TurtleWorkArea.cpp

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// ======================================================================
//  TurtleWorkArea.cpp
// ======================================================================
//                   This file is a part of the book 
//             "Qt 5.10 Professional programming with C++"
//                       http://qt-book.com
// ======================================================================
//  Copyright (c) 2017 by Max Schlee
// ======================================================================

#include <QtWidgets>
#include <QJSEngine>
#include "TurtleWorkArea.h"
#include "Turtle.h"

// ----------------------------------------------------------------------
TurtleWorkArea::TurtleWorkArea(QWidget* pwgt/*=0*/) : QWidget(pwgt)
{
    m_pTurtle = new Turtle;
    m_pTurtle->setFixedSize(400, 400);
    m_ptxt = new QTextEdit;

    QComboBox*  pcbo = new QComboBox;
    QStringList lst;

    lst << "Haus vom Nikolaus" << "Curly" << "Circle" << "Fantasy";
    pcbo->addItems(lst);
    connect(pcbo, SIGNAL(activated(int)), SLOT(slotApplyCode(int)));
    slotApplyCode(0);

    QJSValue scriptTurtle =
        m_scriptEngine.newQObject(m_pTurtle);
    m_scriptEngine.globalObject().setProperty("turtle", scriptTurtle);
        
    QPushButton* pcmd = new QPushButton("&Evaluate");
    connect(pcmd, SIGNAL(clicked()), SLOT(slotEvaluate()));

    QGridLayout* pgrdLayout = new QGridLayout;

    pgrdLayout->addWidget(pcbo, 0, 0);
    pgrdLayout->addWidget(m_ptxt, 1, 0);
    pgrdLayout->addWidget(m_pTurtle, 0, 1, 2, 1);
    pgrdLayout->addWidget(pcmd, 2, 0, 1, 2);
    setLayout(pgrdLayout);
}

// ----------------------------------------------------------------------
void TurtleWorkArea::slotEvaluate()
{
    QJSValue result = 
        m_scriptEngine.evaluate(m_ptxt->toPlainText());
    if (result.isError()) {
        QMessageBox::critical(0, 
                              "Evaluating error", 
                              result.toString(), 
                              QMessageBox::Yes
                             );
    }
}

// ----------------------------------------------------------------------
void TurtleWorkArea::slotApplyCode(int n)
{
    QString strCode;
    switch (n) {
    case 0:
        strCode = "var k = 100;\n"
                  "turtle.reset();\n"
                  "turtle.right(90);\n"
                  "turtle.back(-k);\n"    
                  "turtle.left(90);\n"
                  "turtle.forward(k);\n"
                  "turtle.left(30);\n"
                  "turtle.forward(k);\n"    
                  "turtle.left(120);\n"    
                  "turtle.forward(k);\n"    
                  "turtle.left(30);\n"    
                  "turtle.forward(k);\n"    
                  "turtle.left(135);\n"    
                  "turtle.forward(Math.sqrt(2)*k);\n"    
                  "turtle.left(135);\n"    
                  "turtle.forward(k);\n"    
                  "turtle.left(135);\n"    
                  "turtle.forward(Math.sqrt(2)*k);\n";
        break;
    case 1:
        strCode = "turtle.reset();\n"
                  "for (i = 0; i < 2; ++i) {\n"
                  "   for(j = 0; j < 100; ++j) {\n"
                  "       turtle.forward(15);\n"
                  "       turtle.left(100 - j);\n"
                  "   }\n"
                  "   turtle.right(180);\n"
                  "}";
        break;
    case 2:
        strCode = "turtle.circle = function()\n"
                  "{\n"
                  "    for (var i = 0; i < 360; ++i) {\n"
                  "        this.forward(1);\n"
                  "        this.left(1);\n"
                  "    }\n"
                  "}\n"
                  "turtle.reset();\n"
                  "turtle.circle();\n";
        break;
     default:
        strCode = "turtle.reset();\n"
                  "for (i = 0; i < 200; ++i) {\n"
                  "    turtle.forward(i * 2);\n"
                  "    turtle.left(91);\n"
                  "}";
    }
    m_ptxt->setPlainText(strCode);
}