/****************************************************************************
  Andrzej Borucki
  www.algorytm.org
  Algorytm kreslenia elips
****************************************************************************/
#include <QtGui>
#include <windows.h>
#include "window.h"

Window::Window()
    : QWidget()
{
    label = new QLabel(tr("Image"));

    QFormLayout *layout = new QFormLayout;
    btnDraw = new QPushButton("bresenham");
    editCx = new QLineEdit("100");
    editCy = new QLineEdit("100");
    editRx = new QLineEdit("100");
    editRy = new QLineEdit("100");
    layout->addRow(btnDraw);
    layout->addRow(label);
    layout->addRow("Center X",editCx);
    layout->addRow("Center Y",editCy);
    layout->addRow("RadiusX",editRx);
    layout->addRow("RadiusY",editRy);

    setLayout(layout);
    connect( btnDraw, SIGNAL(clicked()), SLOT(bresenham_clicked()) );
}

int W,H;
uchar *bits;
int bytesPerLine;

void SetPixel(int x, int y, int color)
{
    if ((x >= 0) && (y >= 0) && (x < W) && (y < H))
    {
        uchar* p = bits + y * bytesPerLine + x * 4;
        *((int*)p) = color;
    }
}

void ElipsePoints(int x, int y, int x0, int y0, int color)
{
    SetPixel(x + x0, y + y0, color);
    SetPixel(x + x0, -y + y0, color);
    SetPixel(-x + x0, -y + y0, color);
    SetPixel(-x + x0, y + y0, color);
}

void bresenham_ellipse(int x0, int y0, int radius_a, int radius_b, int color)
{
        int x, y, limit;
        long d;
        int radius_a2, radius_b2;

        if ((radius_a == 0) && (radius_b == 0))
        {
            SetPixel(x0, y0, color);
            return;
        }
        radius_a2 = radius_a * radius_a;
        radius_b2 = radius_b * radius_b;
        if (radius_b2 == 0)
            d = 0;
        else
            d = 4 * radius_b2 - 4 * radius_b * radius_a2 + radius_a2;
        limit = (int)(((double)radius_a2 * radius_a2) / (radius_a2 + radius_b2)+0.5);
        x = 0;
        y = radius_b;

        while (x * x < limit)
        {
            ElipsePoints(x, y, x0, y0, color);
            if (d > 0)
            {
                d += 8 * (long)radius_b2 * x + 12 * radius_b2 - 8 * (long)radius_a2 * y + 8 * radius_a2;
                x++;
                y--;
            }
            else
            {
                if (radius_b2 > 1)
                    d += 7 * (long)radius_b2 * x + 12 * radius_b2;
                else if ((x + 2) * (x + 2) >= limit) y --;
                x++;
            }
        }

        //second part
        int aux = radius_a;
        radius_a = radius_b;
        radius_b = aux;
        radius_a2 = radius_a * radius_a;
        radius_b2 = radius_b * radius_b;
        if (radius_b == 0)
            d = 0;
        else
            d = 4 * radius_b2 - 4 * radius_b * radius_a2 + radius_a2;
        limit = (int)(((double)radius_a2 * radius_a2) / (radius_a2 + radius_b2) + 0.5);
        x = 0;
        y = radius_b;

        while (x * x < limit)
        {
            ElipsePoints(y, x, x0, y0, color);
            if (d > 0)
            {
                d += 8 * (long)radius_b2 * x + 12 * radius_b2 - 8 * (long)radius_a2 * y + 8 * radius_a2;
                x++;
                y--;
            }
            else
            {
                if (radius_b2 > 1)
                    d += 8 * (long)radius_b2 * x + 12 * radius_b2;
                else if ((x + 2) * (x + 2) >= limit) y--;
                x++;
            }
        }
}

void Window::bresenham_clicked()
{
    QImage myImage(200,200,QImage::Format_RGB32);
    bits = myImage.bits();
    bytesPerLine = myImage.bytesPerLine();
    W = myImage.width();
    H = myImage.height();
    bresenham_ellipse(editCx->text().toInt(), editCy->text().toInt(),
                      editRx->text().toInt(), editRy->text().toInt(), 255);
    label->setPixmap(QPixmap::fromImage(myImage));    
}