Serializing a widget

EL-jos

I found in a forum, they say you need to recompile Qt and SQL Drive but it doesn't explain how to do it.

Please if there is someone who knows how to make it watch you manifest

mrjj

@EL-jos
Hi
For QSQLITE
you need to compile nothing or add any libraries.
just
QT += sql
in your .pro file

EL-jos

Thank you very much for your advice, but I have two questions;
first how to update a QscrollArea that already contains elements beforehand?
and the second is how to make a message waiting list like this if a client "A" has just logged out and another client "B" sends him a message, that the message is in a list to wait for the client "A" to read it.
like whatsapp or facebook notification when someone sends us a message while we're away, the message is kept until we read it?

SGaist

Hi,

You just append new widgets to the layout that already contains the others.

As for the messages, if you are thinking on how it’s working on mobile platform, you’ll have several things to take into consideration.

So some questions for you:

On what platform(s) is your application going to run ?
How are the client going to talk to each other ?

EL-jos

Regarding the update of my scroollArea, I don't want to add elements but rather delete completely what it already contains.

then for the messages I want my application to run all over the platform but first on Pc using the windows operating system.

for my clients, I use TCP/ip protocol so with QTcpSocket class

SGaist

The most elegant would likely be to have the messages stored in a model and then have a custom QStyledItemDelegate to paint whatever you want.

Again: how are you client talking to each other ? Through a central server ? How do they know each other ?

EL-jos

Hi,

Yes I use a server for the dialog between client, this means that if a client'A' sends a message to client'B', it will first go through the server then the server will send me to the destination so client'B'.

EL-jos

please someone has an idea.

mrjj

@EL-jos
About ?

EL-jos

In fact I want to make sure that if we send a message to a client that is not connected, that this client sees the message that has been sent as soon as it is connected.

JKSH

@EL-jos said in Serializing a widget:

I want to make sure that if we send a message to a client that is not connected, that this client sees the message that has been sent as soon as it is connected.

Then the central server must store the message. When the client comes online, the server can deliver the message to the client.

Note: This concept is about communications architecture. This is not related to widgets at all.

EL-jos

ahhhhh yes you're right, so I can store the message in a database at the server level then as soon as the concerned client is connected the server will be able to restore the message then send it to the client, thank you very much.

then a second unresolved problem so far;
here I have a scrollArea which first contains many widgets of different type, so I want to delete either empty all these widgets and left the scrollArea blank so without element,
how do I do that?

JKSH

@EL-jos said in Serializing a widget:

here I have a scrollArea which first contains many widgets of different type, so I want to delete either empty all these widgets and left the scrollArea blank so without element,
how do I do that?

Have a read through http://doc.qt.io/qt-5/qscrollarea.html . Do you see anything that might do what you want?

EL-jos

I just read and reread the Qt documentation for the QScrollArea class or even its mother classes but I can't find the solution to my problem because there is not a function that allows to remove all widgets contained in a scrollAreea

mrjj

@EL-jos
Hi
Are the widgets not in a layout ?
You can clear layout with

void clearLayout(QLayout *layout)
    QLayoutItem *item;
    while((item = layout->takeAt(0))) {
        if (item->layout()) {
            clearLayout(item->layout());
            delete item->layout();
        }
        if (item->widget()) {
            delete item->widget();
        }
        delete item;
    }
}

EL-jos

Thank you for your code.
theoretically it works but not in practice according to my example, here is a little project I created to test your code:

[7_1535474695539_fenetre1.cpp](Uploading 100%) [6_1535474695538_fenetre1.h](Uploading 100%) [5_1535474695538_fenetresecond.cpp](Uploading 100%) [4_1535474695537_fenetresecond.h](Uploading 100%) [3_1535474695537_fenetresecond.ui](Uploading 100%) [2_1535474695537_main.cpp](Uploading 100%) [1_1535474695535_Oc.pro](Uploading 100%) [0_1535474695483_Oc.pro.user](Uploading 100%)

EL-jos

sorry I can't send my project on topic, send me your E-mail address so I can send it to you by E-mail

mrjj

@EL-jos
Sorry i dont have email i use for Qt forum.
You can use dropbox or google drive.
Are you sure u give it the correct layout ?
Im sure code works so maybe its other layout u clear that u think.
also use the debugger to see what happens.

EL-jos

Yes thank you sorry it was a small mistake on my part and there it works correctly, here is the code:

void Controleur::on_pushButton_clicked()
{
    QLayoutItem *item;

    int nb = 3;
    int a = 0;
    qDebug() << nb;

    while(ui->scrollAreaWidgetContents->layout()->count() > 0){

    for(int i = 0; i < ui->scrollAreaWidgetContents->layout()->count(); ++i){

        item = ui->scrollAreaWidgetContents->layout()->takeAt(i);
        if(item->layout()){

            qDebug("It's a layout");
            delete item->layout();
        }

        if(item->widget()){

            qDebug("It's a widget");
            delete item->widget();
        }

        delete item;
    }

    qDebug() << "suppression N°" << a;
    ++a;
    }
}

mrjj

@EL-jos
Hi
Ok super.
You also want to remove any layout it has ?
Normally one wish to keep layout and only remove widgets.