--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PluggableEventListener.st	Fri Sep 19 19:45:07 2014 +0200
@@ -0,0 +1,129 @@
+"
+ COPYRIGHT (c) 2014 by Claus Gittinger
+              All Rights Reserved
+
+ This software is furnished under a license and may be used
+ only in accordance with the terms of that license and with the
+ inclusion of the above copyright notice.   This software may not
+ be provided or otherwise made available to, or used by, any
+ other person.  No title to or ownership of the software is
+ hereby transferred.
+"
+"{ Package: 'stx:libview2' }"
+
+EventListener subclass:#PluggableEventListener
+	instanceVariableNames:'keyPressAction keyReleaseAction'
+	classVariableNames:''
+	poolDictionaries:''
+	category:'Interface-Support-UI'
+!
+
+!PluggableEventListener class methodsFor:'documentation'!
+
+copyright
+"
+ COPYRIGHT (c) 2014 by Claus Gittinger
+              All Rights Reserved
+
+ This software is furnished under a license and may be used
+ only in accordance with the terms of that license and with the
+ inclusion of the above copyright notice.   This software may not
+ be provided or otherwise made available to, or used by, any
+ other person.  No title to or ownership of the software is
+ hereby transferred.
+"
+!
+
+documentation
+"
+    a preliminary version of a pluggable event listener.
+    can be configured via handler blocks.
+
+    [see also:]
+        WindowSensor WindowEvent WindowGroup
+
+    [author:]
+        Claus Gittinger
+"
+!
+
+example
+"
+ eat a particular key from another view.
+
+    |v e|
+
+    v := StandardSystemView extent:300@200.
+    v add:(e := EditTextView origin:0.0@0.0 corner:1.0@1.0).
+    v label:'key a is ignored'.
+    v openAndWait.
+
+    e sensor addEventListener:(
+        PluggableEventListener new
+            keyPressAction:[:event |
+                event key == $a ifTrue:[
+                    Transcript showCR:'a key eaten'.
+                    true.
+                ] ifFalse:[
+                    Transcript showCR:'other key ok'.
+                    false
+                ]
+            ]).
+"
+! !
+
+!PluggableEventListener methodsFor:'accessing'!
+
+keyPressAction:aBlock
+    "install a block as handler for keyPress events.    
+     the block will get the windowEvent as argument,
+     and is supposed to return true if it handled the event,
+     false if not (so the event is processed as usual)."
+
+    keyPressAction := aBlock.
+!
+
+keyReleaseAction:aBlock
+    "install a block as handler for keyRelease events.    
+     the block will get the windowEvent as argument,
+     and is supposed to return true if it handled the event,
+     false if not (so the event is processed as usual)."
+
+    keyReleaseAction := aBlock.
+! !
+
+!PluggableEventListener methodsFor:'event processing'!
+
+processEvent:anEvent
+    "process an event; if true is returned, the event is considered to be
+     'eaten' by the listener, and not passed to the view.
+     If false is returned, the event is processed as usual.
+     Here, the event is dispatched into one of the button*/key* etc. methods"
+
+    |handler|
+
+    anEvent isKeyPressEvent ifTrue:[
+        handler := keyPressAction
+    ] ifFalse:[
+        anEvent isKeyReleaseEvent ifTrue:[
+            handler := keyReleaseAction
+        ]
+    ].
+
+    handler notNil ifTrue:[
+        ^ handler value:anEvent
+    ].
+
+    ^ false
+! !
+
+!PluggableEventListener class methodsFor:'documentation'!
+
+version
+    ^ '$Header: /cvs/stx/stx/libview2/PluggableEventListener.st,v 1.1 2014-09-19 17:45:07 cg Exp $'
+!
+
+version_CVS
+    ^ '$Header: /cvs/stx/stx/libview2/PluggableEventListener.st,v 1.1 2014-09-19 17:45:07 cg Exp $'
+! !
+