A Graphical Documentation System for C/C++ projects

#include "diagramwidget.h"

DiagramWidget::DiagramWidget(QWidget *parent) :
    QWidget(parent)
{
    this->setMinimumHeight(200);
    this->setMinimumWidth(200);
    this->setAutoFillBackground(true);
    m_functionSet = false;

    // Background white
    QPalette pal = this->palette();
    pal.setColor(this->backgroundRole(), Qt::white);
    this->setPalette(pal);
}



void DiagramWidget::drawFunc(QString fun)
{
    if(fun.left(2) != "y=" || !fun.contains(QRegExp("x")))
        return;

    fun = fun.right(fun.length()-2);
    fun = fun.replace(QRegExp(" "), "");

    // find x
    myExp.steps.clear();
    for(int i=0; i<fun.length(); i++)
    {
        QChar c = fun.at(i);
        switch(c.toAscii())
        {
        case 'x':
        {
            operationOrOperand op;
            op.type = X;
            myExp.steps.append(op);
        }break;
        case '+':
        {
            operationOrOperand op;
            op.type = OPERATION;
            op.operation = ADD;
            myExp.steps.append(op);
        }break;
        case '-':
        {
            operationOrOperand op;
            op.type = OPERATION;
            op.operation = SUB;
            myExp.steps.append(op);
        }break;
        case '*':
        {
            operationOrOperand op;
            op.type = OPERATION;
            op.operation = MUL;
            myExp.steps.append(op);
        }break;
        case '/':
        {
            operationOrOperand op;
            op.type = OPERATION;
            op.operation = DIV;
            myExp.steps.append(op);
        }break;
        case '^':
        {
            operationOrOperand op;
            op.type = OPERATION;
            op.operation = POW;
            myExp.steps.append(op);
        }break;
        default:
        {
            // number
            QString number;
            number.append(fun.at(i));
            int newIndex = i+1;
            if(fun.size() > newIndex)
            {
                while(fun.at(newIndex).isDigit())
                {
                    number.append(fun.at(newIndex));
                    newIndex++;
                    i++;
                    if(fun.size() <= newIndex)
                        break;
                }
            }
            operationOrOperand op;
            op.type = OPERAND;
            op.operand = number.toFloat();
            myExp.steps.append(op);
        }break;
        }
    }
    m_functionSet = true;
    repaint();
}

qreal DiagramWidget::applyExp(int index, qreal x)
{
    // Until we find an operand
    operationOrOperand op1 = myExp.steps[index];

    switch(op1.type)
    {
    case X:
    {
        // Other operation
        if(myExp.steps.size() <= index+1)
        {
            // End reached
            return x;
            break;
        }
        operationOrOperand op2 = myExp.steps[index+1];
        switch(op2.operation)
        {
        case ADD:
        {
            // Other operand
            return x + applyExp(index+2, x);

        }break;
        case SUB:
        {
            // Other operand
            return x - applyExp(index+2, x);

        }break;
        case MUL:
        {
            // Other operand
            return x * applyExp(index+2, x);

        }break;
        case DIV:
        {
            // Other operand
            return x / applyExp(index+2, x);

        }break;
        case POW:
        {
            // Other operand
            return pow(x,applyExp(index+2, x));

        }break;
        }
    }break;
    case OPERAND:
    {
        // Other operation
        if(myExp.steps.size() <= index+1)
        {
            // End reached
            return op1.operand;
            break;
        }
        operationOrOperand op2 = myExp.steps[index+1];
        switch(op2.operation)
        {
        case ADD:
        {
            // Other operand
            return op1.operand + applyExp(index+2, x);

        }break;
        case SUB:
        {
            // Other operand
            return op1.operand - applyExp(index+2, x);

        }break;
        case MUL:
        {
            // Other operand
            return op1.operand * applyExp(index+2, x);

        }break;
        case DIV:
        {
            // Other operand
            return op1.operand / applyExp(index+2, x);

        }break;
        case POW:
        {
            // Other operand
            return pow(op1.operand,applyExp(index+2, x));
        }break;
        }
    }break;
    default:
    {
        return 0; // Error
    }break;
    }
}

qreal DiagramWidget::XtoPlanCoords(qreal xcoord)
{
    return xcoord - (this->width() / 2);
}

qreal DiagramWidget::YtoScreenCoords(qreal ycoord)
{
    return this->height() - (ycoord + (this->height() / 2));
}

void DiagramWidget::paintEvent(QPaintEvent *)
{
    QPainter painter(this);

    painter.setRenderHint(QPainter::Antialiasing);

    // Border
    painter.setPen(Qt::black);
    painter.drawRect(0,0,this->width(),this->height());

    // Axis
    painter.drawLine(QPointF(this->width()/2, 10), QPointF(this->width()/2, this->height()-10));
    painter.drawLine(QPointF(10, this->height()/2), QPointF(this->width()-10, this->height()/2));

    if(m_functionSet)
    {
        painter.setPen(Qt::red);
        for(int x=0; x<this->width(); x++)
        {
            int xPlan = XtoPlanCoords(x);

            int yPlan = applyExp(0, xPlan);; // Y = X

            int yScreen = YtoScreenCoords(yPlan);

            painter.drawPoint(x, yScreen);
        }
    }
}

DiagramWidget* createWidget()
{
    DiagramWidget *wid = new DiagramWidget();
    return wid;
}