[solved] Newb to child parent forms and how to access the ui elements of child forms

thistleknot

following a tutorial of Inheritance Approach:

http://qt-project.org/doc/qt-5/designer-using-a-ui-file.html#the-single-inheritance-approach

I made an experimental branch on github showcasing the specific changes.

https://github.com/thistleknot/DiffMatchPatch/commit/b0a7eaede6838916a3dda3b2d652c4b484ba4990

It compiles, but I still don't know how to access it as

uiOutput->

what's missing is diffmatchpatch.cpp line 156

uiOutput-> doesn't seem to do anything

I made sure I did a private member var in my diffpatcmatch.h (basically my mainwindow)Ui::PatchOutputWindow *uiOutput;

I have a plainTextEdit on the uiOutput (patchOutputWindow) interface I'm trying to port a QString to. I was hoping to access it in a fashion similar to ui->.

That form specifically (uiOutput) has a menubar that I specifically desire, and so I created a form first using the form editor, and was trying to import it as a new window/form into my project.

Alternatively I could go with a Tabbed window system. That way I wouldn't have to figure out how to implement these new windows so I can gain access to a pre-made form.

SGaist

Hi,

In good written widgets, child widgets don't know anything about their parent. They provide getter and setters for the internal part they allow to modify. If a parent widget needs to react to something happening inside a child widget, it should connect to a signal emitted by the child widget.

So if you want to update the content of a QPlainTextEdit, add a setter in your container widget e.g. DiffMatchPatchWidget::setPatchContent(const QString& patchFilePath); and in that method, update your ui->myPlainTextEdit

Hope it helps

thistleknot

what about a signal emitted by the parent widget?

I have a menu drop down where i'm trying to submit a compute, patch algorithm that dumps to a plainTextEdit, but the plainTextEdit I wanted in a new window, and then the option to save it. It's due to the fact that I'm working with multiple documents of similar nature that I need a new window so a person using the app doesn't get confused (even though it's a patch file vs raw txt data).

I think I see what you mean. If a parent needs to react...

In this case the child needs to react... so the child has a getter function.

I don't know why... but I'm used to calling them member accessor functions. Maybe UML?

thistleknot

I'm still kind of lost. I'm not trying to update the mainwindow or diffmatchpatch.cpp at all, I'm trying to update patchoutputwindow.cpp with a save slot from diffmatchpatch.cpp. So it's the parent window signalling the child window. So... I would just setup a public function that returns a QString? Then this member function is available by invoking the object and it's object.<function name>?

thistleknot

Yeah, i'm completely lost.

I've been working on this all day. My code worked before by pushing objects to a new window that was locally created so I had no issues with encapsulation. But now...

I tried reading this article and implementing it

http://qt-project.org/doc/qt-5/signalsandslots.html

but got stuck here:

Counter a, b;
QObject::connect(&a, &Counter::valueChanged,
                 &b, &Counter::setValue);

a.setValue(12);     // a.value() == 12, b.value() == 12
b.setValue(48);     // a.value() == 12, b.value() == 48

Here's my code (compiles)

https://github.com/thistleknot/DiffMatchPatch/commit/b0a7eaede6838916a3dda3b2d652c4b484ba4990

I'm basically trying to emit a QString from one form to another form.

thistleknot

I think this may be my answer

http://stackoverflow.com/questions/15833535/transfer-data-between-forms-in-qt

thistleknot

I got it by creating a public function on the receiving form:

@
void setOutputWindowText(QString);

void PatchOutputWindow::setOutputWindowText(QString outputString) {
ui->plainTextEditPatchOutput->setPlainText(outputString);
}
@

and calling it

@
diff_match_patch dmp;

QString str1 = ui->plainTextEditLeft->toPlainText();
QString str2 = ui->plainTextEditRight->toPlainText();

childForm = new PatchOutputWindow(this);

//parent window can be in front of child window
//childForm = new PatchOutputWindow();

QString strPatch = dmp.patch_toText(dmp.patch_make(str1, str2));
QTextStream out(&strPatch);

childForm->setOutputWindowText(strPatch);

childForm->show();
@

[edit: added missing coding tags @ SGaist]

SGaist

That's it

On a side note, why the QTextStream ?

Unless you plan to have multiple PatchOutputWindow shown at the same time, you have a design problem here. Each time you will call the second part of your code, you will replace childForm with a new widget.

thistleknot

the sample code used QTextStream is why. What do you suggest.

I'm aware of the duplicate childforms, not a big concern, but a user may desire to run multiple patches before saving them.

SGaist

Just that the out variable is never used so there's not need to have it there.

Then you should write your code taking that possibility into account