Adding the new kFeatureDisableKeyFiltering OSystem feature.

This feature is used by agi's prediction dialog and is a hint to the backend
to temporarily switch off any keyboard mapping, used in devices with limited
keyboard input. Also, supply some comments to the newly added event & feature.

svn-id: r27069

3 files changed, 25 insertions, 2 deletions

diff --git a/common/events.h b/common/events.h
index 9b434e94f9..ac12fd3f4c 100644
--- a/common/events.h
+++ b/common/events.h
@@ -57,6 +57,12 @@ enum EventType {
 
 	EVENT_QUIT = 10,
 	EVENT_SCREEN_CHANGED = 11,
+	/** The backend requests the agi engine's predictive dialog to be shown.
+	 * TODO: Fingolfin suggests that it would be of better value to expand
+	 * on this notion by generalizing its use. For example the backend could
+	 * use events to ask for the save game dialog or to pause the engine.
+	 * An associated enumerated type can accomplish this.
+	 **/
 	EVENT_PREDICTIVE_DIALOG = 12
 };
 
diff --git a/common/system.h b/common/system.h
index ccca1fb7c7..500056e695 100644
--- a/common/system.h
+++ b/common/system.h
@@ -125,7 +125,7 @@ public:
 		kFeatureAutoComputeDirtyRects,
 
 		/**
-		 * This flags determines either cursor can have its own palette or not
+		 * This flag determines either cursor can have its own palette or not
 		 * It is currently used only by some Macintosh versions of Humongous
 		 * Entertainment games. If backend doesn't implement this feature then
 		 * engine switches to b/w version of cursors.
@@ -142,7 +142,22 @@ public:
 		/**
 		 * Set to true to iconify the window.
 		 */
-		kFeatureIconifyWindow
+		kFeatureIconifyWindow,
+
+		/**
+		 * This feature, set to true, is a hint toward the backend to disable all
+		 * key filtering/mapping, in cases where it would be beneficial to do so.
+		 * As an example case, this is used in the agi engine's predictive dialog.
+		 * When the dialog is displayed this feature is set so that backends with
+		 * phone-like keypad temporarily unmap all user actions which leads to
+		 * comfortable word entry. Conversely, when the dialog exits the feature
+		 * is set to false.
+		 * TODO: Fingolfin suggests that the way the feature is used can be 
+		 * generalized in this sense: Have a keyboard mapping feature, which the
+		 * engine queries for to assign keys to actions ("Here's my default key
+		 * map for these actions, what do you want them set to?").
+		 */
+		kFeatureDisableKeyFiltering
 	};
 
 	/**
diff --git a/engines/agi/predictive.cpp b/engines/agi/predictive.cpp
index e3f38463ac..230c15de58 100644
--- a/engines/agi/predictive.cpp
+++ b/engines/agi/predictive.cpp
@@ -120,6 +120,7 @@ bool AgiEngine::predictiveDialog(void) {
 	AgiBlock tmpwindow;
 
 	_predictiveDialogRunning = true;
+	_system->setFeatureState(OSystem::kFeatureDisableKeyFiltering, true);
 	
 	// FIXME: Move this to a more appropriate place.
 	initAsciiToNumTable();
@@ -405,6 +406,7 @@ processkey:
 		_gfx->doUpdate();
 	}
 
+	_system->setFeatureState(OSystem::kFeatureDisableKeyFiltering, false);
 	_predictiveDialogRunning = false;
 
 	return rc;