[Solved] Custom Layout plugin for Qt Designer does not work

Hello everyone!

I am trying to create a custom plugin for QtDesigner, but I fail so far.
I wanted a layout that, when it’s resized, it preserves the aspect ratio of its attached children. Using an online tutorial of how to make custom layouts I finaly did it and it works. But now I want to be able to use this custom layout from inside the QtDesigner. So, I created a new MSVC2008 project using the “Qt4 Designer Plugin” template. This template generates a lot of code. As you already know it creates a plugin class that inherits from QObject and QDesignerCustomWidgetInterface classes. In this code I changed only 2 functions:

• I changed the “isContainer()” function to return true.(but I also tried it with false)
• And I changed the createWidget() function. Here I had an other problem. This function returns a QWidget* while I want to create a CustomLayout* (which inherits QLayout). The only solution I could think of was to create a QWidget object and use “setLayout()” function to set on it my CustomLayout class object. And then return the QWidget object. Is this the right solution? here is my code:
  
  1. QWidget *CustomLayoutPlugin::createWidget(QWidget *parent)
  2. {
  3.     CustomLayout* layout = new CustomLayout(parent);
  4.     QWidget* widget = new QWidget(parent);
  5.     widget->setLayout(layout);
  6.     return widget;
  7. }
  
  After those 2 changes I compiled it, I took the debug and release lib and dlls files and I placed them under the “<QtFolder>\plugins\designer” path. So far so good. Now my CustomLayout appears in the toolbox of the QtDesigner but I have the following problems:
• When I click on the Layout to drag it on the form I get this message: “A class name mismatch occurred when creating a widget using the custom widget factory registered for widgets of class CustomLayout. It returned a widget of class QWidget”
• Regardless the message above, I can place the CustomLayout on the form but it does not seem to work. The widgets I attach to it do not move/resize/stretch at all. Like there is no Layout. Btw: The Class name at the Object inspector is QWidget and there is no CustomLayout attached to it.

What am I doing wrong? Thank you for your time.

Cheers!