Java(TM) 2 Platform, Standard Edition, v1.2.2 API Specification: Class LabelView - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

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javax.swing.text
Class LabelView

java.lang.Object
  |
  +--javax.swing.text.View
        |
        +--javax.swing.text.LabelView

Direct Known Subclasses:: InlineView

public class LabelView
extends View

A LabelView is a styled chunk of text that represents a view mapped over an element in the text 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.

This view is generally responsible for displaying character level attributes in some way. 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.

Fields inherited from class javax.swing.text.View

BadBreakWeight, ExcellentBreakWeight, ForcedBreakWeight, GoodBreakWeight, X_AXIS, Y_AXIS

Constructor Summary

LabelView(Element elem)
          Constructs a new view wrapped on an element.

Method Summary

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.

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.

int getBreakWeight(int axis, float pos, float len)
          Determines how attractive a break opportunity in this view is.

protected Font getFont()
          Fetch the Font used for this view.

protected FontMetrics getFontMetrics()
          Fetch the FontMetrics used for this view.

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 getPreferredSpan(int axis)
          Determines the preferred span for this view along an axis.

void insertUpdate(DocumentEvent e, Shape a, ViewFactory f)
          Gives notification that something was added to the document in a location that this view is responsible for.

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 changes, Shape a, ViewFactory f)
          Gives notification that something was removed from the document in a location that this view is responsible for.

protected void setPropertiesFromAttributes()
          Set the cached properties from the attributes.

protected void setStrikeThrough(boolean s)
          Set whether or not the view has a strike/line through it.

protected void setSubscript(boolean s)
          Set whether or not the view represents a subscript.

protected void setSuperscript(boolean s)
          Set whether or not the view represents a superscript.

protected void setUnderline(boolean u)
          Set whether or not the view is underlined.

String toString()
          Returns a string representation of the object.

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 inherited from class javax.swing.text.View

getAttributes, getChildAllocation, getContainer, getDocument, getElement, getEndOffset, getMaximumSpan, getMinimumSpan, getParent, getResizeWeight, getStartOffset, getView, getViewCount, getViewFactory, isVisible, modelToView, modelToView, preferenceChanged, setParent, setSize, viewToModel

Methods inherited from class java.lang.Object

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

Constructor Detail

LabelView

public LabelView(Element elem)

Constructs a new view wrapped on an element.

Parameters:: elem - the element

Method Detail

setUnderline

protected void setUnderline(boolean u)

Set whether or not the view is underlined.

setStrikeThrough

protected void setStrikeThrough(boolean s)

Set whether or not the view has a strike/line through it.

setSuperscript

protected void setSuperscript(boolean s)

Set whether or not the view represents a superscript.

setSubscript

protected void setSubscript(boolean s)

Set whether or not the view represents a subscript.

setPropertiesFromAttributes

protected void setPropertiesFromAttributes()

Set the cached properties from the attributes.

getFontMetrics

protected FontMetrics getFontMetrics()

Fetch the FontMetrics used for this view.

getFont

protected Font getFont()

Fetch the Font used for this view.

paint

public void paint(Graphics g,
                  Shape a)

Renders a portion of a text style run.

Overrides:: paint in class View

Parameters:: g - the rendering surface to use; a - the allocated region to render into

getPreferredSpan

public float getPreferredSpan(int axis)

Determines the preferred span for this view along an axis.

Overrides:: getPreferredSpan in class View

Parameters:: axis - may be either View.X_AXIS or View.Y_AXIS

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

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.

Overrides:: modelToView in class View

Parameters:: pos - the position to convert >= 0; a - the allocated region to render into
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:: View.modelToView(int, java.awt.Shape, javax.swing.text.Position.Bias)

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.

Overrides:: viewToModel in class View

Parameters:: x - the X coordinate >= 0; y - the Y coordinate >= 0; a - the allocated region to render into
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[])

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.

Overrides:: getNextVisualPositionFrom in class View

Parameters:: pos - the position to convert >= 0; 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.
Returns:: the location within the model that best represents the next location visual position.
Throws:: BadLocationException -; IllegalArgumentException - for an invalid direction

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, BadBreakWeight, GoodBreakWeight, ExcellentBreakWeight, 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.
See Also:: LabelView

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.

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:: View.changedUpdate(javax.swing.event.DocumentEvent, java.awt.Shape, javax.swing.text.ViewFactory)

insertUpdate

public void insertUpdate(DocumentEvent e,
                         Shape a,
                         ViewFactory f)

Gives notification that something was added to the document in a location that this view is responsible for.

Overrides:: insertUpdate in class View

Parameters:: changes - 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:: View.insertUpdate(javax.swing.event.DocumentEvent, java.awt.Shape, javax.swing.text.ViewFactory)

removeUpdate

public void removeUpdate(DocumentEvent changes,
                         Shape a,
                         ViewFactory f)

Gives notification that something was removed from the document in a location that this view is responsible for.

Overrides:: removeUpdate in class View

Parameters:: changes - 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:: View.removeUpdate(javax.swing.event.DocumentEvent, java.awt.Shape, javax.swing.text.ViewFactory)

toString

public String toString()

Description copied from class: Object

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommendedthat all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

 getClass().getName() + '@' + Integer.toHexString(hashCode())

Overrides:: toString in class Object

Tags copied from class: Object

Returns:: a string representation of the object.