Linux C語言解析並顯示.bmp格式圖片


 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 //文件頭結構體
21 typedef struct 
22 { 23   unsigned char    bfType[2];    //文件類型
24   unsigned long bfSize;     //位圖大小
25   unsigned short bfReserved1;  //位0 
26   unsigned short bfReserved2;  //位0
27   unsigned long bfOffBits;    //到數據偏移量
28 } __attribute__((packed)) BitMapFileHeader;   //使編譯器不優化,其大小為14字節 29 
30 //信息頭結構體
31 typedef struct 
32 { 33   unsigned long biSize;          // BitMapFileHeader 字節數
34   long biWidth;                 //位圖寬度 
35   long biHeight;              //位圖高度,正位正向,反之為倒圖 
36   unsigned short biPlanes;        //為目標設備說明位面數,其值將總是被設為1
37   unsigned short biBitCount;        //說明比特數/象素,為1、4、8、16、24、或32。 
38   unsigned long biCompression;       //圖象數據壓縮的類型沒有壓縮的類型:BI_RGB 
39   unsigned long biSizeImage;      //說明圖象的大小,以字節為單位 
40   long biXPelsPerMeter;           //說明水平分辨率 
41   long biYPelsPerMeter;        //說明垂直分辨率 
42   unsigned long biClrUsed;       //說明位圖實際使用的彩色表中的顏色索引數
43   unsigned long biClrImportant;    //對圖象顯示有重要影響的索引數,0都重要。 
44 } __attribute__((packed)) BitMapInfoHeader; 45 
46 //像素點結構體
47 typedef struct 
48 { 49   unsigned char Blue;      //該顏色的藍色分量 
50   unsigned char Green;     //該顏色的綠色分量 
51   unsigned char Red;          //該顏色的紅色分量 
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,映射內存起始地址 14 
15 *scrinfo,屏幕信息結構體 16 
17 *bmpname,.bmp位圖文件名 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;    //屏幕寬(虛擬)
28   int bits_per_pixel = scrinfo->bits_per_pixel;  //屏幕位數
29   BitMapFileHeader FileHead; 30   BitMapInfoHeader InfoHead; 31   RgbQuad rgb;     32 
33   unsigned long location = 0; 34 
35   //打開.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   //讀文件信息
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   //讀位圖信息
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   //跳轉至數據區
66   fseek(fb, FileHead.bfOffBits, SEEK_SET); 67   
68   int len = InfoHead.biBitCount / 8;    //原圖一個像素占幾字節
69   int bits_len = bits_per_pixel / 8;    //屏幕一個像素占幾字節  //循環顯示
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     //計算該像素在映射內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   //打開設備文件
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   //獲取屏幕信息 29 
30   //若屏幕顯示區域大小不合適,可用ioctl(devfb, FBIOPUT_VSCREENINFO, &scrinfo)設置
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   //計算需要的映射內存大小
50   screensize = scrinfo.xres_virtual * scrinfo.yres_virtual * scrinfo.bits_per_pixel / 8; 51   //printf("screensize=%lu!\r\n", screensize); 52   
53   //內存映射
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   //顯示圖片
64   show_photo(fbp, &scrinfo, bmpname); 65 
66  
67 
68   //取消映射,關閉文件
69   munmap(fbp, screensize); 70   close(devfb); 71 
72   return 0; 73 }

 

 

 

/******************************************

*效果圖(我不是給這游戲打廣告,只是隨手拿了一張圖而已)

*說明:1.圖片是24位或32位bmp圖

     2.屏幕是32位屏幕

     3.不同的設備,可能設備文件不同

     4.需要在root用戶下執行

*******************************************/

 


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