kcombobox.h

/*
    This file is part of the KDE libraries
 
    SPDX-FileCopyrightText: 2000, 2001 Dawit Alemayehu <adawit@kde.org>
    SPDX-FileCopyrightText: 2000, 2001 Carsten Pfeiffer <pfeiffer@kde.org>
 
    SPDX-License-Identifier: LGPL-2.1-or-later
*/
 
#ifndef KCOMBOBOX_H
#define KCOMBOBOX_H
 
#include <kcompletion.h>
 
#include <kcompletion_export.h>
#include <kcompletionbase.h>
 
#include <QComboBox>
#include <memory>
 
class KCompletionBox;
class KComboBoxPrivate;
 
class QLineEdit;
class QMenu;
 
/**
 * @class KComboBox kcombobox.h KComboBox
 *
 * @short A combo box with completion support.
 *
 * This widget inherits from QComboBox and implements the following
 * additional features:
 *   @li a completion object that provides both automatic
 * and manual text completion as well as text rotation
 *   @li configurable key bindings to activate these features
 *   @li 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 @c setCompletionObject() call to @c 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, @c 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:
 *
 * \code
 * KComboBox* combo = new KComboBox(true, this);
 * KCompletion* comp = combo->completionObject();
 * combo->setEditable(false);
 * comp->clear(); // CRASH: completion object does not exist anymore.
 * \endcode
 *
 *
 * 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.
 *
 * \b Usage
 *
 * To enable the basic completion feature:
 *
 * \code
 * 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);
 * \endcode
 *
 * To use your own completion object:
 *
 * \code
 * 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); });
 * \endcode
 *
 * Miscellaneous function calls:
 *
 * \code
 * // 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);
 * \endcode
 *
 * \image html kcombobox.png "KComboBox widgets, one non-editable, one editable with KUrlCompletion"
 *
 * @author Dawit Alemayehu <adawit@kde.org>
 */
class KCOMPLETION_EXPORT KComboBox : public QComboBox, public KCompletionBase // krazy:exclude=qclasses
{
    Q_OBJECT
    Q_PROPERTY(bool autoCompletion READ autoCompletion WRITE setAutoCompletion)
    Q_PROPERTY(bool trapReturnKey READ trapReturnKey WRITE setTrapReturnKey)
 
public:
    /**
     * Constructs a read-only (or rather select-only) combo box.
     *
     * @param parent The parent object of this widget
     */
    explicit KComboBox(QWidget *parent = nullptr);
 
    /**
     * Constructs an editable or read-only combo box.
     *
     * @param rw When @c true, widget will be editable.
     * @param parent The parent object of this widget.
     */
    explicit KComboBox(bool rw, QWidget *parent = nullptr);
 
    /**
     * Destructor.
     */
    ~KComboBox() override;
 
    /**
     * Sets @p url into the edit field of the combo box.
     *
     * It uses QUrl::toDisplayString() so that the url is properly decoded for
     * displaying.
     */
    void setEditUrl(const QUrl &url);
 
    /**
     * Appends @p url to the combo box.
     *
     * QUrl::toDisplayString() is used so that the url is properly decoded
     * for displaying.
     */
    void addUrl(const QUrl &url);
 
    /**
     * Appends @p url with the @p icon to the combo box.
     *
     * QUrl::toDisplayString() is used so that the url is properly decoded
     * for displaying.
     */
    void addUrl(const QIcon &icon, const QUrl &url);
 
    /**
     * Inserts @p url at position @p index into the combo box.
     *
     * QUrl::toDisplayString() is used so that the url is properly decoded
     * for displaying.
     */
    void insertUrl(int index, const QUrl &url);
 
    /**
     * Inserts @p url with the @p icon at position @p index into
     * the combo box.
     *
     * QUrl::toDisplayString() is used so that the url is
     * properly decoded for displaying.
     */
    void insertUrl(int index, const QIcon &icon, const QUrl &url);
 
    /**
     * Replaces the item at position @p index with @p url.
     *
     * QUrl::toDisplayString() is used so that the url is properly decoded
     * for displaying.
     */
    void changeUrl(int index, const QUrl &url);
 
    /**
     * Replaces the item at position @p index with @p url and @p icon.
     *
     * QUrl::toDisplayString() is used so that the url is properly decoded
     * for displaying.
     */
    void changeUrl(int index, const QIcon &icon, const QUrl &url);
 
    /**
     * Returns the current cursor position.
     *
     * This method always returns a -1 if the combo box is @em not
     * editable (read-only).
     *
     * @return Current cursor position.
     */
    int cursorPosition() const;
 
    /**
     * Reimplemented from QComboBox.
     *
     * If @c 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().
     *
     * @param autocomplete Flag to enable/disable automatic completion mode.
     */
    virtual void setAutoCompletion(bool autocomplete);
 
    /**
     * Reimplemented from QComboBox.
     *
     * Returns @c true if the current completion mode is set
     * to automatic. See its more comprehensive replacement
     * completionMode().
     *
     * @return @c true when completion mode is automatic.
     */
    bool autoCompletion() const;
 
    /**
     * Returns @c true when decoded URL drops are enabled
     */
    bool urlDropsEnabled() const;
 
    /**
     * Convenience method which iterates over all items and checks if
     * any of them is equal to @p text.
     *
     * If @p text is an empty string, @c false
     * is returned.
     *
     * @return @c true if an item with the string @p text is in the combo box.
     */
    bool contains(const QString &text) const;
 
    /**
     * 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 @p 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.
     *
     * @see setTrapReturnKey()
     */
    void setTrapReturnKey(bool trap);
 
    /**
     * @return @c true if Key_Return or Key_Enter input events will be stopped or
     * @c false if they will be propagated.
     *
     * @see setTrapReturnKey()
     */
    bool trapReturnKey() const;
 
    /**
     * This method will create a completion box by calling
     * KLineEdit::completionBox, if none is there yet.
     *
     * @param 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.
     */
    KCompletionBox *completionBox(bool create = true);
 
    /**
     * 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.
     */
    virtual void setLineEdit(QLineEdit *);
 
    /**
     * 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.
     */
    void setEditable(bool editable);
 
    /**
     * Pointer to KLineEdit's context menu, or nullptr if it does not exist at
     * the given moment.
     *
     * @since 5.78
     */
    QMenu *contextMenu() const;
 
    QSize minimumSizeHint() const override;
 
Q_SIGNALS:
    /**
     * 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.
     *
    */
    void returnPressed(const QString &text); // clazy:exclude=overloaded-signal
 
    /**
     * Emitted when the completion key is pressed.
     *
     * The argument is the current text being edited.
     *
     * Note that this signal is @em not available when the widget is non-editable
     * or the completion mode is set to @c CompletionNone.
     */
    void completion(const QString &);
 
    /**
     * Emitted when the shortcut for substring completion is pressed.
     */
    void substringCompletion(const QString &);
 
    /**
     * 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: @c PrevCompletionMatch,
     * @c NextCompletionMatch, @c RotateUp or @c RotateDown.
     *
     * Note that this signal is @em not emitted if the completion
     * mode is set to CompletionNone.
     *
     * @see KCompletionBase::setKeyBinding() for details
     */
    void textRotation(KCompletionBase::KeyBindingType);
 
    /**
     * Emitted whenever the completion mode is changed by the user
     * through the context menu.
     */
    void completionModeChanged(KCompletion::CompletionMode);
 
    /**
     * Emitted before the context menu is displayed.
     *
     * The signal allows you to add your own entries into the context menu.
     * Note that you <em>must not</em> store the pointer to the QPopupMenu since it is
     * created and deleted on demand. Otherwise, you can crash your app.
     *
     * @param contextMenu the context menu about to be displayed
     */
    void aboutToShowContextMenu(QMenu *contextMenu);
 
public Q_SLOTS:
 
    /**
     * 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 @c QComobBox::AtTop or @c QComboBox::AtBottom.
     * For other insertion modes whatever has been typed by the user
     * when the rotation event was initiated will be lost.
     *
     * @param type The key binding invoked.
     */
    void rotateText(KCompletionBase::KeyBindingType type);
 
    /**
     * Sets the completed text in the line edit appropriately.
     *
     * This function is an implementation for
     * KCompletionBase::setCompletedText.
     */
    void setCompletedText(const QString &) override;
 
    /**
     * Sets @p items into the completion box if completionMode() is
     * CompletionPopup. The popup will be shown immediately.
     */
    void setCompletedItems(const QStringList &items, bool autoSuggest = true) override;
 
    /**
     * Selects the first item that matches @p item.
     *
     * If there is no such item, it is inserted at position @p index
     * if @p insert is true. Otherwise, no item is selected.
     */
    void setCurrentItem(const QString &item, bool insert = false, int index = -1);
 
protected Q_SLOTS:
 
    /**
     * Completes text according to the completion mode.
     *
     * @note This method is not invoked if the completion mode is
     * set to @c CompletionNone. Also if the mode is set to @c 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.
     */
    virtual void makeCompletion(const QString &);
 
protected:
    /**
     * This function sets the line edit text and
     * highlights the text appropriately if the boolean
     * value is set to true.
     *
     * @param text The text to be set in the line edit
     * @param marked Whether the text inserted should be highlighted
     */
    virtual void setCompletedText(const QString &text, bool marked);
 
protected:
    KCOMPLETION_NO_EXPORT KComboBox(KComboBoxPrivate &dd, QWidget *parent);
 
protected:
    std::unique_ptr<KComboBoxPrivate> const d_ptr;
 
private:
    Q_DECLARE_PRIVATE(KComboBox)
};
 
#endif