Does splitting widgets into multiple ui forms reduces compilation time?

jsulm

@Daniella said in Does splitting widgets into multiple ui forms reduces compilation time?:

do you know whats the namespace thing they suggest

I guess they suggest to not to include the ui header file in your widget header file but in the widget cpp file. This is common practise in C++. It also uses forward declaration:

class ui::YOUR_UI_CLASS; // This is forward declaration

class YourWidget
private:
    ui::YOUR_UI_CLASS *ui;

It is always good to use forward declarations for types which are used as pointers. Because then you're including less header files in your header files.

Daniella

What option i should select here? Member pointer?

And then:

// .h
#pragma once
#include <QtWidgets/QMainWindow>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindowClass; };
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private:
    Ui::MainWindowClass *ui;
};

//.cpp
#include "stdafx.h"
#include "MainWindow.h"
#include "ui_MainWindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindowClass())
{
    ui->setupUi(this);
}

This way including ui_MainWindow.h into the .cpp?

JoeCFD

This post is deleted!

jsulm

@Daniella said in Does splitting widgets into multiple ui forms reduces compilation time?:

it didnt compile

Then please post the compiler error.
The code you posted should work.

Daniella

@jsulm I edited my previous answer, is it 'correct' now? whats the advantage of this 'method'?

jsulm

@Daniella said in Does splitting widgets into multiple ui forms reduces compilation time?:

whats the advantage of this 'method'?

I already explained what the advantage is. In short: it reduces compile times. You can also google for "C++ forward declaration".

"What option i should select here?" - member pointer. Forward declarations only work with pointers. For non-pointer members the compiler needs to know the type exactly already in the header file.

Daniella

Thank you, i understand now.
Is possible to modify an existing visual studio project to generate the .ui as member pointer?

jsulm

@Daniella Yes, just edit your code accordingly.

Daniella

@jsulm I'm trying to edit it.

Question, how do i access the ui from others .cpp files than the mainwindow.cpp?

When i try #include mainwindow.h and try ui->centralWidget i get this error:

"pointer to incomplete class type "Ui::MainWindow" is not allowed

Christian Ehrlicher

@Daniella said in Does splitting widgets into multiple ui forms reduces compilation time?:

Question, how do i access the ui from others .cpp files than the mainwindow.cpp?

You must not - write proper functions to access the ui elements.

Daniella

@Christian-Ehrlicher said in Does splitting widgets into multiple ui forms reduces compilation time?:

write proper functions to access the ui elements.

Could you give an example?

// main.cpp
#include "mainwindow.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);    
    MainWindow w;   
    w.show();
}

// mainwindow.h
#include <QtWidgets/QMainWindow>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindowClass; class Form; };
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
    void Test();
    Ui::MainWindowClass *ui;
    Ui::Form *form;
};

// mainwindow.cpp
#include "stdafx.h"
#include "MainWindow.h"
#include "ui_MainWindow.h"
#include "ui_Form.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindowClass())
{
    ui->setupUi(this);
    form->setupUi(this);
}

// test.cpp
#include "mainwindow.h"

void MainWindow::Test()
{ 
     ui->centralWidget; // <-- error: "pointer to incomplete class type "Ui::MainWindowClass" is not allowed
}

how do i access ui in Test()?

SGaist

Hi,

You are missing

#include "ui_MainWindow.h"

in your test.cpp file.

Out of curiosity, why are you creating a new file for that method ? You are making your codebase more complex for no benefit.