ParagraphView (Java Platform SE 8 )
Keywords: javax.swing.text.ParagraphView class
Date: 2015-11-18

javax.swing.text

## 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:
    `View`

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from class javax.swing.text.FlowView

      `FlowView.FlowStrategy`

  - ### Field Summary

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

    - ### Fields inherited from class javax.swing.text.FlowView

      `layoutPool, layoutSpan, strategy`

    - ### Fields inherited from class javax.swing.text.View

      `BadBreakWeight, ExcellentBreakWeight, ForcedBreakWeight, GoodBreakWeight, X_AXIS, Y_AXIS`

    - ### Fields inherited from 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

    Constructors
    Constructor and Description
    `ParagraphView(Element elem)` Constructs a `ParagraphView` for the given element.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and 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 inherited from class javax.swing.text.FlowView

      `getFlowAxis, getViewIndexAtPosition, insertUpdate, layout, loadChildren, removeUpdate, setParent`

    - ### Methods inherited from 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 inherited from class javax.swing.text.CompositeView

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

    - ### Methods inherited from 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 inherited from class java.lang.Object

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

- - ### Field Detail

    - #### firstLineIndent

          protected int firstLineIndent

      Indentation for the first line, from the left inset.

  - ### Constructor Detail

    - #### ParagraphView

          public ParagraphView(Element elem)

      Constructs a `ParagraphView` for the given element.
      Parameters:
        `elem` - the element that this view is responsible for

  - ### Method Detail

    - #### 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 hight

    - #### 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 `View`s 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`
      See Also:
        `CompositeView.getNextVisualPositionFrom(int, javax.swing.text.Position.Bias, java.awt.Shape, int, javax.swing.text.Position.Bias[])`

    - #### 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
        `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`

    - #### 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 `View`s are layed 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 `View`s are layed out in descending order.

      This will return true if the text is layed 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 layed 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:
        `FlowView.getFlowStart(int)`

    - #### 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:
        `FlowView.getFlowSpan(int)`

    - #### 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 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:
        `TabSet`, `TabStop`, `LabelView`

    - #### 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:
        `View.paint(java.awt.Graphics, java.awt.Shape)`

    - #### 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:
        `View.breakView(int, int, float, float)`

    - #### 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:
        `View.getBreakWeight(int, float, float)`

    - #### 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:
        `SizeRequirements`

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

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