Linux C语言解析并显示.bmp格式图片
1 /*************************
2
3 *bmp.h文件
4
5 *************************/
6
7 #ifndef __BMP_H__
8 #define __BMP_H__
9
10 #include <unistd.h>
11 #include <stdio.h>
12 #include <stdlib.h>
13 #include <fcntl.h>
14 #include <string.h>
15 #include <linux/fb.h>
16 #include <sys/mman.h>
17 #include <sys/ioctl.h>
18 #include <arpa/inet.h>
19
20 //文件头结构体
21 typedef struct
22 {
23 unsigned char bfType[2]; //文件类型
24 unsigned long bfSize; //位图大小
25 unsigned short bfReserved1; //位0
26 unsigned short bfReserved2; //位0
27 unsigned long bfOffBits; //到数据偏移量
28 } __attribute__((packed)) BitMapFileHeader; //使编译器不优化，其大小为14字节
29
30 //信息头结构体
31 typedef struct
32 {
33 unsigned long biSize; // BitMapFileHeader 字节数
34 long biWidth; //位图宽度
35 long biHeight; //位图高度，正位正向，反之为倒图
36 unsigned short biPlanes; //为目标设备说明位面数，其值将总是被设为1
37 unsigned short biBitCount; //说明比特数/象素，为1、4、8、16、24、或32。
38 unsigned long biCompression; //图象数据压缩的类型没有压缩的类型：BI_RGB
39 unsigned long biSizeImage; //说明图象的大小，以字节为单位
40 long biXPelsPerMeter; //说明水平分辨率
41 long biYPelsPerMeter; //说明垂直分辨率
42 unsigned long biClrUsed; //说明位图实际使用的彩色表中的颜色索引数
43 unsigned long biClrImportant; //对图象显示有重要影响的索引数，0都重要。
44 } __attribute__((packed)) BitMapInfoHeader;
45
46 //像素点结构体
47 typedef struct
48 {
49 unsigned char Blue; //该颜色的蓝色分量
50 unsigned char Green; //该颜色的绿色分量
51 unsigned char Red; //该颜色的红色分量
52 unsigned char Reserved; //保留值（亮度）
53 } __attribute__((packed)) RgbQuad;
54
55
56
57 int show_photo(const char *fbp, struct fb_var_screeninfo *scrinfo, const char *bmpname);
58
59
60 #endif //__BMP_H__
1 /*************************
2
3 *bmp.c文件
4
5 *************************/
6
7 #include "bmp.h"
8
9
10
11 /*************************
12
13 *fbp，映射内存起始地址
14
15 *scrinfo，屏幕信息结构体
16
17 *bmpname，.bmp位图文件名
18
19 *************************/
20 int show_photo(const char *fbp, struct fb_var_screeninfo *scrinfo, const char *bmpname)
21 {
22 if(NULL == fbp || NULL == scrinfo || NULL == bmpname)
23 return -1;
24
25 int line_x = 0, line_y = 0;
26 unsigned long tmp = 0;
27 int xres = scrinfo->xres_virtual; //屏幕宽（虚拟）
28 int bits_per_pixel = scrinfo->bits_per_pixel; //屏幕位数
29 BitMapFileHeader FileHead;
30 BitMapInfoHeader InfoHead;
31 RgbQuad rgb;
32
33 unsigned long location = 0;
34
35 //打开.bmp文件
36 FILE *fb = fopen(bmpname, "rb");
37 if (fb == NULL)
38 {
39 printf("fopen bmp error\r\n");
40 return -1;
41 }
42
43 //读文件信息
44 if (1 != fread( &FileHead, sizeof(BitMapFileHeader),1, fb))
45 {
46 printf("read BitMapFileHeader error!\n");
47 fclose(fb);
48 return -1;
49 }
50 if (memcmp(FileHead.bfType, "BM", 2) != 0)
51 {
52 printf("it's not a BMP file\n");
53 fclose(fb);
54 return -1;
55 }
56
57 //读位图信息
58 if (1 != fread( (char *)&InfoHead, sizeof(BitMapInfoHeader),1, fb))
59 {
60 printf("read BitMapInfoHeader error!\n");
61 fclose(fb);
62 return -1;
63 }
64
65 //跳转至数据区
66 fseek(fb, FileHead.bfOffBits, SEEK_SET);
67
68 int len = InfoHead.biBitCount / 8; //原图一个像素占几字节
69 int bits_len = bits_per_pixel / 8; //屏幕一个像素占几字节 //循环显示
70
71 while(!feof(fb))
72 {
73 tmp = 0;
74 rgb.Reserved = 0xFF;
75
76 if (len != fread((char *)&rgb, 1, len, fb))
77 break;
78
79 //计算该像素在映射内存起始地址的偏移量
80 location = line_x * bits_len + (InfoHead.biHeight - line_y - 1) * xres * bits_len;
81
82 tmp |= rgb.Reserved << 24 | rgb.Red << 16 | rgb.Green << 8 | rgb.Blue;
83
84 *((unsigned long *)(fbp + location)) = tmp;
85
86 line_x++;
87 if (line_x == InfoHead.biWidth )
88 {
89 line_x = 0;
90 line_y++;
91 if(line_y == InfoHead.biHeight)
92 break;
93 }
94 }
95
96 fclose(fb);
97
98 return 0;
99 }
1 /*************************
2
3 *main.c文件
4
5 *************************/
6
7 #include "bmp.h"
8
9 int main()
10 {
11 int devfb, filefb;
12 struct fb_var_screeninfo scrinfo;
13 unsigned long screensize;
14 char *fbp ;
15 char bmpname[20] = {0};
16
17 //打开设备文件
18 devfb = open("/dev/fb0", O_RDWR);
19 if(!devfb)
20 {
21 printf("devfb open error!\r\n");
22 return -1;
23 }
24 //printf("devfb open OK! %d\r\n", devfb);
25
26
27
28 //获取屏幕信息
29
30 //若屏幕显示区域大小不合适，可用ioctl(devfb, FBIOPUT_VSCREENINFO, &scrinfo)设置
31 if(ioctl(devfb, FBIOGET_VSCREENINFO, &scrinfo))
32 {
33 printf("get screen infomation error!\r\n");
34 return -1;
35 }
36
37 //printf(".xres=%d, .yres=%d, .bit=%d\r\n",scrinfo.xres, scrinfo.yres, scrinfo.bits_per_pixel);
38
39 //printf(".xres_virtual=%d, .yres_virtual=%d\r\n",scrinfo.xres_virtual, scrinfo.yres_virtual);
40
41 if(32 != scrinfo.bits_per_pixel)
42 {
43 printf("screen infomation.bits error!\r\n");
44 return -1;
45 }
46
47
48
49 //计算需要的映射内存大小
50 screensize = scrinfo.xres_virtual * scrinfo.yres_virtual * scrinfo.bits_per_pixel / 8;
51 //printf("screensize=%lu!\r\n", screensize);
52
53 //内存映射
54 fbp = (char *)mmap(NULL, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, devfb, 0);
55 if(-1 == (int)fbp)
56 {
57 printf("mmap error!\r\n");
58 return -1;
59 }
60
61 scanf("%s", bmpname);
62
63 //显示图片
64 show_photo(fbp, &scrinfo, bmpname);
65
66
67
68 //取消映射，关闭文件
69 munmap(fbp, screensize);
70 close(devfb);
71
72 return 0;
73 }
/******************************************
*效果图（我不是给这游戏打广告，只是随手拿了一张图而已）
*说明：1.图片是24位或32位bmp图
2.屏幕是32位屏幕
3.不同的设备，可能设备文件不同
4.需要在root用户下执行
*******************************************/
