/*
* @(#)Spacer.java 1.21 02/10/07 @(#)
*
* Copyright (c) 2002 Sun Microsystems, Inc. All rights reserved.
* PROPRIETARY/CONFIDENTIAL
* Use is subject to license terms.
*/
package javax.microedition.lcdui;
import java.lang.IllegalArgumentException;
/**
* A blank, non-interactive item that has a settable minimum size. The
* minimum width is useful for allocating flexible amounts of space between
* <code>Items</code> within the same row of a
* <code>Form</code>. The minimum height is useful for
* enforcing a particular minimum height of a row. The application can set
* the minimum width or height to any non-negative value. The implementation
* may enforce implementation-defined maximum values for the minimum width and
* height.
*
* <p>The unlocked preferred width of a <code>Spacer</code> is the same as its
* current minimum width. Its unlocked preferred height is the same as its
* current minimum height.</p>
*
* <p>Since a <code>Spacer's</code> primary purpose is to position
* other items, it is
* restricted to be non-interactive, and the application is not allowed to add
* <code>Commands</code> to a <code>Spacer</code>. Since the
* presence of a label on an <code>Item</code> may affect
* layout in device-specific ways, the label of a
* <code>Spacer</code> is restricted to
* always be <code>null</code>, and the application is not allowed
* to change it.</p>
*
* @since MIDP 2.0
*/
public class Spacer extends Item {
/**
* Creates a new <code>Spacer</code> with the given minimum
* size. The <code>Spacer's</code> label
* is <code>null</code>.
* The minimum size must be zero or greater.
* If <code>minWidth</code> is greater than the
* implementation-defined maximum width, the maximum
* width will be used instead.
* If <code>minHeight</code> is greater than the
* implementation-defined maximum height, the maximum
* height will be used instead.
*
* @param minWidth the minimum width in pixels
* @param minHeight the minimum height in pixels
* @throws IllegalArgumentException if either <code>minWidth</code>
* or <code>minHeight</code> is less than zero
*/
public Spacer(int minWidth, int minHeight) {
super(null);
updateSizes(minWidth, minHeight);
}
/**
* Sets the minimum size for this spacer. The
* <code>Form</code> will not
* be allowed to make the item smaller than this size.
* The minimum size must be zero or greater.
* If <code>minWidth</code> is greater than the
* implementation-defined maximum width, the maximum
* width will be used instead.
* If <code>minHeight</code> is greater than the
* implementation-defined maximum height, the maximum
* height will be used instead.
*
* @param minWidth the minimum width in pixels
* @param minHeight the minimum height in pixels
* @throws IllegalArgumentException if either <code>minWidth</code>
* or <code>minHeight</code> is less than zero
*/
public void setMinimumSize(int minWidth, int minHeight) {
updateSizes(minWidth, minHeight);
}
/**
* <code>Spacers</code> are restricted from having
* <code>Commands</code>, so this method will always
* throw <code>IllegalStateException</code> whenever it is called.
*
* @param cmd the <code>Command</code>
*
* @throws IllegalStateException always
*/
public void addCommand(Command cmd) {
throw new IllegalStateException();
}
/**
* Spacers are restricted from having <code>Commands</code>,
* so this method will always
* throw <code>IllegalStateException</code> whenever it is called.
*
* @param cmd the <code>Command</code>
*
* @throws IllegalStateException always
*/
public void setDefaultCommand(Command cmd) {
throw new IllegalStateException();
}
/**
* <code>Spacers</code> are restricted to having
* <code>null</code> labels, so this method will
* always throw
* <code>IllegalStateException</code> whenever it is called.
*
* @param label the label string
*
* @throws IllegalStateException always
*/
public void setLabel(String label) {
throw new IllegalStateException();
}
// package private implementation
/**
* Get the minimum width of this Item
*
* @return the minimum width
*/
int callMinimumWidth() {
return width;
}
/**
* Get the preferred width of this Item
*
* @param h the tentative content height in pixels, or -1 if a
* tentative height has not been computed
* @return the preferred width
*/
int callPreferredWidth(int h) {
return width;
}
/**
* Get the minimum height of this Item
*
* @return the minimum height
*/
int callMinimumHeight() {
return height;
}
/**
* Get the preferred height of this Item
*
* @param w the tentative content width in pixels, or -1 if a
* tentative width has not been computed
* @return the preferred height
*/
int callPreferredHeight(int w) {
return height;
}
/**
* Determine if this Item should not be traversed to
*
* @return true if this Item should not be traversed to
*/
boolean shouldSkipTraverse() {
return true;
}
/**
* Paint the content of this Item
*
* @param g the Graphics object to be used for rendering the item
* @param w current width of the item in pixels
* @param h current height of the item in pixels
*/
void callPaint(Graphics g, int w, int h) {
/*
* There's no reason to erase anything because Form will erase
* any dirty region for us
*
g.setColor(Display.ERASE_COLOR);
g.fillRect(g.getClipX(), g.getClipY(),
g.getClipWidth(), g.getClipHeight());
g.setColor(Display.FG_COLOR);
*/
}
/**
* Update the width and height values of this spacer, guaranteeing
* the new values are positive. This method will also invalidate the
* containing Form.
*
* @param minW the new width
* @param minH the new height
*/
private void updateSizes(int minW, int minH) {
if (minW < 0 || minH < 0) {
throw new IllegalArgumentException();
}
synchronized (Display.LCDUILock) {
width = minW;
height = minH;
invalidate();
}
}
/** The preferred (and minimum) width of this Spacer */
private int width;
/** The preferred (and minimum) height of this Spacer */
private int height;
}
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