How to draw PieCharts under Windows98

[AlionSolutions]

Hi,
in my current project I have to draw several pie-charts using Win-API.
Under Win-NT/Windows2000 this is no problem using AngleArc.

Unfortunately the program must run under Windows98 also. The AngleArc is not supported there. I found some routines that gave me no idea how to use them.

Before I go and code this thing by myself using "old-school" sine and cosine-functions, I ask you, if you know a good source / site with some information about drawing pies on Windows98.

Thanx in advance

Juergen

[mdmd]

HOWTO: AngleArc in Windows 3.1, Win32s, and Windows 95
ID: Q125693

[AlionSolutions]

sorry, and where to look for that ?
I couldn't find it anywhere.

[mdmd]

In the MSDN

HOWTO: AngleArc in Windows 3.1, Win32s, and Windows 95
ID: Q125693



--------------------------------------------------------------------------------
The information in this article applies to:

Microsoft Windows Software Development Kit (SDK) 3.1
Microsoft Win32 Application Programming Interface (API), used with:
Microsoft Windows 95
Microsoft Win32s version 1.3
Microsoft Windows 2000

--------------------------------------------------------------------------------


SUMMARY
In Windows version 3.1, Win32s, and Windows 95, you may want to use the functionality provided by the Win32 API AngleArc(). AngleArc() is only supported on Windows NT.



MORE INFORMATION
The AngleArc() function draws a line segment and an arc. The line segment is drawn from the current position to the beginning of the arc. The arc is drawn along the perimeter of a circle with the given radius and center. The length of the arc is defined by the given start and sweep angles. The starting point of the sweep is determined by measuring counterclockwise from the x-axis of the circle by the number of degrees in the start angle. The ending point is similarly located by measuring counterclockwise from the starting point by the number of degrees in the sweep angle.

The code below provides two possible ways of getting functionality similar to that of the AngleArc() function. While both of these methods will work on any Windows platform, the second (AngleArc2) will be substantially faster due to the fact that it uses the Arc() function to draw the sweep rather than calculating each of the segments on the perimeter of the arc.

NOTE: One limitation of the second method is that if the sweep angle is greater than 360 degrees, the arc will not be swept multiple times. In most cases this will not be a problem but in certain cases (constructing paths, for example) this can be a problem.

Sample Code #1

   BOOL AngleArc1(HDC hdc, int X, int Y, DWORD dwRadius,

               float fStartDegrees, float fSweepDegrees)

   {

   float fCurrentAngle;       // Current angle in radians
   float fStepAngle = 0.03f;  // The sweep increment value in radians
   float fStartRadians;       // Start angle in radians
   float fEndRadians;         // End angle in radians
   int ix, iy;                // Current point on arc
   float fTwoPi = 2.0f * 3.141592f;

   /* Get the starting and ending angle in radians */ 
   if (fSweepDegrees > 0.0f) {
     fStartRadians = ((fStartDegrees / 360.0f) * fTwoPi);
     fEndRadians = (((fStartDegrees + fSweepDegrees) / 360.0f) *
            fTwoPi);
   } else {
     fStartRadians = (((fStartDegrees + fSweepDegrees)  / 360.0f) *
           fTwoPi);
     fEndRadians =  ((fStartDegrees / 360.0f) * fTwoPi);
   }

   /* Calculate the starting point for the sweep via */ 
   /* polar -> cartesian conversion */ 
    ix = X + (int)((float)dwRadius * (float)cos(fStartRadians));
   iy = Y - (int)((float)dwRadius * (float)sin(fStartRadians));

   /* Draw a line to the starting point */ 
   LineTo(hdc, ix, iy);

   /* Calculate and draw the sweep */ 
   for (fCurrentAngle = fStartRadians;
        fCurrentAngle <= fEndRadians;
        fCurrentAngle += fStepAngle) {

    /* Calculate the current point in the sweep via */ 
    /* polar -> cartesian conversion */ 
    ix = X + (int)((float)dwRadius * (float)cos(fCurrentAngle));
    iy = Y - (int)((float)dwRadius * (float)sin(fCurrentAngle));

    /* Draw a line segment to current point */ 
    LineTo(hdc, ix, iy);
     }

   return TRUE;

   } 
Sample Code 2

   BOOL AngleArc2(HDC hdc, int X, int Y, DWORD dwRadius,

                  float fStartDegrees, float fSweepDegrees)

   {

   int iXStart, iYStart;   // End point of starting radial line.
   int iXEnd, iYEnd;       // End point of ending radial line.
   float fStartRadians;    // Start angle in radians.
   float fEndRadians;      // End angle in radians.
   BOOL bResult;           // Function result.
   float fTwoPi = 2.0f * 3.141592f;

   /* Get the starting and ending angle in radians. */ 
   if (fSweepDegrees > 0.0f) {
     fStartRadians = ((fStartDegrees / 360.0f) * fTwoPi);
     fEndRadians = (((fStartDegrees + fSweepDegrees) / 360.0f) * fTwoPi);
   }   else {
     fStartRadians = (((fStartDegrees + fSweepDegrees)  / 360.0f) *
                        fTwoPi);
     fEndRadians =  ((fStartDegrees / 360.0f) * fTwoPi);
   }

   /* Calculate a point on the starting radial line via */ 
   /* polar -> cartesian conversion. */ 
   iXStart = X + (int)((float)dwRadius * (float)cos(fStartRadians));
   iYStart = Y - (int)((float)dwRadius * (float)sin(fStartRadians));

   /* Calculate a point on the ending radial line via */ 
   /* polar -> cartesian conversion. */ 
   iXEnd = X + (int)((float)dwRadius * (float)cos(fEndRadians));
   iYEnd = Y - (int)((float)dwRadius * (float)sin(fEndRadians));

   /* Draw a line to the starting point. */ 
   if (fSweepDegrees > 0.0f)
    LineTo(hdc, iXStart, iYStart);
   else
    LineTo(hdc, iXEnd, iYEnd);

   /* Draw the arc. */ 
   bResult = Arc(hdc, X - dwRadius, Y - dwRadius,
                      X + dwRadius, Y + dwRadius,
                      iXStart, iYStart,
                      iXEnd, iYEnd);

   /* Move to the ending point. Arc() will not do this and ArcTo() */ 
   /* will not work on Win32s or Win16. */ 
   if (fSweepDegrees < 0.0f)
    MoveToEx(hdc, iXStart, iYStart, NULL);
   else
    MoveToEx(hdc, iXEnd, iYEnd, NULL);

   return bResult;

   }

[AlionSolutions]

Hi,
since I had no time to visit CodeGuru in the last time, I forgot to check replies.. sorry for that ;o)

Therefore now a very big THANX late but never too late.

I will have a close look on what you posted and try to implement it.


again thanx

Juergen