Module java.desktop
Package javax.swing.text

Class GlyphView

  • All Implemented Interfaces:
    Cloneable, SwingConstants, TabableView
    Direct Known Subclasses:
    LabelView
    public class GlyphView
extends View
implements TabableView, Cloneable
    A GlyphView is a styled chunk of text that represents a view mapped over an element in the text model. This view is generally responsible for displaying text glyphs using character level attributes in some way. An implementation of the GlyphPainter class is used to do the actual rendering and model/view translations. This separates rendering from layout and management of the association with the model.

    The view supports breaking for the purpose of formatting. The fragments produced by breaking share the view that has primary responsibility for the element (i.e. they are nested classes and carry only a small amount of state of their own) so they can share its resources.

    Since this view represents text that may have tabs embedded in it, it implements the TabableView interface. Tabs will only be expanded if this view is embedded in a container that does tab expansion. ParagraphView is an example of a container that does tab expansion.

    Since:
    1.3

    • Constructor Detail

      • GlyphView

        public GlyphView​(Element elem)
        Constructs a new view wrapped on an element.
        Parameters:
        elem - the element

    • Method Detail

      • clone

        protected final Object clone()
        Creates a shallow copy. This is used by the createFragment and breakView methods.
        Overrides:
        clone in class Object
        Returns:
        the copy
        See Also:
        Cloneable

      • getGlyphPainter

        public GlyphView.GlyphPainter getGlyphPainter()
        Fetch the currently installed glyph painter. If a painter has not yet been installed, and a default was not yet needed, null is returned.
        Returns:
        the currently installed glyph painter

      • setGlyphPainter

        public void setGlyphPainter​(GlyphView.GlyphPainter p)
        Sets the painter to use for rendering glyphs.
        Parameters:
        p - the painter to use for rendering glyphs

      • getText

        public Segment getText​(int p0,
                       int p1)
        Fetch a reference to the text that occupies the given range. This is normally used by the GlyphPainter to determine what characters it should render glyphs for.
        Parameters:
        p0 - the starting document offset >= 0
        p1 - the ending document offset >= p0
        Returns:
        the Segment containing the text

      • getBackground

        public Color getBackground()
        Fetch the background color to use to render the glyphs. If there is no background color, null should be returned. This is implemented to call StyledDocument.getBackground if the associated document is a styled document, otherwise it returns null.
        Returns:
        the background color to use to render the glyphs

      • getForeground

        public Color getForeground()
        Fetch the foreground color to use to render the glyphs. If there is no foreground color, null should be returned. This is implemented to call StyledDocument.getBackground if the associated document is a StyledDocument. If the associated document is not a StyledDocument, the associated components foreground color is used. If there is no associated component, null is returned.
        Returns:
        the foreground color to use to render the glyphs

      • getFont

        public Font getFont()
        Fetch the font that the glyphs should be based upon. This is implemented to call StyledDocument.getFont if the associated document is a StyledDocument. If the associated document is not a StyledDocument, the associated components font is used. If there is no associated component, null is returned.
        Returns:
        the font that the glyphs should be based upon

      • isUnderline

        public boolean isUnderline()
        Determine if the glyphs should be underlined. If true, an underline should be drawn through the baseline.
        Returns:
        if the glyphs should be underlined

      • isStrikeThrough

        public boolean isStrikeThrough()
        Determine if the glyphs should have a strikethrough line. If true, a line should be drawn through the center of the glyphs.
        Returns:
        if the glyphs should have a strikethrough line

      • isSubscript

        public boolean isSubscript()
        Determine if the glyphs should be rendered as superscript.
        Returns:
        if the glyphs should be rendered as superscript

      • isSuperscript

        public boolean isSuperscript()
        Determine if the glyphs should be rendered as subscript.
        Returns:
        if the glyphs should be rendered as subscript

      • getTabExpander

        public TabExpander getTabExpander()
        Fetch the TabExpander to use if tabs are present in this view.
        Returns:
        the TabExpander to use if tabs are present in this view

      • checkPainter

        protected void checkPainter()
        Check to see that a glyph painter exists. If a painter doesn't exist, a default glyph painter will be installed.

      • getPartialSpan

        public float getPartialSpan​(int p0,
                            int p1)
        Determines the span along the same axis as tab expansion for a portion of the view. This is intended for use by the TabExpander for cases where the tab expansion involves aligning the portion of text that doesn't have whitespace relative to the tab stop. There is therefore an assumption that the range given does not contain tabs.

        This method can be called while servicing the getTabbedSpan or getPreferredSize. It has to arrange for its own text buffer to make the measurements.

        Specified by:
        getPartialSpan in interface TabableView
        Parameters:
        p0 - the starting document offset >= 0
        p1 - the ending document offset >= p0
        Returns:
        the span >= 0

      • getStartOffset

        public int getStartOffset()
        Fetches the portion of the model that this view is responsible for.
        Overrides:
        getStartOffset in class View
        Returns:
        the starting offset into the model
        See Also:
        View.getStartOffset()

      • getEndOffset

        public int getEndOffset()
        Fetches the portion of the model that this view is responsible for.
        Overrides:
        getEndOffset in class View
        Returns:
        the ending offset into the model
        See Also:
        View.getEndOffset()

      • paint

        public void paint​(Graphics g,
                  Shape a)
        Renders a portion of a text style run.
        Specified by:
        paint in class View
        Parameters:
        g - the rendering surface to use
        a - the allocated region to render into

      • getMinimumSpan

        public float getMinimumSpan​(int axis)
        Determines the minimum span for this view along an axis.

        This implementation returns the longest non-breakable area within the view as a minimum span for View.X_AXIS.

        Overrides:
        getMinimumSpan in class View
        Parameters:
        axis - may be either View.X_AXIS or View.Y_AXIS
        Returns:
        the minimum span the view can be rendered into
        Throws:
        IllegalArgumentException - if the axis parameter is invalid
        See Also:
        View.getMinimumSpan(int)

      • getPreferredSpan

        public float getPreferredSpan​(int axis)
        Determines the preferred span for this view along an axis.
        Specified by:
        getPreferredSpan in class View
        Parameters:
        axis - may be either View.X_AXIS or View.Y_AXIS
        Returns:
        the span the view would like to be rendered into >= 0. Typically the view is told to render into the span that is returned, although there is no guarantee. The parent may choose to resize or break the view.
        See Also:
        View.getPreferredSpan(int)

      • getAlignment

        public float getAlignment​(int axis)
        Determines the desired alignment for this view along an axis. For the label, the alignment is along the font baseline for the y axis, and the superclasses alignment along the x axis.
        Overrides:
        getAlignment in class View
        Parameters:
        axis - may be either View.X_AXIS or View.Y_AXIS
        Returns:
        the desired alignment. This should be a value between 0.0 and 1.0 inclusive, where 0 indicates alignment at the origin and 1.0 indicates alignment to the full span away from the origin. An alignment of 0.5 would be the center of the view.

      • viewToModel

        public int viewToModel​(float x,
                       float y,
                       Shape a,
                       Position.Bias[] biasReturn)
        Provides a mapping from the view coordinate space to the logical coordinate space of the model.
        Specified by:
        viewToModel in class View
        Parameters:
        x - the X coordinate >= 0
        y - the Y coordinate >= 0
        a - the allocated region to render into
        biasReturn - either Position.Bias.Forward or Position.Bias.Backward is returned as the zero-th element of this array
        Returns:
        the location within the model that best represents the given point of view >= 0
        See Also:
        View.viewToModel(float, float, java.awt.Shape, javax.swing.text.Position.Bias[])

      • getBreakWeight

        public int getBreakWeight​(int axis,
                          float pos,
                          float len)
        Determines how attractive a break opportunity in this view is. This can be used for determining which view is the most attractive to call breakView on in the process of formatting. The higher the weight, the more attractive the break. A value equal to or lower than View.BadBreakWeight should not be considered for a break. A value greater than or equal to View.ForcedBreakWeight should be broken.

        This is implemented to forward to the superclass for the Y_AXIS. Along the X_AXIS the following values may be returned.

        View.ExcellentBreakWeight
        if there is whitespace proceeding the desired break location.
        View.BadBreakWeight
        if the desired break location results in a break location of the starting offset.
        View.GoodBreakWeight
        if the other conditions don't occur.
        This will normally result in the behavior of breaking on a whitespace location if one can be found, otherwise breaking between characters.
        Overrides:
        getBreakWeight in class View
        Parameters:
        axis - may be either View.X_AXIS or View.Y_AXIS
        pos - the potential location of the start of the broken view >= 0. This may be useful for calculating tab positions.
        len - specifies the relative length from pos where a potential break is desired >= 0.
        Returns:
        the weight, which should be a value between View.ForcedBreakWeight and View.BadBreakWeight.
        See Also:
        LabelView, ParagraphView, View.BadBreakWeight, View.GoodBreakWeight, View.ExcellentBreakWeight, View.ForcedBreakWeight

      • breakView

        public View breakView​(int axis,
                      int p0,
                      float pos,
                      float len)
        Breaks this view on the given axis at the given length. This is implemented to attempt to break on a whitespace location, and returns a fragment with the whitespace at the end. If a whitespace location can't be found, the nearest character is used.
        Overrides:
        breakView in class View
        Parameters:
        axis - may be either View.X_AXIS or View.Y_AXIS
        p0 - the location in the model where the fragment should start it's representation >= 0.
        pos - the position along the axis that the broken view would occupy >= 0. This may be useful for things like tab calculations.
        len - specifies the distance along the axis where a potential break is desired >= 0.
        Returns:
        the fragment of the view that represents the given span, if the view can be broken. If the view doesn't support breaking behavior, the view itself is returned.
        See Also:
        View.breakView(int, int, float, float)

      • createFragment

        public View createFragment​(int p0,
                           int p1)
        Creates a view that represents a portion of the element. This is potentially useful during formatting operations for taking measurements of fragments of the view. If the view doesn't support fragmenting (the default), it should return itself.

        This view does support fragmenting. It is implemented to return a nested class that shares state in this view representing only a portion of the view.

        Overrides:
        createFragment in class View
        Parameters:
        p0 - the starting offset >= 0. This should be a value greater or equal to the element starting offset and less than the element ending offset.
        p1 - the ending offset > p0. This should be a value less than or equal to the elements end offset and greater than the elements starting offset.
        Returns:
        the view fragment, or itself if the view doesn't support breaking into fragments
        See Also:
        LabelView

      • getNextVisualPositionFrom

        public int getNextVisualPositionFrom​(int pos,
                                     Position.Bias b,
                                     Shape a,
                                     int direction,
                                     Position.Bias[] biasRet)
                              throws BadLocationException
        Provides a way to determine the next visually represented model location that one might place a caret. Some views may not be visible, they might not be in the same order found in the model, or they just might not allow access to some of the locations in the model. This method enables specifying a position to convert within the range of >=0. If the value is -1, a position will be calculated automatically. If the value < -1, the BadLocationException will be thrown.
        Overrides:
        getNextVisualPositionFrom in class View
        Parameters:
        pos - the position to convert
        a - the allocated region to render into
        direction - the direction from the current position that can be thought of as the arrow keys typically found on a keyboard. This may be SwingConstants.WEST, SwingConstants.EAST, SwingConstants.NORTH, or SwingConstants.SOUTH.
        b - the bias
        biasRet - the returned bias
        Returns:
        the location within the model that best represents the next location visual position.
        Throws:
        BadLocationException - the given position is not a valid position within the document
        IllegalArgumentException - for an invalid direction