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### 12. Using Qt Designer in your Project

The Qt Designer allows the easy construction of widgets and dialogs your application uses all by graphical means. You see the direct appearance of your dialog as it will be presented to the user. Using the Designer is usually the first step you would take after creating a new project with the KAppWizard to create your main view, the user interaction dialogs and, after finishing the graphical work, the code generation. This way, your project will contain all the usually considered "difficult" parts that normally would take a long time to implement. Then, the "rest" of your work is implementing the functionality in the generated code. This chapter deals with how to use the dialog editor to create your project widgets as well as what to do in case you see your widgets need corrections or additions during the further development process.

You can switch to the Designer either by selecting "Dialog Editor" from the "View" menu or by the according toolbar icon. When you are done, simply close the Designer window.

The following chapters give you an overview of the Designer's interface, how to create a new dialog initially and how set up the properties of the child widgets that your dialog contains. You also might want to have a look at the Designer tutorial by Trolltech which can also be found offline in KDevelops documentation browser.

### 12.1 Create a new dialog with the Designer

If you want to create a new dialog, simply add a new Designer file. Go to the menubar and choose File -> New. From the box choose "Qt Designer file" and enter a name, for example ktestdlg.ui. The .ui file is where the Designer stores the information about the dialog. Now the Designer will come up and ask you which kind of template you want to use for your class. Let's choose "QDialog" for our example. Now the Designer will present an empty form called "Form1" and the Property Editor. First, we need to give a human-readable name to our dialog, so we click on the form's background and choose a suitable name for it by changing the "name" property from "Form1" to something suitable. For consistancy reasons you might want to call the class just like the file it is stored in (or vice versa), so we call it KTestDlg.

In order to get used to the Designer, we recommend reading the Designer handbook. It provides vital information about the usage of the Designer ui and the concepts behind signals and slots handling inside the Designer.

#### Excursion: How ui files become source

The Designer stores the dialog class in a XML-compatible format. So, how do we get a C++ file out ouf the Designer file? Answer: KDevelop takes care of this! It adds the .ui file to the makefile which will then ensure that a header- and a source file will be created at compiletime. So you can just use it without really taking care of the source.

Because the files are recreated on every compile, you cannot implement your stuff directly into the generated files but have to derive from it. Read the next chapter to learn how this works.

### 12.2 Using your new dialog inside KDevelop

Next, we create a class inside KDevelop that will derive from the class created with the Designer. From the "Project" menu, choose "New Class". Enter "KTest" as classname. We we derive from KTestDlg, enter "KTestDlg" in "Baseclass". As QDialog (the baseclass for our Dialog) derives from QWidget, you also need to enable the "generate a QWidget-Childclass" checkbox. This are all information KDevelop requires. If you choose "OK", KDevelop will create two files called "ktest.cpp" and "ktest.h" which hold the "KTest" class that derives from "KTestDlg". Note that the "#include" statement for "ktestdlg.h" has already been inserted by KDevelop. Now you can simply implement all your functions and use the class inside your project.

### 12.3 Dialing with virtual slots

If you want to reimplement virtual slots, use the RMB Menu in the classbrower and choose "Add slot" or use the classwizzard button situated on the right of method combobox in KDevelops toolbar.

Note: Do NOT call the underlying virtual function (e.g. KTestDlg::slotCancel()) in the overriding method!

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