Class FieldEditor

  • Direct Known Subclasses:
    AbstractEncodingFieldEditor, BooleanFieldEditor, ColorFieldEditor, ComboFieldEditor, FontFieldEditor, ListEditor, RadioGroupFieldEditor, ScaleFieldEditor, StringFieldEditor

    public abstract class FieldEditor
    extends Object
    Abstract base class for all field editors.

    A field editor presents the value of a preference to the end user. The value is loaded from a preference store; if modified by the end user, the value is validated and eventually stored back to the preference store. A field editor reports an event when the value, or the validity of the value, changes.

    Field editors should be used in conjunction with a field editor preference page (FieldEditorPreferencePage) which coordinates everything and provides the message line which display messages emanating from the editor.

    This package contains ready-to-use field editors for various types of preferences:

    • BooleanFieldEditor - booleans
    • IntegerFieldEditor - integers
    • StringFieldEditor - text strings
    • RadioGroupFieldEditor - enumerations
    • ColorFieldEditor - RGB colors
    • FontFieldEditor - fonts
    • DirectoryFieldEditor - directories
    • FileFieldEditor - files
    • PathEditor - paths
    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected static int HORIZONTAL_GAP
      Gap between label and control.
      static String IS_VALID
      Property name constant (value "field_editor_is_valid") to signal a change in the validity of the value of this field editor.
      static String VALUE
      Property name constant (value "field_editor_value") to signal a change in the value of this field editor.
    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      protected FieldEditor()
      Creates a new field editor.
      protected FieldEditor​(String name, String labelText, Composite parent)
      Creates a new field editor.
    • Field Detail

      • IS_VALID

        public static final String IS_VALID
        Property name constant (value "field_editor_is_valid") to signal a change in the validity of the value of this field editor.
        See Also:
        Constant Field Values
      • VALUE

        public static final String VALUE
        Property name constant (value "field_editor_value") to signal a change in the value of this field editor.
        See Also:
        Constant Field Values
      • HORIZONTAL_GAP

        protected static final int HORIZONTAL_GAP
        Gap between label and control.
        See Also:
        Constant Field Values
    • Constructor Detail

      • FieldEditor

        protected FieldEditor()
        Creates a new field editor.
      • FieldEditor

        protected FieldEditor​(String name,
                              String labelText,
                              Composite parent)
        Creates a new field editor.
        Parameters:
        name - the name of the preference this field editor works on
        labelText - the label text of the field editor
        parent - the parent of the field editor's control
    • Method Detail

      • adjustForNumColumns

        protected abstract void adjustForNumColumns​(int numColumns)
        Adjusts the horizontal span of this field editor's basic controls.

        Subclasses must implement this method to adjust the horizontal span of controls so they appear correct in the given number of columns.

        The number of columns will always be equal to or greater than the value returned by this editor's getNumberOfControls method.

        Parameters:
        numColumns - the number of columns
      • applyFont

        protected void applyFont()
        Applies a font.

        The default implementation of this framework method does nothing. Subclasses should override this method if they want to change the font of the SWT control to a value different than the standard dialog font.

      • checkParent

        protected void checkParent​(Control control,
                                   Composite parent)
        Checks if the given parent is the current parent of the supplied control; throws an (unchecked) exception if they are not correctly related.
        Parameters:
        control - the control
        parent - the parent control
      • clearErrorMessage

        protected void clearErrorMessage()
        Clears the error message from the message line.
      • clearMessage

        protected void clearMessage()
        Clears the normal message from the message line.
      • convertHorizontalDLUsToPixels

        protected int convertHorizontalDLUsToPixels​(Control control,
                                                    int dlus)
        Returns the number of pixels corresponding to the given number of horizontal dialog units.

        Clients may call this framework method, but should not override it.

        Parameters:
        control - the control being sized
        dlus - the number of horizontal dialog units
        Returns:
        the number of pixels
      • convertVerticalDLUsToPixels

        protected int convertVerticalDLUsToPixels​(Control control,
                                                  int dlus)
        Returns the number of pixels corresponding to the given number of vertical dialog units.

        Clients may call this framework method, but should not override it.

        Parameters:
        control - the control being sized
        dlus - the number of vertical dialog units
        Returns:
        the number of pixels
      • createControl

        protected void createControl​(Composite parent)
        Creates this field editor's main control containing all of its basic controls.
        Parameters:
        parent - the parent control
      • dispose

        public void dispose()
        Disposes the SWT resources used by this field editor.
      • doFillIntoGrid

        protected abstract void doFillIntoGrid​(Composite parent,
                                               int numColumns)
        Fills this field editor's basic controls into the given parent.

        Subclasses must implement this method to create the controls for this field editor.

        Note this method may be called by the constructor, so it must not access fields on the receiver object because they will not be fully initialized.

        Parameters:
        parent - the composite used as a parent for the basic controls; the parent's layout must be a GridLayout
        numColumns - the number of columns
      • doLoad

        protected abstract void doLoad()
        Initializes this field editor with the preference value from the preference store.

        Subclasses must implement this method to properly initialize the field editor.

      • doLoadDefault

        protected abstract void doLoadDefault()
        Initializes this field editor with the default preference value from the preference store.

        Subclasses must implement this method to properly initialize the field editor.

      • doStore

        protected abstract void doStore()
        Stores the preference value from this field editor into the preference store.

        Subclasses must implement this method to save the entered value into the preference store.

      • fillIntoGrid

        public void fillIntoGrid​(Composite parent,
                                 int numColumns)
        Fills this field editor's basic controls into the given parent.
        Parameters:
        parent - the composite used as a parent for the basic controls; the parent's layout must be a GridLayout
        numColumns - the number of columns
      • fireStateChanged

        protected void fireStateChanged​(String property,
                                        boolean oldValue,
                                        boolean newValue)
        Informs this field editor's listener, if it has one, about a change to one of this field editor's boolean-valued properties. Does nothing if the old and new values are the same.
        Parameters:
        property - the field editor property name, such as VALUE or IS_VALID
        oldValue - the old value
        newValue - the new value
      • fireValueChanged

        protected void fireValueChanged​(String property,
                                        Object oldValue,
                                        Object newValue)
        Informs this field editor's listener, if it has one, about a change to one of this field editor's properties.
        Parameters:
        property - the field editor property name, such as VALUE or IS_VALID
        oldValue - the old value object, or null
        newValue - the new value, or null
      • getFieldEditorFontName

        public String getFieldEditorFontName()
        Returns the symbolic font name used by this field editor.
        Returns:
        the symbolic font name
      • getLabelControl

        protected Label getLabelControl()
        Returns the label control.
        Returns:
        the label control, or null if no label control has been created
      • getLabelControl

        public Label getLabelControl​(Composite parent)
        Returns this field editor's label component.

        The label is created if it does not already exist

        Parameters:
        parent - the parent
        Returns:
        the label control
      • getLabelText

        public String getLabelText()
        Returns this field editor's label text.
        Returns:
        the label text
      • getNumberOfControls

        public abstract int getNumberOfControls()
        Returns the number of basic controls this field editor consists of.
        Returns:
        the number of controls
      • getPreferenceName

        public String getPreferenceName()
        Returns the name of the preference this field editor operates on.
        Returns:
        the name of the preference
      • getPreferencePage

        @Deprecated
        protected PreferencePage getPreferencePage()
        Deprecated.
        use #getPage()
        Returns the preference page in which this field editor appears.
        Returns:
        the preference page, or null if none
      • getPage

        protected DialogPage getPage()
        Return the DialogPage that the receiver is sending updates to.
        Returns:
        DialogPage or null if it has not been set.
        Since:
        3.1
      • init

        protected void init​(String name,
                            String text)
        Initialize the field editor with the given preference name and label.
        Parameters:
        name - the name of the preference this field editor works on
        text - the label text of the field editor
      • isValid

        public boolean isValid()
        Returns whether this field editor contains a valid value.

        The default implementation of this framework method returns true. Subclasses wishing to perform validation should override both this method and refreshValidState.

        Returns:
        true if the field value is valid, and false if invalid
        See Also:
        refreshValidState()
      • load

        public void load()
        Initializes this field editor with the preference value from the preference store.
      • loadDefault

        public void loadDefault()
        Initializes this field editor with the default preference value from the preference store.
      • presentsDefaultValue

        public boolean presentsDefaultValue()
        Returns whether this field editor currently presents the default value for its preference.
        Returns:
        true if the default value is presented, and false otherwise
      • refreshValidState

        protected void refreshValidState()
        Refreshes this field editor's valid state after a value change and fires an IS_VALID property change event if warranted.

        The default implementation of this framework method does nothing. Subclasses wishing to perform validation should override both this method and isValid.

        See Also:
        isValid()
      • setFocus

        public void setFocus()
        Sets the focus to this field editor.

        The default implementation of this framework method does nothing. Subclasses may reimplement.

      • setLabelText

        public void setLabelText​(String text)
        Sets this field editor's label text. The label is typically presented to the left of the entry field.
        Parameters:
        text - the label text
      • setPreferenceName

        public void setPreferenceName​(String name)
        Sets the name of the preference this field editor operates on.

        The ability to change this allows the same field editor object to be reused for different preferences.

        For example:

                ...
          editor.setPreferenceName("font");
                editor.load();
         
        Parameters:
        name - the name of the preference
      • setPreferencePage

        @Deprecated
        public void setPreferencePage​(PreferencePage preferencePage)
        Deprecated.
        use #setPage(DialogPage)
        Sets the preference page in which this field editor appears.
        Parameters:
        preferencePage - the preference page, or null if none
      • setPage

        public void setPage​(DialogPage dialogPage)
        Set the page to be the receiver.
        Parameters:
        dialogPage -
        Since:
        3.1
      • setPreferenceStore

        public void setPreferenceStore​(IPreferenceStore store)
        Sets the preference store used by this field editor.
        Parameters:
        store - the preference store, or null if none
        See Also:
        getPreferenceStore()
      • setPresentsDefaultValue

        protected void setPresentsDefaultValue​(boolean booleanValue)
        Sets whether this field editor is presenting the default value.
        Parameters:
        booleanValue - true if the default value is being presented, and false otherwise
      • setPropertyChangeListener

        public void setPropertyChangeListener​(IPropertyChangeListener listener)
        Sets or removes the property change listener for this field editor.

        Note that field editors can support only a single listener.

        Parameters:
        listener - a property change listener, or null to remove
      • showErrorMessage

        protected void showErrorMessage​(String msg)
        Shows the given error message in the page for this field editor if it has one.
        Parameters:
        msg - the error message
      • showMessage

        protected void showMessage​(String msg)
        Shows the given message in the page for this field editor if it has one.
        Parameters:
        msg - the message
      • store

        public void store()
        Stores this field editor's value back into the preference store.
      • setButtonLayoutData

        protected void setButtonLayoutData​(Button button)
        Set the GridData on button to be one that is spaced for the current font.
        Parameters:
        button - the button the data is being set on.
      • setEnabled

        public void setEnabled​(boolean enabled,
                               Composite parent)
        Set whether or not the controls in the field editor are enabled.
        Parameters:
        enabled - The enabled state.
        parent - The parent of the controls in the group. Used to create the controls if required.