javax.swing.text.BoxView

BoxView

Java SE 6

Extended by: BlockView, FlowView, TableView, TableView.TableCell, TableView.TableRow, WrappedPlainView, ZoneView

A view that arranges its children into a box shape by tiling its children along an axis. The box is somewhat like that found in TeX where there is alignment of the children, flexibility of the children is considered, etc. This is a building block that might be useful to represent things like a collection of lines, paragraphs, lists, columns, pages, etc. The axis along which the children are tiled is considered the major axis. The orthoginal axis is the minor axis.

Layout for each axis is handled separately by the methods layoutMajorAxis and layoutMinorAxis. Subclasses can change the layout algorithm by reimplementing these methods. These methods will be called as necessary depending upon whether or not there is cached layout information and the cache is considered valid. These methods are typically called if the given size along the axis changes, or if layoutChanged is called to force an updated layout. The layoutChanged method invalidates cached layout information, if there is any. The requirements published to the parent view are calculated by the methods calculateMajorAxisRequirements and calculateMinorAxisRequirements. If the layout algorithm is changed, these methods will likely need to be reimplemented.

version 1.68 07/28/06

Constructors

public

BoxView(Element elem, int axis) Details

Constructs a BoxView.

elem	the element this view is responsible for
axis	either `View.X_AXIS` or `View.Y_AXIS`

Methods

protected void

baselineLayout(int targetSpan, int axis, int[] offsets, int[] spans) Details

Computes the location and extent of each child view in this BoxView given the targetSpan, which is the width (or height) of the region we have to work with.

targetSpan	the total span given to the view, which would be used to layout the children
axis	the axis being studied, either `View.X_AXIS` or `View.Y_AXIS`
offsets	an empty array filled by this method with values specifying the location of each child view
spans	an empty array filled by this method with values specifying the extent of each child view

protected SizeRequirements

baselineRequirements(int axis, SizeRequirements r) Details

Calculates the size requirements for this BoxView by examining the size of each child view.

axis	the axis being studied
r	the `SizeRequirements` object; if `null` one will be created
return	the newly initialized `SizeRequirements` object

protected SizeRequirements

calculateMajorAxisRequirements(int axis, SizeRequirements r) Details

Calculates the size requirements for the major axis axis.

axis	the axis being studied
r	the `SizeRequirements` object; if `null` one will be created
return	the newly initialized `SizeRequirements` object
See also	javax.swing.SizeRequirements

protected SizeRequirements

calculateMinorAxisRequirements(int axis, SizeRequirements r) Details

Calculates the size requirements for the minor axis axis.

axis	the axis being studied
r	the `SizeRequirements` object; if `null` one will be created
return	the newly initialized `SizeRequirements` object
See also	javax.swing.SizeRequirements

protected void

childAllocation(int index, Rectangle alloc) Details

Allocates a region for a child view.

index	the index of the child view to allocate, >= 0 && < getViewCount()
alloc	the allocated region

protected boolean

flipEastAndWestAtEnds(int position, Position.Bias bias) Details

Determines in which direction the next view lays. Consider the View at index n. Typically the Views 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 Views are layed out in descending order. Otherwise the method would return false indicating the Views are layed out in ascending order.

If the receiver is laying its Views along the Y_AXIS, this will will return the value from invoking the same method on the View responsible for rendering position and bias. Otherwise this will return false.

position position into the model

bias either Position.Bias.Forward or Position.Bias.Backward

return true if the Views surrounding the View responding for rendering position and bias are layed out in descending order; otherwise false

protected void

forwardUpdate(DocumentEvent.ElementChange ec, DocumentEvent e, Shape a, ViewFactory f) Details

Forwards the given DocumentEvent to the child views that need to be notified of the change to the model. If a child changed its requirements and the allocation was valid prior to forwarding the portion of the box from the starting child to the end of the box will be repainted.

ec	changes to the element this view is responsible for (may be `null` if there were no changes)
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
since	1.3
See also	insertUpdate, removeUpdate, changedUpdate

protected void

layout(int width, int height) Details

Perform layout on the box

width	the width (inside of the insets) >= 0the width (inside of the insets) >= 0
height	the height (inside of the insets) >= 0the height (inside of the insets) >= 0

public void

layoutChanged(int axis) Details

Invalidates the layout along an axis. This happens automatically if the preferences have changed for any of the child views. In some cases the layout may need to be recalculated when the preferences have not changed. The layout can be marked as invalid by calling this method. The layout will be updated the next time the setSize method is called on this view (typically in paint).

axis	either `View.X_AXIS` or `View.Y_AXIS`
since	1.3

protected void

layoutMajorAxis(int targetSpan, int axis, int[] offsets, int[] spans) Details

Performs layout for the major axis of the box (i.e. 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 major axis.

targetSpan	the total span given to the view, which would be used to layout the children
axis	the axis being layed 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

protected void

layoutMinorAxis(int targetSpan, int axis, int[] offsets, int[] spans) Details

Performs layout for the minor axis of the box (i.e. the axis orthoginal 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.

targetSpan	the total span given to the view, which would be used to layout the children
axis	the axis being layed 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

public Shape

modelToView(int pos, Shape a, Position.Bias b) throws BadLocationException Details

Provides a mapping from the document model coordinate space to the coordinate space of the view mapped to it. This makes sure the allocation is valid before calling the superclass.

pos	the position to convert >= 0the position to convert >= 0
a	the allocated region to render into
return	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	modelToView

public void

paint(Graphics g, Shape allocation) Details

Renders the BoxView using the given rendering surface and area on that surface. Only the children that intersect the clip bounds of the given Graphics will be rendered.

g	the rendering surface to use
allocation	the allocated region to render into
See also	paint

protected void

paintChild(Graphics g, Rectangle alloc, int index) Details

Paints a child. By default that is all it does, but a subclass can use this to paint things relative to the child.

g	the graphics context
alloc	the allocated region to paint into
index	the child index, >= 0 && < getViewCount()the child index, >= 0 && < getViewCount()

public void

preferenceChanged(View child, boolean width, boolean height) Details

This is called by a child to indicate its preferred span has changed. This is implemented to throw away cached layout information so that new calculations will be done the next time the children need an allocation.

child	the child view
width	true if the width preference should change
height	true if the height preference should change

public void

replace(int index, int length, View[] elems) Details

Invalidates the layout and resizes the cache of requests/allocations. The child allocations can still be accessed for the old layout, but the new children will have an offset and span of 0.

index	the starting index into the child views to insert the new views; this should be a value >= 0 and <= getViewCount
length	the number of existing child views to remove; This should be a value >= 0 and <= (getViewCount() - offset)
elems	the child views to add; this value can be `null`to indicate no children are being added (useful to remove)

public int

viewToModel(float x, float y, Shape a, Position.Bias[] bias) Details

Provides a mapping from the view coordinate space to the logical coordinate space of the model.

x	x coordinate of the view location to convert >= 0x coordinate of the view location to convert >= 0
y	y coordinate of the view location to convert >= 0y coordinate of the view location to convert >= 0
a	the allocated region to render into
return	the location within the model that best represents the given point in the view >= 0
See also	viewToModel

Properties

protected boolean

isAfter(int x, int y, Rectangle innerAlloc) Details

Determines if a point falls after an allocated region.

x	the X coordinate >= 0the X coordinate >= 0
y	the Y coordinate >= 0the Y coordinate >= 0
innerAlloc	the allocated region; this is the area inside of the insets
return	true if the point lies after the region else false

public float

getAlignment(int axis) Details

Determines the desired alignment for this view along an axis. This is implemented to give the total alignment needed to position the children with the alignment points lined up along the axis orthoginal to the axis that is being tiled. The axis being tiled will request to be centered (i.e. 0.5f).

axis	may be either `View.X_AXIS` or `View.Y_AXIS`
return	the desired alignment >= 0.0f && <= 1.0f; this should be a value between 0.0 and 1.0 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 viewthe desired alignment >= 0.0f && <= 1.0f; this should be a value between 0.0 and 1.0 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
Throws	IllegalArgumentException: for an invalid axis

protected boolean

isAllocationValid() Details

Are the allocations for the children still valid?

return

true if allocations still valid

public void

setAxis(int axis) Details

Sets the tile axis property. This is the axis along which the child views are tiled.

axis	either `View.X_AXIS` or `View.Y_AXIS`
since	1.3

public int

getAxis() Details

Fetches the tile axis property. This is the axis along which the child views are tiled.

return	the major axis of the box, either `View.X_AXIS` or `View.Y_AXIS`
since	1.3

protected boolean

isBefore(int x, int y, Rectangle innerAlloc) Details

Determines if a point falls before an allocated region.

x	the X coordinate >= 0the X coordinate >= 0
y	the Y coordinate >= 0the Y coordinate >= 0
innerAlloc	the allocated region; this is the area inside of the insets
return	true if the point lies before the region else false

public Shape

getChildAllocation(int index, Shape a) Details

Fetches the allocation for the given child view. This enables finding out where various views are located. This is implemented to return null if the layout is invalid, otherwise the superclass behavior is executed.

index	the index of the child, >= 0 && < getViewCount()the index of the child, >= 0 && < getViewCount()
a	the allocation to this view
return	the allocation to the child; or `null` if `a` is `null`; or `null` if the layout is invalid

public int

getHeight() Details

Returns the current height of the box. This is the height that it was last allocated.

return

the current height of the box

protected boolean

isLayoutValid(int axis) Details

Determines if the layout is valid along the given axis.

axis	either `View.X_AXIS` or `View.Y_AXIS`
since	1.4

public float

getMaximumSpan(int axis) Details

Determines the maximum span for this view along an axis.

axis	may be either `View.X_AXIS` or `View.Y_AXIS`
return	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 viewthe 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

public float

getMinimumSpan(int axis) Details

Determines the minimum span for this view along an axis.

axis	may be either `View.X_AXIS` or `View.Y_AXIS`
return	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 viewthe 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

protected int

getOffset(int axis, int childIndex) Details

Fetches the offset of a particular child's current layout.

axis	the axis being studied
childIndex	the index of the requested child
return	the offset (location) for the specified child

public float

getPreferredSpan(int axis) Details

Determines the preferred span for this view along an axis.

axis	may be either `View.X_AXIS` or `View.Y_AXIS`
return	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 viewthe 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

public int

getResizeWeight(int axis) Details

Gets the resize weight. A value of 0 or less is not resizable.

axis	may be either `View.X_AXIS` or `View.Y_AXIS`
return	the weight
Throws	IllegalArgumentException: for an invalid axis

public void

setSize(float width, float height) Details

Sets the size of the view. This should cause layout of the view if the view caches any layout information. This is implemented to call the layout method with the sizes inside of the insets.

width	the width >= 0the width >= 0
height	the height >= 0the height >= 0

protected int

getSpan(int axis, int childIndex) Details

Fetches the span of a particular childs current layout.

axis	the axis being studied
childIndex	the index of the requested child
return	the span (width or height) of the specified child

protected View

getViewAtPoint(int x, int y, Rectangle alloc) Details

Fetches the child view at the given coordinates.

x	the X coordinate >= 0the X coordinate >= 0
y	the Y coordinate >= 0the Y coordinate >= 0
alloc	the parents inner allocation on entry, which should be changed to the childs allocation on exit
return	the view

public int

getWidth() Details

Returns the current width of the box. This is the width that it was last allocated.

return

the current width of the box

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Java SE 6