litesoft
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litesoft / trunk / GWT_Sandbox / MultiModule / common / src / org / litesoft / sandbox / infrastructure / client / internal / PanelPlaceActivityHelper.java
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package org.litesoft.sandbox.infrastructure.client.internal; import org.litesoft.sandbox.anywhere.util.*; import org.litesoft.sandbox.infrastructure.client.*; import com.google.gwt.event.shared.*; import com.google.gwt.place.shared.*; import com.google.gwt.user.client.ui.*; import java.util.*; public class PanelPlaceActivityHelper<CommonActivityParam extends CommonActivityParameter> extends ActivityFactoryRegistry { private static final Activity NULL_ACTIVITY = new AbstractActivity() { @Override public void start( AcceptsOneWidget panel ) { panel.setWidget( new Label( "!" ) ); } }; private final AcceptsOneWidget mPanel; private final CommonActivityParam mCommonActivityParam; private Activity mCurrentActivity = NULL_ACTIVITY; private Activity mPendingActivity; private Place mCurrentPlace = Place.NOWHERE; private Place mPendingAsyncPlace; public PanelPlaceActivityHelper( AcceptsOneWidget pPanel, CommonActivityParam pCommonActivityParam ) { mPanel = pPanel; mCommonActivityParam = pCommonActivityParam; } public Place getCurrentPlace() { return mCurrentPlace; } public boolean isPendingAsync( Place pPlace ) { return pPlace.equals( mPendingAsyncPlace ); } public void clearPendingAsync() { mPendingAsyncPlace = null; } public ActivityFactory get( Place pPlace ) { return get( PlaceIdExtractor.getPlaceId( pPlace ) ); } public String getCurrentActivityMayStop() { return mCurrentActivity.mayStop(); } public boolean activate( Place pNewPlace ) { if ( !isPendingAsync( pNewPlace ) ) { mPendingAsyncPlace = null; ActivityFactory zFactory = get( pNewPlace ); if ( zFactory == null ) { return false; } if ( zFactory instanceof ActivityFactory.Asynchronous ) // Un-Happy Case! { loadSyncFactory( (ActivityFactory.Asynchronous) zFactory, mPendingAsyncPlace = pNewPlace ); } else { activate( pNewPlace, (ActivityFactory.Synchronous) zFactory ); } } return true; } /** * Activate the New Place and it's associated Activity (deactivating the current activity. */ public void activate( Place pNewPlace, ActivityFactory.Synchronous pSyncFactory ) { Set<Throwable> zIssues = new LinkedHashSet<Throwable>(); mCurrentPlace = pNewPlace; Activity zNewActivity = UtilsCommon.deNull( createActivity( zIssues, pSyncFactory, pNewPlace ), NULL_ACTIVITY ); if ( (mPendingActivity != null) && (mPendingActivity != zNewActivity) ) // The place changed again before the new Activity showed its widget { tryCancel( zIssues, mPendingActivity ); } mPendingActivity = zNewActivity; // Wrap the actual panel with a per-call instance that protects the actual panel from canceled or stopped activities, and // which handles the Pending Activity becoming the Current Activity. AcceptsOneWidget zPanel = new ProtectedDisplay( zIssues, mPendingActivity ); if ( !canStart( zIssues, mPendingActivity, zPanel ) ) { NULL_ACTIVITY.start( new ProtectedDisplay( zIssues, mPendingActivity = NULL_ACTIVITY ) ); // Can NOT fail! } } @SuppressWarnings({"unchecked"}) protected Activity createActivity( Collection<Throwable> pIssues, ActivityFactory.Synchronous pFactory, Place pPlace ) { try { return pFactory.createActivity( mCommonActivityParam, pFactory.getView(), pPlace ); } catch ( Exception e ) { pIssues.add( e ); } return null; } private boolean canStart( Set<Throwable> pIssues, Activity pActivity, AcceptsOneWidget pPanel ) { try { pActivity.start( pPanel ); return true; } catch ( Exception e ) { pIssues.add( e ); } return false; } private void tryCancel( Collection<Throwable> pIssues, Activity pActivity ) { try { pActivity.onCancel(); } catch ( Exception e ) { pIssues.add( e ); } } private void tryStop( Collection<Throwable> pIssues, Activity pActivity ) { try { pActivity.onStop(); } catch ( Exception e ) { pIssues.add( e ); } } private void possiblyUpdateActivityAndShowWidget( Set<Throwable> pIssues, Activity pActivity, IsWidget pWidget ) { if ( mPendingActivity == null ) // Normal? Happy case when No Pending Activity and request is from Current Activity { if ( pActivity == mCurrentActivity ) { showWidget( pWidget ); } return; } if ( pActivity != mPendingActivity ) // Is a Pending Activity, but the request is NOT from it! { return; } tryStop( pIssues, mCurrentActivity ); mCurrentActivity = mPendingActivity; mPendingActivity = null; showWidget( pWidget ); if ( !pIssues.isEmpty() ) { throw new UmbrellaException( pIssues ); } } private void showWidget( IsWidget pWidget ) { if ( mPanel != null ) { mPanel.setWidget( pWidget ); } } @SuppressWarnings({"unchecked"}) private void loadSyncFactory( final ActivityFactory.Asynchronous pAsyncFactory, final Place pPlace ) { pAsyncFactory.load( mCommonActivityParam, new ActivityFactory.Asynchronous.Callback<CommonActivityParam, IsWidget, Place>() { @Override public void loaded( ActivityFactory.Synchronous<CommonActivityParam, IsWidget, Place> pSynchronousFactory ) { switchAsyncToSync( pPlace, pAsyncFactory, pSynchronousFactory ); } } ); } private void switchAsyncToSync( Place pPlace, ActivityFactory.Asynchronous pAsyncFactory, ActivityFactory.Synchronous pSyncFactory ) { System.out.println( "Switched " + UtilsCommon.justSimpleName( pPlace ) + " from Async to Sync" ); boolean zStillGoing = pPlace.equals( mPendingAsyncPlace ); mPendingAsyncPlace = null; if ( replace( pAsyncFactory, pSyncFactory ) && zStillGoing ) { activate( pPlace, pSyncFactory ); } } /** * Wraps our real display to prevent an Activity from taking it over if it is * not the currentActivity. */ private class ProtectedDisplay implements AcceptsOneWidget { private final Set<Throwable> mIssues; private final Activity mExpectedActivity; ProtectedDisplay( Set<Throwable> pIssues, Activity pExpectedActivity ) { mIssues = pIssues; mExpectedActivity = pExpectedActivity; } @Override public void setWidget( IsWidget pWidget ) { possiblyUpdateActivityAndShowWidget( mIssues, mExpectedActivity, pWidget ); } } } |