c - 在c中生成条形码BMP

Question

我被分配根据我随机生成的数字创建条形码图像(我已经完成了)。到目前为止，我尝试创建一个 BMP 文件并放入简单的黑白列，但我的图片被其他颜色扭曲，甚至在列中也没有。我什至没有开始编写条形码本身(这本身对我来说仍然是一个谜)，我尝试创建它几乎两周了，但没有成功。我主要需要一个将黑色或白色写入条形码的程序按列或逐行编程，这样我就可以随意放置黑色或白色。

这是我的代码:

`int width, hight;
width = 141;
hight = 70;
FILE* barcode;
fopen_s(&barcode,NEWBARCODE, "wb");

int filesize = 54 + 3 * width*height;  //w is your image width, h is image height, both int

char bmpfileheader[14] = { 'B','M', 0,0,0,0, 0,0, 0,0, 54,0,0,0 };
char bmpinfoheader[40] = { 0x28,0,0,0, 141,0,0,0, 70,0,0,0, 1,0, 24,0,0,0,0,0,0x8c,0x05,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
unsigned char white[3] = {255,255,255 };
unsigned char black[3] = {0,0,0 };
unsigned char pad[1] = { 0 };

bmpfileheader[2] = (unsigned char)(filesize);
bmpfileheader[3] = (unsigned char)(filesize >> 8);
bmpfileheader[4] = (unsigned char)(filesize >> 16);
bmpfileheader[5] = (unsigned char)(filesize >> 24);

fwrite(&bmpfileheader, 1, 14, barcode);
fwrite(&bmpinfoheader, 1, 40, barcode);

for (int i = 0; i < height; i++) { //columns
    for (int j = 0; j < width*3+1; j++) {
        if (i % 2 == 0) {
            fwrite(&white, 1, 3, barcode);
            fwrite(&black, 1, 3, barcode);
        }
        else {
            fwrite(&black, 1, 3, barcode);
            fwrite(&white, 1, 3, barcode);
        }
    }
    fwrite(&pad, 1, 1, barcode);
}

输出 bmp 文件

出了什么问题？如果有任何关于创建 bmp 文件的提示，我们将不胜感激:)

Answer 1

尝试以下操作。请注意，我已将 BMP 的位深度移至 32。包装函数 setColumn 将允许您根据需要将各个列设置为黑色或白色。将 BMP 视为一个可以自由操作的数组，而不必处理大量的 fwrite 逻辑，这样更容易管理。

#include "stdafx.h"
#include <fstream>

#define NEWBARCODE "test.bmp"
#define WHITE 255
#define BLACK 0

void setColumn(unsigned char *data, const int height, const int width, const int colIndex, const int grayVal)
{
    for (int r = 0; r < height; ++r)
    {
        data[r * width * 4 + colIndex * 4 + 0] = grayVal;
        data[r * width * 4 + colIndex * 4 + 1] = grayVal;
        data[r * width * 4 + colIndex * 4 + 2] = grayVal;
        data[r * width * 4 + colIndex * 4 + 3] = 255;
    }
}

int main()
{
    int width, height;
    width = 141;
    height = 70;

    std::ofstream filestream;

    filestream.open(NEWBARCODE, std::ios::beg | std::ios::out | std::ios::binary);

    int filesize = 54 + 4 * width * height; 

    char bmpfileheader[14] = { 'B','M', 0,0,0,0, 0,0, 0,0, 54,0,0,0 };
    char bmpinfoheader[40] = { 0x28,0,0,0, 141,0,0,0, 70,0,0,0, 1,0, 32,0,0,0,0,0,0x8c,0x05,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 };

    bmpfileheader[2] = (unsigned char)(filesize);
    bmpfileheader[3] = (unsigned char)(filesize >> 8);
    bmpfileheader[4] = (unsigned char)(filesize >> 16);
    bmpfileheader[5] = (unsigned char)(filesize >> 24);

    filestream.write(bmpfileheader, 14);
    filestream.write(bmpinfoheader, 40);

    //Allocate BMP data block
    unsigned char *data = new unsigned char[width * height * 4]{ 0 };

    //Initialize BMP data to all black pixels
    for (int i = 0; i < width * height * 4; ++i)
        data[i] = 0;

    //Set white
    for (int i = 75; i < 100; ++i)
        setColumn(data, height, width, i, WHITE);

    //Set white
    for (int i = 15; i < 25; ++i)
        setColumn(data, height, width, i, WHITE);

    //Set black
    for (int i = 20; i < 23; ++i)
        setColumn(data, height, width, i, BLACK);

    filestream.write((const char *)data, height * width * 4);
    filestream.close();

    delete data;

    return 0;
}