View source for C: Trapping two mouse buttons at the same time

Detecting multiple mouse actions isn’t quite as easy as it would appear. The natural thing would be to do this:
 
  if((mouse_flags & MOUSE_LEFTSINGLE)&&(mouse_flags & MOUSE_RIGHTSINGLE))
 
but the value of mouse_flags is a reflection of action, not state. One answer is to use variables to detect the mouse button actions.

  // Add these to a global variable file
  bool bBtnLeft=false;
  bool bBtnRight=false;
  bool bBtnMid=false;
  int iBtnStatus=0;

 // Inside the mouse callback
 BOOL FSAPI myMouse_mcb( PPIXPOINT relative_point, FLAGS32 mouse_flags )
 {
   static int initbtn = 0; // Used to detect which button is pressed first
  
   if (mouse_flags & MOUSE_LEFTSINGLE)
   {
     bBtnLeft = true;
     if (!initbtn)initbtn = 1;	// First button pressed - left
   }
   else if (mouse_flags & MOUSE_LEFTRELEASE)bBtnLeft = false;
  
   if (mouse_flags & MOUSE_RIGHTSINGLE)
   {
     bBtnRight = true;
     if (!initbtn)initbtn = 2;	// First button pressed - right
   }
   else if (mouse_flags & MOUSE_RIGHTRELEASE)bBtnRight = false;
  
   // Button down status
   if (bBtnLeft == false && bBtnRight == false)iBtnStatus = 0, initbtn = 0;  // Neither
   if (bBtnLeft == true && bBtnRight == false)iBtnStatus = 1;                // Left
   if (bBtnLeft == false && bBtnRight == true)iBtnStatus = 2;                // Right
   if (bBtnLeft == true && bBtnRight == true)iBtnStatus = 3;                 // Both
  
   // Action code here
   // Mouse buttons released
   if(!iBtnStatus)
   {
   }
   else
   // Left mouse button only
   if(iBtnStatus==1)
   {
   }
   else
   // Right mouse button only
   if(iBtnStatus==2)
   {
   }
   else
   // Both mouse buttons pressed
   if (iBtnStatus==3)
   {
     if(initbtn==1)	// Left mouse button was pressed first
     {
     }
     if(initbtn==2)	// Right mouse button was pressed first
     {
     }		
   }
 }

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