/*
*
*
* Copyright 1990-2007 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 only, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License version 2 for more details (a copy is
* included at /legal/license.txt).
*
* You should have received a copy of the GNU General Public License
* version 2 along with this work; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*/
package javax.microedition.lcdui;
/**
* An alert is a screen that shows data to the user and waits for a certain
* period of time before proceeding to the next
* <code>Displayable</code>. An alert can
* contain a text string and an image.
* The intended use of <code>Alert</code> is to inform the user about
* errors and other
* exceptional conditions.
*
* <P>The application can set the alert time to be infinity with
* <code> setTimeout(Alert.FOREVER)</code>
* in which case the <code>Alert</code> is considered to be <em>modal</em> and
* the implementation provide a feature that allows the
* user to "dismiss" the alert, whereupon the next
* <code>Displayable</code>
* is displayed as if the timeout had expired immediately.</P>
*
* <P>If an application specifies an alert to be of a
* timed variety <em>and</em> gives it too much content such that it must
* scroll,
* then it automatically becomes a modal alert.</P>
*
* <P> An alert may have an <code>AlertType</code> associated with it
* to provide an indication of the nature of the alert.
* The implementation may use this type to play an
* appropriate sound when the <code>Alert</code> is presented to the user.
* See {@link AlertType#playSound(javax.microedition.lcdui.Display)
* AlertType.playSound()}.</P>
*
* <P>An alert may contain an optional <code>Image</code>. The
* <code>Image</code> may be mutable or
* immutable. If the <code>Image</code> is mutable, the effect is as
* if a snapshot of its
* contents is taken at the time the <code>Alert</code> is constructed
* with this <code>Image</code> and
* when <code>setImage</code> is called with an <code>Image</code>.
* This snapshot is used whenever the contents of the
* <code>Alert</code> are to be
* displayed. Even if the application subsequently draws into the
* <code>Image</code>, the
* snapshot is not modified until the next call to <code>setImage</code>. The
* snapshot is <em>not</em> updated when the <code>Alert</code>
* becomes current or becomes
* visible on the display. (This is because the application does not have
* control over exactly when <code>Displayables</code> appear and
* disappear from the
* display.)</P>
*
* <a name="indicator"></a>
* <h3>Activity Indicators</h3>
*
* <P>An alert may contain an optional {@link Gauge} object that is used as an
* activity or progress indicator. By default, an <code>Alert</code>
* has no activity
* indicator; one may be set with the {@link #setIndicator} method.
* The <code>Gauge</code>
* object used for the activity indicator must conform to all of the following
* restrictions:</P>
*
* <ul>
* <li>it must be non-interactive;</li>
* <li>it must not be owned by another container (<code>Alert</code>
* or <code>Form</code>);</li>
* <li>it must not have any <code>Commands</code>;</li>
* <li>it must not have an <code>ItemCommandListener</code>;</li>
* <li>it must not have a label (that is, its label must be
* <code>null</code>;</li>
* <li>its preferred width and height must both be unlocked; and</li>
* <li>its layout value must be <code>LAYOUT_DEFAULT</code>.</li>
* </ul>
*
* <P>It is an error for the application to attempt to use a
* <code>Gauge</code> object that
* violates any of these restrictions. In addition, when the
* <code>Gauge</code> object is
* being used as the indicator within an <code>Alert</code>, the
* application is prevented
* from modifying any of these pieces of the <code>Gauge's</code> state.</P>
*
* <a name="commands"></a>
* <h3>Commands and Listeners</h3>
*
* <P>Like the other <code>Displayable</code> classes, an
* <code>Alert</code> can accept <code>Commands</code>, which
* can be delivered to a <code>CommandListener</code> set by the
* application. The <code>Alert</code>
* class adds some special behavior for <code>Commands</code> and listeners.</P>
*
* <P>When it is created, an <code>Alert</code> implicitly has the
* special <code>Command</code>
* {@link #DISMISS_COMMAND} present on it. If the application adds any
* other <code>Commands</code> to the <code>Alert</code>,
* <code>DISMISS_COMMAND</code> is implicitly removed. If the
* application removes all other <code>Commands</code>,
* <code>DISMISS_COMMAND</code> is implicitly
* restored. Attempts to add or remove <code>DISMISS_COMMAND</code>
* explicitly are
* ignored. Thus, there is always at least one <code>Command</code>
* present on an <code>Alert</code>.
* </P>
*
* <P>If there are two or more <code>Commands</code> present on the
* <code>Alert</code>, it is
* automatically turned into a modal <code>Alert</code>, and the
* timeout value is always
* {@link #FOREVER}. The <code>Alert</code> remains on the display
* until a <code>Command</code> is
* invoked. If the Alert has one Command (whether it is DISMISS_COMMAND or it
* is one provided by the application), the <code>Alert</code> may have
* the timed behavior
* as described above. When a timeout occurs, the effect is the same as if
* the user had invoked the <code>Command</code> explicitly.</P>
*
* <P>When it is created, an <code>Alert</code> implicitly has a
* <code>CommandListener</code> called the
* <em>default listener</em> associated with it. This listener may be
* replaced by an application-provided listener through use of the {@link
* #setCommandListener} method. If the application removes its listener by
* passing <code>null</code> to the <code>setCommandListener</code> method,
* the default listener is implicitly restored.</P>
*
* <P>The {@link Display#setCurrent(Alert, Displayable)} method and the {@link
* Display#setCurrent(Displayable)} method (when called with an
* <code>Alert</code>) define
* special behavior for automatically advancing to another
* <code>Displayable</code> after
* the <code>Alert</code> is dismissed. This special behavior occurs
* only when the default
* listener is present on the <code>Alert</code> at the time it is
* dismissed or when a
* command is invoked. If the user invokes a <code>Command</code> and
* the default listener
* is present, the default listener ignores the <code>Command</code>
* and implements the
* automatic-advance behavior.</P>
*
* <P>If the application has set its own <code>CommandListener</code>, the
* automatic-advance behavior is disabled. The listener code is responsible
* for advancing to another <code>Displayable</code>. When the
* application has provided a
* listener, <code>Commands</code> are invoked normally by passing
* them to the listener's
* <code>commandAction</code> method. The <code>Command</code> passed
* will be one of the
* <code>Commands</code> present on the <code>Alert</code>: either
* <code>DISMISS_COMMAND</code> or one of the
* application-provided <code>Commands</code>.</P>
*
* <P>The application can restore the default listener by passing
* <code>null</code> to the <code>setCommandListener</code> method.</P>
*
* <P>
* <strong>Note:</strong> An application may set a {@link Ticker Ticker}
* with {@link Displayable#setTicker Displayable.setTicker} on an
* <code>Alert</code>, however it may not be displayed due to
* implementation restrictions.
* </P>
*
* @see AlertType
* @since MIDP 1.0
*/
public class Alert extends Screen {
// *****************************************************
// Public members
// *****************************************************
/**
* <code>FOREVER</code> indicates that an <code>Alert</code> is
* kept visible until the user
* dismisses it. It is used as a value for the parameter to
* {@link #setTimeout(int) setTimeout()}
* to indicate that the alert is modal. Instead of waiting for a
* specified period of time, a modal <code>Alert</code> will wait
* for the user to take
* some explicit action, such as pressing a button, before proceeding to
* the next <code>Displayable</code>.
*
* <P>Value <code>-2</code> is assigned to <code>FOREVER</code>.</P>
*/
public final static int FOREVER = -2;
/**
* A <code>Command</code> delivered to a listener to indicate that
* the <code>Alert</code> has been
* dismissed. This Command is implicitly present an on
* <code>Alert</code> whenever
* there are no other Commands present. The field values of
* <code>DISMISS_COMMAND</code> are as follows:
*
* <ul>
* <li>label = "" (an empty string)</li>
* <li>type = Command.OK</li>
* <li>priority = 0</li>
* </ul>
*
* <p>The label value visible to the application must be as specified
* above. However, the implementation may display
* <code>DISMISS_COMMAND</code> to the
* user using an implementation-specific label.</p>
*
* <p>Attempting to add or remove <code>DISMISS_COMMAND</code>
* from an <code>Alert</code> has no
* effect. However, <code>DISMISS_COMMAND</code> is treated as an
* ordinary <code>Command</code> if
* it is used with other <code>Displayable</code> types.</p>
*
*/
public final static Command DISMISS_COMMAND =
new Command("", Command.OK, 0);
// *****************************************************
// Constructor(s)
// *****************************************************
/**
* Constructs a new, empty <code>Alert</code> object with the
* given title. If <code>null</code> is
* passed, the <code>Alert</code> will have no title. Calling
* this constructor is
* equivalent to calling
*
* <pre>
* <code>Alert(title, null, null, null)</code>
* </pre>
*
* @param title the title string, or <code>null</code>
*
* @see #Alert(String, String, Image, AlertType)
*/
public Alert(String title) {
this(title, null, null, null);
}
/**
* Constructs a new <code>Alert</code> object with the given title,
* content
* string and image, and alert type.
* The layout of the contents is implementation dependent.
* The timeout value of this new alert is the same value that is
* returned by <code>getDefaultTimeout()</code>.
* The <code>Image</code> provided may either be mutable or immutable.
* The handling and behavior of specific <code>AlertTypes</code>
* is described in
* {@link AlertType}. <code>null</code> is allowed as the value
* of the <code>alertType</code>
* parameter and indicates that the <code>Alert</code> is not to
* have a specific alert
* type. <code>DISMISS_COMMAND</code> is the only
* <code>Command</code> present on the new
* <code>Alert</code>. The <code>CommandListener</code>
* associated with the new <code>Alert</code> is the
* <em>default listener</em>. Its behavior is described in more detail in
* the section <a href="#commands">Commands and Listeners</a>.
*
* @param title the title string, or <code>null</code> if there is no title
* @param alertText the string contents, or <code>null</code> if there
* is no string
* @param alertImage the image contents, or <code>null</code> if there
* is no image
* @param alertType the type of the <code>Alert</code>, or
* <code>null</code>
* if the <code>Alert</code> has no
* specific type
*/
public Alert(String title, String alertText,
Image alertImage, AlertType alertType) {
super(title);
synchronized (Display.LCDUILock) {
this.text = alertText;
this.type = alertType;
setImageImpl(alertImage);
displayableLF = alertLF = LFFactory.getFactory().getAlertLF(this);
this.time = alertLF.lGetDefaultTimeout();
// Call addCommandImpl to avoid notification to AlertLF
// cause we know this Alert is not yet visible
addCommandImpl(alertLF.lGetDismissCommand());
// Note that we have to call super.setCommandListener since
// this.setCommandListener will set application's command
// listener
super.setCommandListener(implicitListener);
}
}
// *****************************************************
// Public methods
// *****************************************************
/**
* Gets the default time for showing an <code>Alert</code>. This
* is either a
* positive value, which indicates a time in milliseconds, or the special
* value
* {@link #FOREVER FOREVER},
* which indicates that <code>Alerts</code> are modal by default. The
* value returned will vary across implementations and is presumably
* tailored to be suitable for each.
*
* @return default timeout in milliseconds, or <code>FOREVER</code>
*/
public int getDefaultTimeout() {
synchronized (Display.LCDUILock) {
return alertLF.lGetDefaultTimeout();
}
}
/**
* Gets the time this <code>Alert</code> will be shown. This is
* either a positive
* value, which indicates a time in milliseconds, or the special value
* <code>FOREVER</code>, which indicates that this
* <code>Alert</code> is modal. This value is not
* necessarily the same value that might have been set by the
* application
* in a call to {@link #setTimeout}. In particular, if the
* <code>Alert</code> is made
* modal because its contents is large enough to scroll, the value
* returned by <code>getTimeout</code> will be <code>FOREVER</code>.
*
* @return timeout in milliseconds, or <code>FOREVER</code>
* @see #setTimeout
*/
public int getTimeout() {
synchronized (Display.LCDUILock) {
if (alertLF.lIsModal()) {
return FOREVER;
} else {
return time;
}
}
}
/**
* Set the time for which the <code>Alert</code> is to be shown.
* This must either
* be a positive time value in milliseconds, or the special value
* <code>FOREVER</code>.
*
* @param time timeout in milliseconds, or <code>FOREVER</code>
* @throws IllegalArgumentException if time is not positive and is
* not <code>FOREVER</code>
* @see #getTimeout
*/
public void setTimeout(int time) {
if (time <= 0 && time != FOREVER) {
throw new IllegalArgumentException();
}
synchronized (Display.LCDUILock) {
this.time = time;
alertLF.lSetTimeout(time);
}
}
/**
* Gets the type of the <code>Alert</code>.
* @return a reference to an instance of <code>AlertType</code>,
* or <code>null</code>
* if the <code>Alert</code>
* has no specific type
* @see #setType
*/
public AlertType getType() {
// SYNC NOTE: return of atomic value, no locking necessary
return type;
}
/**
* Sets the type of the <code>Alert</code>.
* The handling and behavior of specific <code>AlertTypes</code>
* is described in
* {@link AlertType}.
* @param type an <code>AlertType</code>, or <code>null</code> if the
* <code>Alert</code> has no
* specific type
* @see #getType
*/
public void setType(AlertType type) {
synchronized (Display.LCDUILock) {
if (this.type != type) {
this.type = type;
alertLF.lSetType(type);
}
}
}
/**
* Gets the text string used in the <code>Alert</code>.
* @return the <code>Alert's</code> text string, or <code>null</code>
* if there is no text
* @see #setString
*/
public String getString() {
// SYNC NOTE: no locking necessary
return text;
}
/**
* Sets the text string used in the <code>Alert</code>.
*
* <p>If the <code>Alert</code> is visible on the display when its
* contents are updated
* through a call to <code>setString</code>, the display will be
* updated with the new
* contents as soon as it is feasible for the implementation to do so.
* </p>
*
* @param str the <code>Alert's</code> text string, or <code>null</code>
* if there is no text
* @see #getString
*/
public void setString(String str) {
synchronized (Display.LCDUILock) {
if (str == text || (str != null && str.equals(text))) {
return;
}
String oldStr = text;
text = str;
alertLF.lSetString(oldStr, str);
}
}
/**
* Gets the <code>Image</code> used in the <code>Alert</code>.
* @return the <code>Alert's</code> image, or <code>null</code>
* if there is no image
* @see #setImage
*/
public Image getImage() {
synchronized (Display.LCDUILock) {
if (mutableImage != null) {
return mutableImage;
} else {
return image;
}
}
}
/**
* Sets the <code>Image</code> used in the <code>Alert</code>.
* The <code>Image</code> may be mutable or
* immutable. If <code>img</code> is <code>null</code>, specifies
* that this <code>Alert</code> has no image.
* If <code>img</code> is mutable, the effect is as if a snapshot is taken
* of <code>img's</code> contents immediately prior to the call to
* <code>setImage</code>. This
* snapshot is used whenever the contents of the
* <code>Alert</code> are to be
* displayed. If <code>img</code> is already the
* <code>Image</code> of this <code>Alert</code>, the effect
* is as if a new snapshot of img's contents is taken. Thus, after
* painting into a mutable image contained by an <code>Alert</code>, the
* application can call
*
* <TABLE BORDER="2">
* <TR>
* <TD ROWSPAN="1" COLSPAN="1">
* <pre><code>
* alert.setImage(alert.getImage()); </code></pre>
* </TD>
* </TR>
* </TABLE>
* <p>to refresh the <code>Alert's</code> snapshot of its
* <code>Image</code>.</p>
*
* <p>If the <code>Alert</code> is visible on the display when its
* contents are updated
* through a call to <code>setImage</code>, the display will be
* updated with the new
* snapshot as soon as it is feasible for the implementation to do so.
* </p>
*
* @param img the <code>Alert's</code> image, or <code>null</code>
* if there is no image
* @see #getImage
*/
public void setImage(Image img) {
synchronized (Display.LCDUILock) {
Image oldImg = image;
if (setImageImpl(img)) {
// Always pass the immutable image snapshot as new image
alertLF.lSetImage(oldImg, image);
}
}
}
/**
* Sets an activity indicator on this <code>Alert</code>. The
* activity indicator is a
* {@link Gauge} object. It must be in a restricted state in order for it
* to be used as the activity indicator for an <code>Alert</code>.
* The restrictions
* are listed <a href="#indicator">above</a>. If the
* <code>Gauge</code> object
* violates any of these restrictions,
* <code>IllegalArgumentException</code> is thrown.
*
* <p>If <code>indicator</code> is <code>null</code>, this removes any
* activity indicator present on this <code>Alert</code>.</p>
*
* @param indicator the activity indicator for this <code>Alert</code>,
* or <code>null</code> if
* there is to be none
*
* @throws IllegalArgumentException if <code>indicator</code> does not
* meet the restrictions for its use in an <code>Alert</code>
* @see #getIndicator
*/
public void setIndicator(Gauge indicator) {
synchronized (Display.LCDUILock) {
// do nothing if indicator is the same
// that includes both indicators (old and new) being null
if (this.indicator == indicator) {
return;
}
Gauge oldIndicator = this.indicator;
if (indicator == null) {
// The Alert no longer owns this Gauge;
// We do not need to check if this.indicator != null
// since we already returned if they are both null
oldIndicator.lSetOwner(null);
} else {
if (!isConformantIndicator(indicator)) {
throw new IllegalArgumentException("Gauge in wrong state");
}
indicator.lSetOwner(this);
// if old indicator is not null
// it is no longer is owned by this alert
if (oldIndicator != null) {
oldIndicator.lSetOwner(null);
}
}
this.indicator = indicator;
alertLF.lSetIndicator(oldIndicator, indicator);
}
}
/**
* Gets the activity indicator for this <code>Alert</code>.
*
* @return a reference to this <code>Alert's</code> activity indicator,
* or <code>null</code> if
* there is none
* @see #setIndicator
*/
public Gauge getIndicator() {
// SYNC NOTE: no locking necessary
return indicator;
}
/**
* Similar to {@link Displayable#addCommand}, however when the
* application first adds a command to an <code>Alert</code>,
* {@link #DISMISS_COMMAND} is implicitly removed. Calling this
* method with <code>DISMISS_COMMAND</code> as the parameter has
* no effect.
*
* @param cmd the command to be added
*
* @throws NullPointerException if cmd is <code>null</code>
*/
public void addCommand(Command cmd) {
if (cmd == null) {
throw new NullPointerException();
}
if (cmd == DISMISS_COMMAND) {
return;
}
synchronized (Display.LCDUILock) {
Command dismissCmd = alertLF.lGetDismissCommand();
if (commands[0] == dismissCmd) {
super.removeCommand(dismissCmd);
}
super.addCommand(cmd);
}
}
/**
* Similar to {@link Displayable#removeCommand}, however when the
* application removes the last command from an
* <code>Alert</code>, {@link #DISMISS_COMMAND} is implicitly
* added. Calling this method with <code>DISMISS_COMMAND</code>
* as the parameter has no effect.
*
* @param cmd the command to be removed
*/
public void removeCommand(Command cmd) {
if (cmd == DISMISS_COMMAND) {
return;
}
synchronized (Display.LCDUILock) {
super.removeCommand(cmd);
if (numCommands == 0) {
super.addCommand(alertLF.lGetDismissCommand());
}
}
}
/**
* The same as {@link Displayable#setCommandListener} but with the
* following additional semantics. If the listener parameter is
* <code>null</code>, the <em>default listener</em> is restored.
* See <a href="#commands">Commands and Listeners</a> for the definition
* of the behavior of the default listener.
*
* @param l the new listener, or <code>null</code>
*/
public void setCommandListener(CommandListener l) {
synchronized (Display.LCDUILock) {
userCommandListener = l;
}
}
// *****************************************************
// Package private methods
// *****************************************************
/**
* Set the screen that the display should return to
* when this Alert is dismissed.
*
* @param d The Displayable to display when this Alert is completed
*/
void setReturnScreen(Displayable d) {
this.returnScreen = d;
}
/**
* Get the screen that the display should return to
* when this Alert is dismissed.
* @return The Displayable to display when this Alert is completed
*/
Displayable getReturnScreen() {
return returnScreen;
}
/**
* Dismisses this alert.
*/
void lDismiss() {
Display dpy = alertLF.lGetCurrentDisplay();
if (dpy != null && returnScreen != null) {
dpy.clearAlert(this, returnScreen);
}
}
/**
* LF notifies that the Alert is dismissed due to timeout,
* instead of user action.
* Commandlistener will be notified with the default Command.
*/
void uNotifyTimeout() {
try {
synchronized (Display.calloutLock) {
listener.commandAction(commands[0], this);
}
} catch (Throwable thr) {
Display.handleThrowable(thr);
}
}
// *****************************************************
// Private methods
// *****************************************************
/**
* Verify the activity indicator is conformant with the spec
* requirements for addition to an Alert.
*
* @param ind The indicator to be verified
* @return boolean True if the gauge is conformant; false otherwise
*/
private boolean isConformantIndicator(Gauge ind) {
return ((ind.interactive == false) &&
(ind.owner == null) &&
(ind.numCommands == 0) &&
(ind.commandListener == null) &&
(ind.label == null) &&
(ind.layout == Item.LAYOUT_DEFAULT) &&
(ind.lockedWidth == -1) &&
(ind.lockedHeight == -1));
}
/**
* Set the Image for this Alert.
*
* @param img The img to use for this Alert
* @return true if look&feel object has to be notified of an image change
*/
private boolean setImageImpl(Image img) {
if (img != null && img.isMutable()) {
this.image = Image.createImage(img); // use immutable copy of img
this.mutableImage = img;
} else {
if (image == img) {
return false;
}
this.image = img;
this.mutableImage = null; // Make sure to clear mutableImage
}
return true;
}
// *****************************************************
// Package private members
// *****************************************************
/**
* The type of this alert
*/
AlertType type;
/**
* The layout object for the alert text string
*/
String text;
/**
* The image of this alert
*/
Image image;
/**
* A reference to the original, mutable Image passed to setImage(). This
* is only so getImage() can return the correct Image Object.
*/
private Image mutableImage;
/**
* The activity indicator for this alert
*/
Gauge indicator;
/**
* The timeout value of this alert
*/
int time;
/**
* The screen which the display will return to when this Alert
* is completed
*/
Displayable returnScreen;
/**
* The application's command listener
*/
CommandListener userCommandListener;
/** The Alert look&feel object associated with this Alert */
AlertLF alertLF;
// *****************************************************
// Private members
// *****************************************************
/**
* Special CommandListener instance to handle execution of
* the default "OK" Command
*/
private CommandListener implicitListener = new CommandListener() {
/**
* Handle the execution of the given Command and Displayable.
* Caller of this function should hold calloutLock and catch Throwable.
*
* @param c The Command to execute
* @param s The Displayable from which the Command originated
*/
public void commandAction(Command c, Displayable s) {
CommandListener listenerToCall = null;
synchronized (Display.LCDUILock) {
if (userCommandListener != null) {
// translate 'OK' to 'DISMISS_COMMAND
if (c == alertLF.lGetDismissCommand()) {
c = DISMISS_COMMAND;
}
// To be called outside LCDUILock
listenerToCall = userCommandListener;
} else {
// Treat all commands as if they were 'DISMISS'
lDismiss();
}
} // synchronized
// SYNC NOTE: We are protected by the calloutLock obtained
// previously. (either in Display or the timeout task)
// We do not need to re-acquire the calloutLock when
// calling the application's command listener.
if (listenerToCall != null) {
listenerToCall.commandAction(c, s);
}
}
};
}
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