pie chart with Pie?

strange question...
I want to create a piechart of 42 equal, individual sections, I need to use 42 calls to pie() rather than a pie chart control for some very strange reasons! The pie chart should take up the whole windowIf anyone has any ideas how to do this in a nice loop I would love to hear it, I have been mulling over my geometry book for the last while...

There is a Pie function in API. I'll try to write something to demonstrate it's uses.

Finished. I attached the cpp file. Basically it's C code but with some C++ syntax, so it won't compile on a C compiler.
This is of course only a rude example. You should add color (maybe an array of COLORREF values that go along with the pies) and description.

cool this makes sense... but one small problem I want to create * degree sections that means 360/8= 45 pieces, but when I put in:

Code:

---

    case WM_PAINT:
        hdc = BeginPaint(hwnd, &ps);
        {
        // an array of percentages
        float ar[45];

        for(i=0;i<=45;i++)
                ar[i]= 8f;

---

I get like 21 sections, any idea how to fix that one?

Syntactical error!!!
for(i=0;i<=45;i+)
is wrong! The highest allowed index is always the size of the array - 1 (in your case 44). You must use <45, not <=45.

And as I said, the array contains percentual values! If you want 45 pieces, you must use 100/45 (= 2.222222f) as values for the array members.

humm I get what you did and made it a little more object oriented, (just so I could be sure I understood it :)) I made the individual sections objects.
One last question, how do I shrink or expand individual sections of the pie, I want to randomly make them longer or shorter? I know this is a bit of a strange idea, I have made a few tries at it but I'm not getting it all it does for me is change the width.
Any ideas how to change the length of sections?

Code:

---

#define STRICT
#include <windows.h>
#include <math.h>
#include <time.h>


#define CSECTSIZE 2.22222222f
#define NUMOFSEC 45
class CSect {

private:
        int vect1x;
        int vect1y;
        int vect2x;       
        int vect2y;

        int recttx;
        int rectty;
        int rectbx;
        int rectby;

        HBRUSH hbrush;

public:
        SetRect(int,int,int,int);
        SetVect(int,int,int,int);
        DecVect();
        IncVect();
        SetBrush(COLORREF);
        DrawSect(HDC*);
};

CSect::SetBrush(COLORREF Color){
        LOGBRUSH logbrush;
       
        logbrush.lbStyle = BS_SOLID;
        logbrush.lbColor = Color;

        hbrush = CreateBrushIndirect(&logbrush);
}

CSect::SetVect(int x1,int y1, int x2,int y2){
        vect1x = x1;
        vect1y = y1;
        vect2x = x2;       
        vect2y = y2;
}

CSect::SetRect(int tx,int ty, int bx, int by){
        recttx = tx;
        rectty = ty;
        rectbx = bx;
        rectby = by;
}

CSect::IncVect(){
        vect1y+=5;
        vect2y+=5;
}

CSect::DecVect(){
        vect1y-=5;
        vect2y-=5;
}

CSect::DrawSect(HDC *hdc){
        SelectObject(*hdc, hbrush);
        Pie(*hdc,recttx, rectty, rectbx, rectby,
                vect2x, vect2y, vect1x, vect1y);
}

typedef struct tagFPOINT{
        float x, y;
} FPOINT, *PFPOINT;


template<class T>
inline T tmin(T a, T b){
        return (a < b) ? a : b;
}

template<>
inline char* tmin(char* a, char* b){
        return (lstrcmp(a, b) > 0) ? b : a;
}

const float PI = 3.1415926535f;

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
void SectInitVects(float arfPiePercents, RECT rcArea, CSect sections[]);
void SetSection(CSect sections[], float *lastAngle,FPOINT ptMid,float radius,int i);

LPCSTR szClassName = "Mod- 5";


int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE, LPSTR szCmdLine, int iShowCmd){
        MSG msg;
        HWND hWnd;
        WNDCLASS wc;
       
        memset(&wc, 0, sizeof(WNDCLASS));
        wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
        wc.hCursor = LoadCursor(NULL, IDC_ARROW);
        wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
        wc.hInstance = hInstance;
        wc.lpfnWndProc = WndProc;
        wc.lpszClassName = szClassName;
        wc.lpszMenuName = NULL;
        wc.style = CS_HREDRAW | CS_VREDRAW;

        RegisterClass(&wc);

        hWnd = CreateWindow(szClassName, szClassName, WS_CLIPCHILDREN | WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 200, 200, NULL, NULL, hInstance, NULL);

        ShowWindow(hWnd, iShowCmd);
        UpdateWindow(hWnd);

        while(GetMessage(&msg, NULL, 0, 0) > 0){
                TranslateMessage(&msg);
                DispatchMessage(&msg);
        }
        return (msg.wParam);
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam){
        PAINTSTRUCT ps;
        HDC hdc;
        int i;
        static RECT rc;
        static CSect sections [NUMOFSEC];
        static BOOLEAN sized;
        static COLORREF Color;

        switch(message){

        case WM_CREATE:
                GetClientRect(hwnd, &rc);

                // an array of percentages
                for(i=0;i<NUMOFSEC;i++){
                        sections[i].SetRect(rc.left, rc.top, rc.right, rc.bottom);

                        Color= RGB(rand() % 255,rand() % 255,rand() % 255);
                        sections[i].SetBrush(Color);
                }
               
                SectInitVects(CSECTSIZE, rc, sections);
               
                SetTimer(hwnd,1,1000,NULL);
                return (0);

        case WM_TIMER:
                srand(time(NULL));
                sections[(rand()% NUMOFSEC)].IncVect();
                sections[(rand()% NUMOFSEC)].DecVect();
                InvalidateRect(hwnd,NULL,TRUE);
                return(0);

        case WM_PAINT:
                hdc = BeginPaint(hwnd, &ps);
                {
                        for(i=0;i<NUMOFSEC;i++)
                                sections[i].DrawSect(&hdc);
                }
                EndPaint(hwnd, &ps);
                return (0);

        case WM_DESTROY:
                PostQuitMessage(0);
                return (0);
        }

        return (DefWindowProc(hwnd, message, wParam, lParam));
}

// disable the "double to float conversion" warning
#pragma warning(push)
#pragma warning(disable: 4244)

void SectInitVects(float arfPiePercents, RECT rcArea, CSect sections[]){
        float radius;
        float lastAngle =0.0f;// the two angles that make up the pie
        SIZE sizeArea;
        FPOINT ptMid;
        int i;

        // calculate the size of the rectangle
        sizeArea.cx = rcArea.right - rcArea.left;
        sizeArea.cy = rcArea.bottom - rcArea.top;

        // calculate the center of the area
        ptMid.x = rcArea.left + sizeArea.cx / 2;
        ptMid.y = rcArea.top + sizeArea.cy / 2;

        // radius of ellpise
        radius = (float)(rcArea.right - rcArea.left) / 2;

        /*Draw the pie sections*/
        for(i = 0; i < NUMOFSEC; i++)
                SetSection(sections,&lastAngle,ptMid,radius,i);
}

void SetSection(CSect sections[], float *lastAngle,FPOINT ptMid,float radius,int i){
        static float nextAngle;
        static FPOINT fptStart, fptEnd;// start point and end point of pie, actually the

                        // calculate next radian
                // it is old radian + radians that next pie needs
                // those are full circle * (percentage/100)
                nextAngle = *lastAngle + ((2 * PI) * (CSECTSIZE / 100.0f));
               
                // calculate x and y of start point
                fptStart.x        = ptMid.x + (cos(*lastAngle) * radius);
                fptStart.y        = ptMid.y + (sin(*lastAngle) * radius);
               
                // and of end point
                fptEnd.x        = ptMid.x + (cos(nextAngle) * radius);
                fptEnd.y        = ptMid.y + (sin(nextAngle) * radius);
               
                sections[i].SetVect((int)fptStart.x, (int)fptStart.y,
                        (int)fptEnd.x, (int)fptEnd.y);
               
                // now set new angles
                *lastAngle = nextAngle;
}

#pragma warning(pop)

---

You mean that they sort of "come out" of the chart? Like a pie piece that is taken away from the whole thing? You'd need to make the bounding rectangle bigger for this special pie. For example:

Code:

---

// add this function to your CSect class:
void CSect::MoveOut()
{
  recttx -= 10;
  rectty -= 10;
  rectbx += 10;
  rectby += 10;
}

---

Then redraw the chart.