C / C++ / MFC

SetPixel(x    , y, (bmp_byte &   1)?foreColor:backColor);
SetPixel(x + 1, y, (bmp_byte &   2)?foreColor:backColor);
SetPixel(x + 2, y, (bmp_byte &   4)?foreColor:backColor);
SetPixel(x + 3, y, (bmp_byte &   8)?foreColor:backColor);
SetPixel(x + 4, y, (bmp_byte &  16)?foreColor:backColor);
SetPixel(x + 5, y, (bmp_byte &  32)?foreColor:backColor);
SetPixel(x + 6, y, (bmp_byte &  64)?foreColor:backColor);
SetPixel(x + 7, y, (bmp_byte & 128)?foreColor:backColor);

Member 2116736 wrote:

but how can I convert from a Byte into those 8 bits?

• use the shift and AND operators:
  

  unsigned int getbit(BYTE byte, int bit){ return ( (byte >> bit) & 0x01; ) }

  
  It may be used as follows:
  

  void main()
    BYTE byte = 205; 
    cout << (int) mb.byte << " decimal is ";
    int i=8;
    while (i--)
    {
      cout << getbit(byte, i);
    }
    cout << " binary " << endl;
  }

• use the 'union trick', i.e.
  

  struct BitField
  {
    unsigned int bit0 : 1;
    unsigned int bit1 : 1;
    unsigned int bit2 : 1;
    unsigned int bit3 : 1;
    unsigned int bit4 : 1;
    unsigned int bit5 : 1;
    unsigned int bit6 : 1;
    unsigned int bit7 : 1;
  };
  union MyByte
  {
    BYTE byte;
    BitField bf;
  };

  
  That you may use this way:
  

  bool main()
  {
    MyByte mb;
    mb.byte = 205;
    cout << (int) mb.byte << " decimal is ";
    cout <<  mb.bf.bit7 <<  mb.bf.bit6 <<  mb.bf.bit5 <<  mb.bf.bit4 << mb.bf.bit3 << mb.bf.bit2 << mb.bf.bit1 << mb.bf.bit0;
    cout << " binary " << endl;
  }

BITMAPFILEHEADER bmpHeader;
BITMAPINFO bmpInfo;
FILE *fp = fopen("C:\\test.bmp","rb");
fread((char*)&bmpHeader,sizeof(BITMAPFILEHEADER),1,fp);
fread((char*)&bmpInfo,sizeof(BITMAPINFO),1,fp);

WORD bmpWidth = (WORD)bmpInfo.bmiHeader.biWidth;
WORD bmpHeight = (WORD)bmpInfo.bmiHeader.biHeight;

int counter=0;

fseek(fp,bmpHeader.bfOffBits,SEEK_SET);

BYTE *data = new BYTE[bmpWidth*bmpHeight];
// Read the pixels
while(!feof(fp))
{
  for(int i=0; i<bmpwidth;>  {
    if(!feof(fp))
    {
      fread((BYTE*)&data[counter], sizeof(BYTE), 1, fp);
      counter++;
    }
    else
    {
      break;
    }
  }
}
fclose(fp);

int bytesPerLine = Width / 8; // eight pixels per byte
if (Width % 8) bytesPerLine++; // take into account the reminder

// pad the line to make it to a 32-bit multiple
if (bytesPerLine % 4 ) bytesPerLine += 4 - (bytesPerLine % 4);

// finally you get the size
int iSize = bytesPerLine * Height;

• If you allocate memory of a given size don't trust any other counter (you're using EOF) while filling it: check always you're not exceeding the allocated size (in your code try to read until the allocated buffer is filled and not until the end of the file: if the file contains more bytes your application crashes).
• If you need to read a block, the read it directly, don't read a byte at time.
  



If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Babu@codeproject wrote:

Wat is the difference between closing a dialog by using CDIalog::OnOK() or PostQuitMessage(0).