V853的芯片，接的是800*480的RGB屏幕。QT是可以正常显示的。从网上找了个通过fb的ioctrl去显示bmp图片的程序，执行后不论是什么图片都是显示黑屏。同样的应用程序在 V3S+同样的屏幕 是可以正常显示bmp图片的。也有用过fbv去显示图片，fbv xxxx.bmp 但也是显示全黑。
有没有遇到同样问题的朋友帮忙解答一下呢？
以下是显示bmp图片的应用程序：
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#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 <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
typedef struct
{
int fbfd;
char *fbp;
unsigned int xres;
unsigned int yres;
unsigned int xres_virtual;
unsigned int yres_virtual;
unsigned int xoffset;
unsigned int yoffset;
unsigned int bpp;
unsigned long line_length;
unsigned long size;
struct fb_bitfield red;
struct fb_bitfield green;
struct fb_bitfield blue;
} FB_INFO;
typedef struct
{
unsigned int width;
unsigned int height;
unsigned int bpp;
unsigned long size;
unsigned int data_offset;
} IMG_INFO;
FB_INFO fb_info;
IMG_INFO img_info;
int show_bmp(char *img_name);
static int cursor_bitmap_format_convert(char *dst,char *src, unsigned long img_len_one_line)
{
int img_len ,fb_len ;
char *p;
__u32 val;
PIXEL pix;
p = (char *)&val;
img_len = img_info.width; /*一行图片的长度*/
fb_len = fb_info.xres; /*一行显示屏的长度*/
/*进行x轴的偏移*/
dst += fb_info.xoffset * (fb_info.bpp / 8);
fb_len -= fb_info.xoffset;
/*bmp 数据是上下左右颠倒的，这里只进行左右的处理*/
/*先定位到图片的最后一个像素的地址，然后往第一个像素的方向处理，进行左右颠倒的处理*/
src += img_len_one_line - 1;
/*处理一行要显示的数据*/
while(1) {
if (img_info.bpp == 32)
pix.reserved = *(src--);
pix.red = *(src--);
pix.green = *(src--);
pix.blue = *(src--);
val = 0x00;
val |= (pix.red >> (8 - fb_info.red.length)) << fb_info.red.offset;
val |= (pix.green >> (8 - fb_info.green.length)) << fb_info.green.offset;
val |= (pix.blue >> (8 - fb_info.blue.length)) << fb_info.blue.offset;
val = 0x000000;
if (fb_info.bpp == 16) {
*(dst++) = *(p + 0);
*(dst++) = *(p + 1);
}
else if (fb_info.bpp == 24) {
*(dst++) = *(p + 0);
*(dst++) = *(p + 1);
*(dst++) = *(p + 2);
}
else if (fb_info.bpp == 32) {
*(dst++) = *(p + 0);
*(dst++) = *(p + 1);
*(dst++) = *(p + 2);
*(dst++) = *(p + 3);
}
/*超过图片长度或显示屏长度认为一行处理完了*/
img_len--;
fb_len--;
if (img_len <= 0 || fb_len <= 0)
break;
}
#if 0
printf("r = %d\n", pix.red);
printf("g = %d\n", pix.green);
printf("b = %d\n", pix.blue);
#endif
return 0;
}
int show_bmp(char *img_name)
{
FILE *fp;
int ret = 0;
BITMAPFILEHEADER FileHead;
BITMAPINFOHEADER InfoHead;
if(img_name == NULL) {
printf("img_name is null\n");
return -1;
}
fp = fopen( img_name, "rb" );
if(fp == NULL) {
printf("img[%s] open failed\n", img_name);
ret = -1;
goto err_showbmp;
}
/* 移位到文件头部 */
fseek(fp, 0, SEEK_SET);
ret = fread(&FileHead, sizeof(BITMAPFILEHEADER), 1, fp);
if ( ret != 1) {
printf("img read failed\n");
ret = -1;
goto err_showbmp;
}
//检测是否是bmp图像
if (memcmp(FileHead.cfType, "BM", 2) != 0) {
printf("it's not a BMP file[%c%c]\n", FileHead.cfType[0], FileHead.cfType[1]);
ret = -1;
goto err_showbmp;
}
ret = fread( (char *)&InfoHead, sizeof(BITMAPINFOHEADER),1, fp );
if ( ret != 1) {
printf("read infoheader error!\n");
ret = -1;
goto err_showbmp;
}
img_info.width = InfoHead.ciWidth;
img_info.height = InfoHead.ciHeight;
img_info.bpp = InfoHead.ciBitCount;
img_info.size = FileHead.cfSize;
img_info.data_offset = FileHead.cfoffBits;
printf("img info w[%d] h[%d] bpp[%d] size[%ld] offset[%d]\n", img_info.width, img_info.height, img_info.bpp, img_info.size, img_info.data_offset);
if (img_info.bpp != 24 && img_info.bpp != 32) {
printf("img bpp is not 24 or 32\n");
ret = -1;
goto err_showbmp;
}
/*
*一行行处理
*/
char *buf_img_one_line;
char *buf_fb_one_line;
char *p;
int fb_height;
long img_len_one_line = img_info.width * (img_info.bpp / 8);
long fb_len_one_line = fb_info.line_length;
// printf("img_len_one_line = %d\n", img_len_one_line);
// printf("fb_len_one_line = %d\n", fb_info.line_length);
buf_img_one_line = (char *)calloc(1, img_len_one_line + 256);
if(buf_img_one_line == NULL) {
printf("alloc failed\n");
ret = -1;
goto err_showbmp;
}
buf_fb_one_line = (char *)calloc(1, fb_len_one_line + 256);
if(buf_fb_one_line == NULL) {
printf("alloc failed\n");
ret = -1;
goto err_showbmp;
}
fseek(fp, img_info.data_offset, SEEK_SET);
p = fb_info.fbp + fb_info.yoffset * fb_info.line_length; /*进行y轴的偏移*/
fb_height = fb_info.yres;
while (1) {
memset(buf_img_one_line, 0, img_len_one_line);
memset(buf_fb_one_line, 0, fb_len_one_line);
ret = fread(buf_img_one_line, 1, img_len_one_line, fp);
if (ret < img_len_one_line) {
/*图片读取完成，则图片显示完成*/
printf("read to end of img file\n");
cursor_bitmap_format_convert(buf_fb_one_line, buf_img_one_line, img_len_one_line); /*数据转换*/
memcpy(fb_info.fbp, buf_fb_one_line, fb_len_one_line);
break;
}
cursor_bitmap_format_convert(buf_fb_one_line, buf_img_one_line, img_len_one_line); /*数据转换*/
memcpy(p, buf_fb_one_line, fb_len_one_line); /*显示一行*/
p += fb_len_one_line;
/*超过显示屏宽度认为图片显示完成*/
fb_height--;
if (fb_height <= 0)
break;
}
free(buf_img_one_line);
free(buf_fb_one_line);
fclose(fp);
return ret;
err_showbmp:
if (fp)
fclose(fp);
return ret;
}
int show_picture(char *img_name)
{
struct fb_var_screeninfo vinfo;
struct fb_fix_screeninfo finfo;
if (fb_info.fbfd <= -1) {
printf("fb open fialed\n");
return -1;
}
if (ioctl(fb_info.fbfd, FBIOGET_FSCREENINFO, &finfo)) {
printf("fb ioctl fialed\n");
return -1;
}
if (ioctl(fb_info.fbfd, FBIOGET_VSCREENINFO, &vinfo)) {
printf("fb ioctl fialed\n");
return -1;
}
fb_info.xres = vinfo.xres;
fb_info.yres = vinfo.yres;
fb_info.xres_virtual = vinfo.xres_virtual;
fb_info.yres_virtual = vinfo.yres_virtual;
fb_info.xoffset = vinfo.xoffset;
fb_info.yoffset = vinfo.yoffset;
fb_info.bpp = vinfo.bits_per_pixel;
fb_info.line_length = finfo.line_length;
fb_info.size = finfo.smem_len;
memcpy(&fb_info.red, &vinfo.red, sizeof(struct fb_bitfield));
memcpy(&fb_info.green, &vinfo.green, sizeof(struct fb_bitfield));
memcpy(&fb_info.blue, &vinfo.blue, sizeof(struct fb_bitfield));
#if 1
printf("fb info x[%d] y[%d] x_v[%d] y_v[%d] xoffset[%d] yoffset[%d] bpp[%d] line_length[%ld] size[%ld]\n", fb_info.xres, fb_info.yres, fb_info.xres_virtual, fb_info.yres_virtual, fb_info.xoffset, fb_info.yoffset, fb_info.bpp, fb_info.line_length, fb_info.size);
printf("fb info red off[%d] len[%d] msb[%d]\n", fb_info.red.offset, fb_info.red.length, fb_info.red.msb_right);
printf("fb info green off[%d] len[%d] msb[%d]\n", fb_info.green.offset, fb_info.green.length, fb_info.green.msb_right);
printf("fb info blue off[%d] len[%d] msb[%d]\n", fb_info.blue.offset, fb_info.blue.length, fb_info.blue.msb_right);
#endif
if (fb_info.bpp != 16 && fb_info.bpp != 24 && fb_info.bpp != 32) {
printf("fb bpp is not 16,24 or 32\n");
return -1;
}
if (fb_info.red.length > 8 || fb_info.green.length > 8 || fb_info.blue.length > 8) {
printf("fb red|green|blue length is invalid\n");
return -1;
}
// 内存映射
fb_info.fbp = (char *)mmap(0, fb_info.size, PROT_READ | PROT_WRITE, MAP_SHARED, fb_info.fbfd, 0);
if (fb_info.fbp == (char *)-1) {
printf("mmap fialed\n");
return -1;
}
show_bmp(img_name);
//删除映射
munmap(fb_info.fbp, fb_info.size);
return 0;
}
int main(int argc, char **argv)
{
char img_name[64];
if (argc != 2) {
printf("arg error\n");
return 0;
}
snprintf(img_name, sizeof(img_name), "%s", argv[1]);
printf("img_name = %s\n", img_name);
fb_info.fbfd = open("/dev/fb0", O_RDWR);
if (!fb_info.fbfd) {
printf("Error: cannot open framebuffer device(/dev/fb0).\n");
return -1;
}
show_picture(img_name);
close(fb_info.fbfd);
return 0;
}
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最后还是没有找到原因，只能是通过QT显示图片后，将/dev/fb0里面的数据抓出来，要显示的时候再cat这个数据到fb0里显示。有哪位大神知道是什么原因导致的吗？
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有想过可能是通道的问题，但是不知道怎么操作，可以给点提示吗？感谢
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非常感谢，我去试试看。
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