com.trolltech.qt.gui
Class QInputMethodEvent

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.core.QEvent
                  extended by com.trolltech.qt.gui.QInputMethodEvent
All Implemented Interfaces:
QtJambiInterface

public class QInputMethodEvent
extends QEvent

The QInputMethodEvent class provides parameters for input method events. Input method events are sent to widgets when an input method is used to enter text into a widget. Input methods are widely used to enter text for languages with non-Latin alphabets.

Note that when creating custom text editing widgets, the Qt::WA_InputMethodEnabled window attribute must be set explicitly (using the QWidget::setAttribute() function) in order to receive input method events.

The events are of interest to authors of keyboard entry widgets who want to be able to correctly handle languages with complex character input. Text input in such languages is usually a three step process:

  1. Starting to Compose

    When the user presses the first key on a keyboard, an input context is created. This input context will contain a string of the typed characters.

  2. Composing

    With every new key pressed, the input method will try to create a matching string for the text typed so far called preedit string. While the input context is active, the user can only move the cursor inside the string belonging to this input context.

  3. Completing

    At some point, the user will activate a user interface component (perhaps using a particular key) where they can choose from a number of strings matching the text they have typed so far. The user can either confirm their choice cancel the input; in either case the input context will be closed.

QInputMethodEvent models these three stages, and transfers the information needed to correctly render the intermediate result. A QInputMethodEvent has two main parameters: preeditString() and commitString(). The preeditString() parameter gives the currently active preedit string. The commitString() parameter gives a text that should get added to (or replace parts of) the text of the editor widget. It usually is a result of the input operations and has to be inserted to the widgets text directly before the preedit string.

If the commitString() should replace parts of the of the text in the editor, replacementLength() will contain the number of characters to be replaced. replacementStart() contains the position at which characters are to be replaced relative from the start of the preedit string.

A number of attributes control the visual appearance of the preedit string (the visual appearance of text outside the preedit string is controlled by the widget only). The AttributeType enum describes the different attributes that can be set.

A class implementing QWidget::inputMethodEvent() should at least understand and honor the TextFormat and Cursor attributes.

Since input methods need to be able to query certain properties from the widget, the widget must also implement QWidget::inputMethodQuery().

When receiving an input method event, the text widget has to performs the following steps:

  1. If the widget has selected text, the selected text should get removed.
  2. Remove the text starting at replacementStart() with length replacementLength() and replace it by the commitString(). If replacementLength() is 0, replacementStart() gives the insertion position for the commitString().

    When doing replacement the area of the preedit string is ignored, thus a replacement starting at -1 with a length of 2 will remove the last character before the preedit string and the first character afterwards, and insert the commit string directly before the preedit string.

    If the widget implements undo/redo, this operation gets added to the undo stack.

  3. If there is no current preedit string, insert the preeditString() at the current cursor position; otherwise replace the previous preeditString with the one received from this event.

    If the widget implements undo/redo, the preeditString() should not influence the undo/redo stack in any way.

    The widget should examine the list of attributes to apply to the preedit string. It has to understand at least the TextFormat and Cursor attributes and render them as specified.

See also:
QInputContext.


Nested Class Summary
static class QInputMethodEvent.AttributeType
          See also.
Attribute.
 
Nested classes/interfaces inherited from class com.trolltech.qt.core.QEvent
QEvent.Type
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QInputMethodEvent()
          Constructs an event of type QEvent::InputMethod .
QInputMethodEvent(QInputMethodEvent other)
          Constructs a copy of other.
QInputMethodEvent(java.lang.String preeditText, java.util.List attributes)
          Construcs an event of type QEvent::InputMethod .
 
Method Summary
 java.util.List attributes()
          Returns the list of attributes passed to the QInputMethodEvent constructor.
 java.lang.String commitString()
          Returns the text that should get added to (or replace parts of) the text of the editor widget.
 java.lang.String preeditString()
          Returns the preedit text, i.
 int replacementLength()
          Returns the number of characters to be replaced in the preedit string.
 int replacementStart()
          Returns the position at which characters are to be replaced relative from the start of the preedit string.
 void setCommitString(java.lang.String commitString)
          Sets the commit string to commitString.
 void setCommitString(java.lang.String commitString, int replaceFrom)
          Sets the commit string to commitString.
 void setCommitString(java.lang.String commitString, int replaceFrom, int replaceLength)
          Sets the commit string to commitString.
 java.lang.String toString()
          Returns a string representation of the this QInputMethodEvent.
 
Methods inherited from class com.trolltech.qt.core.QEvent
accept, ignore, isAccepted, registerEventType, registerEventType, setAccepted, setT, spontaneous, t, type
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
clone, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QInputMethodEvent

public QInputMethodEvent()
Constructs an event of type QEvent::InputMethod . The attributes(), preeditString(), commitString(), replacementStart(), and replacementLength() are initialized to default values.

See also:
setCommitString().


QInputMethodEvent

public QInputMethodEvent(QInputMethodEvent other)
Constructs a copy of other.


QInputMethodEvent

public QInputMethodEvent(java.lang.String preeditText,
                         java.util.List attributes)
Construcs an event of type QEvent::InputMethod . The preedit text is set to preeditText, the attributes to attributes.

The commitString(), replacementStart(), and replacementLength() values can be set using setCommitString().

See also:
preeditString(), and attributes().

Method Detail

attributes

public final java.util.List attributes()
Returns the list of attributes passed to the QInputMethodEvent constructor. The attributes control the visual appearance of the preedit string (the visual appearance of text outside the preedit string is controlled by the widget only).

See also:
preeditString(), and Attribute.


commitString

public final java.lang.String commitString()
Returns the text that should get added to (or replace parts of) the text of the editor widget. It usually is a result of the input operations and has to be inserted to the widgets text directly before the preedit string.

See also:
setCommitString(), preeditString(), replacementStart(), and replacementLength().


preeditString

public final java.lang.String preeditString()
Returns the preedit text, i. . the text before the user started editing it.

See also:
commitString(), and attributes().


replacementLength

public final int replacementLength()
Returns the number of characters to be replaced in the preedit string.

See also:
replacementStart(), and setCommitString().


replacementStart

public final int replacementStart()
Returns the position at which characters are to be replaced relative from the start of the preedit string.

See also:
replacementLength(), and setCommitString().


setCommitString

public final void setCommitString(java.lang.String commitString,
                                  int replaceFrom)
Sets the commit string to commitString.

The commit string is the text that should get added to (or replace parts of) the text of the editor widget. It usually is a result of the input operations and has to be inserted to the widgets text directly before the preedit string.

If the commit string should replace parts of the of the text in the editor, replaceLength specifies the number of characters to be replaced. replaceFrom specifies the position at which characters are to be replaced relative from the start of the preedit string.

See also:
commitString(), replacementStart(), and replacementLength().


setCommitString

public final void setCommitString(java.lang.String commitString)
Sets the commit string to commitString.

The commit string is the text that should get added to (or replace parts of) the text of the editor widget. It usually is a result of the input operations and has to be inserted to the widgets text directly before the preedit string.

If the commit string should replace parts of the of the text in the editor, replaceLength specifies the number of characters to be replaced. replaceFrom specifies the position at which characters are to be replaced relative from the start of the preedit string.

See also:
commitString(), replacementStart(), and replacementLength().


setCommitString

public final void setCommitString(java.lang.String commitString,
                                  int replaceFrom,
                                  int replaceLength)
Sets the commit string to commitString.

The commit string is the text that should get added to (or replace parts of) the text of the editor widget. It usually is a result of the input operations and has to be inserted to the widgets text directly before the preedit string.

If the commit string should replace parts of the of the text in the editor, replaceLength specifies the number of characters to be replaced. replaceFrom specifies the position at which characters are to be replaced relative from the start of the preedit string.

See also:
commitString(), replacementStart(), and replacementLength().


toString

public java.lang.String toString()
Returns a string representation of the this QInputMethodEvent.

Overrides:
toString in class QEvent