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package javax.swing.text;

import java.io.PrintStream;
import java.util.Vector;
import java.awt.*;
import javax.swing.event.DocumentEvent;
import javax.swing.SizeRequirements;


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.

Author: Timothy Prinzing
/**
 * 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.
 * <p>
 * Layout for each axis is handled separately by the methods
 * <code>layoutMajorAxis</code> and <code>layoutMinorAxis</code>.
 * 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 <code>layoutChanged</code> is
 * called to force an updated layout.  The <code>layoutChanged</code>
 * method invalidates cached layout information, if there is any.
 * The requirements published to the parent view are calculated by
 * the methods <code>calculateMajorAxisRequirements</code>
 * and  <code>calculateMinorAxisRequirements</code>.
 * If the layout algorithm is changed, these methods will
 * likely need to be reimplemented.
 *
 * @author  Timothy Prinzing
 */
public class BoxView extends CompositeView {

    
Constructs a BoxView.

Params:
  • elem – the element this view is responsible for
  • axis – either View.X_AXIS or View.Y_AXIS
/**
     * Constructs a <code>BoxView</code>.
     *
     * @param elem the element this view is responsible for
     * @param axis either <code>View.X_AXIS</code> or <code>View.Y_AXIS</code>
     */
    public BoxView(Element elem, int axis) {
        super(elem);
        tempRect = new Rectangle();
        this.majorAxis = axis;

        majorOffsets = new int[0];
        majorSpans = new int[0];
        majorReqValid = false;
        majorAllocValid = false;
        minorOffsets = new int[0];
        minorSpans = new int[0];
        minorReqValid = false;
        minorAllocValid = false;
    }

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

Returns:the major axis of the box, either
 View.X_AXIS or View.Y_AXIS
Since:1.3
/**
     * Fetches the tile axis property.  This is the axis along which
     * the child views are tiled.
     *
     * @return the major axis of the box, either
     *  <code>View.X_AXIS</code> or <code>View.Y_AXIS</code>
     *
     * @since 1.3
     */
    public int getAxis() {
        return majorAxis;
    }

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

Params:
  • axis – either View.X_AXIS or View.Y_AXIS
Since:1.3
/**
     * Sets the tile axis property.  This is the axis along which
     * the child views are tiled.
     *
     * @param axis either <code>View.X_AXIS</code> or <code>View.Y_AXIS</code>
     *
     * @since 1.3
     */
    public void setAxis(int axis) {
        boolean axisChanged = (axis != majorAxis);
        majorAxis = axis;
        if (axisChanged) {
            preferenceChanged(null, true, true);
        }
    }

    
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).

Params:
  • axis – either View.X_AXIS or View.Y_AXIS
Since:1.3
/**
     * 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 <code>setSize</code> method
     * is called on this view (typically in paint).
     *
     * @param axis either <code>View.X_AXIS</code> or <code>View.Y_AXIS</code>
     *
     * @since 1.3
     */
    public void layoutChanged(int axis) {
        if (axis == majorAxis) {
            majorAllocValid = false;
        } else {
            minorAllocValid = false;
        }
    }

    
Determines if the layout is valid along the given axis.

Params:
  • axis – either View.X_AXIS or View.Y_AXIS
Since:1.4
/**
     * Determines if the layout is valid along the given axis.
     *
     * @param axis either <code>View.X_AXIS</code> or <code>View.Y_AXIS</code>
     *
     * @since 1.4
     */
    protected boolean isLayoutValid(int axis) {
        if (axis == majorAxis) {
            return majorAllocValid;
        } else {
            return minorAllocValid;
        }
    }

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

Params:
  • g – the graphics context
  • alloc – the allocated region to paint into
  • index – the child index, >= 0 && < getViewCount()
/**
     * Paints a child.  By default
     * that is all it does, but a subclass can use this to paint
     * things relative to the child.
     *
     * @param g the graphics context
     * @param alloc the allocated region to paint into
     * @param index the child index, >= 0 && < getViewCount()
     */
    protected void paintChild(Graphics g, Rectangle alloc, int index) {
        View child = getView(index);
        child.paint(g, alloc);
    }

    // --- View methods ---------------------------------------------

    
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.

Params:
  • 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
  nullto indicate no children are being added
  (useful to remove)
/**
     * 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.
     *
     * @param index the starting index into the child views to insert
     *   the new views; this should be a value >= 0 and <= getViewCount
     * @param length the number of existing child views to remove;
     *   This should be a value >= 0 and <= (getViewCount() - offset)
     * @param elems the child views to add; this value can be
     *   <code>null</code>to indicate no children are being added
     *   (useful to remove)
     */
    public void replace(int index, int length, View[] elems) {
        super.replace(index, length, elems);

        // invalidate cache
        int nInserted = (elems != null) ? elems.length : 0;
        majorOffsets = updateLayoutArray(majorOffsets, index, nInserted);
        majorSpans = updateLayoutArray(majorSpans, index, nInserted);
        majorReqValid = false;
        majorAllocValid = false;
        minorOffsets = updateLayoutArray(minorOffsets, index, nInserted);
        minorSpans = updateLayoutArray(minorSpans, index, nInserted);
        minorReqValid = false;
        minorAllocValid = false;
    }

    
Resizes the given layout array to match the new number of
child views.  The current number of child views are used to
produce the new array.  The contents of the old array are
inserted into the new array at the appropriate places so that
the old layout information is transferred to the new array.

Params:
  • oldArray – the original layout array
  • offset – location where new views will be inserted
  • nInserted – the number of child views being inserted;
         therefore the number of blank spaces to leave in the
         new array at location offset
Returns:the new layout array
/**
     * Resizes the given layout array to match the new number of
     * child views.  The current number of child views are used to
     * produce the new array.  The contents of the old array are
     * inserted into the new array at the appropriate places so that
     * the old layout information is transferred to the new array.
     *
     * @param oldArray the original layout array
     * @param offset location where new views will be inserted
     * @param nInserted the number of child views being inserted;
     *          therefore the number of blank spaces to leave in the
     *          new array at location <code>offset</code>
     * @return the new layout array
     */
    int[] updateLayoutArray(int[] oldArray, int offset, int nInserted) {
        int n = getViewCount();
        int[] newArray = new int[n];

        System.arraycopy(oldArray, 0, newArray, 0, offset);
        System.arraycopy(oldArray, offset,
                         newArray, offset + nInserted, n - nInserted - offset);
        return newArray;
    }

    
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.

Params:
  • 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
See Also:
Since:1.3
/**
     * Forwards the given <code>DocumentEvent</code> 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.
     *
     * @param ec changes to the element this view is responsible
     *  for (may be <code>null</code> if there were no changes)
     * @param e the change information from the associated document
     * @param a the current allocation of the view
     * @param f the factory to use to rebuild if the view has children
     * @see #insertUpdate
     * @see #removeUpdate
     * @see #changedUpdate
     * @since 1.3
     */
    protected void forwardUpdate(DocumentEvent.ElementChange ec,
                                 DocumentEvent e, Shape a, ViewFactory f) {
        boolean wasValid = isLayoutValid(majorAxis);
        super.forwardUpdate(ec, e, a, f);

        // determine if a repaint is needed
        if (wasValid && (! isLayoutValid(majorAxis))) {
            // Repaint is needed because one of the tiled children
            // have changed their span along the major axis.  If there
            // is a hosting component and an allocated shape we repaint.
            Component c = getContainer();
            if ((a != null) && (c != null)) {
                int pos = e.getOffset();
                int index = getViewIndexAtPosition(pos);
                Rectangle alloc = getInsideAllocation(a);
                if (majorAxis == X_AXIS) {
                    alloc.x += majorOffsets[index];
                    alloc.width -= majorOffsets[index];
                } else {
                    alloc.y += minorOffsets[index];
                    alloc.height -= minorOffsets[index];
                }
                c.repaint(alloc.x, alloc.y, alloc.width, alloc.height);
            }
        }
    }

    
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.

Params:
  • child – the child view
  • width – true if the width preference should change
  • height – true if the height preference should change
/**
     * 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.
     *
     * @param child the child view
     * @param width true if the width preference should change
     * @param height true if the height preference should change
     */
    public void preferenceChanged(View child, boolean width, boolean height) {
        boolean majorChanged = (majorAxis == X_AXIS) ? width : height;
        boolean minorChanged = (majorAxis == X_AXIS) ? height : width;
        if (majorChanged) {
            majorReqValid = false;
            majorAllocValid = false;
        }
        if (minorChanged) {
            minorReqValid = false;
            minorAllocValid = false;
        }
        super.preferenceChanged(child, width, height);
    }

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

Params:
  • axis – may be either View.X_AXIS or
         View.Y_AXIS
Throws:
Returns:the weight
/**
     * Gets the resize weight.  A value of 0 or less is not resizable.
     *
     * @param axis may be either <code>View.X_AXIS</code> or
     *          <code>View.Y_AXIS</code>
     * @return the weight
     * @exception IllegalArgumentException for an invalid axis
     */
    public int getResizeWeight(int axis) {
        checkRequests(axis);
        if (axis == majorAxis) {
            if ((majorRequest.preferred != majorRequest.minimum) ||
                (majorRequest.preferred != majorRequest.maximum)) {
                return 1;
            }
        } else {
            if ((minorRequest.preferred != minorRequest.minimum) ||
                (minorRequest.preferred != minorRequest.maximum)) {
                return 1;
            }
        }
        return 0;
    }

    
Sets the size of the view along an axis.  This should cause
layout of the view along the given axis.

Params:
  • axis – may be either View.X_AXIS or
         View.Y_AXIS
  • span – the span to layout to >= 0
/**
     * Sets the size of the view along an axis.  This should cause
     * layout of the view along the given axis.
     *
     * @param axis may be either <code>View.X_AXIS</code> or
     *          <code>View.Y_AXIS</code>
     * @param span the span to layout to >= 0
     */
    void setSpanOnAxis(int axis, float span) {
        if (axis == majorAxis) {
            if (majorSpan != (int) span) {
                majorAllocValid = false;
            }
            if (! majorAllocValid) {
                // layout the major axis
                majorSpan = (int) span;
                checkRequests(majorAxis);
                layoutMajorAxis(majorSpan, axis, majorOffsets, majorSpans);
                majorAllocValid = true;

                // flush changes to the children
                updateChildSizes();
            }
        } else {
            if (((int) span) != minorSpan) {
                minorAllocValid = false;
            }
            if (! minorAllocValid) {
                // layout the minor axis
                minorSpan = (int) span;
                checkRequests(axis);
                layoutMinorAxis(minorSpan, axis, minorOffsets, minorSpans);
                minorAllocValid = true;

                // flush changes to the children
                updateChildSizes();
            }
        }
    }

    
Propagates the current allocations to the child views.

/**
     * Propagates the current allocations to the child views.
     */
    void updateChildSizes() {
        int n = getViewCount();
        if (majorAxis == X_AXIS) {
            for (int i = 0; i < n; i++) {
                View v = getView(i);
                v.setSize((float) majorSpans[i], (float) minorSpans[i]);
            }
        } else {
            for (int i = 0; i < n; i++) {
                View v = getView(i);
                v.setSize((float) minorSpans[i], (float) majorSpans[i]);
            }
        }
    }

    
Returns the size of the view along an axis.  This is implemented
to return zero.

Params:
  • axis – may be either View.X_AXIS or
         View.Y_AXIS
Returns:the current span of the view along the given axis, >= 0
/**
     * Returns the size of the view along an axis.  This is implemented
     * to return zero.
     *
     * @param axis may be either <code>View.X_AXIS</code> or
     *          <code>View.Y_AXIS</code>
     * @return the current span of the view along the given axis, >= 0
     */
    float getSpanOnAxis(int axis) {
        if (axis == majorAxis) {
            return majorSpan;
        } else {
            return minorSpan;
        }
    }

    
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.

Params:
  • width – the width >= 0
  • height – the height >= 0
/**
     * 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.
     *
     * @param width the width >= 0
     * @param height the height >= 0
     */
    public void setSize(float width, float height) {
        layout(Math.max(0, (int)(width - getLeftInset() - getRightInset())),
               Math.max(0, (int)(height - getTopInset() - getBottomInset())));
    }

    
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.

Params:
  • g – the rendering surface to use
  • allocation – the allocated region to render into
See Also:
/**
     * Renders the <code>BoxView</code> using the given
     * rendering surface and area
     * on that surface.  Only the children that intersect
     * the clip bounds of the given <code>Graphics</code>
     * will be rendered.
     *
     * @param g the rendering surface to use
     * @param allocation the allocated region to render into
     * @see View#paint
     */
    public void paint(Graphics g, Shape allocation) {
        Rectangle alloc = (allocation instanceof Rectangle) ?
                           (Rectangle)allocation : allocation.getBounds();
        int n = getViewCount();
        int x = alloc.x + getLeftInset();
        int y = alloc.y + getTopInset();
        Rectangle clip = g.getClipBounds();
        for (int i = 0; i < n; i++) {
            tempRect.x = x + getOffset(X_AXIS, i);
            tempRect.y = y + getOffset(Y_AXIS, i);
            tempRect.width = getSpan(X_AXIS, i);
            tempRect.height = getSpan(Y_AXIS, i);
            int trx0 = tempRect.x, trx1 = trx0 + tempRect.width;
            int try0 = tempRect.y, try1 = try0 + tempRect.height;
            int crx0 = clip.x, crx1 = crx0 + clip.width;
            int cry0 = clip.y, cry1 = cry0 + clip.height;
            // We should paint views that intersect with clipping region
            // even if the intersection has no inside points (is a line).
            // This is needed for supporting views that have zero width, like
            // views that contain only combining marks.
            if ((trx1 >= crx0) && (try1 >= cry0) && (crx1 >= trx0) && (cry1 >= try0)) {
                paintChild(g, tempRect, i);
            }
        }
    }

    
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.

Params:
  • index – the index of the child, >= 0 && < getViewCount()
  • a –  the allocation to this view
Returns:the allocation to the child; or null
         if a is null;
         or null if the layout is invalid
/**
     * Fetches the allocation for the given child view.
     * This enables finding out where various views
     * are located.  This is implemented to return
     * <code>null</code> if the layout is invalid,
     * otherwise the superclass behavior is executed.
     *
     * @param index the index of the child, >= 0 && < getViewCount()
     * @param a  the allocation to this view
     * @return the allocation to the child; or <code>null</code>
     *          if <code>a</code> is <code>null</code>;
     *          or <code>null</code> if the layout is invalid
     */
    public Shape getChildAllocation(int index, Shape a) {
        if (a != null) {
            Shape ca = super.getChildAllocation(index, a);
            if ((ca != null) && (! isAllocationValid())) {
                // The child allocation may not have been set yet.
                Rectangle r = (ca instanceof Rectangle) ?
                    (Rectangle) ca : ca.getBounds();
                if ((r.width == 0) && (r.height == 0)) {
                    return null;
                }
            }
            return ca;
        }
        return null;
    }

    
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.

Params:
  • pos – the position to convert >= 0
  • a – the allocated region to render into
Throws:
  • BadLocationException –  if the given position does
 not represent a valid location in the associated document
See Also:
Returns:the bounding box of the given position
/**
     * 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.
     *
     * @param pos the position to convert >= 0
     * @param a the allocated region to render into
     * @return the bounding box of the given position
     * @exception BadLocationException  if the given position does
     *  not represent a valid location in the associated document
     * @see View#modelToView
     */
    public Shape modelToView(int pos, Shape a, Position.Bias b) throws BadLocationException {
        if (! isAllocationValid()) {
            Rectangle alloc = a.getBounds();
            setSize(alloc.width, alloc.height);
        }
        return super.modelToView(pos, a, b);
    }

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

Params:
  • x –   x coordinate of the view location to convert >= 0
  • y –   y coordinate of the view location to convert >= 0
  • a – the allocated region to render into
See Also:
Returns:the location within the model that best represents the
 given point in the view >= 0
/**
     * Provides a mapping from the view coordinate space to the logical
     * coordinate space of the model.
     *
     * @param x   x coordinate of the view location to convert >= 0
     * @param y   y coordinate of the view location to convert >= 0
     * @param a the allocated region to render into
     * @return the location within the model that best represents the
     *  given point in the view >= 0
     * @see View#viewToModel
     */
    public int viewToModel(float x, float y, Shape a, Position.Bias[] bias) {
        if (! isAllocationValid()) {
            Rectangle alloc = a.getBounds();
            setSize(alloc.width, alloc.height);
        }
        return super.viewToModel(x, y, a, bias);
    }

    
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).

Params:
  • axis – may be either View.X_AXIS
  or View.Y_AXIS
Throws:
Returns: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 view
/**
     * 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).
     *
     * @param axis may be either <code>View.X_AXIS</code>
     *   or <code>View.Y_AXIS</code>
     * @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 view
     * @exception IllegalArgumentException for an invalid axis
     */
    public float getAlignment(int axis) {
        checkRequests(axis);
        if (axis == majorAxis) {
            return majorRequest.alignment;
        } else {
            return minorRequest.alignment;
        }
    }

    
Determines the preferred span for this view along an
axis.

Params:
  • axis – may be either View.X_AXIS
          or View.Y_AXIS
Throws:
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
/**
     * Determines the preferred span for this view along an
     * axis.
     *
     * @param axis may be either <code>View.X_AXIS</code>
     *           or <code>View.Y_AXIS</code>
     * @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 view
     * @exception IllegalArgumentException for an invalid axis type
     */
    public float getPreferredSpan(int axis) {
        checkRequests(axis);
        float marginSpan = (axis == X_AXIS) ? getLeftInset() + getRightInset() :
            getTopInset() + getBottomInset();
        if (axis == majorAxis) {
            return ((float)majorRequest.preferred) + marginSpan;
        } else {
            return ((float)minorRequest.preferred) + marginSpan;
        }
    }

    
Determines the minimum span for this view along an
axis.

Params:
  • axis – may be either View.X_AXIS
          or View.Y_AXIS
Throws:
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
/**
     * Determines the minimum span for this view along an
     * axis.
     *
     * @param axis may be either <code>View.X_AXIS</code>
     *           or <code>View.Y_AXIS</code>
     * @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 view
     * @exception IllegalArgumentException for an invalid axis type
     */
    public float getMinimumSpan(int axis) {
        checkRequests(axis);
        float marginSpan = (axis == X_AXIS) ? getLeftInset() + getRightInset() :
            getTopInset() + getBottomInset();
        if (axis == majorAxis) {
            return ((float)majorRequest.minimum) + marginSpan;
        } else {
            return ((float)minorRequest.minimum) + marginSpan;
        }
    }

    
Determines the maximum span for this view along an
axis.

Params:
  • axis – may be either View.X_AXIS
          or View.Y_AXIS
Throws:
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
/**
     * Determines the maximum span for this view along an
     * axis.
     *
     * @param axis may be either <code>View.X_AXIS</code>
     *           or <code>View.Y_AXIS</code>
     * @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 view
     * @exception IllegalArgumentException for an invalid axis type
     */
    public float getMaximumSpan(int axis) {
        checkRequests(axis);
        float marginSpan = (axis == X_AXIS) ? getLeftInset() + getRightInset() :
            getTopInset() + getBottomInset();
        if (axis == majorAxis) {
            return ((float)majorRequest.maximum) + marginSpan;
        } else {
            return ((float)minorRequest.maximum) + marginSpan;
        }
    }

    // --- local methods ----------------------------------------------------

    
Are the allocations for the children still
valid?

Returns:true if allocations still valid
/**
     * Are the allocations for the children still
     * valid?
     *
     * @return true if allocations still valid
     */
    protected boolean isAllocationValid() {
        return (majorAllocValid && minorAllocValid);
    }

    
Determines if a point falls before an allocated region.

Params:
  • x – the X coordinate >= 0
  • y – the Y coordinate >= 0
  • innerAlloc – the allocated region; this is the area
  inside of the insets
Returns:true if the point lies before the region else false
/**
     * Determines if a point falls before an allocated region.
     *
     * @param x the X coordinate >= 0
     * @param y the Y coordinate >= 0
     * @param innerAlloc the allocated region; this is the area
     *   inside of the insets
     * @return true if the point lies before the region else false
     */
    protected boolean isBefore(int x, int y, Rectangle innerAlloc) {
        if (majorAxis == View.X_AXIS) {
            return (x < innerAlloc.x);
        } else {
            return (y < innerAlloc.y);
        }
    }

    
Determines if a point falls after an allocated region.

Params:
  • x – the X coordinate >= 0
  • y – the Y coordinate >= 0
  • innerAlloc – the allocated region; this is the area
  inside of the insets
Returns:true if the point lies after the region else false
/**
     * Determines if a point falls after an allocated region.
     *
     * @param x the X coordinate >= 0
     * @param y the Y coordinate >= 0
     * @param innerAlloc the allocated region; this is the area
     *   inside of the insets
     * @return true if the point lies after the region else false
     */
    protected boolean isAfter(int x, int y, Rectangle innerAlloc) {
        if (majorAxis == View.X_AXIS) {
            return (x > (innerAlloc.width + innerAlloc.x));
        } else {
            return (y > (innerAlloc.height + innerAlloc.y));
        }
    }

    
Fetches the child view at the given coordinates.

Params:
  • x – the X coordinate >= 0
  • y – the Y coordinate >= 0
  • alloc – the parents inner allocation on entry, which should
  be changed to the childs allocation on exit
Returns:the view
/**
     * Fetches the child view at the given coordinates.
     *
     * @param x the X coordinate >= 0
     * @param y the Y coordinate >= 0
     * @param alloc the parents inner allocation on entry, which should
     *   be changed to the childs allocation on exit
     * @return the view
     */
    protected View getViewAtPoint(int x, int y, Rectangle alloc) {
        int n = getViewCount();
        if (majorAxis == View.X_AXIS) {
            if (x < (alloc.x + majorOffsets[0])) {
                childAllocation(0, alloc);
                return getView(0);
            }
            for (int i = 0; i < n; i++) {
                if (x < (alloc.x + majorOffsets[i])) {
                    childAllocation(i - 1, alloc);
                    return getView(i - 1);
                }
            }
            childAllocation(n - 1, alloc);
            return getView(n - 1);
        } else {
            if (y < (alloc.y + majorOffsets[0])) {
                childAllocation(0, alloc);
                return getView(0);
            }
            for (int i = 0; i < n; i++) {
                if (y < (alloc.y + majorOffsets[i])) {
                    childAllocation(i - 1, alloc);
                    return getView(i - 1);
                }
            }
            childAllocation(n - 1, alloc);
            return getView(n - 1);
        }
    }

    
Allocates a region for a child view.

Params:
  • index – the index of the child view to
  allocate, >= 0 && < getViewCount()
  • alloc – the allocated region
/**
     * Allocates a region for a child view.
     *
     * @param index the index of the child view to
     *   allocate, >= 0 && < getViewCount()
     * @param alloc the allocated region
     */
    protected void childAllocation(int index, Rectangle alloc) {
        alloc.x += getOffset(X_AXIS, index);
        alloc.y += getOffset(Y_AXIS, index);
        alloc.width = getSpan(X_AXIS, index);
        alloc.height = getSpan(Y_AXIS, index);
    }

    
Perform layout on the box

Params:
  • width – the width (inside of the insets) >= 0
  • height – the height (inside of the insets) >= 0
/**
     * Perform layout on the box
     *
     * @param width the width (inside of the insets) >= 0
     * @param height the height (inside of the insets) >= 0
     */
    protected void layout(int width, int height) {
        setSpanOnAxis(X_AXIS, width);
        setSpanOnAxis(Y_AXIS, height);
    }

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

Returns:the current width of the box
/**
     * Returns the current width of the box.  This is the width that
     * it was last allocated.
     * @return the current width of the box
     */
    public int getWidth() {
        int span;
        if (majorAxis == X_AXIS) {
            span = majorSpan;
        } else {
            span = minorSpan;
        }
        span += getLeftInset() - getRightInset();
        return span;
    }

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

Returns:the current height of the box
/**
     * Returns the current height of the box.  This is the height that
     * it was last allocated.
     * @return the current height of the box
     */
    public int getHeight() {
        int span;
        if (majorAxis == Y_AXIS) {
            span = majorSpan;
        } else {
            span = minorSpan;
        }
        span += getTopInset() - getBottomInset();
        return span;
    }

    
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.

Params:
  • 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
/**
     * 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.
     *
     * @param targetSpan the total span given to the view, which
     *  would be used to layout the children
     * @param axis the axis being layed out
     * @param 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
     * @param spans the span of each child view; this is a return
     *  value and is filled in by the implementation of this method
     */
    protected void layoutMajorAxis(int targetSpan, int axis, int[] offsets, int[] spans) {
        /*
         * first pass, calculate the preferred sizes
         * and the flexibility to adjust the sizes.
         */
        long preferred = 0;
        int n = getViewCount();
        for (int i = 0; i < n; i++) {
            View v = getView(i);
            spans[i] = (int) v.getPreferredSpan(axis);
            preferred += spans[i];
        }

        /*
         * Second pass, expand or contract by as much as possible to reach
         * the target span.
         */

        // determine the adjustment to be made
        long desiredAdjustment = targetSpan - preferred;
        float adjustmentFactor = 0.0f;
        int[] diffs = null;

        if (desiredAdjustment != 0) {
            long totalSpan = 0;
            diffs = new int[n];
            for (int i = 0; i < n; i++) {
                View v = getView(i);
                int tmp;
                if (desiredAdjustment < 0) {
                    tmp = (int)v.getMinimumSpan(axis);
                    diffs[i] = spans[i] - tmp;
                } else {
                    tmp = (int)v.getMaximumSpan(axis);
                    diffs[i] = tmp - spans[i];
                }
                totalSpan += tmp;
            }

            float maximumAdjustment = Math.abs(totalSpan - preferred);
                adjustmentFactor = desiredAdjustment / maximumAdjustment;
                adjustmentFactor = Math.min(adjustmentFactor, 1.0f);
                adjustmentFactor = Math.max(adjustmentFactor, -1.0f);
            }

        // make the adjustments
        int totalOffset = 0;
        for (int i = 0; i < n; i++) {
            offsets[i] = totalOffset;
            if (desiredAdjustment != 0) {
                float adjF = adjustmentFactor * diffs[i];
                spans[i] += Math.round(adjF);
            }
            totalOffset = (int) Math.min((long) totalOffset + (long) spans[i], Integer.MAX_VALUE);
        }
    }

    
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.

Params:
  • 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
/**
     * 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.
     *
     * @param targetSpan the total span given to the view, which
     *  would be used to layout the children
     * @param axis the axis being layed out
     * @param 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
     * @param 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) {
        int n = getViewCount();
        for (int i = 0; i < n; i++) {
            View v = getView(i);
            int max = (int) v.getMaximumSpan(axis);
            if (max < targetSpan) {
                // can't make the child this wide, align it
                float align = v.getAlignment(axis);
                offsets[i] = (int) ((targetSpan - max) * align);
                spans[i] = max;
            } else {
                // make it the target width, or as small as it can get.
                int min = (int)v.getMinimumSpan(axis);
                offsets[i] = 0;
                spans[i] = Math.max(min, targetSpan);
            }
        }
    }

    
Calculates the size requirements for the major axis
axis.

Params:
  • axis – the axis being studied
  • r – the SizeRequirements object;
         if null one will be created
See Also:
Returns:the newly initialized SizeRequirements object
/**
     * Calculates the size requirements for the major axis
     * <code>axis</code>.
     *
     * @param axis the axis being studied
     * @param r the <code>SizeRequirements</code> object;
     *          if <code>null</code> one will be created
     * @return the newly initialized <code>SizeRequirements</code> object
     * @see javax.swing.SizeRequirements
     */
    protected SizeRequirements calculateMajorAxisRequirements(int axis, SizeRequirements r) {
        // calculate tiled request
        float min = 0;
        float pref = 0;
        float max = 0;

        int n = getViewCount();
        for (int i = 0; i < n; i++) {
            View v = getView(i);
            min += v.getMinimumSpan(axis);
            pref += v.getPreferredSpan(axis);
            max += v.getMaximumSpan(axis);
        }

        if (r == null) {
            r = new SizeRequirements();
        }
        r.alignment = 0.5f;
        r.minimum = (int) min;
        r.preferred = (int) pref;
        r.maximum = (int) max;
        return r;
    }

    
Calculates the size requirements for the minor axis
axis.

Params:
  • axis – the axis being studied
  • r – the SizeRequirements object;
         if null one will be created
See Also:
Returns:the newly initialized SizeRequirements object
/**
     * Calculates the size requirements for the minor axis
     * <code>axis</code>.
     *
     * @param axis the axis being studied
     * @param r the <code>SizeRequirements</code> object;
     *          if <code>null</code> one will be created
     * @return the newly initialized <code>SizeRequirements</code> object
     * @see javax.swing.SizeRequirements
     */
    protected SizeRequirements calculateMinorAxisRequirements(int axis, SizeRequirements r) {
        int min = 0;
        long pref = 0;
        int max = Integer.MAX_VALUE;
        int n = getViewCount();
        for (int i = 0; i < n; i++) {
            View v = getView(i);
            min = Math.max((int) v.getMinimumSpan(axis), min);
            pref = Math.max((int) v.getPreferredSpan(axis), pref);
            max = Math.max((int) v.getMaximumSpan(axis), max);
        }

        if (r == null) {
            r = new SizeRequirements();
            r.alignment = 0.5f;
        }
        r.preferred = (int) pref;
        r.minimum = min;
        r.maximum = max;
        return r;
    }

    
Checks the request cache and update if needed.

Params:
  • axis – the axis being studied
Throws:
/**
     * Checks the request cache and update if needed.
     * @param axis the axis being studied
     * @exception IllegalArgumentException if <code>axis</code> is
     *  neither <code>View.X_AXIS</code> nor <code>View.Y_AXIS</code>
     */
    void checkRequests(int axis) {
        if ((axis != X_AXIS) && (axis != Y_AXIS)) {
            throw new IllegalArgumentException("Invalid axis: " + axis);
        }
        if (axis == majorAxis) {
            if (!majorReqValid) {
                majorRequest = calculateMajorAxisRequirements(axis,
                                                              majorRequest);
                majorReqValid = true;
            }
        } else if (! minorReqValid) {
            minorRequest = calculateMinorAxisRequirements(axis, minorRequest);
            minorReqValid = true;
        }
    }

    
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.

Params:
  • 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
/**
     * Computes the location and extent of each child view
     * in this <code>BoxView</code> given the <code>targetSpan</code>,
     * which is the width (or height) of the region we have to
     * work with.
     *
     * @param targetSpan the total span given to the view, which
     *  would be used to layout the children
     * @param axis the axis being studied, either
     *          <code>View.X_AXIS</code> or <code>View.Y_AXIS</code>
     * @param offsets an empty array filled by this method with
     *          values specifying the location  of each child view
     * @param spans  an empty array filled by this method with
     *          values specifying the extent of each child view
     */
    protected void baselineLayout(int targetSpan, int axis, int[] offsets, int[] spans) {
        int totalAscent = (int)(targetSpan * getAlignment(axis));
        int totalDescent = targetSpan - totalAscent;

        int n = getViewCount();

        for (int i = 0; i < n; i++) {
            View v = getView(i);
            float align = v.getAlignment(axis);
            float viewSpan;

            if (v.getResizeWeight(axis) > 0) {
                // if resizable then resize to the best fit

                // the smallest span possible
                float minSpan = v.getMinimumSpan(axis);
                // the largest span possible
                float maxSpan = v.getMaximumSpan(axis);

                if (align == 0.0f) {
                    // if the alignment is 0 then we need to fit into the descent
                    viewSpan = Math.max(Math.min(maxSpan, totalDescent), minSpan);
                } else if (align == 1.0f) {
                    // if the alignment is 1 then we need to fit into the ascent
                    viewSpan = Math.max(Math.min(maxSpan, totalAscent), minSpan);
                } else {
                    // figure out the span that we must fit into
                    float fitSpan = Math.min(totalAscent / align,
                                             totalDescent / (1.0f - align));
                    // fit into the calculated span
                    viewSpan = Math.max(Math.min(maxSpan, fitSpan), minSpan);
                }
            } else {
                // otherwise use the preferred spans
                viewSpan = v.getPreferredSpan(axis);
            }

            offsets[i] = totalAscent - (int)(viewSpan * align);
            spans[i] = (int)viewSpan;
        }
    }

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

Params:
  • axis – the axis being studied
  • r – the SizeRequirements object;
         if null one will be created
Returns:the newly initialized SizeRequirements object
/**
     * Calculates the size requirements for this <code>BoxView</code>
     * by examining the size of each child view.
     *
     * @param axis the axis being studied
     * @param r the <code>SizeRequirements</code> object;
     *          if <code>null</code> one will be created
     * @return the newly initialized <code>SizeRequirements</code> object
     */
    protected SizeRequirements baselineRequirements(int axis, SizeRequirements r) {
        SizeRequirements totalAscent = new SizeRequirements();
        SizeRequirements totalDescent = new SizeRequirements();

        if (r == null) {
            r = new SizeRequirements();
        }

        r.alignment = 0.5f;

        int n = getViewCount();

        // loop through all children calculating the max of all their ascents and
        // descents at minimum, preferred, and maximum sizes
        for (int i = 0; i < n; i++) {
            View v = getView(i);
            float align = v.getAlignment(axis);
            float span;
            int ascent;
            int descent;

            // find the maximum of the preferred ascents and descents
            span = v.getPreferredSpan(axis);
            ascent = (int)(align * span);
            descent = (int)(span - ascent);
            totalAscent.preferred = Math.max(ascent, totalAscent.preferred);
            totalDescent.preferred = Math.max(descent, totalDescent.preferred);

            if (v.getResizeWeight(axis) > 0) {
                // if the view is resizable then do the same for the minimum and
                // maximum ascents and descents
                span = v.getMinimumSpan(axis);
                ascent = (int)(align * span);
                descent = (int)(span - ascent);
                totalAscent.minimum = Math.max(ascent, totalAscent.minimum);
                totalDescent.minimum = Math.max(descent, totalDescent.minimum);

                span = v.getMaximumSpan(axis);
                ascent = (int)(align * span);
                descent = (int)(span - ascent);
                totalAscent.maximum = Math.max(ascent, totalAscent.maximum);
                totalDescent.maximum = Math.max(descent, totalDescent.maximum);
            } else {
                // otherwise use the preferred
                totalAscent.minimum = Math.max(ascent, totalAscent.minimum);
                totalDescent.minimum = Math.max(descent, totalDescent.minimum);
                totalAscent.maximum = Math.max(ascent, totalAscent.maximum);
                totalDescent.maximum = Math.max(descent, totalDescent.maximum);
            }
        }

        // we now have an overall preferred, minimum, and maximum ascent and descent

        // calculate the preferred span as the sum of the preferred ascent and preferred descent
        r.preferred = (int)Math.min((long)totalAscent.preferred + (long)totalDescent.preferred,
                                    Integer.MAX_VALUE);

        // calculate the preferred alignment as the preferred ascent divided by the preferred span
        if (r.preferred > 0) {
            r.alignment = (float)totalAscent.preferred / r.preferred;
        }


        if (r.alignment == 0.0f) {
            // if the preferred alignment is 0 then the minimum and maximum spans are simply
            // the minimum and maximum descents since there's nothing above the baseline
            r.minimum = totalDescent.minimum;
            r.maximum = totalDescent.maximum;
        } else if (r.alignment == 1.0f) {
            // if the preferred alignment is 1 then the minimum and maximum spans are simply
            // the minimum and maximum ascents since there's nothing below the baseline
            r.minimum = totalAscent.minimum;
            r.maximum = totalAscent.maximum;
        } else {
            // we want to honor the preferred alignment so we calculate two possible minimum
            // span values using 1) the minimum ascent and the alignment, and 2) the minimum
            // descent and the alignment. We'll choose the larger of these two numbers.
            r.minimum = Math.round(Math.max(totalAscent.minimum / r.alignment,
                                          totalDescent.minimum / (1.0f - r.alignment)));
            // a similar calculation is made for the maximum but we choose the smaller number.
            r.maximum = Math.round(Math.min(totalAscent.maximum / r.alignment,
                                          totalDescent.maximum / (1.0f - r.alignment)));
        }

        return r;
    }

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

Params:
  • axis – the axis being studied
  • childIndex – the index of the requested child
Returns:the offset (location) for the specified child
/**
     * Fetches the offset of a particular child's current layout.
     * @param axis the axis being studied
     * @param childIndex the index of the requested child
     * @return the offset (location) for the specified child
     */
    protected int getOffset(int axis, int childIndex) {
        int[] offsets = (axis == majorAxis) ? majorOffsets : minorOffsets;
        return offsets[childIndex];
    }

    
Fetches the span of a particular childs current layout.

Params:
  • axis – the axis being studied
  • childIndex – the index of the requested child
Returns:the span (width or height) of the specified child
/**
     * Fetches the span of a particular childs current layout.
     * @param axis the axis being studied
     * @param childIndex the index of the requested child
     * @return the span (width or height) of the specified child
     */
    protected int getSpan(int axis, int childIndex) {
        int[] spans = (axis == majorAxis) ? majorSpans : minorSpans;
        return spans[childIndex];
    }

    
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.

Params:
  • position – position into the model
  • bias – either Position.Bias.Forward or
         Position.Bias.Backward
Returns:true if the Views surrounding the
         View responding for rendering
         position and bias
         are layed out in descending order; otherwise false
/**
     * Determines in which direction the next view lays.
     * Consider the View at index n. Typically the <code>View</code>s
     * are layed out from left to right, so that the <code>View</code>
     * to the EAST will be at index n + 1, and the <code>View</code>
     * to the WEST will be at index n - 1. In certain situations,
     * such as with bidirectional text, it is possible
     * that the <code>View</code> to EAST is not at index n + 1,
     * but rather at index n - 1, or that the <code>View</code>
     * to the WEST is not at index n - 1, but index n + 1.
     * In this case this method would return true,
     * indicating the <code>View</code>s are layed out in
     * descending order. Otherwise the method would return false
     * indicating the <code>View</code>s are layed out in ascending order.
     * <p>
     * If the receiver is laying its <code>View</code>s along the
     * <code>Y_AXIS</code>, this will will return the value from
     * invoking the same method on the <code>View</code>
     * responsible for rendering <code>position</code> and
     * <code>bias</code>. Otherwise this will return false.
     *
     * @param position position into the model
     * @param bias either <code>Position.Bias.Forward</code> or
     *          <code>Position.Bias.Backward</code>
     * @return true if the <code>View</code>s surrounding the
     *          <code>View</code> responding for rendering
     *          <code>position</code> and <code>bias</code>
     *          are layed out in descending order; otherwise false
     */
    protected boolean flipEastAndWestAtEnds(int position,
                                            Position.Bias bias) {
        if(majorAxis == Y_AXIS) {
            int testPos = (bias == Position.Bias.Backward) ?
                          Math.max(0, position - 1) : position;
            int index = getViewIndexAtPosition(testPos);
            if(index != -1) {
                View v = getView(index);
                if(v != null && v instanceof CompositeView) {
                    return ((CompositeView)v).flipEastAndWestAtEnds(position,
                                                                    bias);
                }
            }
        }
        return false;
    }

    // --- variables ------------------------------------------------

    int majorAxis;

    int majorSpan;
    int minorSpan;

    /*
     * Request cache
     */
    boolean majorReqValid;
    boolean minorReqValid;
    SizeRequirements majorRequest;
    SizeRequirements minorRequest;

    /*
     * Allocation cache
     */
    boolean majorAllocValid;
    int[] majorOffsets;
    int[] majorSpans;
    boolean minorAllocValid;
    int[] minorOffsets;
    int[] minorSpans;

    
used in paint. 
/** used in paint. */
    Rectangle tempRect;
}