/*
parabola2.cpp

Draws a parabola with horizontal axis (pg 52)
made up of line segments
*/

#include <stdio.h>
#include <windows.h>

#include "resource.h"

// your path for this include may vary
#include "GraphicsFramework.h"

// Global variable to store the graphics framwork object
GraphicsFramework* PGraphics;

HWND HOutput = 0;  // handle to the output control
HWND HDialog = 0;

// function to get the absolute value of an integer
int Abs(int x) {
    if (x < 0)  return -x;
    else        return x;
}

// function to get the sign (+1 or -1) of an integer
int Sign(int x) {
    if (x < 0)  return -1;
    else        return 1;
}

void drawLine(int xPrev, int yPrev, int x, int y)
{
    int x1 = xPrev;
    int y1 = yPrev;
    int x2 = x;
    int y2 = y;
    int dy = y2 - y1;
    int dx = x2 - x1;
    COLORREF purple = RGB(255, 0, 255);

    

    if (Abs(dy) > Abs(dx)) {
        // since there is a greater change in y than x we must
        // loop in y, calculate x and draw
        for (y=y1; y != y2; y += Sign(dy)) {
            x = x1 + (y - y1) * dx / dy;
            PGraphics->AddPoint(x, y, purple);
        }
    }else {
        // since there is a greater (or equal) change in x than y we must
        // loop in x, calculate y and draw
        for (x=x1; x != x2; x += Sign(dx)) {
            y = y1 + (x - x1) * dy / dx;
            PGraphics->AddPoint(x, y, purple);
    
        }
    }

    // draw the last pixel
    PGraphics->AddPoint(x2, y2, purple);

    // draw the points
    PGraphics->Draw();
}

void DrawStuff() {
    COLORREF green = RGB(0, 255, 0);     // green color to draw with
    COLORREF purple = RGB(255, 0, 255);  // purple color to draw with

    char str[32];                       // string to store user input
    int h, k;                           // parabola vertex
    double a;                           // parabola constant - might be a decimal
    int x, y;                           // loop and point variables
    int xPrev, yPrev;                   // previous point for drawng line segments
    int ymin, ymax;                     // limits for y loop
    RECT rect;                          // rectangle for the output window

    // get the user input from the edit boxes and
    // convert string input to integer
    GetDlgItemText(HDialog, IDC_EDIT_VERTEXX, str, 32);
    h = atoi(str);
    GetDlgItemText(HDialog, IDC_EDIT_VERTEXY, str, 32);
    k = atoi(str);
    GetDlgItemText(HDialog, IDC_EDIT_CONSTA, str, 32);
    a = atof(str);                              // use atof to allow user to enter a decimal

    // get the rect for this window
    GetClientRect(HOutput, &rect);

    // use the rectangle info to set up y loop limits
    ymin = -(rect.bottom - rect.top) / 2;
    ymax =  (rect.bottom - rect.top) / 2;

    // clear the scene and add an axis
    PGraphics->ClearScene(RGB(0, 0, 0));
    PGraphics->AddAxis(RGB(150, 150, 150), 10);

    // loop in y, calculate x and draw
    yPrev = ymin;
    xPrev = (int) (a * (yPrev-k)*(yPrev-k))+h;
    for (y = ymin; y <= ymax; y++) {
        x = (int)( a * (y-k) * (y-k) ) + h;
        PGraphics->AddPoint(x, y, green);
        drawLine(xPrev, yPrev, x, y);
        
    }

    // draw the points
    PGraphics->Draw();
}

/*
DialogProc
this is the window event handler for the main dialog
*/
BOOL CALLBACK DialogProc (HWND hwnd,
    UINT message,
    WPARAM wParam,
    LPARAM lParam)
{
    switch(message)
    {
    case WM_INITDIALOG:
        // dialog is initializing - store the picture box handle in a global variable for later
        HOutput = GetDlgItem(hwnd, IDC_PICTURE_OUTPUT);        

        // instantiate and initialize our graphics framework object
        PGraphics = new GraphicsFramework(HOutput);

        break;

    case WM_COMMAND:
        switch(LOWORD(wParam))
        {
            case IDC_BTN_DRAW:
                // draw button was pressed
                DrawStuff();
                break;
            case IDC_BTN_CLEAR:
                // clear button was pressed so clear the scene and draw the empty scene
                PGraphics->ClearScene(RGB(0, 0, 0));
                PGraphics->Draw();
                break;
            case IDCANCEL:
                // user is quitting so release the GraphicsFramework object and quit
                delete PGraphics;
                PostQuitMessage(0);
                break;
        }
                  
    }
    return FALSE;
}

// this is the main function that starts the application
int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst, char * cmdParam, int cmdShow)
{
    // create the main window
    // store its handle in a global if needed
    HDialog = CreateDialog (GetModuleHandle(NULL),
        MAKEINTRESOURCE(IDD_DIALOG1),
        0,
        DialogProc);

    // make the dialog visible
    ShowWindow(HDialog, SW_SHOW);

    // standard windows message loop
    MSG  msg;
    int status;
    while ((status = GetMessage (&msg, 0, 0, 0)) != 0)
    {
        if (status == -1)
            return -1;
        // avoid processing messages for the dialog
        if (!IsDialogMessage (HDialog, & msg))
        {
            TranslateMessage ( & msg );
            DispatchMessage ( & msg );
        }
    }

    return (int)(msg.wParam);
}