Create CompositeAppState.java (#2193)

A composite app state which auto manages child app states.

Author: scenemax3d

jme3-core/src/main/java/com/jme3/app/state/CompositeAppState.java

@@ -0,0 +1,236 @@
+/*
+ * 
+ * Copyright (c) 2014-2024 jMonkeyEngine
+ * Copied with Paul Speed's permission from: https://github.com/Simsilica/SiO2
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions 
+ * are met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright 
+ *    notice, this list of conditions and the following disclaimer.
+ * 
+ * 2. Redistributions in binary form must reproduce the above copyright 
+ *    notice, this list of conditions and the following disclaimer in 
+ *    the documentation and/or other materials provided with the 
+ *    distribution.
+ * 
+ * 3. Neither the name of the copyright holder nor the names of its 
+ *    contributors may be used to endorse or promote products derived 
+ *    from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package com.jme3.app.state;
+
+import com.jme3.app.Application;
+import com.jme3.util.SafeArrayList;
+
+/**
+ *  An AppState that manages a set of child app states, making sure
+ *  they are attached/detached and optional enabled/disabled with the
+ *  parent state.
+ *
+ *  @author    Paul Speed
+ */
+public class CompositeAppState extends BaseAppState {
+
+    private final SafeArrayList<AppStateEntry> states = new SafeArrayList<>(AppStateEntry.class);
+    private boolean childrenEnabled;
+    
+    /**
+     *  Since we manage attachmend/detachment possibly before
+     *  initialization, we need to keep track of the stateManager we
+     *  were given in stateAttached() in case we have to attach another
+     *  child prior to initialization (but after we're attached).
+     *  It's possible that we should actually be waiting for initialize
+     *  to add these but I feel like there was some reason I did it this 
+     *  way originally.  Past-me did not leave any clues.
+     */
+    private AppStateManager stateManager;
+    private boolean attached;  
+    
+    public CompositeAppState( AppState... states ) {
+        for( AppState a : states ) {
+            this.states.add(new AppStateEntry(a, false));
+        }
+    }
+
+    private int indexOf( AppState state ) {
+        for( int i = 0; i < states.size(); i++ ) {
+            AppStateEntry e = states.get(i);
+            if( e.state == state ) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+    private AppStateEntry entry( AppState state ) {
+        for( AppStateEntry e : states.getArray() ) {
+            if( e.state == state ) {
+                return e;
+            }
+        }
+        return null;
+    }
+
+    protected <T extends AppState> T addChild( T state ) {
+        return addChild(state, false);
+    }
+    
+    protected <T extends AppState> T addChild( T state, boolean overrideEnable ) {
+        if( indexOf(state) >= 0 ) {
+            return state;
+        }
+        states.add(new AppStateEntry(state, overrideEnable));
+        if( attached ) {
+            stateManager.attach(state);
+        }
+        return state;   
+    }
+ 
+    protected void removeChild( AppState state ) {
+        int index = indexOf(state);
+        if( index < 0 ) {
+            return;
+        }
+        states.remove(index);
+        if( attached ) {
+            stateManager.detach(state);
+        }
+    }
+    
+    protected <T extends AppState> T getChild( Class<T> stateType ) {
+        for( AppStateEntry e : states.getArray() ) {
+            if( stateType.isInstance(e.state) ) {
+                return stateType.cast(e.state);
+            }
+        }
+        return null;
+    }
+
+    protected void clearChildren() {
+        for( AppStateEntry e : states.getArray() ) {
+            removeChild(e.state);
+        }
+    }
+    
+    @Override 
+    public void stateAttached( AppStateManager stateManager ) {
+        this.stateManager = stateManager;
+        for( AppStateEntry e : states.getArray() ) {
+            stateManager.attach(e.state);
+        }
+        this.attached = true;
+    }
+    
+    @Override
+    public void stateDetached( AppStateManager stateManager ) {
+        // Reverse order
+        for( int i = states.size() - 1; i >= 0; i-- ) {
+            stateManager.detach(states.get(i).state);
+        }
+        this.attached = false;
+        this.stateManager = null;
+    }
+
+    protected void setChildrenEnabled( boolean b ) {
+        if( childrenEnabled == b ) {
+            return;
+        }
+        childrenEnabled = b;
+        for( AppStateEntry e : states.getArray() ) {
+            e.setEnabled(b);
+        }
+    }
+
+    /**
+     *  Overrides the automatic synching of a child's enabled state.
+     *  When override is true, a child will remember its old state when
+     *  the parent's enabled state is false so that when the parent is
+     *  re-enabled the child can resume its previous enabled state.  This
+     *  is useful for the cases where a child may want to be disabled
+     *  independent of the parent... and then not automatically become
+     *  enabled just because the parent does.
+     *  Currently, the parent's disabled state always disables the children,
+     *  too.  Override is about remembering the child's state before that
+     *  happened and restoring it when the 'family' is enabled again as a whole.
+     */
+    public void setOverrideEnabled( AppState state, boolean override ) {
+        AppStateEntry e = entry(state);
+        if( e == null ) {
+            throw new IllegalArgumentException("State not managed:" + state);
+        }
+        if( override ) {
+            e.override = true;
+        } else {
+            e.override = false;
+            e.state.setEnabled(isEnabled());
+        }   
+    }
+
+    @Override
+    protected void initialize(Application app) {
+    }
+
+    @Override
+    protected void cleanup(Application app) {
+    }
+
+    @Override
+    protected void onEnable() {
+        setChildrenEnabled(true);
+    }
+
+    @Override
+    protected void onDisable() {
+        setChildrenEnabled(false);
+    }
+    
+    private class AppStateEntry {
+        AppState state;
+        boolean enabled;
+        boolean override;
+        
+        public AppStateEntry( AppState state, boolean overrideEnable ) {
+            this.state = state;
+            this.override = overrideEnable;
+            this.enabled = state.isEnabled();
+        }
+        
+        public void setEnabled( boolean b ) {
+ 
+            if( override ) {
+                if( b ) {
+                    // Set it to whatever its enabled state
+                    // was before going disabled last time.
+                    state.setEnabled(enabled);
+                } else {
+                    // We are going to set enabled to false
+                    // but keep track of what it was before we did
+                    // that
+                    this.enabled = state.isEnabled();
+                    state.setEnabled(false);
+                }               
+            } else {
+                // Just synch it always
+                state.setEnabled(b);
+            }
+        }
+    }
+}
+