The SizeRequirements.java Java example source code
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package javax.swing;
import java.awt.*;
import java.io.Serializable;
/**
* For the convenience of layout managers,
* calculates information about the size and position of components.
* All size and position calculation methods are class methods
* that take arrays of SizeRequirements as arguments.
* The SizeRequirements class supports two types of layout:
*
* <blockquote>
* <dl>
* <dt> tiled
* <dd> The components are placed end-to-end,
* starting either at coordinate 0 (the leftmost or topmost position)
* or at the coordinate representing the end of the allocated span
* (the rightmost or bottommost position).
*
* <dt> aligned
* <dd> The components are aligned as specified
* by each component's X or Y alignment value.
* </dl>
* </blockquote>
*
* <p>
*
* Each SizeRequirements object contains information
* about either the width (and X alignment)
* or height (and Y alignment)
* of a single component or a group of components:
*
* <blockquote>
* <dl>
* <dt> minimum
* <dd> The smallest reasonable width/height of the component
* or component group, in pixels.
*
* <dt> preferred
* <dd> The natural width/height of the component
* or component group, in pixels.
*
* <dt> maximum
* <dd> The largest reasonable width/height of the component
* or component group, in pixels.
*
* <dt> alignment
* <dd> The X/Y alignment of the component
* or component group.
* </dl>
* </blockquote>
* <p>
* <strong>Warning:
* Serialized objects of this class will not be compatible with
* future Swing releases. The current serialization support is
* appropriate for short term storage or RMI between applications running
* the same version of Swing. As of 1.4, support for long term storage
* of all JavaBeans™
* has been added to the <code>java.beans package.
* Please see {@link java.beans.XMLEncoder}.
*
* @see Component#getMinimumSize
* @see Component#getPreferredSize
* @see Component#getMaximumSize
* @see Component#getAlignmentX
* @see Component#getAlignmentY
*
* @author Timothy Prinzing
*/
public class SizeRequirements implements Serializable {
/**
* The minimum size required.
* For a component <code>comp, this should be equal to either
* <code>comp.getMinimumSize().width or
* <code>comp.getMinimumSize().height.
*/
public int minimum;
/**
* The preferred (natural) size.
* For a component <code>comp, this should be equal to either
* <code>comp.getPreferredSize().width or
* <code>comp.getPreferredSize().height.
*/
public int preferred;
/**
* The maximum size allowed.
* For a component <code>comp, this should be equal to either
* <code>comp.getMaximumSize().width or
* <code>comp.getMaximumSize().height.
*/
public int maximum;
/**
* The alignment, specified as a value between 0.0 and 1.0,
* inclusive.
* To specify centering, the alignment should be 0.5.
*/
public float alignment;
/**
* Creates a SizeRequirements object with the minimum, preferred,
* and maximum sizes set to zero and an alignment value of 0.5
* (centered).
*/
public SizeRequirements() {
minimum = 0;
preferred = 0;
maximum = 0;
alignment = 0.5f;
}
/**
* Creates a SizeRequirements object with the specified minimum, preferred,
* and maximum sizes and the specified alignment.
*
* @param min the minimum size >= 0
* @param pref the preferred size >= 0
* @param max the maximum size >= 0
* @param a the alignment >= 0.0f && <= 1.0f
*/
public SizeRequirements(int min, int pref, int max, float a) {
minimum = min;
preferred = pref;
maximum = max;
alignment = a > 1.0f ? 1.0f : a < 0.0f ? 0.0f : a;
}
/**
* Returns a string describing the minimum, preferred, and maximum
* size requirements, along with the alignment.
*
* @return the string
*/
public String toString() {
return "[" + minimum + "," + preferred + "," + maximum + "]@" + alignment;
}
/**
* Determines the total space necessary to
* place a set of components end-to-end. The needs
* of each component in the set are represented by an entry in the
* passed-in SizeRequirements array.
* The returned SizeRequirements object has an alignment of 0.5
* (centered). The space requirement is never more than
* Integer.MAX_VALUE.
*
* @param children the space requirements for a set of components.
* The vector may be of zero length, which will result in a
* default SizeRequirements object instance being passed back.
* @return the total space requirements.
*/
public static SizeRequirements getTiledSizeRequirements(SizeRequirements[]
children) {
SizeRequirements total = new SizeRequirements();
for (int i = 0; i < children.length; i++) {
SizeRequirements req = children[i];
total.minimum = (int) Math.min((long) total.minimum + (long) req.minimum, Integer.MAX_VALUE);
total.preferred = (int) Math.min((long) total.preferred + (long) req.preferred, Integer.MAX_VALUE);
total.maximum = (int) Math.min((long) total.maximum + (long) req.maximum, Integer.MAX_VALUE);
}
return total;
}
/**
* Determines the total space necessary to
* align a set of components. The needs
* of each component in the set are represented by an entry in the
* passed-in SizeRequirements array. The total space required will
* never be more than Integer.MAX_VALUE.
*
* @param children the set of child requirements. If of zero length,
* the returns result will be a default instance of SizeRequirements.
* @return the total space requirements.
*/
public static SizeRequirements getAlignedSizeRequirements(SizeRequirements[]
children) {
SizeRequirements totalAscent = new SizeRequirements();
SizeRequirements totalDescent = new SizeRequirements();
for (int i = 0; i < children.length; i++) {
SizeRequirements req = children[i];
int ascent = (int) (req.alignment * req.minimum);
int descent = req.minimum - ascent;
totalAscent.minimum = Math.max(ascent, totalAscent.minimum);
totalDescent.minimum = Math.max(descent, totalDescent.minimum);
ascent = (int) (req.alignment * req.preferred);
descent = req.preferred - ascent;
totalAscent.preferred = Math.max(ascent, totalAscent.preferred);
totalDescent.preferred = Math.max(descent, totalDescent.preferred);
ascent = (int) (req.alignment * req.maximum);
descent = req.maximum - ascent;
totalAscent.maximum = Math.max(ascent, totalAscent.maximum);
totalDescent.maximum = Math.max(descent, totalDescent.maximum);
}
int min = (int) Math.min((long) totalAscent.minimum + (long) totalDescent.minimum, Integer.MAX_VALUE);
int pref = (int) Math.min((long) totalAscent.preferred + (long) totalDescent.preferred, Integer.MAX_VALUE);
int max = (int) Math.min((long) totalAscent.maximum + (long) totalDescent.maximum, Integer.MAX_VALUE);
float alignment = 0.0f;
if (min > 0) {
alignment = (float) totalAscent.minimum / min;
alignment = alignment > 1.0f ? 1.0f : alignment < 0.0f ? 0.0f : alignment;
}
return new SizeRequirements(min, pref, max, alignment);
}
/**
* Creates a set of offset/span pairs representing how to
* lay out a set of components end-to-end.
* This method requires that you specify
* the total amount of space to be allocated,
* the size requirements for each component to be placed
* (specified as an array of SizeRequirements), and
* the total size requirement of the set of components.
* You can get the total size requirement
* by invoking the getTiledSizeRequirements method. The components
* will be tiled in the forward direction with offsets increasing from 0.
*
* @param allocated the total span to be allocated >= 0.
* @param total the total of the children requests. This argument
* is optional and may be null.
* @param children the size requirements for each component.
* @param offsets the offset from 0 for each child where
* the spans were allocated (determines placement of the span).
* @param spans the span allocated for each child to make the
* total target span.
*/
public static void calculateTiledPositions(int allocated,
SizeRequirements total,
SizeRequirements[] children,
int[] offsets,
int[] spans) {
calculateTiledPositions(allocated, total, children, offsets, spans, true);
}
/**
* Creates a set of offset/span pairs representing how to
* lay out a set of components end-to-end.
* This method requires that you specify
* the total amount of space to be allocated,
* the size requirements for each component to be placed
* (specified as an array of SizeRequirements), and
* the total size requirement of the set of components.
* You can get the total size requirement
* by invoking the getTiledSizeRequirements method.
*
* This method also requires a flag indicating whether components
* should be tiled in the forward direction (offsets increasing
* from 0) or reverse direction (offsets decreasing from the end
* of the allocated space). The forward direction represents
* components tiled from left to right or top to bottom. The
* reverse direction represents components tiled from right to left
* or bottom to top.
*
* @param allocated the total span to be allocated >= 0.
* @param total the total of the children requests. This argument
* is optional and may be null.
* @param children the size requirements for each component.
* @param offsets the offset from 0 for each child where
* the spans were allocated (determines placement of the span).
* @param spans the span allocated for each child to make the
* total target span.
* @param forward tile with offsets increasing from 0 if true
* and with offsets decreasing from the end of the allocated space
* if false.
* @since 1.4
*/
public static void calculateTiledPositions(int allocated,
SizeRequirements total,
SizeRequirements[] children,
int[] offsets,
int[] spans,
boolean forward) {
// The total argument turns out to be a bad idea since the
// total of all the children can overflow the integer used to
// hold the total. The total must therefore be calculated and
// stored in long variables.
long min = 0;
long pref = 0;
long max = 0;
for (int i = 0; i < children.length; i++) {
min += children[i].minimum;
pref += children[i].preferred;
max += children[i].maximum;
}
if (allocated >= pref) {
expandedTile(allocated, min, pref, max, children, offsets, spans, forward);
} else {
compressedTile(allocated, min, pref, max, children, offsets, spans, forward);
}
}
private static void compressedTile(int allocated, long min, long pref, long max,
SizeRequirements[] request,
int[] offsets, int[] spans,
boolean forward) {
// ---- determine what we have to work with ----
float totalPlay = Math.min(pref - allocated, pref - min);
float factor = (pref - min == 0) ? 0.0f : totalPlay / (pref - min);
// ---- make the adjustments ----
int totalOffset;
if( forward ) {
// lay out with offsets increasing from 0
totalOffset = 0;
for (int i = 0; i < spans.length; i++) {
offsets[i] = totalOffset;
SizeRequirements req = request[i];
float play = factor * (req.preferred - req.minimum);
spans[i] = (int)(req.preferred - play);
totalOffset = (int) Math.min((long) totalOffset + (long) spans[i], Integer.MAX_VALUE);
}
} else {
// lay out with offsets decreasing from the end of the allocation
totalOffset = allocated;
for (int i = 0; i < spans.length; i++) {
SizeRequirements req = request[i];
float play = factor * (req.preferred - req.minimum);
spans[i] = (int)(req.preferred - play);
offsets[i] = totalOffset - spans[i];
totalOffset = (int) Math.max((long) totalOffset - (long) spans[i], 0);
}
}
}
private static void expandedTile(int allocated, long min, long pref, long max,
SizeRequirements[] request,
int[] offsets, int[] spans,
boolean forward) {
// ---- determine what we have to work with ----
float totalPlay = Math.min(allocated - pref, max - pref);
float factor = (max - pref == 0) ? 0.0f : totalPlay / (max - pref);
// ---- make the adjustments ----
int totalOffset;
if( forward ) {
// lay out with offsets increasing from 0
totalOffset = 0;
for (int i = 0; i < spans.length; i++) {
offsets[i] = totalOffset;
SizeRequirements req = request[i];
int play = (int)(factor * (req.maximum - req.preferred));
spans[i] = (int) Math.min((long) req.preferred + (long) play, Integer.MAX_VALUE);
totalOffset = (int) Math.min((long) totalOffset + (long) spans[i], Integer.MAX_VALUE);
}
} else {
// lay out with offsets decreasing from the end of the allocation
totalOffset = allocated;
for (int i = 0; i < spans.length; i++) {
SizeRequirements req = request[i];
int play = (int)(factor * (req.maximum - req.preferred));
spans[i] = (int) Math.min((long) req.preferred + (long) play, Integer.MAX_VALUE);
offsets[i] = totalOffset - spans[i];
totalOffset = (int) Math.max((long) totalOffset - (long) spans[i], 0);
}
}
}
/**
* Creates a bunch of offset/span pairs specifying how to
* lay out a set of components with the specified alignments.
* The resulting span allocations will overlap, with each one
* fitting as well as possible into the given total allocation.
* This method requires that you specify
* the total amount of space to be allocated,
* the size requirements for each component to be placed
* (specified as an array of SizeRequirements), and
* the total size requirements of the set of components
* (only the alignment field of which is actually used).
* You can get the total size requirement by invoking
* getAlignedSizeRequirements.
*
* Normal alignment will be done with an alignment value of 0.0f
* representing the left/top edge of a component.
*
* @param allocated the total span to be allocated >= 0.
* @param total the total of the children requests.
* @param children the size requirements for each component.
* @param offsets the offset from 0 for each child where
* the spans were allocated (determines placement of the span).
* @param spans the span allocated for each child to make the
* total target span.
*/
public static void calculateAlignedPositions(int allocated,
SizeRequirements total,
SizeRequirements[] children,
int[] offsets,
int[] spans) {
calculateAlignedPositions( allocated, total, children, offsets, spans, true );
}
/**
* Creates a set of offset/span pairs specifying how to
* lay out a set of components with the specified alignments.
* The resulting span allocations will overlap, with each one
* fitting as well as possible into the given total allocation.
* This method requires that you specify
* the total amount of space to be allocated,
* the size requirements for each component to be placed
* (specified as an array of SizeRequirements), and
* the total size requirements of the set of components
* (only the alignment field of which is actually used)
* You can get the total size requirement by invoking
* getAlignedSizeRequirements.
*
* This method also requires a flag indicating whether normal or
* reverse alignment should be performed. With normal alignment
* the value 0.0f represents the left/top edge of the component
* to be aligned. With reverse alignment, 0.0f represents the
* right/bottom edge.
*
* @param allocated the total span to be allocated >= 0.
* @param total the total of the children requests.
* @param children the size requirements for each component.
* @param offsets the offset from 0 for each child where
* the spans were allocated (determines placement of the span).
* @param spans the span allocated for each child to make the
* total target span.
* @param normal when true, the alignment value 0.0f means
* left/top; when false, it means right/bottom.
* @since 1.4
*/
public static void calculateAlignedPositions(int allocated,
SizeRequirements total,
SizeRequirements[] children,
int[] offsets,
int[] spans,
boolean normal) {
float totalAlignment = normal ? total.alignment : 1.0f - total.alignment;
int totalAscent = (int)(allocated * totalAlignment);
int totalDescent = allocated - totalAscent;
for (int i = 0; i < children.length; i++) {
SizeRequirements req = children[i];
float alignment = normal ? req.alignment : 1.0f - req.alignment;
int maxAscent = (int)(req.maximum * alignment);
int maxDescent = req.maximum - maxAscent;
int ascent = Math.min(totalAscent, maxAscent);
int descent = Math.min(totalDescent, maxDescent);
offsets[i] = totalAscent - ascent;
spans[i] = (int) Math.min((long) ascent + (long) descent, Integer.MAX_VALUE);
}
}
// This method was used by the JTable - which now uses a different technique.
/**
* Adjust a specified array of sizes by a given amount.
*
* @param delta an int specifying the size difference
* @param children an array of SizeRequirements objects
* @return an array of ints containing the final size for each item
*/
public static int[] adjustSizes(int delta, SizeRequirements[] children) {
return new int[0];
}
}
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