Component.BaselineResizeBehavior (Java Platform SE 6) - JDK 5 Documentation v6.0, Java 2 SDK 英文文档

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Java™ Platform
Standard Ed. 6

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java.awt
Enum Component.BaselineResizeBehavior

java.lang.Object
  java.lang.Enum<Component.BaselineResizeBehavior>
      java.awt.Component.BaselineResizeBehavior

All Implemented Interfaces:: Serializable, Comparable<Component.BaselineResizeBehavior>

Enclosing class:: Component

public static enum Component.BaselineResizeBehavior
extends Enum<Component.BaselineResizeBehavior>
extends Enum<Component.BaselineResizeBehavior>

Enumeration of the common ways the baseline of a component can change as the size changes. The baseline resize behavior is primarily for layout managers that need to know how the position of the baseline changes as the component size changes. In general the baseline resize behavior will be valid for sizes greater than or equal to the minimum size (the actual minimum size; not a developer specified minimum size). For sizes smaller than the minimum size the baseline may change in a way other than the baseline resize behavior indicates. Similarly, as the size approaches Integer.MAX_VALUE and/or Short.MAX_VALUE the baseline may change in a way other than the baseline resize behavior indicates.

Since:: 1.6
See Also:: Component.getBaselineResizeBehavior(), Component.getBaseline(int,int)

Enum Constant Summary

CENTER_OFFSET
          Indicates the baseline remains a fixed distance from the center of the component.

CONSTANT_ASCENT
          Indicates the baseline remains fixed relative to the y-origin.

CONSTANT_DESCENT
          Indicates the baseline remains fixed relative to the height and does not change as the width is varied.

OTHER
          Indicates the baseline resize behavior can not be expressed using any of the other constants.

Method Summary

static Component.BaselineResizeBehavior valueOf(String name)
          Returns the enum constant of this type with the specified name.

static Component.BaselineResizeBehavior[] values()
          Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Summary
`CENTER_OFFSET` Indicates the baseline remains a fixed distance from the center of the component.
`CONSTANT_ASCENT` Indicates the baseline remains fixed relative to the y-origin.
`CONSTANT_DESCENT` Indicates the baseline remains fixed relative to the height and does not change as the width is varied.
`OTHER` Indicates the baseline resize behavior can not be expressed using any of the other constants.

Method Summary
`static Component.BaselineResizeBehavior`	`valueOf(String name)` Returns the enum constant of this type with the specified name.
`static Component.BaselineResizeBehavior[]`	`values()` Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum
`clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf`

Methods inherited from class java.lang.Object
`getClass, notify, notifyAll, wait, wait, wait`

Enum Constant Detail

CONSTANT_ASCENT

public static final Component.BaselineResizeBehavior CONSTANT_ASCENT

Indicates the baseline remains fixed relative to the y-origin. That is, getBaseline returns the same value regardless of the height or width. For example, a JLabel containing non-empty text with a vertical alignment of TOP should have a baseline type of CONSTANT_ASCENT.

CONSTANT_DESCENT

public static final Component.BaselineResizeBehavior CONSTANT_DESCENT

Indicates the baseline remains fixed relative to the height and does not change as the width is varied. That is, for any height H the difference between H and getBaseline(w, H) is the same. For example, a JLabel containing non-empty text with a vertical alignment of BOTTOM should have a baseline type of CONSTANT_DESCENT.

CENTER_OFFSET

public static final Component.BaselineResizeBehavior CENTER_OFFSET

Indicates the baseline remains a fixed distance from the center of the component. That is, for any height H the difference between getBaseline(w, H) and H / 2 is the same (plus or minus one depending upon rounding error).

Because of possible rounding errors it is recommended you ask for the baseline with two consecutive heights and use the return value to determine if you need to pad calculations by 1. The following shows how to calculate the baseline for any height:

   Dimension preferredSize = component.getPreferredSize();
   int baseline = getBaseline(preferredSize.width,
                              preferredSize.height);
   int nextBaseline = getBaseline(preferredSize.width,
                                  preferredSize.height + 1);
   // Amount to add to height when calculating where baseline
   // lands for a particular height:
   int padding = 0;
   // Where the baseline is relative to the mid point
   int baselineOffset = baseline - height / 2;
   if (preferredSize.height % 2 == 0 &&
       baseline != nextBaseline) {
       padding = 1;
   }
   else if (preferredSize.height % 2 == 1 &&
            baseline == nextBaseline) {
       baselineOffset--;
       padding = 1;
   }
   // The following calculates where the baseline lands for
   // the height z:
   int calculatedBaseline = (z + padding) / 2 + baselineOffset;

OTHER

public static final Component.BaselineResizeBehavior OTHER

Indicates the baseline resize behavior can not be expressed using any of the other constants. This may also indicate the baseline varies with the width of the component. This is also returned by components that do not have a baseline.

Method Detail

values

public static Component.BaselineResizeBehavior[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (Component.BaselineResizeBehavior c : Component.BaselineResizeBehavior.values())
    System.out.println(c);

Returns:: an array containing the constants of this enum type, in the order they are declared

valueOf

public static Component.BaselineResizeBehavior valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:: name - the name of the enum constant to be returned.
Returns:: the enum constant with the specified name
Throws:: IllegalArgumentException - if this enum type has no constant with the specified name; NullPointerException - if the argument is null