Ui file loaded by UiLoader , but NULL pointer to custom widgets

i am using Qt 4.7.0 and windows7, i have a Huge problem with custom widgets, i founded QLed custom widget, i use it.

i want to add a signal properties to QLed widget and in design time with QtDesigner i want to add 100 QLed's on my Ui file and set each QLed's signal properties to a number(type of signal properties is not important), so i want to access this 100 QLeds when i am coding and make a QList and access those

QFile file(":/test.ui");
QUiLoader loader;
file.open(QFile::ReadOnly);
QWidget *formWidget = loader.load(&file, this);
file.close();
formWidget->show();
QList<QLed *> allQLed = formWidget->findChildren<QLed *>();

now i want to send data to QLeds

for(int i=0; i<allQLed.size(); i++){
    if(allQLed.at(i)->SIGNAL_PROPERTIES == 123)
        allQLed.at(i)->setValue(true);
    else    
        allQLed.at(i)->setValue(false);
}

now it will ON all QLeds that SIGNAL_PROPERTIES == 123

is my theory and metod incorect or i can do in other way? i wrote my problem step by step i changed dialog.cpp and cunstructor Dialog::Dialog(QWidget *parent) : and *.pro file i attached my test program. Thanks.

*.pro file:

TARGET = example
TEMPLATE = app

QT += svg

CONFIG      += uitools

SOURCES += main.cpp\
        dialog.cpp\

HEADERS  += dialog.h\
            qled.h

FORMS    += dialog.ui

LIBS += libqledplugin

RESOURCES = test.qrc

** dialog.cpp

#include "dialog.h"
#include "ui_dialog.h"

#include <QFileDialog>
#include <QtUiTools>
#include "QLed.h"

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);

//---------------------------------------------------------------
        QFile file(":/test.ui");
        QUiLoader loader;
        file.open(QFile::ReadOnly);
        QWidget *formWidget = loader.load(&file, this);
        file.close();
        formWidget->show();
        qDebug() << formWidget->children();

        QList<QCheckBox *> allCheckBox = formWidget->findChildren<QCheckBox *>();
        qDebug() << allCheckBox;
        qDebug() << allCheckBox.size();
        allCheckBox.at(2)->setChecked(true);
        QCheckBox *hello1 = formWidget->findChild<QCheckBox *>("checkBox_2");
        qDebug() << hello1;
        hello1->setChecked(true);

        QList<QLed *> allQLed = formWidget->findChildren<QLed *>();
        qDebug() << allQLed;
        qDebug() << allQLed.size();
        QLed *led = formWidget->findChild<QLed *>("qLed");
        qDebug() << led;
//---------------------------------------------------------------
}

i copied qledplugin-build-desktop\release folder files: qledplugin.dll, libqledplugin.a, moc_qled.cpp, moc_qledplugin.cpp, qrc_qled.cpp, moc_qled.o, moc_qledplugin.o, qled.o, qledplugin.o, qrc_qled.o,

to:

1) C:\QledTEST\my test program\mytest-build-desktop
2) C:\QledTEST\my test program\mytest-build-desktop\release
3) C:\QledTEST\my test program\mytest-build-desktop\debug
4) C:\Qt\2010.05\qt\include\QtGui
5) C:\Qt\2010.05\qt\include\Qt
6) C:\Qt\2010.05\qt\lib
7) C:\Qt\2010.05\qt\plugins\designer

, i can design a Ui dialog with QtDesigner and placing QLeds and QLabels, every thing is good, and i also can use other widgets. after it, i want to show this Ui file in my program, i am using UiLoader, i load Ui file in a QWidget object QWidget *formWidget = loader.load(&file, this); and .show() it, in compile time i get this warnings in 1)Build Issues tab:

release/moc_qled.cpp:75: warning: 'QLed::staticMetaObject' redeclared without dllimport attribute after being referenced with dll linkage
release/moc_qled.cpp:84: warning: 'virtual const QMetaObject* QLed::metaObject() const' redeclared without dllimport attribute: previous dllimport ignored
release/moc_qled.cpp:89: warning: 'virtual void* QLed::qt_metacast(const char*)' redeclared without dllimport attribute: previous dllimport ignored
release/moc_qled.cpp:97: warning: 'virtual int QLed::qt_metacall(QMetaObject::Call, int, void**)' redeclared without dllimport attribute: previous dllimport ignored

but my program work. every thing is good, and my designed file is loading. i use this command:

qDebug() << formWidget->children();

and i can see in 3) Application Output tab:

Starting C:\QledTEST\my test program\mytest-build-desktop\release\example.exe...
(QFormInternal::TranslationWatcher(0x14683d8) ,  QLed(0x1472320, name = "qLed_2") ,  QLed(0x14722a0, name = "qLed_3") ,  QLed(0x14723a0, name = "qLed_4") ,  QCheckBox(0x14810b8, name = "checkBox_2") ,  QCheckBox(0x14810d8, name = "checkBox_3") ,  QCheckBox(0x14810f8, name = "checkBox_4") ,  QLabel(0x1481118, name = "label") ,  QCheckBox(0x1481138, name = "checkBox") ,  QLed(0x14724e0, name = "qLed") )  
C:\QledTEST\my test program\mytest-build-desktop\release\example.exe exited with code 0

so i can see formWidget children, that containes QLeds my Custom Widgets.

now i need to send data to my QLeds and QCheckBoxs, i make a QList and try it:

QList<QCheckBox *> allCheckBox = formWidget->findChildren<QCheckBox *>();
qDebug() << allCheckBox;
qDebug() << allCheckBox.size();
allCheckBo开发者_StackOverflow中文版x.at(2)->setChecked(true); // i can send data
QCheckBox *hello1=formWidget->findChild<QCheckBox*>("checkBox_2");
qDebug() << hello1;
hello1->setChecked(true);// i can send data

i get:

(QCheckBox(0x14e10b8, name = "checkBox_2") ,  QCheckBox(0x14e10d8, name = "checkBox_3") ,  QCheckBox(0x14e10f8, name = "checkBox_4") ,  QCheckBox(0x14e1138, name = "checkBox") ) 
 4
QCheckBox(0x6f10b8, name = "checkBox_2")

it showes 4 QCheckBox

now i try Custom Widget:

QList<QLed *> allQLed = formWidget->findChildren<QLed *>();
    qDebug() << allQLed;
    qDebug() << allQLed.size();

i get:

() 
0 
QObject(0x0) //null pointer

my HUGE problem is here: allQLed.size() is zero and i get null pointers

if i add QLed widget with coding i have no problem BUT i need QtDesigner.

i tested this on Q3Frame it is a custom widget plugin in QtDesigner and same problem.

why this happend and what can i do? Qt cant do this?

thanks in advance cheers