How to access Qt GUI from an library using qt designer form
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@Srujan said in how to access Qt GUI from an library using qt designer form:
void show_dialog1( )
{
Ui:Dialog *uiTestDlg;
uiTestDlg->show();
}Well, you are dereferencing a dangling pointer. You did not create any instance of Dialog. It should be:
void show_dialog1( ) { Ui::Dialog *uiTestDlg = new Ui::Dialog(); uiTestDlg->show(); } -
Hi
That means it want the include file#include "dialog.h"
in same cpp file where u have
void show_dialog1( ) -
Hi
That means it want the include file#include "dialog.h"
in same cpp file where u have
void show_dialog1( ) -
@mrjj already made that update by referring from this link that you have answered earlier..
https://forum.qt.io/topic/58057/solved-invalid-use-of-incomplete-type-class-ui-mainwindow
Still getting same error...@Srujan
ok. then something is really wrong :)Just to be 1000% sure. it still say same error if u do :
void show_dialog1( )
{
Dialog *uiTestDlg = new Dialog();
uiTestDlg->show();
}and then
Build->clean all
Build->qmake
Build->Rebuild all. -
@Srujan
ok. then something is really wrong :)Just to be 1000% sure. it still say same error if u do :
void show_dialog1( )
{
Dialog *uiTestDlg = new Dialog();
uiTestDlg->show();
}and then
Build->clean all
Build->qmake
Build->Rebuild all. -
"QWidget: Must construct a QApplication before a QWidget"
That often comes from Global variables. Like in main.cpp
And as much as i wish, i cannot guess the reason for crash :)
Please show main.cpp.
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"QWidget: Must construct a QApplication before a QWidget"
That often comes from Global variables. Like in main.cpp
And as much as i wish, i cannot guess the reason for crash :)
Please show main.cpp.
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@mrjj
Actually in our case we are using some standard applications like cryptokimanager e.t.c..@Srujan said in how to access Qt GUI from an library using qt designer form:
@mrjj
Actually in our case we are using some standard applications like cryptokimanager e.t.c..Meaning that there should not be any globals variables?
Try google
"QWidget: Must construct a QApplication before a QWidget"
and you see there are various reason for this message.Most often the use of "extern" or static variables.
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@Srujan said in how to access Qt GUI from an library using qt designer form:
@mrjj
Actually in our case we are using some standard applications like cryptokimanager e.t.c..Meaning that there should not be any globals variables?
Try google
"QWidget: Must construct a QApplication before a QWidget"
and you see there are various reason for this message.Most often the use of "extern" or static variables.
@mrjj
Through normal application I am able to invoke QT GUI part.
Here my application code..// //main.cpp // #include <QCoreApplication> #include"helper.h" #include <QtWidgets/QApplication> int main(int argc, char *argv[]) { QApplication a(argc, argv); // previously its like QCoreApplication show_dialog1( ); return a.exec(); }//changes in .pro file QT += gui greaterThan(QT_MAJOR_VERSION, 4): QT += widgetsAfter these changes in application project, able to invoke GUI part in shared library
But through our standard applications not able to invoke.
Any idea-
That what changes required for such applications....!!Any way thanks for your support....
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Hi,
What are your "standard application" ?
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Let me rephrase that: what toolkit does it use ?
Is it already using Qt ?
Are you building that app yourself or are you writing a plugin for it and have no access to its internals ?
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Let me rephrase that: what toolkit does it use ?
Is it already using Qt ?
Are you building that app yourself or are you writing a plugin for it and have no access to its internals ?
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The question you are not answering is: are you working on that software code source directly ?
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The question you are not answering is: are you working on that software code source directly ?
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Ok, then are you converting it to a full-blown Qt application ?
