Question

我试图弄清楚如何在通过c ++生成的硬编码位图文件中绘制直线垂直线：

#include <fstream>
using std::ifstream;
using std::ofstream;
#include <iostream>
using std::cout;
using std::endl;



int main ()
{
   ifstream infile ("white8x8.bmp");
   ofstream outfile ("output.bmp");
   char c;
   cout << "Start of original read/write: " << endl;
   for (int i = 0; i <= 53; i++)
   {
      infile.read (&c, 1);
      cout << (int) c << ' ' << c;
      outfile.write (&c, 1);
   }
   char z = 0;
   char x = 0;
   int j_prev = 0;
   for (int i = 0; i <= 250; i++){
      for (int j = 0; j <= 250; j++)
      {

         if(j == 10){
           c = 0;
           z = 0;
           x = 0;
           outfile.write (&c, 1);
           outfile.write (&x, 1);
           outfile.write (&z, 1);
           j_prev = j;
         }
         /*if(j %250 == 0){
           c = 0;
           z = 0;
           x = 0;
           outfile.write (&c, 1);
           outfile.write (&x, 1);
           outfile.write (&z, 1);
         }*/
         else{
           c = 255;
           x = 255;
           z = 255;
           outfile.write (&c, 1);
           outfile.write (&x, 1);
           outfile.write (&z, 1);
         }
      }
   }

   cout << endl << "Start of read new file: " << endl;
   infile.close();
   outfile.close();
   ifstream out2 ("output.bmp");
   out2.seekg(53);
   int count = 0;
   for(int i = 53; i < 15000; i++){

     out2.read(&c, 1);
     cout << count << ":" << (int) c << ' ' << c;
     count++;
   }
   out2.close();
   return 0;
}

我认为您可以将像素阵列视为二维数组，并且获得水平线只需要在每次j点击特定数字时绘制像素。这似乎并非如此，因为这样做会给我一个如下所示的偏斜线。

output.jpg

为了澄清我只是从已经创建的位图复制位图标题信息，然后简单地创建一个伴随的像素数组并从那里修改它。

Answer 1

每行需要将BMP文件填充为4个字节的倍数。你的行是250 * 3 = 750，不是是4的倍数;在每行的开头吞下2个字节进行填充，使其偏移。只需在j循环结束时再写2个字节的零。

c ++中的硬编码位图会产生倾斜的线

1 个答案: