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/OpenJDK 21

Class ParagraphView

java.lang.Object
javax.swing.text.View
javax.swing.text.CompositeView
javax.swing.text.BoxView
javax.swing.text.FlowView
javax.swing.text.ParagraphView
All Implemented Interfaces:
SwingConstants, TabExpander
Direct Known Subclasses:
ParagraphView
public class ParagraphView extends FlowView implements TabExpander
View of a simple line-wrapping paragraph that supports multiple fonts, colors, components, icons, etc. It is basically a vertical box with a margin around it. The contents of the box are a bunch of rows which are special horizontal boxes. This view creates a collection of views that represent the child elements of the paragraph element. Each of these views are placed into a row directly if they will fit, otherwise the breakView method is called to try and carve the view into pieces that fit.
See Also:

Nested Class Summary

Nested classes/interfaces declared in class javax.swing.text.FlowView

FlowView.FlowStrategy

Field Summary

Modifier and Type Field Description
protected int firstLineIndent
Indentation for the first line, from the left inset.

Fields declared in class javax.swing.text.FlowView

layoutPool, layoutSpan, strategy

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
ParagraphView(Element elem)
Constructs a ParagraphView for the given element.

Method Summary

Modifier and Type Method Description
View breakView(int axis, float len, Shape a)
Breaks this view on the given axis at the given length.
protected SizeRequirements calculateMinorAxisRequirements(int axis, SizeRequirements r)
Calculate the needs for the paragraph along the minor axis.
void changedUpdate(DocumentEvent changes, Shape a, ViewFactory f)
Gives notification from the document that attributes were changed in a location that this view is responsible for.
protected View createRow()
Create a View that should be used to hold a a row's worth of children in a flow.
protected int findOffsetToCharactersInString(char[] string, int start)
Finds the next character in the document with a character in string, starting at offset start.
protected boolean flipEastAndWestAtEnds(int position, Position.Bias bias)
Determines in which direction the next view lays.
float getAlignment(int axis)
Determines the desired alignment for this view along an axis.
int getBreakWeight(int axis, float len)
Gets the break weight for a given location.
protected int getClosestPositionTo(int pos, Position.Bias b, Shape a, int direction, Position.Bias[] biasRet, int rowIndex, int x)
Returns the closest model position to x.
int getFlowSpan(int index)
Fetches the constraining span to flow against for the given child index.
int getFlowStart(int index)
Fetches the location along the flow axis that the flow span will start at.
protected View getLayoutView(int index)
Returns the view at a given index.
protected int getLayoutViewCount()
Returns the number of views that this view is responsible for.
protected int getNextNorthSouthVisualPositionFrom(int pos, Position.Bias b, Shape a, int direction, Position.Bias[] biasRet)
Returns the next visual position for the cursor, in either the east or west direction.
protected float getPartialSize(int startOffset, int endOffset)
Returns the size used by the views between startOffset and endOffset.
protected float getTabBase()
Returns where the tabs are calculated from.
protected TabSet getTabSet()
Gets the Tabset to be used in calculating tabs.
float nextTabStop(float x, int tabOffset)
Returns the next tab stop position given a reference position.
void paint(Graphics g, Shape a)
Renders using the given rendering surface and area on that surface.
protected void setFirstLineIndent(float fi)
Sets the indent on the first line.
protected void setJustification(int j)
Sets the type of justification.
protected void setLineSpacing(float ls)
Sets the line spacing.
protected void setPropertiesFromAttributes()
Set the cached properties from the attributes.

Methods declared in class javax.swing.text.FlowView

getFlowAxis, getViewIndexAtPosition, insertUpdate, layout, loadChildren, removeUpdate

Methods declared in class javax.swing.text.BoxView

baselineLayout, baselineRequirements, calculateMajorAxisRequirements, childAllocation, forwardUpdate, getAxis, getChildAllocation, getHeight, getMaximumSpan, getMinimumSpan, getOffset, getPreferredSpan, getResizeWeight, getSpan, getViewAtPoint, getWidth, isAfter, isAllocationValid, isBefore, isLayoutValid, layoutChanged, layoutMajorAxis, layoutMinorAxis, modelToView, paintChild, preferenceChanged, replace, setAxis, setSize, viewToModel

Methods declared in class javax.swing.text.CompositeView

getBottomInset, getInsideAllocation, getLeftInset, getNextEastWestVisualPositionFrom, getNextVisualPositionFrom, getRightInset, getTopInset, getView, getViewAtPosition, getViewCount, getViewIndex, modelToView, setInsets, setParagraphInsets, setParent

Methods declared in class javax.swing.text.View

append, breakView, createFragment, forwardUpdateToView, getAttributes, getBreakWeight, getContainer, getDocument, getElement, getEndOffset, getGraphics, getParent, getStartOffset, getToolTipText, getViewFactory, getViewIndex, insert, isVisible, modelToView, remove, removeAll, updateChildren, updateLayout, viewToModel

Methods declared in class java.lang.Object

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

Field Details

firstLineIndent

protected int firstLineIndent
Indentation for the first line, from the left inset.

Constructor Details

ParagraphView

public ParagraphView(Element elem)
Constructs a ParagraphView for the given element.
Parameters:
elem - the element that this view is responsible for

Method Details

setJustification

protected void setJustification(int j)
Sets the type of justification.
Parameters:
j - one of the following values:
  • StyleConstants.ALIGN_LEFT
  • StyleConstants.ALIGN_CENTER
  • StyleConstants.ALIGN_RIGHT

setLineSpacing

protected void setLineSpacing(float ls)
Sets the line spacing.
Parameters:
ls - the value is a factor of the line height

setFirstLineIndent

protected void setFirstLineIndent(float fi)
Sets the indent on the first line.
Parameters:
fi - the value in points

setPropertiesFromAttributes

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

getLayoutViewCount

protected int getLayoutViewCount()
Returns the number of views that this view is responsible for. The child views of the paragraph are rows which have been used to arrange pieces of the Views that represent the child elements. This is the number of views that have been tiled in two dimensions, and should be equivalent to the number of child elements to the element this view is responsible for.
Returns:
the number of views that this ParagraphView is responsible for

getLayoutView

protected View getLayoutView(int index)
Returns the view at a given index. The child views of the paragraph are rows which have been used to arrange pieces of the Views that represent the child elements. This methods returns the view responsible for the child element index (prior to breaking). These are the Views that were produced from a factory (to represent the child elements) and used for layout.
Parameters:
index - the index of the desired view
Returns:
the view at index

getNextNorthSouthVisualPositionFrom

protected int getNextNorthSouthVisualPositionFrom(int pos, Position.Bias b, Shape a, int direction, Position.Bias[] biasRet) throws BadLocationException
Returns the next visual position for the cursor, in either the east or west direction. Overridden from CompositeView.
Overrides:
getNextNorthSouthVisualPositionFrom in class CompositeView
Parameters:
pos - position into the model
b - either Position.Bias.Forward or Position.Bias.Backward
a - the allocated region to render into
direction - either SwingConstants.NORTH or SwingConstants.SOUTH
biasRet - an array containing the bias that were checked in this method
Returns:
the location in the model that represents the next location visual position
Throws:
BadLocationException - for a bad location within a document model
See Also:

getClosestPositionTo

protected int getClosestPositionTo(int pos, Position.Bias b, Shape a, int direction, Position.Bias[] biasRet, int rowIndex, int x) throws BadLocationException
Returns the closest model position to x. rowIndex gives the index of the view that corresponds that should be looked in.
Parameters:
pos - position into the model
b - the bias
a - the allocated region to render into
direction - one of the following values:
  • SwingConstants.NORTH
  • SwingConstants.SOUTH
biasRet - an array containing the bias that were checked in this method
rowIndex - the index of the view
x - the x coordinate of interest
Returns:
the closest model position to x
Throws:
BadLocationException - if a bad location is encountered

flipEastAndWestAtEnds

protected boolean flipEastAndWestAtEnds(int position, Position.Bias bias)
Determines in which direction the next view lays. Consider the View at index n. Typically the Views are laid out from left to right, so that the View to the EAST will be at index n + 1, and the View to the WEST will be at index n - 1. In certain situations, such as with bidirectional text, it is possible that the View to EAST is not at index n + 1, but rather at index n - 1, or that the View to the WEST is not at index n - 1, but index n + 1. In this case this method would return true, indicating the Views are laid out in descending order.

This will return true if the text is laid out right to left at position, otherwise false.

Overrides:
flipEastAndWestAtEnds in class BoxView
Parameters:
position - position into the model
bias - either Position.Bias.Forward or Position.Bias.Backward
Returns:
true if the text is laid out right to left at position, otherwise false.

getFlowSpan

public int getFlowSpan(int index)
Fetches the constraining span to flow against for the given child index.
Overrides:
getFlowSpan in class FlowView
Parameters:
index - the index of the view being queried
Returns:
the constraining span for the given view at index
Since:
1.3
See Also:

getFlowStart

public int getFlowStart(int index)
Fetches the location along the flow axis that the flow span will start at.
Overrides:
getFlowStart in class FlowView
Parameters:
index - the index of the view being queried
Returns:
the location for the given view at index
Since:
1.3
See Also:

createRow

protected View createRow()
Create a View that should be used to hold a a row's worth of children in a flow.
Specified by:
createRow in class FlowView
Returns:
the new View
Since:
1.3

nextTabStop

public float nextTabStop(float x, int tabOffset)
Returns the next tab stop position given a reference position. This view implements the tab coordinate system, and calls getTabbedSpan on the logical children in the process of layout to determine the desired span of the children. The logical children can delegate their tab expansion upward to the paragraph which knows how to expand tabs. LabelView is an example of a view that delegates its tab expansion needs upward to the paragraph.

This is implemented to try and locate a TabSet in the paragraph element's attribute set. If one can be found, its settings will be used, otherwise a default expansion will be provided. The base location for tab expansion is the left inset from the paragraphs most recent allocation (which is what the layout of the children is based upon).

Specified by:
nextTabStop in interface TabExpander
Parameters:
x - the X reference position
tabOffset - the position within the text stream that the tab occurred at >= 0
Returns:
the trailing end of the tab expansion >= 0
See Also:

getTabSet

protected TabSet getTabSet()
Gets the Tabset to be used in calculating tabs.
Returns:
the TabSet

getPartialSize

protected float getPartialSize(int startOffset, int endOffset)
Returns the size used by the views between startOffset and endOffset. This uses getPartialView to calculate the size if the child view implements the TabableView interface. If a size is needed and a View does not implement the TabableView interface, the preferredSpan will be used.
Parameters:
startOffset - the starting document offset >= 0
endOffset - the ending document offset >= startOffset
Returns:
the size >= 0

findOffsetToCharactersInString

protected int findOffsetToCharactersInString(char[] string, int start)
Finds the next character in the document with a character in string, starting at offset start. If there are no characters found, -1 will be returned.
Parameters:
string - the string of characters
start - where to start in the model >= 0
Returns:
the document offset, or -1 if no characters found

getTabBase

protected float getTabBase()
Returns where the tabs are calculated from.
Returns:
where tabs are calculated from

paint

public void paint(Graphics g, Shape a)
Renders using the given rendering surface and area on that surface. This is implemented to delegate to the superclass after stashing the base coordinate for tab calculations.
Overrides:
paint in class BoxView
Parameters:
g - the rendering surface to use
a - the allocated region to render into
See Also:

getAlignment

public float getAlignment(int axis)
Determines the desired alignment for this view along an axis. This is implemented to give the alignment to the center of the first row along the y axis, and the default along the x axis.
Overrides:
getAlignment in class BoxView
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.

breakView

public View breakView(int axis, float len, Shape a)
Breaks this view on the given axis at the given length.

ParagraphView instances are breakable along the Y_AXIS only, and only if len is after the first line.

Parameters:
axis - may be either View.X_AXIS or View.Y_AXIS
len - specifies where a potential break is desired along the given axis >= 0
a - the current allocation of the view
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:

getBreakWeight

public int getBreakWeight(int axis, float len)
Gets the break weight for a given location.

ParagraphView instances are breakable along the Y_AXIS only, and only if len is after the first row. If the length is less than one row, a value of BadBreakWeight is returned.

Parameters:
axis - may be either View.X_AXIS or View.Y_AXIS
len - specifies where a potential break is desired >= 0
Returns:
a value indicating the attractiveness of breaking here; either GoodBreakWeight or BadBreakWeight
See Also:

calculateMinorAxisRequirements

protected SizeRequirements calculateMinorAxisRequirements(int axis, SizeRequirements r)
Calculate the needs for the paragraph along the minor axis.

This uses size requirements of the superclass, modified to take into account the non-breakable areas at the adjacent views edges. The minimal size requirements for such views should be no less than the sum of all adjacent fragments.

If the axis parameter is neither View.X_AXIS nor View.Y_AXIS, IllegalArgumentException is thrown. If the r parameter is null, a new SizeRequirements object is created, otherwise the supplied SizeRequirements object is returned.

Overrides:
calculateMinorAxisRequirements in class FlowView
Parameters:
axis - the minor axis
r - the input SizeRequirements object
Returns:
the new or adjusted SizeRequirements object
Throws:
IllegalArgumentException - if the axis parameter is invalid
See Also:

changedUpdate

public void changedUpdate(DocumentEvent changes, 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 FlowView
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:

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https://docs.oracle.com/en/java/javase/21/docs/api/java.desktop/javax/swing/text/ParagraphView.html