Where is QLayout property leftMargin

A.v.O

Question

Where is QLayout property leftMargin in the code?

Situation

When I got the ui-file as described below.
The QFormLayout has clearly a leftMargin property.
But when I set this property from the code, like:

Root->layout()->setProperty("leftMargin", 33);

This is not working.
There must be some magic at work here.

Expected

I expected actually the QMargins typed property to behave like the QRect typed ones.

 <property name="contentMargins">
  <margins>
    <left>6</left>
    <top>6</top>
    <right>6</right>
    <bottom>6</bottom>
 </margins>

Has anyone an idea why this is?

Maybe an irreversible mistake made in an earlier version :(

The mentioned Ui-file

 <?xml version="1.0" encoding="UTF-8"?>
 <ui version="4.0">
  <class>Form</class>
  <widget class="QWidget" name="Root">
   <property name="windowTitle">
    <string>Form</string>
   </property>
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>421</width>
     <height>100</height>
    </rect>
   </property>
   <layout class="QFormLayout" name="formLayout">
    <property name="leftMargin">
     <number>100</number>
    </property>
    <property name="topMargin">
     <number>6</number>
    </property>
    <property name="rightMargin">
     <number>6</number>
    </property>
    <property name="bottomMargin">
     <number>6</number>
    </property>
    <item row="0" column="0">
     <widget class="QLabel" name="label">
      <property name="text">
       <string>TextLabel</string>
      </property>
      <property name="buddy">
       <cstring>lineEdit</cstring>
      </property>
     </widget>
    </item>
    <item row="0" column="1">
     <widget class="QLineEdit" name="lineEdit"/>
    </item>
   </layout>
  </widget>
 </ui>

ChrisW67

There is no such property documented in QFormLayout or QLayout, so it is unsurprising you cannot set it that way.
To set the individual (or all) margins use a combination of QLayout::contentsMargins() and QLayout::setContentsMargins().

Here is an excerpt of what uic generates from your UI file:

...
        if (Root->objectName().isEmpty())
            Root->setObjectName(QString::fromUtf8("Root"));
        Root->resize(421, 100);
        formLayout = new QFormLayout(Root);
        formLayout->setObjectName(QString::fromUtf8("formLayout"));
        formLayout->setContentsMargins(100, 6, 6, 6);
...

Has anyone an idea why this is?
Maybe an irreversible mistake made in an earlier version :(

No, not a mistake, a design choice. QRect and QLayout are different beasts. There is also no requirement for a one-to-one mapping between the UI file XML and properties.

A.v.O

@ChrisW67 said in Where is QLayout property leftMargin:

No, not a mistake, a design choice. QRect and QLayout are different beasts. There is also no requirement for a one-to-one mapping between the UI file XML and properties.

It seems just inconsequent having ui-file have properties on an QObject that does not exist in the code.

By the way, I'm not using the ui-file to be compiled but using QFormBuilder with some of work-arounds to load/create modify and save ui-files from the Concept Application I'm working on.
That is why I'm missing the properties on the layout object.