item.java

用于移动设备上的java虚拟机源代码

     *
     * <P>Value <code>0x30</code> is assigned to 
     * <code>LAYOUT_VCENTER</code>.</P>
     * @since MIDP 2.0
     */
    public final static int LAYOUT_VCENTER = 0x30;

    /**
     * A layout directive indicating that this <code>Item</code> 
     * should be placed at the beginning of a new line or row.
     *
     * <P>Value <code>0x100</code> is assigned to 
     * <code>LAYOUT_NEWLINE_BEFORE</code>.</P>
     * @since MIDP 2.0
     */
    public final static int LAYOUT_NEWLINE_BEFORE = 0x100;

    /**
     * A layout directive indicating that this <code>Item</code>
     * should the last on its line or row, and that the next
     * <code>Item</code> (if any) in the container
     * should be placed on a new line or row.
     *
     * <P>Value <code>0x200</code> is assigned to 
     * <code>LAYOUT_NEWLINE_AFTER</code>.</P>
     * @since MIDP 2.0
     */
    public final static int LAYOUT_NEWLINE_AFTER = 0x200;

    /**
     * A layout directive indicating that this <code>Item's</code>
     * width may be reduced to its minimum width.
     *
     *<P>Value <code>0x400</code> is assigned to <code>LAYOUT_SHRINK</code></P>
     * @since MIDP 2.0
     */
    public final static int LAYOUT_SHRINK = 0x400;

    /**
     * A layout directive indicating that this <code>Item's</code> 
     * width may be increased to fill available space.
     *
     *<P>Value <code>0x800</code> is assigned to <code>LAYOUT_EXPAND</code>.</P>
     * @since MIDP 2.0
     */
    public final static int LAYOUT_EXPAND = 0x800;

    /**
     * A layout directive indicating that this <code>Item's</code>
     * height may be reduced to its minimum height.
     *
     * <P>Value <code>0x1000</code> is assigned to
     * <code>LAYOUT_VSHRINK</code>.</P>
     * @since MIDP 2.0
     */
    public final static int LAYOUT_VSHRINK = 0x1000;

    /**
     * A layout directive indicating that this <code>Item's</code> 
     * height may be increased to fill available space.
     *
     * <P>Value <code>0x2000</code> is assigned to 
     * <code>LAYOUT_VEXPAND</code>.</P>
     * @since MIDP 2.0
     */
    public final static int LAYOUT_VEXPAND = 0x2000;

    /**
     * A layout directive indicating that new MIDP 2.0 layout
     * rules are in effect for this <code>Item</code>.  If this
     * bit is clear, indicates that MIDP 1.0 layout behavior
     * applies to this <code>Item</code>.
     *
     * <P>Value <code>0x4000</code> is assigned to
     * <code>LAYOUT_2</code>.</P>
     * 
     * @since MIDP 2.0
     */
    public static final int LAYOUT_2 = 0x4000;

    /**
     * An appearance mode value indicating that the <code>Item</code> is to have
     * a normal appearance.
     *
     * <P>Value <code>0</code> is assigned to <code>PLAIN</code>.</P>
     * @since MIDP 2.0
     */
    public final static int PLAIN = 0;

    /**
     * An appearance mode value indicating that the <code>Item</code>
     * is to appear as a hyperlink.
     * <P>Value <code>1</code> is assigned to <code>HYPERLINK</code>.</P>
     * @since MIDP 2.0
     */
    public final static int HYPERLINK = 1;

    /**
     * An appearance mode value indicating that the <code>Item</code>
     * is to appear as a button.
     * <P>Value <code>2</code> is assigned to <code>BUTTON</code>.</P>
     * @since MIDP 2.0
     */
    public final static int BUTTON = 2;

// ************************************************************
//  protected member variables
// ************************************************************

// ************************************************************
//  package private member variables
// ************************************************************

    /** bounds[] array index to x coordinate */
    final static int X      = Displayable.X;

    /** bounds[] array index to y coordinate */
    final static int Y      = Displayable.Y;

    /** bounds[] array index to width */
    final static int WIDTH  = Displayable.WIDTH;

    /** bounds[] array index to height */
    final static int HEIGHT = Displayable.HEIGHT;

    /** internal bitmask representing a valid layout mask */
    final static int VALID_LAYOUT;

    /**
     * An array of 4 elements, describing the x, y, width, height
     * of this Item's bounds in the viewport coordinate space. If
     * its null, it means the Item is currently not in the viewport
     */
    int[] bounds;

    /**
     * A flag indicating this Item has the input focus. This is
     * maintained by the Item superclass for easy use by subclass
     * code.
     */
    boolean hasFocus;

    /**
     * A flag indicating this Item is currently (at least partially)
     * visible on the Form it is on. This is maintained by the Item
     * superclass for easy use by subclass code.
     */
    boolean visible;

    /**
     * A flag indicating the size of this Item has changed in a
     * subsequent layout operation
     */
    boolean sizeChanged;

    /**
     * commandListener that has to be notified of when ITEM command is
     * activated
     */
    ItemCommandListener commandListener; // = null;

    /** The label of this Item */
    String label;

    /**
     * The owner Screen for this Item
     */
    Screen owner;     // = null

    /**
     * The layout type of this Item
     */
    int layout;       // = 0 ; LAYOUT_DEFAULT = 0

    /**
     * This is a default Command which represents the callback
     * to a selection event.
     */
    Command defaultCommand;

    /** The number of Commands added to this Item */
    int numCommands;

    /** The locked width of this Item, -1 by default */
    int lockedWidth = -1;

    /** The locked height of this Item, -1 by default */
    int lockedHeight = -1;

    /**
     * A flag signaling how labels are painted. If true,
     * labels are only painted bold on traverse, else they
     * are always painted bold
     */
    final static boolean LABEL_BOLD_ON_TRAVERSE = false;

    /**
     * Padding used between Button Border and ImageItem
     */
    final static int BUTTON_PAD = 2;

    /**
     * Button Border is 3 pixel wide and 3 pixel high
     */
    final static int BUTTON_BORDER = 3;

    /** Button border color for light gray border */
    static final int LIGHT_GRAY_COLOR = 0x00AFAFAF; // light gray

    /** Button border color for dark gray border */
    static final int DARK_GRAY_COLOR = 0x00606060; // dark gray

    /** The font to render item labels with focus */
    final static Font LABEL_FONT = Font.getFont(
        Screen.CONTENT_FONT.getFace(),
        Font.STYLE_BOLD,
        Screen.CONTENT_FONT.getSize());

    /** 2 pixel padding between the label and the item's contents */
    final static int LABEL_PAD = 2;

    /** The height of the label (maximum of 1 line */
    final static int LABEL_HEIGHT = LABEL_FONT.getHeight() + LABEL_PAD;

    /** Maximum width available to any Item */
    final static int DEFAULT_WIDTH = 
        Display.WIDTH - Form.CELL_SPACING - Form.CELL_SPACING;

// ************************************************************
//  private member variables
// ************************************************************

    /** An array of Commands added to this Item */
    private Command commands[];

// ************************************************************
//  Static initializer, constructor
// ************************************************************

    static {
        VALID_LAYOUT =
            Item.LAYOUT_DEFAULT |
            Item.LAYOUT_LEFT |
            Item.LAYOUT_RIGHT |
            Item.LAYOUT_CENTER |
            Item.LAYOUT_TOP |
            Item.LAYOUT_BOTTOM |
            Item.LAYOUT_VCENTER |
            Item.LAYOUT_SHRINK |
            Item.LAYOUT_EXPAND |
            Item.LAYOUT_VSHRINK |
            Item.LAYOUT_VEXPAND |
            Item.LAYOUT_NEWLINE_BEFORE |
            Item.LAYOUT_NEWLINE_AFTER |
            Item.LAYOUT_2;
    }

    /**
     * Creates a new item with a given label.
     *
     * @param label the label string; null is allowed
     */
    Item(String label) {
        // SYNC NOTE: probably safe, but since subclasses can't lock
        // around their call to super(), we'll lock it here
        synchronized (Display.LCDUILock) {
            this.label = label;
        }
    }

// ************************************************************
//  public methods
// ************************************************************

    /**
     * Sets the label of the <code>Item</code>. If <code>label</code>
     * is <code>null</code>, specifies that this item has no label.
     * 
     * <p>It is illegal to call this method if this <code>Item</code>
     * is contained within  an <code>Alert</code>.</p>
     * 
     * @param label the label string
     * @throws IllegalStateException if this <code>Item</code> is contained 
     * within an <code>Alert</code>
     * @see #getLabel
     */
    public void setLabel(String label) {
        synchronized (Display.LCDUILock) {
            this.label = label;
            invalidate();
        }
    }
    
    /**
     * Gets the label of this <code>Item</code> object.
     * @return the label string
     * @see #setLabel
     */
    public String getLabel() {
        // SYNC NOTE: return of atomic value, no locking necessary
        return label;
    }

    /**
     * Gets the layout directives used for placing the item.
     * @return a combination of layout directive values
     * @since MIDP 2.0
     * @see #setLayout
     */
    public int getLayout() {
        // SYNC NOTE: return of atomic value, no locking necessary
        return layout;
    }

    /**
     * Sets the layout directives for this item.
     *
     * <p>It is illegal to call this method if this <code>Item</code> 
     * is contained within an <code>Alert</code>.</p>
     * 
     * @param layout a combination of layout directive values for this item
     * @throws IllegalArgumentException if the value of layout is not a
     * bit-wise OR combination of layout directives
     * @throws IllegalStateException if this <code>Item</code> is
     * contained within an <code>Alert</code>
     * @since MIDP 2.0
     * @see #getLayout
     */
    public void setLayout(int layout) {
        synchronized (Display.LCDUILock) {
            setLayoutImpl(layout);
            invalidate();
        }
    }

    /**
     * Adds a context sensitive <code>Command</code> to the item.
     * The semantic type of
     * <code>Command</code> should be <code>ITEM</code>. The implementation
     * will present the command
     * only when the item is active, for example, highlighted.
     * <p>
     * If the added command is already in the item (tested by comparing the
     * object references), the method has no effect. If the item is
     * actually visible on the display, and this call affects the set of
     * visible commands, the implementation should update the display as soon
     * as it is feasible to do so.
     *
     * <p>It is illegal to call this method if this <code>Item</code>
     * is contained within an <code>Alert</code>.</p>
     *
     * @param cmd the command to be added
     * @throws IllegalStateException if this <code>Item</code> is contained
     * within an <code>Alert</code>
     * @throws NullPointerException if cmd is <code>null</code>
     * @since MIDP 2.0
     */
    public void addCommand(Command cmd) {
        synchronized (Display.LCDUILock) {
            addCommandImpl(cmd);
        }
        }

    /**
     * Removes the context sensitive command from item. If the command is not
     * in the <code>Item</code> (tested by comparing the object references),
     * the method has
     * no effect. If the <code>Item</code> is actually visible on the display, 
     * and this  call
     * affects the set of visible commands, the implementation should update
     * the display as soon as it is feasible to do so.
     *
     *
     * If the command to be removed happens to be the default command,
     * the command is removed and the default command on this Item is
     * set to <code>null</code>.
     *
     * The following code:
     * <CODE> <pre>
     *     // Command c is the default command on Item item
     *     item.removeCommand(c);
     * </pre> </CODE>
     * is equivalent to the following code:
     * <CODE> <pre>
     *     // Command c is the default command on Item item
     *     item.setDefaultCommand(null);
     *     item.removeCommand(c);
     * </pre> </CODE>
     *
     *
     * @param cmd the command to be removed
     * @since MIDP 2.0
     */
    public void removeCommand(Command cmd) {
        synchronized (Display.LCDUILock) {
            removeCommandImpl(cmd);
        }