error nodesEditor' was not declared in this scope?

[stackprogramer]

i defined a class name nodesEditor,i added heaer file qnodeseditor.h to mainwindow:(the header file and source.cpp in /path source)
this my main windows source:

/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the examples of the Qt Toolkit.
**
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**
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** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
**     of its contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
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** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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#include "arrow.h"
#include "diagramitem.h"
#include "diagramscene.h"
#include "diagramtextitem.h"
#include "mainwindow.h"

#include <QtWidgets>
///////////////
#include <qmessagebox.h>
#include <QInputDialog>

////////////////////////
#include "qnemainwindow.h"
#include "ui_qnemainwindow.h"

#include "qneblock.h"
#include "qnodeseditor.h"

#include <QGraphicsScene>
#include <QFileDialog>

#include "qneport.h"


/////////////////////

const int InsertTextButton = 10;

//! [0]
MainWindow::MainWindow()
{/*QMessageBox msgBox;
    msgBox.setText("The document has been modified.");
    msgBox.exec();*/

    /////////////////////////////////////
  nodesEditor= new QNodesEditor(this);

    QAction *quitAct = new QAction(tr("&Quit"), this);
    quitAct->setShortcuts(QKeySequence::Quit);
    quitAct->setStatusTip(tr("Quit the application"));
    connect(quitAct, SIGNAL(triggered()), qApp, SLOT(quit()));

    QAction *loadAct = new QAction(tr("&Load"), this);
    loadAct->setShortcuts(QKeySequence::Open);
    loadAct->setStatusTip(tr("Open a file"));
    connect(loadAct, SIGNAL(triggered()), this, SLOT(loadFile()));

    QAction *saveAct = new QAction(tr("&Save"), this);
    saveAct->setShortcuts(QKeySequence::Save);
    saveAct->setStatusTip(tr("Save a file"));
    connect(saveAct, SIGNAL(triggered()), this, SLOT(saveFile()));

    QAction *addAct = new QAction(tr("&Add"), this);
    addAct->setStatusTip(tr("Add a block"));
    connect(addAct, SIGNAL(triggered()), this, SLOT(addBlock()));

    fileMenu = menuBar()->addMenu(tr("&File"));
    fileMenu->addAction(addAct);
    fileMenu->addAction(loadAct);
    fileMenu->addAction(saveAct);
    fileMenu->addSeparator();
    fileMenu->addAction(quitAct);

    setWindowTitle(tr("Node Editor"));


    /// ////////////////////////////////////////////////


   createActions();
   createToolBox();
   createMenus();

    scene = new DiagramScene(itemMenu, this);
    scene->setSceneRect(QRectF(0, 0, 5000, 5000));
    connect(scene, SIGNAL(itemInserted(DiagramItem*)),
            this, SLOT(itemInserted(DiagramItem*)));
    connect(scene, SIGNAL(textInserted(QGraphicsTextItem*)),
            this, SLOT(textInserted(QGraphicsTextItem*)));
    connect(scene, SIGNAL(itemSelected(QGraphicsItem*)),
            this, SLOT(itemSelected(QGraphicsItem*)));
    createToolbars();

    QHBoxLayout *layout = new QHBoxLayout;
    layout->addWidget(toolBox);
    view = new QGraphicsView(scene);
    layout->addWidget(view);

    QWidget *widget = new QWidget;
    widget->setLayout(layout);


    setCentralWidget(widget);
    setWindowTitle(tr("DataFlow"));
    setUnifiedTitleAndToolBarOnMac(true);
}
//! [0]

//! [1]
void MainWindow::backgroundButtonGroupClicked(QAbstractButton *button)
{
    QList<QAbstractButton *> buttons = backgroundButtonGroup->buttons();
    foreach (QAbstractButton *myButton, buttons) {
        if (myButton != button)
            button->setChecked(false);
    }
    QString text = button->text();
    if (text == tr("Blue Grid"))
        scene->setBackgroundBrush(QPixmap(":/images/background1.png"));
    else if (text == tr("White Grid"))
        scene->setBackgroundBrush(QPixmap(":/images/background2.png"));
    else if (text == tr("Gray Grid"))
        scene->setBackgroundBrush(QPixmap(":/images/background3.png"));
    else
        scene->setBackgroundBrush(QPixmap(":/images/background4.png"));

    scene->update();
    view->update();
}
//! [1]

//! [2]
void MainWindow::buttonGroupClicked(int id)
{
    QList<QAbstractButton *> buttons = buttonGroup->buttons();
    foreach (QAbstractButton *button, buttons) {
        if (buttonGroup->button(id) != button)
            button->setChecked(false);
    }
    if (id == InsertTextButton) {
        scene->setMode(DiagramScene::InsertText);
    } else {
        scene->setItemType(DiagramItem::DiagramType(id));
        scene->setMode(DiagramScene::InsertItem);
    }
}
//! [2]

//! [3]
void MainWindow::deleteItem()
{
    foreach (QGraphicsItem *item, scene->selectedItems()) {
        if (item->type() == Arrow::Type) {
            scene->removeItem(item);
            Arrow *arrow = qgraphicsitem_cast<Arrow *>(item);
            arrow->startItem()->removeArrow(arrow);
            arrow->endItem()->removeArrow(arrow);
            delete item;
        }
    }

    foreach (QGraphicsItem *item, scene->selectedItems()) {
         if (item->type() == DiagramItem::Type)
             qgraphicsitem_cast<DiagramItem *>(item)->removeArrows();
         scene->removeItem(item);
         delete item;
     }
}
//! [3]

//! [4]
void MainWindow::pointerGroupClicked(int)
{
    scene->setMode(DiagramScene::Mode(pointerTypeGroup->checkedId()));
}
//! [4]

//! [5]
void MainWindow::bringToFront()
{
    if (scene->selectedItems().isEmpty())
        return;

    QGraphicsItem *selectedItem = scene->selectedItems().first();
    QList<QGraphicsItem *> overlapItems = selectedItem->collidingItems();

    qreal zValue = 0;
    foreach (QGraphicsItem *item, overlapItems) {
        if (item->zValue() >= zValue && item->type() == DiagramItem::Type)
            zValue = item->zValue() + 0.1;
    }
    selectedItem->setZValue(zValue);
}

//! [5]
//! //////////////
void MainWindow::propertySet(){
    if (scene->selectedItems().isEmpty())
        return;
        QMessageBox msgBox;
        msgBox.setText("please enter your property");
        msgBox.exec();
            bool ok;
           QString text = QInputDialog::getText(this, tr("Properties Window"),
                                                tr("User name:"),QLineEdit::Normal,
                                                QDir::home().dirName(), &ok);
              QString text2 = QInputDialog::getMultiLineText(this, tr("QInputDialog::getMultiLineText()"),
                                                            tr("Address:"), "John Doe\nFreedom Street", &ok);
              QStringList items;
                 items << tr("Spring") << tr("Summer") << tr("Fall") << tr("Winter");


                 QString item = QInputDialog::getItem(this, tr("QInputDialog::getItem()"),
                                                      tr("Season:"), items, 0, false, &ok);

}
//! ////////////

//! [6]
void MainWindow::sendToBack()
{
    if (scene->selectedItems().isEmpty())
        return;

    QGraphicsItem *selectedItem = scene->selectedItems().first();
    QList<QGraphicsItem *> overlapItems = selectedItem->collidingItems();

    qreal zValue = 0;
    foreach (QGraphicsItem *item, overlapItems) {
        if (item->zValue() <= zValue && item->type() == DiagramItem::Type)
            zValue = item->zValue() - 0.1;
    }
    selectedItem->setZValue(zValue);
}
//! [6]

//! [7]
void MainWindow::itemInserted(DiagramItem *item)
{
    pointerTypeGroup->button(int(DiagramScene::MoveItem))->setChecked(true);
    scene->setMode(DiagramScene::Mode(pointerTypeGroup->checkedId()));
    buttonGroup->button(int(item->diagramType()))->setChecked(false);
}
//! [7]

//! [8]
void MainWindow::textInserted(QGraphicsTextItem *)
{
    buttonGroup->button(InsertTextButton)->setChecked(false);
    scene->setMode(DiagramScene::Mode(pointerTypeGroup->checkedId()));
}
//! [8]

//! [9]
void MainWindow::currentFontChanged(const QFont &)
{
    handleFontChange();
}
//! [9]

//! [10]
void MainWindow::fontSizeChanged(const QString &)
{
    handleFontChange();
}
//! [10]

//! [11]
void MainWindow::sceneScaleChanged(const QString &scale)
{
    double newScale = scale.left(scale.indexOf(tr("%"))).toDouble() / 100.0;
    QMatrix oldMatrix = view->matrix();
    view->resetMatrix();
    view->translate(oldMatrix.dx(), oldMatrix.dy());
    view->scale(newScale, newScale);
}
//! [11]

//! [12]
void MainWindow::textColorChanged()
{
    textAction = qobject_cast<QAction *>(sender());
    fontColorToolButton->setIcon(createColorToolButtonIcon(
                                     ":/images/textpointer.png",
                                     qvariant_cast<QColor>(textAction->data())));
    textButtonTriggered();
}
//! [12]

//! [13]
void MainWindow::itemColorChanged()
{
    fillAction = qobject_cast<QAction *>(sender());
    fillColorToolButton->setIcon(createColorToolButtonIcon(
                                     ":/images/floodfill.png",
                                     qvariant_cast<QColor>(fillAction->data())));
    fillButtonTriggered();
}
//! [13]

//! [14]
void MainWindow::lineColorChanged()
{
    lineAction = qobject_cast<QAction *>(sender());
    lineColorToolButton->setIcon(createColorToolButtonIcon(
                                     ":/images/linecolor.png",
                                     qvariant_cast<QColor>(lineAction->data())));
    lineButtonTriggered();
}
//! [14]

//! [15]
void MainWindow::textButtonTriggered()
{
    scene->setTextColor(qvariant_cast<QColor>(textAction->data()));
}
//! [15]

//! [16]
void MainWindow::fillButtonTriggered()
{
    scene->setItemColor(qvariant_cast<QColor>(fillAction->data()));
}
//! [16]

//! [17]
void MainWindow::lineButtonTriggered()
{
    scene->setLineColor(qvariant_cast<QColor>(lineAction->data()));
}
//! [17]

//! [18]
void MainWindow::handleFontChange()
{
    QFont font = fontCombo->currentFont();
    font.setPointSize(fontSizeCombo->currentText().toInt());
    font.setWeight(boldAction->isChecked() ? QFont::Bold : QFont::Normal);
    font.setItalic(italicAction->isChecked());
    font.setUnderline(underlineAction->isChecked());

    scene->setFont(font);
}
//! [18]

//! [19]
void MainWindow::itemSelected(QGraphicsItem *item)
{
    DiagramTextItem *textItem =
    qgraphicsitem_cast<DiagramTextItem *>(item);

    QFont font = textItem->font();
    fontCombo->setCurrentFont(font);
    fontSizeCombo->setEditText(QString().setNum(font.pointSize()));
    boldAction->setChecked(font.weight() == QFont::Bold);
    italicAction->setChecked(font.italic());
    underlineAction->setChecked(font.underline());
}
//! [19]

//! [20]
void MainWindow::about()
{
    QMessageBox::about(this, tr("About Diagram Scene"),
                       tr("The <b>Diagram Scene</b> example shows "
                          "use of the graphics framework."));
}
//! [20]

//! [21]
void MainWindow::createToolBox()
{
    buttonGroup = new QButtonGroup(this);
    buttonGroup->setExclusive(false);
    connect(buttonGroup, SIGNAL(buttonClicked(int)),
            this, SLOT(buttonGroupClicked(int)));
    QGridLayout *layout = new QGridLayout;
    layout->addWidget(createCellWidget(tr("Conditional"), DiagramItem::Conditional), 0, 0);
    layout->addWidget(createCellWidget(tr("Process"), DiagramItem::Step),0, 1);
    layout->addWidget(createCellWidget(tr("Input/Output"), DiagramItem::Io), 1, 0);
    layout->addWidget(createCellWidget(tr("myobject "), DiagramItem::Conditional),2, 1);
    layout->addWidget(createCellWidget(tr("myobject "), DiagramItem::Conditional),3, 0);


//! [21]

    QToolButton *textButton = new QToolButton;
    textButton->setCheckable(true);
    buttonGroup->addButton(textButton, InsertTextButton);
    textButton->setIcon(QIcon(QPixmap(":/images/textpointer.png")));
    textButton->setIconSize(QSize(50, 50));
    QGridLayout *textLayout = new QGridLayout;
    textLayout->addWidget(textButton, 0, 0, Qt::AlignHCenter);
    textLayout->addWidget(new QLabel(tr("Text")), 1, 0, Qt::AlignCenter);
    QWidget *textWidget = new QWidget;
    textWidget->setLayout(textLayout);
    layout->addWidget(textWidget, 1, 1);

    layout->setRowStretch(3, 10);
    layout->setColumnStretch(2, 10);

    QWidget *itemWidget = new QWidget;
    itemWidget->setLayout(layout);

    backgroundButtonGroup = new QButtonGroup(this);
    connect(backgroundButtonGroup, SIGNAL(buttonClicked(QAbstractButton*)),
            this, SLOT(backgroundButtonGroupClicked(QAbstractButton*)));

    QGridLayout *backgroundLayout = new QGridLayout;
    backgroundLayout->addWidget(createBackgroundCellWidget(tr("Blue Grid"),
                                                           ":/images/background1.png"), 0, 0);
    backgroundLayout->addWidget(createBackgroundCellWidget(tr("White Grid"),
                                                           ":/images/background2.png"), 0, 1);
    backgroundLayout->addWidget(createBackgroundCellWidget(tr("Gray Grid"),
                                                           ":/images/background3.png"), 1, 0);
    backgroundLayout->addWidget(createBackgroundCellWidget(tr("No Grid"),
                                                           ":/images/background4.png"), 1, 1);

    backgroundLayout->setRowStretch(2, 10);
    backgroundLayout->setColumnStretch(2, 10);

    QWidget *backgroundWidget = new QWidget;
    backgroundWidget->setLayout(backgroundLayout);


//! [22]
    toolBox = new QToolBox;
    toolBox->setSizePolicy(QSizePolicy(QSizePolicy::Maximum, QSizePolicy::Ignored));
    toolBox->setMinimumWidth(itemWidget->sizeHint().width());
    toolBox->addItem(itemWidget, tr("Basic Flowchart Shapes"));
    toolBox->addItem(backgroundWidget, tr("Backgrounds"));
}
//! [22]

//! [23]
void MainWindow::createActions()
{
    toFrontAction = new QAction(QIcon(":/images/bringtofront.png"),
                                tr("Bring to &Front"), this);
    toFrontAction->setShortcut(tr("Ctrl+F"));
    toFrontAction->setStatusTip(tr("Bring item to front"));
    connect(toFrontAction, SIGNAL(triggered()), this, SLOT(bringToFront()));
//! [23]
//! /////////////////
    propertiesAction= new QAction(QIcon(":/images/bringtofront.png"), tr("Properties"), this);
    propertiesAction->setShortcut(tr("Ctrl+P"));
      propertiesAction->setStatusTip(tr("Properties"));
    connect( propertiesAction, SIGNAL(triggered()), this, SLOT(propertySet()));
//! [23]
//!
//! //////////////////

    sendBackAction = new QAction(QIcon(":/images/sendtoback.png"), tr("Send to &Back"), this);
    sendBackAction->setShortcut(tr("Ctrl+B"));
    sendBackAction->setStatusTip(tr("Send item to back"));
    connect(sendBackAction, SIGNAL(triggered()), this, SLOT(sendToBack()));

    deleteAction = new QAction(QIcon(":/images/delete.png"), tr("&Delete"), this);
    deleteAction->setShortcut(tr("Delete"));
    deleteAction->setStatusTip(tr("Delete item from diagram"));
    connect(deleteAction, SIGNAL(triggered()), this, SLOT(deleteItem()));

    exitAction = new QAction(tr("E&xit"), this);
    exitAction->setShortcuts(QKeySequence::Quit);
    exitAction->setStatusTip(tr("Quit Scenediagram example"));
    connect(exitAction, SIGNAL(triggered()), this, SLOT(close()));

    boldAction = new QAction(tr("Bold"), this);
    boldAction->setCheckable(true);
    QPixmap pixmap(":/images/bold.png");
    boldAction->setIcon(QIcon(pixmap));
    boldAction->setShortcut(tr("Ctrl+B"));
    connect(boldAction, SIGNAL(triggered()), this, SLOT(handleFontChange()));

    italicAction = new QAction(QIcon(":/images/italic.png"), tr("Italic"), this);
    italicAction->setCheckable(true);
    italicAction->setShortcut(tr("Ctrl+I"));
    connect(italicAction, SIGNAL(triggered()), this, SLOT(handleFontChange()));

    underlineAction = new QAction(QIcon(":/images/underline.png"), tr("Underline"), this);
    underlineAction->setCheckable(true);
    underlineAction->setShortcut(tr("Ctrl+U"));
    connect(underlineAction, SIGNAL(triggered()), this, SLOT(handleFontChange()));

    aboutAction = new QAction(tr("A&bout"), this);
    aboutAction->setShortcut(tr("Ctrl+B"));
    connect(aboutAction, SIGNAL(triggered()), this, SLOT(about()));
}

//! [24]
void MainWindow::createMenus()
{
    fileMenu = menuBar()->addMenu(tr("&File"));
    fileMenu->addAction(exitAction);

    itemMenu = menuBar()->addMenu(tr("&Item"));
    itemMenu->addAction(deleteAction);
    itemMenu->addSeparator();
    itemMenu->addAction(toFrontAction);
    itemMenu->addAction(sendBackAction);
    itemMenu->addAction(propertiesAction);


    aboutMenu = menuBar()->addMenu(tr("&Help"));
    aboutMenu->addAction(aboutAction);
}
//! [24]

//! [25]
void MainWindow::createToolbars()
{
//! [25]
    editToolBar = addToolBar(tr("Edit"));
    editToolBar->addAction(deleteAction);
    editToolBar->addAction(toFrontAction);
    editToolBar->addAction(sendBackAction);
    editToolBar->addAction( propertiesAction);


    fontCombo = new QFontComboBox();
    connect(fontCombo, SIGNAL(currentFontChanged(QFont)),
            this, SLOT(currentFontChanged(QFont)));

    fontSizeCombo = new QComboBox;
    fontSizeCombo->setEditable(true);
    for (int i = 8; i < 30; i = i + 2)
        fontSizeCombo->addItem(QString().setNum(i));
    QIntValidator *validator = new QIntValidator(2, 64, this);
    fontSizeCombo->setValidator(validator);
    connect(fontSizeCombo, SIGNAL(currentIndexChanged(QString)),
            this, SLOT(fontSizeChanged(QString)));

    fontColorToolButton = new QToolButton;
    fontColorToolButton->setPopupMode(QToolButton::MenuButtonPopup);
    fontColorToolButton->setMenu(createColorMenu(SLOT(textColorChanged()), Qt::black));
    textAction = fontColorToolButton->menu()->defaultAction();
    fontColorToolButton->setIcon(createColorToolButtonIcon(":/images/textpointer.png", Qt::black));
    fontColorToolButton->setAutoFillBackground(true);
    connect(fontColorToolButton, SIGNAL(clicked()),
            this, SLOT(textButtonTriggered()));

//! [26]
    fillColorToolButton = new QToolButton;
    fillColorToolButton->setPopupMode(QToolButton::MenuButtonPopup);
    fillColorToolButton->setMenu(createColorMenu(SLOT(itemColorChanged()), Qt::white));
    fillAction = fillColorToolButton->menu()->defaultAction();
    fillColorToolButton->setIcon(createColorToolButtonIcon(
                                     ":/images/floodfill.png", Qt::white));
    connect(fillColorToolButton, SIGNAL(clicked()),
            this, SLOT(fillButtonTriggered()));
//! [26]

    lineColorToolButton = new QToolButton;
    lineColorToolButton->setPopupMode(QToolButton::MenuButtonPopup);
    lineColorToolButton->setMenu(createColorMenu(SLOT(lineColorChanged()), Qt::black));
    lineAction = lineColorToolButton->menu()->defaultAction();
    lineColorToolButton->setIcon(createColorToolButtonIcon(
                                     ":/images/linecolor.png", Qt::black));
    connect(lineColorToolButton, SIGNAL(clicked()),
            this, SLOT(lineButtonTriggered()));

    textToolBar = addToolBar(tr("Font"));
    textToolBar->addWidget(fontCombo);
    textToolBar->addWidget(fontSizeCombo);
    textToolBar->addAction(boldAction);
    textToolBar->addAction(italicAction);
    textToolBar->addAction(underlineAction);

    colorToolBar = addToolBar(tr("Color"));
    colorToolBar->addWidget(fontColorToolButton);
    colorToolBar->addWidget(fillColorToolButton);
    colorToolBar->addWidget(lineColorToolButton);

    QToolButton *pointerButton = new QToolButton;
    pointerButton->setCheckable(true);
    pointerButton->setChecked(true);
    pointerButton->setIcon(QIcon(":/images/pointer.png"));
    QToolButton *linePointerButton = new QToolButton;
    linePointerButton->setCheckable(true);
    linePointerButton->setIcon(QIcon(":/images/linepointer.png"));

    pointerTypeGroup = new QButtonGroup(this);
    pointerTypeGroup->addButton(pointerButton, int(DiagramScene::MoveItem));
    pointerTypeGroup->addButton(linePointerButton, int(DiagramScene::InsertLine));
    connect(pointerTypeGroup, SIGNAL(buttonClicked(int)),
            this, SLOT(pointerGroupClicked(int)));

    sceneScaleCombo = new QComboBox;
    QStringList scales;
    scales << tr("50%") << tr("75%") << tr("100%") << tr("125%") << tr("150%");
    sceneScaleCombo->addItems(scales);
    sceneScaleCombo->setCurrentIndex(2);
    connect(sceneScaleCombo, SIGNAL(currentIndexChanged(QString)),
            this, SLOT(sceneScaleChanged(QString)));

    pointerToolbar = addToolBar(tr("Pointer type"));
    pointerToolbar->addWidget(pointerButton);
    pointerToolbar->addWidget(linePointerButton);
    pointerToolbar->addWidget(sceneScaleCombo);
//! [27]
}
//! [27]

//! [28]
QWidget *MainWindow::createBackgroundCellWidget(const QString &text, const QString &image)
{
    QMessageBox msgBox;
        msgBox.setText("createBackgroundCellWidget");
        msgBox.exec();


    QToolButton *button = new QToolButton;
    button->setText(text);
    button->setIcon(QIcon(image));
    button->setIconSize(QSize(50, 50));
    button->setCheckable(true);
    backgroundButtonGroup->addButton(button);

    QGridLayout *layout = new QGridLayout;
    layout->addWidget(button, 0, 0, Qt::AlignHCenter);
    layout->addWidget(new QLabel(text), 1, 0, Qt::AlignCenter);

    QWidget *widget = new QWidget;
    widget->setLayout(layout);

    return widget;
}
//! [28]

//! [29]
QWidget *MainWindow::createCellWidget(const QString &text, DiagramItem::DiagramType type)
{    QMessageBox msgBox;
     msgBox.setText("createCellWidget");
     msgBox.exec();


    DiagramItem item(type, itemMenu);
    QIcon icon(item.image());

    QToolButton *button = new QToolButton;
    button->setIcon(icon);
    button->setIconSize(QSize(50, 50));
    button->setCheckable(true);
    buttonGroup->addButton(button, int(type));

    QGridLayout *layout = new QGridLayout;
    layout->addWidget(button, 0, 0, Qt::AlignHCenter);
    layout->addWidget(new QLabel(text), 1, 0, Qt::AlignCenter);

    QWidget *widget = new QWidget;
    widget->setLayout(layout);

    return widget;
}
//! [29]

//! [30]
QMenu *MainWindow::createColorMenu(const char *slot, QColor defaultColor)
{
    QList<QColor> colors;
    colors << Qt::black << Qt::white << Qt::red << Qt::blue << Qt::yellow;
    QStringList names;
    names << tr("black") << tr("white") << tr("red") << tr("blue")
          << tr("yellow");

    QMenu *colorMenu = new QMenu(this);
    for (int i = 0; i < colors.count(); ++i) {
        QAction *action = new QAction(names.at(i), this);
        action->setData(colors.at(i));
        action->setIcon(createColorIcon(colors.at(i)));
        connect(action, SIGNAL(triggered()), this, slot);
        colorMenu->addAction(action);
        if (colors.at(i) == defaultColor)
            colorMenu->setDefaultAction(action);
    }
    return colorMenu;
}
//! [30]

//! [31]
QIcon MainWindow::createColorToolButtonIcon(const QString &imageFile, QColor color)
{


    QPixmap pixmap(50, 80);
    pixmap.fill(Qt::transparent);
    QPainter painter(&pixmap);
    QPixmap image(imageFile);
    // Draw icon centred horizontally on button.
    QRect target(4, 0, 42, 43);
    QRect source(0, 0, 42, 43);
    painter.fillRect(QRect(0, 60, 50, 80), color);
    painter.drawPixmap(target, image, source);

    return QIcon(pixmap);
}
//! [31]

//! [32]
QIcon MainWindow::createColorIcon(QColor color)
{
    QPixmap pixmap(20, 20);
    QPainter painter(&pixmap);
    painter.setPen(Qt::NoPen);
    painter.fillRect(QRect(0, 0, 20, 20), color);

    return QIcon(pixmap);
}
//! [32]

this has errors:please help me
F:\Users\ROOT\Desktop\newpro\newpro\mainwindow.cpp:76: error: 'nodesEditor' was not declared in this scope
nodesEditor = new QNodesEditor();

thanks for reply

[JohanSolo]

@stackprogramer said:

nodesEditor= new QNodesEditor(this);

From the snippet you gave us we have to assume that nodeEditor is a member of MainWindow. How did you declare it?

[stackprogramer]

@JohanSolo i have a question,if this class it not member mainwindow,
it should not work?why?
i define class in header file qnodeseditor.
why for some class that is defined in Qt,it not necessary is defined a member class mainwindow.

thanks for reply

[JohanSolo]

@stackprogramer said:

@JohanSolo i have a question,if this class it not member mainwindow,
it should not work?why?
i define class in header file qnodeseditor.

I understood you have a header defining the class QNodesEditor, but where is the instance nodesEditor defined?

[stackprogramer]

@JohanSolo
i now defined instance it .its works now thanks for reply.

[JohanSolo]

@stackprogramer said:

@JohanSolo
i now defined its works now thanks for reply.

I'm glad I could help, Please don't forget to mark the question as solved.