Class GlyphView

java.lang.Object
javax.swing.text.View
javax.swing.text.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

Nested Class Summary

Modifier and Type Class Description
static class  GlyphView.GlyphPainter
A class to perform rendering of the glyphs.

Field Summary

Fields declared in class javax.swing.text.View

BadBreakWeight, ExcellentBreakWeight, ForcedBreakWeight, GoodBreakWeight, X_AXIS, Y_AXIS

Fields declared in interface javax.swing.SwingConstants

BOTTOM, CENTER, EAST, HORIZONTAL, LEADING, LEFT, NEXT, NORTH, NORTH_EAST, NORTH_WEST, PREVIOUS, RIGHT, SOUTH, SOUTH_EAST, SOUTH_WEST, TOP, TRAILING, VERTICAL, WEST

Constructor Summary

Constructor Description
GlyphView(Element elem)
Constructs a new view wrapped on an element.

Method Summary

Modifier and Type Method Description
View breakView(int axis, int p0, float pos, float len)
Breaks this view on the given axis at the given length.
void changedUpdate(DocumentEvent e, Shape a, ViewFactory f)
Gives notification from the document that attributes were changed in a location that this view is responsible for.
protected void checkPainter()
Check to see that a glyph painter exists.
protected final Object clone()
Creates a shallow copy.
View createFragment(int p0, int p1)
Creates a view that represents a portion of the element.
float getAlignment(int axis)
Determines the desired alignment for this view along an axis.
Color getBackground()
Fetch the background color to use to render the glyphs.
int getBreakWeight(int axis, float pos, float len)
Determines how attractive a break opportunity in this view is.
int getEndOffset()
Fetches the portion of the model that this view is responsible for.
Font getFont()
Fetch the font that the glyphs should be based upon.
Color getForeground()
Fetch the foreground color to use to render the glyphs.
GlyphView.GlyphPainter getGlyphPainter()
Fetch the currently installed glyph painter.
float getMinimumSpan(int axis)
Determines the minimum span for this view along an axis.
int getNextVisualPositionFrom(int pos, Position.Bias b, Shape a, int direction, Position.Bias[] biasRet)
Provides a way to determine the next visually represented model location that one might place a caret.
float getPartialSpan(int p0, int p1)
Determines the span along the same axis as tab expansion for a portion of the view.
float getPreferredSpan(int axis)
Determines the preferred span for this view along an axis.
int getStartOffset()
Fetches the portion of the model that this view is responsible for.
float getTabbedSpan(float x, TabExpander e)
Determines the desired span when using the given tab expansion implementation.
TabExpander getTabExpander()
Fetch the TabExpander to use if tabs are present in this view.
Segment getText(int p0, int p1)
Fetch a reference to the text that occupies the given range.
void insertUpdate(DocumentEvent e, Shape a, ViewFactory f)
Gives notification that something was inserted into the document in a location that this view is responsible for.
boolean isStrikeThrough()
Determine if the glyphs should have a strikethrough line.
boolean isSubscript()
Determine if the glyphs should be rendered as superscript.
boolean isSuperscript()
Determine if the glyphs should be rendered as subscript.
boolean isUnderline()
Determine if the glyphs should be underlined.
Shape modelToView(int pos, Shape a, Position.Bias b)
Provides a mapping from the document model coordinate space to the coordinate space of the view mapped to it.
void paint(Graphics g, Shape a)
Renders a portion of a text style run.
void removeUpdate(DocumentEvent e, Shape a, ViewFactory f)
Gives notification that something was removed from the document in a location that this view is responsible for.
void setGlyphPainter(GlyphView.GlyphPainter p)
Sets the painter to use for rendering glyphs.
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.

Methods declared in class javax.swing.text.View

append, forwardUpdate, forwardUpdateToView, getAttributes, getChildAllocation, getContainer, getDocument, getElement, getGraphics, getMaximumSpan, getParent, getResizeWeight, getToolTipText, getView, getViewCount, getViewFactory, getViewIndex, getViewIndex, insert, isVisible, modelToView, modelToView, preferenceChanged, remove, removeAll, replace, setParent, setSize, updateChildren, updateLayout, viewToModel

Methods declared in class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

GlyphView

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

Method Details

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:

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.

getTabbedSpan

public float getTabbedSpan(float x, TabExpander e)
Determines the desired span when using the given tab expansion implementation.
Specified by:
getTabbedSpan in interface TabableView
Parameters:
x - the position the view would be located at for the purpose of tab expansion >= 0.
e - how to expand the tabs when encountered.
Returns:
the desired span >= 0
See Also:

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:

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:

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:

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.

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.

modelToView

public Shape modelToView(int pos, Shape a, Position.Bias b) throws BadLocationException
Provides a mapping from the document model coordinate space to the coordinate space of the view mapped to it.
Specified by:
modelToView in class View
Parameters:
pos - the position to convert >= 0
a - the allocated region to render into
b - either Position.Bias.Forward or Position.Bias.Backward
Returns:
the bounding box of the given position
Throws:
BadLocationException - if the given position does not represent a valid location in the associated document
See Also:

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:

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:

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:

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:

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

insertUpdate

public void insertUpdate(DocumentEvent e, Shape a, ViewFactory f)
Gives notification that something was inserted into the document in a location that this view is responsible for. This is implemented to call preferenceChanged along the axis the glyphs are rendered.
Overrides:
insertUpdate in class View
Parameters:
e - the change information from the associated document
a - the current allocation of the view
f - the factory to use to rebuild if the view has children
See Also:

removeUpdate

public void removeUpdate(DocumentEvent e, Shape a, ViewFactory f)
Gives notification that something was removed from the document in a location that this view is responsible for. This is implemented to call preferenceChanged along the axis the glyphs are rendered.
Overrides:
removeUpdate in class View
Parameters:
e - the change information from the associated document
a - the current allocation of the view
f - the factory to use to rebuild if the view has children
See Also:

changedUpdate

public void changedUpdate(DocumentEvent e, Shape a, ViewFactory f)
Gives notification from the document that attributes were changed in a location that this view is responsible for. This is implemented to call preferenceChanged along both the horizontal and vertical axis.
Overrides:
changedUpdate in class View
Parameters:
e - the change information from the associated document
a - the current allocation of the view
f - the factory to use to rebuild if the view has children
See Also:

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https://docs.oracle.com/en/java/javase/17/docs/api/java.desktop/javax/swing/text/GlyphView.html