001package votorola.s.gwt.wic; // Copyright 2012, Michael Allan. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Votorola Software"), to deal in the Votorola Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicence, and/or sell copies of the Votorola Software, and to permit persons to whom the Votorola Software is furnished to do so, subject to the following conditions: The preceding copyright notice and this permission notice shall be included in all copies or substantial portions of the Votorola Software. THE VOTOROLA SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE VOTOROLA SOFTWARE OR THE USE OR OTHER DEALINGS IN THE VOTOROLA SOFTWARE. 002 003import com.google.gwt.http.client.UrlBuilder; 004import com.google.gwt.user.client.Window; 005import java.util.*; 006import votorola.a.count.*; 007import votorola.g.lang.*; 008import votorola.g.web.gwt.*; 009import votorola.g.web.gwt.event.*; 010import votorola.s.gwt.stage.*; 011 012 013/** A controller that loads a new page when the poll changes on stage. 014 */ 015class PollPager implements PropertyChangeHandler 016{ 017 018 019 /** Creates the single instance of PollPager. 020 */ 021 PollPager( final Stage stage ) // called by CountIn 022 { 023 pollName0 = stage.getPollName(); 024 GWTX.i().bus().addHandlerToSource( PropertyChange.TYPE, /*source*/stage.prompter(), 025 PollPager.this ); // no need to unregister, registry does not outlive this handler 026 } 027 028 029 030 /** The single instance of PollPager. 031 */ 032 private static PollPager instance; 033 034 { 035 if( instance != null ) throw new IllegalStateException(); 036 037 instance = PollPager.this; 038 } 039 040 041 042 // ------------------------------------------------------------------------------------ 043 044 045 /** The initial poll name. 046 */ 047 String pollName0; // matching (it is assumed) query parameter 'p' 048 049 050 051 /** Returns true if the named parameter was set to the specified value, false if it 052 * had already been set. 053 */ 054 static boolean setParameter( final String name, final String value, final UrlBuilder u ) 055 { 056 final String oldValue = Window.Location.getParameter( name ); 057 final boolean wasSet; 058 if( value == null ) 059 { 060 if( null == oldValue ) wasSet = false; 061 else 062 { 063 u.removeParameter( name ); 064 wasSet = true; 065 } 066 } 067 else 068 { 069 if( value.equals( oldValue )) wasSet = false; 070 else 071 { 072 u.setParameter( name, value ); 073 wasSet = true; 074 } 075 } 076 return wasSet; 077 } 078 079 080 081 // - P r o p e r t y - C h a n g e - H a n d l e r ------------------------------------ 082 083 084 public void onPropertyChange( final PropertyChange e ) 085 { 086 // cf. PositionPager.onPropertyChange 087 088 final String propertyName = e.propertyName(); 089 if( !propertyName.startsWith( "pollName" ) ) return; 090 091 final Stage stage = Stage.i(); 092 final String pollName = stage.getPollName(); 093 if( ObjectX.nullEquals( pollName, pollName0 )) 094 { 095 // no actual change. Either event is from setPollName below (page load 096 // pending) or another change that was reverted before the event got here. In 097 // either case, it is safe to suppress to lighten the burden 098 // stage.prompter().setSuppressed( true ); 099 //// not actually safe, as an intermediate value may possibly have been read somewhere 100 return; 101 } 102 103 final UrlBuilder u = Window.Location.createUrlBuilder(); 104 if( !setParameter( "p", Poll.U.toQuery(pollName), u )) 105 { 106 // parameters are already set correctly, so apparently pollName0 wasn't 107 assert false: "pollName0 to 'p'"; 108 pollName0 = pollName; // ensure it's now correct 109 return; 110 } 111 112 stage.setPollName( pollName0 ); // back to original values, keep state clean in BFCache 113 stage.prompter().setSuppressed( true ); // suppress event, which is now redundant 114 Window.Location.assign( u.buildString() ); 115 } 116 117 118}