BlockView (Java SE 25 & JDK 25)
Description: declaration: module: java.desktop, package: javax.swing.text.html, class: BlockView
Keywords: javax.swing.text.html.BlockView class

# Class BlockView

java.lang.Object
javax.swing.text.View
javax.swing.text.CompositeView
javax.swing.text.BoxView
javax.swing.text.html.BlockView

All Implemented Interfaces:
  `SwingConstants`

Direct Known Subclasses:
  `ListView`

public class BlockView extends BoxView
A view implementation to display a block (as a box) with CSS specifications.

- ## Field Summary

  ### Fields declared in class View

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

  ### Fields declared in interface 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
  Description
  `BlockView(Element elem, int axis)`
  Creates a new view that represents an html box.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `protected SizeRequirements`
  `calculateMajorAxisRequirements(int axis, SizeRequirements r)`
  Calculate the requirements of the block along the major axis (i.e. the axis along with it tiles).
  `protected SizeRequirements`
  `calculateMinorAxisRequirements(int axis, SizeRequirements r)`
  Calculate the requirements of the block along the minor axis (i.e. the axis orthogonal to the axis along with it tiles).
  `float`
  `getAlignment(int axis)`
  Gets the alignment.
  `AttributeSet`
  `getAttributes()`
  Fetches the attributes to use when rendering.
  `float`
  `getMaximumSpan(int axis)`
  Determines the maximum span for this view along an axis.
  `float`
  `getMinimumSpan(int axis)`
  Determines the minimum span for this view along an axis.
  `float`
  `getPreferredSpan(int axis)`
  Determines the preferred span for this view along an axis.
  `int`
  `getResizeWeight(int axis)`
  Gets the resize weight.
  `protected StyleSheet`
  `getStyleSheet()`
  Convenient method to get the StyleSheet.
  `protected void`
  `layoutMinorAxis(int targetSpan, int axis, int[] offsets, int[] spans)`
  Performs layout for the minor axis of the box (i.e. the axis orthogonal to the axis that it represents).
  `void`
  `paint(Graphics g, Shape allocation)`
  Renders using the given rendering surface and area on that surface.
  `void`
  `setParent(View parent)`
  Establishes the parent view for this view.
  `protected void`
  `setPropertiesFromAttributes()`
  Update any cached values that come from attributes.

  ### Methods declared in class BoxView

  `baselineLayout, baselineRequirements, childAllocation, flipEastAndWestAtEnds, forwardUpdate, getAxis, getChildAllocation, getHeight, getOffset, getSpan, getViewAtPoint, getWidth, isAfter, isAllocationValid, isBefore, isLayoutValid, layout, layoutChanged, layoutMajorAxis, modelToView, paintChild, preferenceChanged, replace, setAxis, setSize, viewToModel`

  ### Methods declared in class CompositeView

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

  ### Methods declared in class View

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

  ### Methods declared in class Object

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

- ## Constructor Details

  - ### BlockView

    public BlockView(Element elem, int axis)
    Creates a new view that represents an html box. This can be used for a number of elements.
    Parameters:
      `elem` - the element to create a view for
      `axis` - either View.X_AXIS or View.Y_AXIS

- ## Method Details

  - ### setParent

    public void setParent(View parent)
    Establishes the parent view for this view. This is guaranteed to be called before any other methods if the parent view is functioning properly.

    This is implemented to forward to the superclass as well as call the `setPropertiesFromAttributes()` method to set the paragraph properties from the css attributes. The call is made at this time to ensure the ability to resolve upward through the parents view attributes.

    Overrides:
      `setParent` in class `CompositeView`
    Parameters:
      `parent` - the new parent, or null if the view is being removed from a parent it was previously added to

  - ### calculateMajorAxisRequirements

    protected SizeRequirements calculateMajorAxisRequirements(int axis, SizeRequirements r)
    Calculate the requirements of the block along the major axis (i.e. the axis along with it tiles). This is implemented to provide the superclass behavior and then adjust it if the CSS width or height attribute is specified and applicable to the axis.
    Overrides:
      `calculateMajorAxisRequirements` in class `BoxView`
    Parameters:
      `axis` - the axis being studied
      `r` - the `SizeRequirements` object; if `null` one will be created
    Returns:
      the newly initialized `SizeRequirements` object
    See Also:
      - `SizeRequirements`

  - ### calculateMinorAxisRequirements

    protected SizeRequirements calculateMinorAxisRequirements(int axis, SizeRequirements r)
    Calculate the requirements of the block along the minor axis (i.e. the axis orthogonal to the axis along with it tiles). This is implemented to provide the superclass behavior and then adjust it if the CSS width or height attribute is specified and applicable to the axis.
    Overrides:
      `calculateMinorAxisRequirements` in class `BoxView`
    Parameters:
      `axis` - the axis being studied
      `r` - the `SizeRequirements` object; if `null` one will be created
    Returns:
      the newly initialized `SizeRequirements` object
    See Also:
      - `SizeRequirements`

  - ### layoutMinorAxis

    protected void layoutMinorAxis(int targetSpan, int axis, int[] offsets, int[] spans)
    Performs layout for the minor axis of the box (i.e. the axis orthogonal to the axis that it represents). The results of the layout (the offset and span for each children) are placed in the given arrays which represent the allocations to the children along the minor axis.
    Overrides:
      `layoutMinorAxis` in class `BoxView`
    Parameters:
      `targetSpan` - the total span given to the view, which would be used to layout the children.
      `axis` - the axis being laid out
      `offsets` - the offsets from the origin of the view for each of the child views; this is a return value and is filled in by the implementation of this method
      `spans` - the span of each child view; this is a return value and is filled in by the implementation of this method

  - ### paint

    public void paint(Graphics g, Shape allocation)
    Renders using the given rendering surface and area on that surface. This is implemented to delegate to the css box painter to paint the border and background prior to the interior.
    Overrides:
      `paint` in class `BoxView`
    Parameters:
      `g` - the rendering surface to use
      `allocation` - the allocated region to render into
    See Also:
      - `View.paint(Graphics, Shape)`

  - ### getAttributes

    public AttributeSet getAttributes()
    Fetches the attributes to use when rendering. This is implemented to multiplex the attributes specified in the model with a StyleSheet.
    Overrides:
      `getAttributes` in class `View`
    Returns:
      the attributes to use when rendering

  - ### getResizeWeight

    public int getResizeWeight(int axis)
    Gets the resize weight.
    Overrides:
      `getResizeWeight` in class `BoxView`
    Parameters:
      `axis` - may be either X_AXIS or Y_AXIS
    Returns:
      the weight
    Throws:
      `IllegalArgumentException` - for an invalid axis

  - ### getAlignment

    public float getAlignment(int axis)
    Gets the alignment.
    Overrides:
      `getAlignment` in class `BoxView`
    Parameters:
      `axis` - may be either X_AXIS or Y_AXIS
    Returns:
      the alignment

  - ### getPreferredSpan

    public float getPreferredSpan(int axis)
    Determines the preferred span for this view along an axis.
    Overrides:
      `getPreferredSpan` in class `BoxView`
    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
    Throws:
      `IllegalArgumentException` - for an invalid axis type

  - ### getMinimumSpan

    public float getMinimumSpan(int axis)
    Determines the minimum span for this view along an axis.
    Overrides:
      `getMinimumSpan` in class `BoxView`
    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
    Throws:
      `IllegalArgumentException` - for an invalid axis type
    See Also:
      - `View.getPreferredSpan(int)`

  - ### getMaximumSpan

    public float getMaximumSpan(int axis)
    Determines the maximum span for this view along an axis.
    Overrides:
      `getMaximumSpan` in class `BoxView`
    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
    Throws:
      `IllegalArgumentException` - for an invalid axis type
    See Also:
      - `View.getPreferredSpan(int)`

  - ### setPropertiesFromAttributes

    protected void setPropertiesFromAttributes()
    Update any cached values that come from attributes.

  - ### getStyleSheet

    protected StyleSheet getStyleSheet()
    Convenient method to get the StyleSheet.
    Returns:
      the StyleSheet