pie chart with Pie?

[bob323]

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...

[CornedBee]

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

[CornedBee]

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.

[bob323]

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:

    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?

[CornedBee]

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.

[bob323]

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?

#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)

[CornedBee]

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:

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

Then redraw the chart.