KDE API Reference

Contents

KComboBox Class

A combo box with completion support. More...

Header: #include <KComboBox>
CMake: find_package(KF6 REQUIRED COMPONENTS Completion)
target_link_libraries(mytarget PRIVATE KF6::Completion)
Inherits: QComboBox and KCompletionBase
Inherited By:

KHistoryComboBox

Properties

Public Functions

KComboBox(QWidget *parent = nullptr)
KComboBox(bool rw, QWidget *parent = nullptr)
void addUrl(const QUrl &url)
void addUrl(const QIcon &icon, const QUrl &url)
bool autoCompletion() const
void changeUrl(int index, const QUrl &url)
void changeUrl(int index, const QIcon &icon, const QUrl &url)
KCompletionBox *completionBox(bool create = true)
bool contains(const QString &text) const
(since 5.78) QMenu *contextMenu() const
int cursorPosition() const
void insertUrl(int index, const QUrl &url)
void insertUrl(int index, const QIcon &icon, const QUrl &url)
virtual void setAutoCompletion(bool autocomplete)
void setEditUrl(const QUrl &url)
void setEditable(bool editable)
virtual void setLineEdit(QLineEdit *)
void setTrapReturnKey(bool trap)
bool trapReturnKey() const
bool urlDropsEnabled() const

Public Slots

void rotateText(KCompletionBase::KeyBindingType type)
virtual void setCompletedItems(const QStringList &items, bool autoSuggest = true) override
virtual void setCompletedText(const QString &) override
void setCurrentItem(const QString &item, bool insert = false, int index = -1)

Signals

void aboutToShowContextMenu(QMenu *contextMenu)
void completion(const QString &)
void completionModeChanged(KCompletion::CompletionMode)
void returnPressed(const QString &text)
void substringCompletion(const QString &)
void textRotation(KCompletionBase::KeyBindingType)

Protected Functions

virtual void setCompletedText(const QString &text, bool marked)

Protected Slots

virtual void makeCompletion(const QString &)

Detailed Description

This widget inherits from QComboBox and implements the following additional features:

  • A completion object that provides both automatic and manual text completion as well as text rotation
  • Configurable key bindings to activate these features
  • A popup menu item that can be used to allow the user to change the text completion mode on the fly.

    To support these additional features, KComboBox emits a few additional signals such as completion(const QString&) and textRotation(KeyBindingType).

    The completion signal can be connected to a slot that will assist the user in filling out the remaining text while the rotation signal can be used to traverse through all possible matches whenever text completion results in multiple matches. Additionally, the returnPressed(const QString &) signal is emitted when the user presses the Return or Enter key.

    KCombobox by default creates a completion object when you invoke the completionObject(bool) member function for the first time or explicitly use setCompletionObject(KCompletion*, bool) to assign your own completion object. Additionally, to make this widget more functional, KComboBox will by default handle text rotation and completion events internally whenever a completion object is created through either one of the methods mentioned above. If you do not need this functionality, simply use KCompletionBase::setHandleSignals(bool) or alternatively set the boolean parameter in the setCompletionObject() call to false.

    Beware: The completion object can be deleted on you, especially if a call such as setEditable(false) is made. Store the pointer at your own risk, and consider using QPointer<KCompletion>.

    The default key bindings for completion and rotation are determined from the global settings in KStandardShortcut. These values, however, can be overridden locally by invoking KCompletionBase::setKeyBinding(). The values can easily be reverted back to the default settings by calling useGlobalSettings(). An alternate method would be to default individual key bindings by using setKeyBinding() with the default second argument.

    A non-editable combo box only has one completion mode, CompletionAuto. Unlike an editable combo box, the CompletionAuto mode works by matching any typed key with the first letter of entries in the combo box. Please note that if you call setEditable(false) to change an editable combo box to a non-editable one, the text completion object associated with the combo box will no longer exist unless you created the completion object yourself and assigned it to this widget or you called setAutoDeleteCompletionObject(false). In other words do not do the following:

    KComboBox* combo = new KComboBox(true, this);
KCompletion* comp = combo->completionObject();
combo->setEditable(false);
comp->clear(); // CRASH: completion object does not exist anymore.

    A read-only KComboBox will have the same background color as a disabled KComboBox, but its foreground color will be the one used for the editable mode. This differs from QComboBox's implementation and is done to give visual distinction between the three different modes: disabled, read-only, and editable.

    Usage

    To enable the basic completion feature:

    KComboBox *combo = new KComboBox(true, this);
KCompletion *comp = combo->completionObject();
// Connect to the Return pressed signal - optional
connect(combo, &KComboBox::returnPressed, comp, [this](const QString &text) { addItem(text); });

// Provide the to be completed strings. Note that those are separate from the combo's
// contents.
comp->insertItems(someQStringList);

    To use your own completion object:

    KComboBox *combo = new KComboBox(this);
KUrlCompletion *comp = new KUrlCompletion();
// You can either delete the allocated completion object manually when you
// don't need it anymore, or call setAutoDeleteCompletionObject(true) and it
// will be deleted automatically
comp->setAutoDeleteCompletionObject(true);
combo->setCompletionObject(comp);
// Connect to the return pressed signal - optional
connect(combo, &KComboBox::returnPressed, comp, [this](const QString &text) { addItem(text); });

    Miscellaneous function calls:

    // Tell the widget not to handle completion and rotation
combo->setHandleSignals(false);
// Set your own completion key for manual completions.
combo->setKeyBinding(KCompletionBase::TextCompletion, Qt::End);

    TODO qdoc

    [Missing image html]

Property Documentation

autoCompletion : bool

Access functions:

bool autoCompletion() const
virtual void setAutoCompletion(bool autocomplete)

trapReturnKey : bool

Access functions:

bool trapReturnKey() const
void setTrapReturnKey(bool trap)

Member Function Documentation

[explicit] KComboBox::KComboBox(QWidget *parent = nullptr)

Constructs a read-only (or rather select-only) combo box.

parent The parent object of this widget

[explicit] KComboBox::KComboBox(bool rw, QWidget *parent = nullptr)

Constructs an editable or read-only combo box.

rw When true, widget will be editable.

parent The parent object of this widget.

[signal] void KComboBox::aboutToShowContextMenu(QMenu *contextMenu)

Emitted before the context menu is displayed.

The signal allows you to add your own entries into the context menu. Note that you must not store the pointer to the QPopupMenu since it is created and deleted on demand. Otherwise, you can crash your app.

contextMenu the context menu about to be displayed

void KComboBox::addUrl(const QUrl &url)

Appends url to the combo box.

QUrl::toDisplayString() is used so that the url is properly decoded for displaying.

void KComboBox::addUrl(const QIcon &icon, const QUrl &url)

Appends url with the icon to the combo box.

QUrl::toDisplayString() is used so that the url is properly decoded for displaying.

bool KComboBox::autoCompletion() const

Returns true if the current completion mode is set to automatic. See its more comprehensive replacement completionMode().

Returns true when completion mode is automatic.

Note: Getter function for property autoCompletion.

See also setAutoCompletion().

void KComboBox::changeUrl(int index, const QUrl &url)

Replaces the item at position index with url.

QUrl::toDisplayString() is used so that the url is properly decoded for displaying.

void KComboBox::changeUrl(int index, const QIcon &icon, const QUrl &url)

Replaces the item at position index with url and icon.

QUrl::toDisplayString() is used so that the url is properly decoded for displaying.

[signal] void KComboBox::completion(const QString &)

Emitted when the completion key is pressed.

The argument is the current text being edited.

Note that this signal is not available when the widget is non-editable or the completion mode is set to CompletionNone.

KCompletionBox *KComboBox::completionBox(bool create = true)

This method will create a completion box by calling KLineEdit::completionBox, if none is there yet.

create Set this to false if you don't want the box to be created i.e. to test if it is available. Returns the completion box that is used in completion mode CompletionPopup and CompletionPopupAuto.

[signal] void KComboBox::completionModeChanged(KCompletion::CompletionMode)

Emitted whenever the completion mode is changed by the user through the context menu.

bool KComboBox::contains(const QString &text) const

Convenience method which iterates over all items and checks if any of them is equal to text.

If text is an empty string, false is returned.

Returns true if an item with the string text is in the combo box.

[since 5.78] QMenu *KComboBox::contextMenu() const

Pointer to KLineEdit's context menu, or nullptr if it does not exist at the given moment.

This function was introduced in 5.78.

int KComboBox::cursorPosition() const

Returns the current cursor position.

This method always returns a -1 if the combo box is not editable (read-only).

Returns current cursor position.

void KComboBox::insertUrl(int index, const QUrl &url)

Inserts url at position index into the combo box.

QUrl::toDisplayString() is used so that the url is properly decoded for displaying.

void KComboBox::insertUrl(int index, const QIcon &icon, const QUrl &url)

Inserts url with the icon at position index into the combo box.

QUrl::toDisplayString() is used so that the url is properly decoded for displaying.

[virtual protected slot] void KComboBox::makeCompletion(const QString &)

Completes text according to the completion mode.

Note: This method is not invoked if the completion mode is set to CompletionNone. Also if the mode is set to CompletionShell and multiple matches are found, this method will complete the text to the first match with a beep to indicate that there are more matches. Then any successive completion key event iterates through the remaining matches. This way the rotation functionality is left to iterate through the list as usual.

[signal] void KComboBox::returnPressed(const QString &text)

Emitted when the user presses the Return or Enter key.

The argument is the current text being edited.

Note: This signal is only emitted when the widget is editable.

[slot] void KComboBox::rotateText(KCompletionBase::KeyBindingType type)

Iterates through all possible matches of the completed text or the history list.

Depending on the value of the argument, this function either iterates through the history list of this widget or all the possible matches in whenever multiple matches result from a text completion request. Note that the all-possible-match iteration will not work if there are no previous matches, i.e. no text has been completed and the *nix shell history list rotation is only available if the insertion policy for this widget is set either QComobBox::AtTop or QComboBox::AtBottom. For other insertion modes whatever has been typed by the user when the rotation event was initiated will be lost.

type The key binding invoked.

[virtual] void KComboBox::setAutoCompletion(bool autocomplete)

If true, the completion mode will be set to automatic. Otherwise, it is defaulted to the global setting. This method has been replaced by the more comprehensive setCompletionMode().

autocomplete Flag to enable/disable automatic completion mode.

Note: Setter function for property autoCompletion.

See also autoCompletion().

[override virtual slot] void KComboBox::setCompletedItems(const QStringList &items, bool autoSuggest = true)

Reimplements: KCompletionBase::setCompletedItems(const QStringList &items, bool autoSuggest).

Sets items into the completion box if completionMode() is CompletionPopup. The popup will be shown immediately.

[override virtual slot] void KComboBox::setCompletedText(const QString &)

Reimplements: KCompletionBase::setCompletedText(const QString &text).

Sets the completed text in the line edit appropriately.

This function is an implementation for KCompletionBase::setCompletedText.

[virtual protected] void KComboBox::setCompletedText(const QString &text, bool marked)

This function sets the line edit text and highlights the text appropriately if the boolean value is set to true.

text The text to be set in the line edit

marked Whether the text inserted should be highlighted

[slot] void KComboBox::setCurrentItem(const QString &item, bool insert = false, int index = -1)

Selects the first item that matches item.

If there is no such item, it is inserted at position index if insert is true. Otherwise, no item is selected.

void KComboBox::setEditUrl(const QUrl &url)

Sets url into the edit field of the combo box.

It uses QUrl::toDisplayString() so that the url is properly decoded for displaying.

void KComboBox::setEditable(bool editable)

Reimplemented so that setEditable(true) creates a KLineEdit instead of QLineEdit.

Note that QComboBox::setEditable is not virtual, so do not use a KComboBox in a QComboBox pointer.

[virtual] void KComboBox::setLineEdit(QLineEdit *)

Reimplemented for internal reasons. API remains unaffected. Note that QComboBox::setLineEdit is not virtual in Qt4, do not use a KComboBox in a QComboBox pointer.

NOTE: Only editable combo boxes can have a line editor. As such any attempt to assign a line edit to a non-editable combo box will simply be ignored.

void KComboBox::setTrapReturnKey(bool trap)

By default, KComboBox recognizes Key_Return and Key_Enter and emits the returnPressed(const QString &) signal, but it also lets the event pass, for example causing a dialog's default button to be called.

Call this method with trap set to true to make KComboBox stop these events. The signals will still be emitted of course.

Note: This only affects editable combo boxes.

Note: Setter function for property trapReturnKey.

See also trapReturnKey() and setTrapReturnKey().

[signal] void KComboBox::substringCompletion(const QString &)

Emitted when the shortcut for substring completion is pressed.

[signal] void KComboBox::textRotation(KCompletionBase::KeyBindingType)

Emitted when the text rotation key bindings are pressed.

The argument indicates which key binding was pressed. In this case this can be either one of four values: PrevCompletionMatch, NextCompletionMatch, RotateUp or RotateDown.

Note that this signal is not emitted if the completion mode is set to CompletionNone.

See also KCompletionBase::setKeyBinding(), for, and details.

bool KComboBox::trapReturnKey() const

Returns true if Key_Return or Key_Enter input events will be stopped or false if they will be propagated.

Note: Getter function for property trapReturnKey.

See also setTrapReturnKey().

bool KComboBox::urlDropsEnabled() const

Returns true when decoded URL drops are enabled