Extension Example▲

The Extension application lets the user add search parameters in a dialog and launch a simple or advanced search.
The simple search has two options: Match case and Search from start. The advanced search offers search for Whole words, Search backward, and Search selection. The application starts with simple search as the default. Click the More button to show the advanced search options:

FindDialog Class Definition▲
The FindDialog class inherits QDialog. QDialog is the base class for dialog windows. A dialog window is a top-level window mostly used for short-term tasks and brief communications with the user.
class
FindDialog : public
QDialog
{
Q_OBJECT
public
:
FindDialog(QWidget *
parent =
0
);
private
:
QLabel *
label;
QLineEdit *
lineEdit;
QCheckBox *
caseCheckBox;
QCheckBox *
fromStartCheckBox;
QCheckBox *
wholeWordsCheckBox;
QCheckBox *
searchSelectionCheckBox;
QCheckBox *
backwardCheckBox;
QDialogButtonBox *
buttonBox;
QPushButton *
findButton;
QPushButton *
moreButton;
QWidget *
extension;
}
;
The FindDialog widget is the main application widget, and displays the application's search options and controlling buttons.
In addition to the constructor, there are several child widgets:
-
A QLineEdit with an associated QLabel to let the user type a word to search for.
-
Several QCheckBoxes to facilitate the search options.
-
Three QPushButtons:
-
the Find button to start a search
-
the More button to enable an advanced search
-
a QWidget representing the application's extension part
-
FindDialog Class Implementation▲
Create the standard child widgets for the simple search in the constructor: the QLineEdit with the associated QLabel, two {QCheckBox}es and all the QPushButtons.
FindDialog::
FindDialog(QWidget *
parent)
:
QDialog(parent)
{
label =
new
QLabel(tr("Find &what:"
));
lineEdit =
new
QLineEdit;
label-&
gt;setBuddy(lineEdit);
caseCheckBox =
new
QCheckBox(tr("Match &case"
));
fromStartCheckBox =
new
QCheckBox(tr("Search from &start"
));
fromStartCheckBox-&
gt;setChecked(true
);
findButton =
new
QPushButton(tr("&Find"
));
findButton-&
gt;setDefault(true
);
moreButton =
new
QPushButton(tr("&More"
));
moreButton-&
gt;setCheckable(true
);
This snippet illustrates how you can define a shortcut key for a widget. A shortcut should be defined by putting the ampersand character (&) in front of the letter that should become the shortcut. For example, for Find what, pressing Alt and w transfers focus to the QLineEdit widget. Shortcuts can also be used for checking on or off a checkmark. For example, pressing Alt and c puts the check mark on Match Case if it was unchecked and vice versa. It is the QLabel::setBuddy() method that links a widget to the shortcut character if it has been defined.
Set the Find button's default property to true, using the QPushButton::setDefault() function. Then the push button will be pressed if the user presses the Enter (or Return) key. Note that a QDialog can only have one default button.
extension =
new
QWidget;
wholeWordsCheckBox =
new
QCheckBox(tr("&Whole words"
));
backwardCheckBox =
new
QCheckBox(tr("Search &backward"
));
searchSelectionCheckBox =
new
QCheckBox(tr("Search se&lection"
));
Create the extension widget, and the QCheckBoxes associated with the advanced search options.
buttonBox =
new
QDialogButtonBox(Qt::
Vertical);
buttonBox-&
gt;addButton(findButton, QDialogButtonBox::
ActionRole);
buttonBox