=%ld,ret = %ld\n", total_length,ret);
buf = ((char*) buf) + ret;
total_length = total_length - ret;
if(total_length == 0)
break;
}
///重新计算，很重要！！
total_length = width * height *3; //由于biBitCount=24，所以一个像素是rgb三色占据了3个byte,所以总的数据大小是长宽*3
bmp_buf_dst = (char*)calloc(1,total_length );
if(bmp_buf_dst == NULL){
printf("load > malloc bmp out of memory!\n");
return -1;
}
cursor_bitmap_format_convert(bmp_buf_dst, bmp_buf);
if(total_length <1536000)//要注意buffer的大小，不要出现越界
{
memcpy(fbp,bmp_buf_dst,total_length);
}else
{
memcpy(fbp,bmp_buf_dst,1536000);
}
free(bmp_buf);
free(bmp_buf_dst);
fclose(fp);
printf("show logo return 0\n");
return 0;
}
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////
int show_picture(int fd, char *path)
{
struct fb_var_screeninfo vinfo;
struct fb_fix_screeninfo finfo;
long int screensize = 0;
struct fb_bitfield red;
struct fb_bitfield green;
struct fb_bitfield blue;
//打开显示设备
fbfd = fd; //open("/dev/graphics/fb0", O_RDWR);
printf("fbfd = %d\n", fbfd);
if (fbfd == -1)
{
//printf("Error opening frame buffer errno=%d (%s)\n",errno, strerror(errno));
return -1;
}
if (ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo))
{
//printf("Error：reading fixed information.\n");
return -1;
}
if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo))
{
//printf("Error: reading variable information.\n");
return -1;
}
//printf("R:%x ;G:%d ;B:%d \n", (int)vinfo.red, vinfo.green, vinfo.blue );
//printf("%dx%d, %dbpp\n", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel );
xres = vinfo.xres;
yres = vinfo.yres;
bits_per_pixel = vinfo.bits_per_pixel;
//计算屏幕的总大小（字节）
screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
printf("vinfo.xres=%d,vinfo.yres=%d,vinfo.bits_per_pixel=%ld,screensize=%ld byte\n",vinfo.xres,vinfo.yres,vinfo.bits_per_pixel,screensize);
//对象映射
fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fbfd, 0);
if (fbp == (char *)-1)
{
printf("Error: failed to map framebuffer device to memory.\n");
return -1;
}
printf("sizeof file header=%ld\n", sizeof(BITMAPFILEHEADER)); //ok
//显示图像
show_bmp(path);
///在屏幕上显示多久
sleep(1000);
//fb_update(&vinfo);
//删除对象映射
munmap(fbp, screensize);
return 0;
}
int main(int argc,char* argv[])
{
int fbfd = 0;
char* picname=NULL;
if(argc != 2)
{
printf("Error: please enter picture name .\n");
goto done;
}
picname = argv[1];
fbfd = open("/dev/fb0", O_RDWR);
if (!fbfd)
{
printf("Error: cannot open framebuffer device.\n");
exit(1);
}
show_picture(fbfd, picname);
close(fbfd);
done: exit(0);
}
记住两点：1.一定要格式对应的文件，也就是像素和屏幕xy一样的图片才能正常显示
2.要注意bpp和InfoHead.ciBitCount要对应起来，不能一个32一个24，这个尤其要注意，制作bmp文件的工具在我的下载中（32bpp只有微软用，而且前8位是透明色）