Package docking.widgets.autocomplete

Class TextFieldAutocompleter<T>

  • Type Parameters:
    T - the type of suggestions presented by this autocompleter.
    public class TextFieldAutocompleter<T>
extends java.lang.Object
    An autocompleter that may be attached to one or more JTextField. Each autocompleter instance has one associated window (displaying the list of suggestions) and one associated model (generating the list of suggestions). Thus, the list can only be active on one of the attached text fields at a time. This is usually the desired behavior, and it allows for one autocompleter to be reused on many fields. Behavior is undefined when multiple autocompleters are attached to the same text field. More likely, you should implement a composite model if you wish to present completions from multiple models on a single text field. By default, the autocompleter is activated when the user presses CTRL-SPACE, at which point, the model is queried for possible suggestions. The completer gives the model all the text preceding the current field's caret. This behavior can be changed by overriding the getPrefix(JTextField) method. This may be useful, e.g., to obtain a prefix for the current word, rather than the full field contents, preceding the caret. The list is displayed such that its top-left corner is placed directly under the current field's caret. As the user continues typing, the suggestions are re-computed, and the list tracks with the caret. This positioning behavior can be modified by overriding the getCompletionWindowPosition() method. As a convenience, the getCaretPositionOnScreen(JTextField) method is available to compute the default position. Whether or not the list is currently displayed, when the user presses CTRL-SPACE, if only one completion is possible, it is automatically activated. This logic is applied again and again, until either no suggestions are given, or more than one suggestion is given (or until the autocompleter detects an infinite loop). This behavior can by modified on an item-by-item basis by overriding the getCompletionCanDefault(T) method. This same behavior can be activated by calling the startCompletion(JTextField) method, which may be useful, e.g., to bind a different key sequence to start autocompletion. The appearance of each item in the suggestion list can be modified by overriding the various getCompletion... methods. Note that it's possible for an item to be displayed one way, but cause the insertion of different text. In any case, it is best to ensure any modification produces an intuitive behavior. The simplest use case is to create a text field, create an autocompleter with a custom model, and then attach and show. 
     JTextField field = new JTextField();
 
 AutocompletionModel<String> model = new AutocompletionModel<String>() {
     @Override
     public Collection<String> computeCompletions(String text) {
         ... // Populate the completion list based on the given prefix.
     }
 }
 TextFieldAutocompleter<String> completer = new TextFieldAutocompleter<String>(model);
 completer.attachTo(field);
 ... // Add the field to, e.g., a dialog, and show.

    • Constructor Detail

      • TextFieldAutocompleter

        public TextFieldAutocompleter​(AutocompletionModel<T> model)
        Create a new autocompleter associated with the given model.
        Parameters:
        model - the model giving the suggestions.

    • Method Detail

      • dispose

        public void dispose()

      • addContent

        protected void addContent​(javax.swing.JPanel contentPanel)

      • updateDisplayLocation

        public void updateDisplayLocation()
        Recompute the display location and move with list window. This is useful, e.g., when the window containing the associated text field(s) moves.

      • updateDisplayContents

        protected void updateDisplayContents()
        Update the contents of the suggestion list. This entails taking the prefix, querying the model, and rendering the list.

      • destroyCompletionWindow

        protected void destroyCompletionWindow()
        Dispose of the completion window resources.

      • buildCompletionWindow

        protected void buildCompletionWindow()
        Build the completion window, parented to the attached field that last had focus.

      • setCompletionListVisible

        public void setCompletionListVisible​(boolean visible)
        Show or hide the completion list window
        Parameters:
        visible - true to show, false to hide

      • isCompletionListVisible

        public boolean isCompletionListVisible()
        Check if the completion list window is visible. If it is visible, this implies that the user is actively using the autocompleter.
        Returns:
        true if shown, false if hidden.

      • getPrefix

        protected java.lang.String getPrefix​(javax.swing.JTextField field)
        Gets the prefix from the given text field, used to query the model.
        Parameters:
        field - an attached field, usually the one with focus.
        Returns:
        the prefix to use as the query.

      • getCompletionWindowPosition

        protected java.awt.Point getCompletionWindowPosition()
        Get the preferred location (on screen) of the completion list window. Typically, this is a location near the focused field. Ideally, it is positioned such that the displayed suggestions coincide with the applicable text in the focused field. For example, if the suggestions display some portion of the prefix, the window could be positioned such that the portion in the suggestion appears directly below the same portion in the field.
        Returns:
        the point giving the top-left corner of the completion window

      • getDefaultCompletionWindowDimension

        protected java.awt.Dimension getDefaultCompletionWindowDimension()
        Get the preferred dimensions of the completion list window. Typically, this is the width of the focused field.
        Returns:
        the dimension giving the preferred height and width. A value can be -1 to indicate no preference.

      • getCaretPositionOnScreen

        protected java.awt.Point getCaretPositionOnScreen​(javax.swing.JTextField field)
        A convenience function that returns the bottom on-screen position of the given field's caret.
        Parameters:
        field - the field, typically the one having focus
        Returns:
        the on-screen position of the caret's bottom.

      • buildListCellRenderer

        protected javax.swing.ListCellRenderer<? super T> buildListCellRenderer()
        Builds the list cell renderer for the autocompletion list. A programmer may override this if the various getCompletion... methods prove insufficient for customizing the display of the suggestions. Please remember that JLabels can render HTML, so getCompletionDisplay(T) is quite powerful with the default AutocompletionCellRenderer.
        Returns:
        a list cell renderer for the completion list.

      • attachTo

        public boolean attachTo​(javax.swing.JTextField field)
        Attach the autocompleter to the given text field. If this method is never called, then the autocompleter can never appear.
        Parameters:
        field - the field that will gain this autocompletion feature
        Returns:
        true, if this field is not already attached

      • detachFrom

        public boolean detachFrom​(javax.swing.JTextField field)
        Deprive the given field of this autocompleter.
        Parameters:
        field - the field that will lose this autocompletion feature
        Returns:
        true, if this field was actually attached

      • activateCurrentCompletion

        protected void activateCurrentCompletion()
        Cause the currently-selected suggestion to be activated. By default, this is called when the user presses ENTER or clicks a suggestion.

      • fireAutocompletionListeners

        protected boolean fireAutocompletionListeners​(AutocompletionEvent<T> ev)
        Fire the registered autocompletion listeners on the given event. Each registered listener is invoked in order of registration. If any listener consumes the event, then later-registered listeners will not be notified of the event. If any listener cancels the event, then the suggested text will not be inserted.
        Parameters:
        ev - the event
        Returns:
        true, if no listener cancelled the event

      • addAutocompletionListener

        public void addAutocompletionListener​(AutocompletionListener<T> l)
        Register the given auto-completion listener
        Parameters:
        l - the listener to register

      • removeAutocompletionListener

        public void removeAutocompletionListener​(AutocompletionListener<T> l)
        Unregister the given auto-completion listener
        Parameters:
        l - the listener to unregister

      • getAutocompletionListeners

        public AutocompletionListener<T>[] getAutocompletionListeners()
        Get all the registered auto-completion listeners
        Returns:
        an array of registered listeners

      • getListeners

        public <T> T[] getListeners​(java.lang.Class<T> listenerType)
        Get all registered listeners of the given type
        Parameters:
        listenerType - the type of listeners to get
        Returns:
        an array of registered listeners

      • getCompletionText

        protected java.lang.String getCompletionText​(T sel)
        Get the text to insert when the given suggestion is activated
        Parameters:
        sel - the activated suggestion
        Returns:
        the text to insert

      • getCompletionDisplay

        protected java.lang.String getCompletionDisplay​(T sel)
        Get the (possibly HTML) text to display for the given suggestion in the list
        Parameters:
        sel - the suggestion to display
        Returns:
        the text or HTML representing the suggestion

      • getCompletionForeground

        protected java.awt.Color getCompletionForeground​(T sel,
                                                 boolean isSelected,
                                                 boolean cellHasFocus)
        Get the foreground color to display for the given suggestion in the list
        Parameters:
        sel - the suggestion to display
        isSelected - true if the suggestion is currently selected
        cellHasFocus - true if the suggestion currently has focus
        Returns:
        the foreground color for the suggestion

      • getCompletionBackground

        protected java.awt.Color getCompletionBackground​(T sel,
                                                 boolean isSelected,
                                                 boolean cellHasFocus)
        Get the background color to display for the given suggestion in the list
        Parameters:
        sel - the suggestion to display
        isSelected - true if the suggestion is currently selected
        cellHasFocus - true if the suggestion currently has focus
        Returns:
        the background color for the suggestion

      • getCompletionIcon

        protected javax.swing.Icon getCompletionIcon​(T sel,
                                             boolean isSelected,
                                             boolean cellHasFocus)
        Get the icon to display with the given suggestion in the list
        Parameters:
        sel - the suggestion to display
        isSelected - true if the suggestion is currently selected
        cellHasFocus - true if the suggestion currently has focus
        Returns:
        the icon to display with the suggestion

      • getCompletionFont

        protected java.awt.Font getCompletionFont​(T sel,
                                          boolean isSelected,
                                          boolean cellHasFocus)
        Get the font for the given suggestion in the list
        Parameters:
        sel - the suggestion to display
        isSelected - true if the suggestion is currently selected
        cellHasFocus - true if the suggestion currently has focus
        Returns:
        the font to use

      • getCompletionCanDefault

        protected boolean getCompletionCanDefault​(T sel)
        Decide whether the given suggestion can be automatically activated. When autocompletion is started (via startCompletion(JTextField)) or when the user presses CTRL-SPACE, if there is only a single suggestion, it is taken automatically, and the process repeats until there is not a sole suggestion. Before the suggestion is taken, though, it calls this method. If it returns false, the single suggestion is displayed in a 1-long list instead. This is useful to prevent consequential actions from being automatically activated by the autocompleter.
        Parameters:
        sel - the potentially auto-activated suggestion.
        Returns:
        true to permit auto-activation, false to prevent it.

      • startCompletion

        public void startCompletion​(javax.swing.JTextField field)
        Starts the autocompleter on the given text field. First, this repeatedly attempts auto-activation. When there are many suggestions, or when auto-activation is prevented (see getCompletionCanDefault(T)), a list is displayed (usually below the caret) containing the suggestions given the fields current contents. The list remains open until either the user cancels it (usually via ESC) or the user activates a suggestion. NOTE: The text field must already be attached.
        Parameters:
        field - the field on which to start autocompletion.

      • select

        protected void select​(int index)
        Cause the suggestion at the given index to be selected
        Parameters:
        index - the index of the selection

      • selectNext

        protected void selectNext()
        Cause the next suggestion to be selected, wrapping if applicable

      • selectPrev

        protected void selectPrev()
        Cause the previous suggestion to be selected, wrapping if applicable

      • selectNextPage

        protected void selectNextPage()
        Advance the selection down a page

      • selectPrevPage

        protected void selectPrevPage()
        Advance the selection up a page

      • selectFirst

        protected void selectFirst()
        Select the first suggestion

      • selectLast

        protected void selectLast()
        Select the last suggestion