嫁接了一下，OK.
/* -------------------------------------------------------------------------
original source: https://blog.csdn.net/luxiaoxun/article/details/7622988
1. Modified for a 240x320 SPI LCD display.
2. The width of the displaying picture must be a multiple of 4.
./open-gcc -L./lib -I./include -ljpeg -o jpgshow fbshow.c
Midas
---------------------------------------------------------------------------*/
#include <unistd.h>
#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 <jpeglib.h>
#include <jerror.h>
//14byte文件头
typedef struct
{
char cfType[2];//文件类型，"BM"(0x4D42)
long cfSize;//文件大小（字节）
long cfReserved;//保留，值为0
long 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
long ciWidth;//宽度
long 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; // for 32bit pix only
}__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; //tft lcd
/* ----- functions --------*/
int show_bmp(char* fpath);
int show_jpg(char* fpath);
unsigned char * open_jpgImg(char * filename, int *w, int *h);
void close_jpgImg(unsigned char *imgbuf);
/*================== main =================*/
int main ( int argc, char *argv[] )
{
int fbfd = 0;
struct fb_var_screeninfo vinfo;
struct fb_fix_screeninfo finfo;
long int screensize = 0;
//打开显示设备
fbfd = open("/dev/fb0", O_RDWR);
if (!fbfd)
{
printf("Error: cannot open framebuffer device.\n");
exit(1);
}
if (ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo))
{
printf("Error：reading fixed information.\n");
exit(2);
}
if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo))
{
printf("Error: reading variable information.\n");
exit(3);
}
printf("R:%d,G:%d,B:%d \n", vinfo.red.length, vinfo.green.length, vinfo.blue.length );
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;
if(bits_per_pixel != 16)
printf("WARNING: bits_per_pixel !=16, this program is base on R5_G6_B5 fb color format!\n");
//计算屏幕的总大小（字节）
screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
printf("screensize=%d byte\n",(int)screensize);
//对象映射
fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fbfd, 0);
if ((int)fbp == -1)
{
printf("Error: failed to map framebuffer device to memory.\n");
exit(4);
}
printf("sizeof file header=%d\n", sizeof(BITMAPFILEHEADER));
printf("into show_bmp function\n");
//显示图像
// show_bmp(argv[1]);
show_jpg(argv[1]);
//删除对象映射
munmap(fbp, screensize);
close(fbfd);
return 0;
}
int show_bmp(char* fpath)
{
FILE *fp;
int rc;
int line_x, line_y;
long int location = 0;
printf("fpath=%s\n",fpath);
fp = fopen( fpath, "rb" );
if (fp == NULL)
{
return( -1 );
}
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 );
}
printf("BMP width=%d,height=%d ciBitCount=%d\n",(int)InfoHead.ciWidth, (int)InfoHead.ciHeight, (int)InfoHead.ciBitCount);
//检查是否24bit色
if(InfoHead.ciBitCount != 24 ){
printf("It's not 24bit_color BMP!\n");
return -1;
}
//检查宽度是否240x320
if(InfoHead.ciWidth > 240 ){
printf("The width is great than 240!\n");
return -1;
}
if(InfoHead.ciHeight > 320 ){
printf("The height is great than 320!\n");
return -1;
}
//跳转的数据区
fseek(fp, FileHead.cfoffBits, SEEK_SET);
int x0=0,y0=0; //set original coodinate
if( InfoHead.ciHeight+y0 > 320 || InfoHead.ciWidth+x0 > 240 )
{
printf("The origin of picture (x0,y0) is too big for a 240x320 LCD.\n");
return -1;
}
line_x = line_y = 0;
//向framebuffer中写BMP图片
while(!feof(fp))
{
PIXEL pix;
//unsigned short int tmp;
rc = fread( (char *)&pix, 1, sizeof(PIXEL), fp);
if (rc != sizeof(PIXEL))
break;
// frame buffer location
location = line_x * bits_per_pixel / 8 +x0 + (InfoHead.ciHeight - line_y - 1 +y0) * xres * bits_per_pixel / 8;
//显示每一个像素, in ili9431 node of dts, color sequence is defined as 'bgr'(as for ili9431) .
// little endian is noticed.
// ---- converting to format R5G6B5(as for framebuffer) -----
*(fbp + location + 0)=(((pix.green)&0b11100)<<3) + (((pix.blue)&0b11111000)>>3);
*(fbp + location + 1)=((pix.red)&0b11111000) + (((pix.green)&0b11100000)>>5);
line_x++;
if (line_x == InfoHead.ciWidth )
{
line_x = 0;
line_y++;
//printf("line_y = %d\n",line_y);
if(line_y == InfoHead.ciHeight)
break;
}
}
fclose( fp );
return( 0 );
}
int show_jpg(char* fpath)
{
int width,height;
unsigned char *imgbuf;
unsigned char *dat;
uint16_t tmp;
long int location = 0;
int line_x,line_y;
imgbuf=open_jpgImg(fpath,&width,&height);
if(imgbuf==NULL) {
printf("open_jpgImg fails!\n");
return -1;
}
dat=imgbuf;
printf("open_jpgImg() succeed, width=%d, height=%d\n",width,height);
int x0=0,y0=0; //set original coodinate
line_x = line_y = 0;
for(line_y=0;line_y<height;line_y++) {
for(line_x=0;line_x<width;line_x++) {
location = line_x * bits_per_pixel / 8 +x0 + (height - line_y - 1 +y0) * xres * bits_per_pixel / 8;
//显示每一个像素, in ili9431 node of dts, color sequence is defined as 'bgr'(as for ili9431) .
// little endian is noticed.
// ---- dat(R8G8B8) converting to format R5G6B5(as for framebuffer) -----
*(fbp + location + 0)=((*(dat+1)&0b11100)<<3) + ((*(dat+2) & 0b11111000)>>3);
*(fbp + location + 1)=(*dat&0b11111000) + ((*(dat+1)&0b11100000)>>5);
dat+=3;
}
}
close_jpgImg(imgbuf);
}
/*--------------------------------------------------------------
open jpg file and return decompressed image buffer pointer
int *w,*h: with and height of the image
return:
=NULL fail
>0 decompressed image buffer pointer
--------------------------------------------------------------*/
unsigned char * open_jpgImg(char * filename, int *w, int *h)
{
struct jpeg_decompress_struct cinfo;
struct jpeg_error_mgr jerr;
FILE *infile;
unsigned char *buffer;
unsigned char *temp;
if ((infile = fopen(filename, "rb")) == NULL) {
fprintf(stderr, "open %s failed\n", filename);
exit(-1);
}
cinfo.err = jpeg_std_error(&jerr);
jpeg_create_decompress(&cinfo);
jpeg_stdio_src(&cinfo, infile);
jpeg_read_header(&cinfo, TRUE);
jpeg_start_decompress(&cinfo);
*w = cinfo.output_width;
*h = cinfo.output_height;
printf("output_width====%d\n",cinfo.output_width);
printf("output_height====%d\n",cinfo.output_height);
/* --- check size ----*/
if ((cinfo.output_width > 240) ||
(cinfo.output_height > 320)) {
printf("too large size JPEG file,cannot display\n");
return NULL;
}
buffer = (unsigned char *) malloc(cinfo.output_width *
cinfo.output_components * cinfo.output_height);
temp = buffer;
while (cinfo.output_scanline < cinfo.output_height) {
jpeg_read_scanlines(&cinfo, &buffer, 1);
buffer += cinfo.output_width * cinfo.output_components;
}
jpeg_finish_decompress(&cinfo);
jpeg_destroy_decompress(&cinfo);
return temp;
fclose(infile);
}
/* release mem for decompressed jpeg image buffer */
void close_jpgImg(unsigned char *imgbuf)
{
if(imgbuf != NULL)
free(imgbuf);
}
