2.4/user/src/com/google/gwt/user/client/ui/HeaderPanel.java - gwt - Git at Google

 /*
  * Copyright 2011 Google Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
  * the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  * License for the specific language governing permissions and limitations under
  * the License.
  */
 package com.google.gwt.user.client.ui;

 import com.google.gwt.core.client.GWT;
 import com.google.gwt.core.client.Scheduler;
 import com.google.gwt.core.client.Scheduler.ScheduledCommand;
 import com.google.gwt.dom.client.Document;
 import com.google.gwt.dom.client.Style.Display;
 import com.google.gwt.dom.client.Style.Overflow;
 import com.google.gwt.dom.client.Style.Position;
 import com.google.gwt.dom.client.Style.Unit;
 import com.google.gwt.user.client.Element;
 import com.google.gwt.user.client.ui.FiniteWidgetIterator.WidgetProvider;

 import java.util.Iterator;

 /**
  * A panel that includes a header (top), footer (bottom), and content (middle)
  * area. The header and footer areas resize naturally. The content area is
  * allocated all of the remaining space between the header and footer area.
  */
 public class HeaderPanel extends Panel implements RequiresResize {

   /**
    * The widget provider for this panel.
    *
    * <p>
    * Widgets are returned in the following order:
    * <ol>
    * <li>Header widget</li>
    * <li>Content widget</li>
    * <li>Footer widget</li>
    * </ol>
    */
   private class WidgetProviderImpl implements WidgetProvider {

     public Widget get(int index) {
       switch (index) {
         case 0:
           return header;
         case 1:
           return content;
         case 2:
           return footer;
       }
       throw new ArrayIndexOutOfBoundsException(index);
     }
   }

   private Widget content;
   private final Element contentContainer;
   private Widget footer;
   private final Element footerContainer;
   private final ResizeLayoutPanel.Impl footerImpl = GWT.create(ResizeLayoutPanel.Impl.class);
   private Widget header;
   private final Element headerContainer;
   private final ResizeLayoutPanel.Impl headerImpl = GWT.create(ResizeLayoutPanel.Impl.class);
   private final ScheduledCommand layoutCmd = new ScheduledCommand() {
     public void execute() {
       layoutScheduled = false;
       forceLayout();
     }
   };
   private boolean layoutScheduled = false;

   public HeaderPanel() {
     // Create the outer element
     Element elem = Document.get().createDivElement().cast();
     elem.getStyle().setPosition(Position.RELATIVE);
     elem.getStyle().setOverflow(Overflow.HIDDEN);
     setElement(elem);

     // Create a delegate to handle resize from the header and footer.
     ResizeLayoutPanel.Impl.Delegate resizeDelegate = new ResizeLayoutPanel.Impl.Delegate() {
       public void onResize() {
         scheduledLayout();
       }
     };

     // Create the header container.
     headerContainer = createContainer();
     headerContainer.getStyle().setTop(0.0, Unit.PX);
     headerImpl.init(headerContainer, resizeDelegate);
     elem.appendChild(headerContainer);

     // Create the footer container.
     footerContainer = createContainer();
     footerContainer.getStyle().setBottom(0.0, Unit.PX);
     footerImpl.init(footerContainer, resizeDelegate);
     elem.appendChild(footerContainer);

     // Create the content container.
     contentContainer = createContainer();
     contentContainer.getStyle().setOverflow(Overflow.HIDDEN);
     contentContainer.getStyle().setTop(0.0, Unit.PX);
     contentContainer.getStyle().setHeight(0.0, Unit.PX);
     elem.appendChild(contentContainer);
   }

   /**
    * Adds a widget to this panel.
    *
    * @param w the child widget to be added
    */
   @Override
   public void add(Widget w) {
     // Add widgets in the order that they appear.
     if (header == null) {
       setHeaderWidget(w);
     } else if (content == null) {
       setContentWidget(w);
     } else if (footer == null) {
       setFooterWidget(w);
     } else {
       throw new IllegalStateException(
           "HeaderPanel already contains header, content, and footer widgets.");
     }
   }

   /**
    * Get the content widget that appears between the header and footer.
    *
    * @return the content {@link Widget}
    */
   public Widget getContentWidget() {
     return content;
   }

   /**
    * Get the footer widget at the bottom of the panel.
    *
    * @return the footer {@link Widget}
    */
   public Widget getFooterWidget() {
     return footer;
   }

   /**
    * Get the header widget at the top of the panel.
    *
    * @return the header {@link Widget}
    */
   public Widget getHeaderWidget() {
     return header;
   }

   public Iterator<Widget> iterator() {
     return new FiniteWidgetIterator(new WidgetProviderImpl(), 3);
   }

   @Override
   public void onAttach() {
     super.onAttach();
     headerImpl.onAttach();
     footerImpl.onAttach();
     scheduledLayout();
   }

   @Override
   public void onDetach() {
     super.onDetach();
     headerImpl.onDetach();
     footerImpl.onDetach();
   }

   public void onResize() {
     // Handle the outer element resizing.
     scheduledLayout();
   }

   @Override
   public boolean remove(Widget w) {
     // Validate.
     if (w.getParent() != this) {
       return false;
     }
     // Orphan.
     try {
       orphan(w);
     } finally {
       // Physical detach.
       w.getElement().removeFromParent();

       // Logical detach.
       if (w == content) {
         content = null;
         contentContainer.getStyle().setDisplay(Display.NONE);
       } else if (w == header) {
         header = null;
         headerContainer.getStyle().setDisplay(Display.NONE);
       } else if (w == footer) {
         footer = null;
         footerContainer.getStyle().setDisplay(Display.NONE);
       }
     }
     return true;
   }

   /**
    * Set the widget in the content portion between the header and footer.
    *
    * @param w the widget to use as the content
    */
   public void setContentWidget(Widget w) {
     contentContainer.getStyle().clearDisplay();
     add(w, content, contentContainer);

     // Logical attach.
     content = w;
     scheduledLayout();
   }

   /**
    * Set the widget in the footer portion at the bottom of the panel.
    *
    * @param w the widget to use as the footer
    */
   public void setFooterWidget(Widget w) {
     footerContainer.getStyle().clearDisplay();
     add(w, footer, footerContainer);

     // Logical attach.
     footer = w;
     scheduledLayout();
   }

   /**
    * Set the widget in the header portion at the top of the panel.
    *
    * @param w the widget to use as the header
    */
   public void setHeaderWidget(Widget w) {
     headerContainer.getStyle().clearDisplay();
     add(w, header, headerContainer);

     // Logical attach.
     header = w;
     scheduledLayout();
   }

   /**
    * Add a widget to the panel in the specified container. Note that this method
    * does not do the logical attach.
    *
    * @param w the widget to add
    * @param toReplace the widget to replace
    * @param container the container in which to place the widget
    */
   private void add(Widget w, Widget toReplace, Element container) {
     // Validate.
     if (w == toReplace) {
       return;
     }

     // Detach new child.
     if (w != null) {
       w.removeFromParent();
     }

     // Remove old child.
     if (toReplace != null) {
       remove(toReplace);
     }

     if (w != null) {
       // Physical attach.
       container.appendChild(w.getElement());

       adopt(w);
     }
   }

   private Element createContainer() {
     Element container = Document.get().createDivElement().cast();
     container.getStyle().setPosition(Position.ABSOLUTE);
     container.getStyle().setDisplay(Display.NONE);
     container.getStyle().setLeft(0.0, Unit.PX);
     container.getStyle().setWidth(100.0, Unit.PCT);
     return container;
   }

   /**
    * Update the layout.
    */
   private void forceLayout() {
     // No sense in doing layout if we aren't attached or have no content.
     if (!isAttached() || content == null) {
       return;
     }

     // Resize the content area to fit between the header and footer.
     int remainingHeight = getElement().getClientHeight();
     if (header != null) {
       int height = Math.max(0, headerContainer.getOffsetHeight());
       remainingHeight -= height;
       contentContainer.getStyle().setTop(height, Unit.PX);
     } else {
       contentContainer.getStyle().setTop(0.0, Unit.PX);
     }
     if (footer != null) {
       remainingHeight -= footerContainer.getOffsetHeight();
     }
     contentContainer.getStyle().setHeight(Math.max(0, remainingHeight), Unit.PX);

     // Provide resize to child.
     if (content instanceof RequiresResize) {
       ((RequiresResize) content).onResize();
     }
   }

   /**
    * Schedule layout to adjust the height of the content area.
    */
   private void scheduledLayout() {
     if (isAttached() && !layoutScheduled) {
       layoutScheduled = true;
       Scheduler.get().scheduleDeferred(layoutCmd);
     }
   }
 }
	/*
	* Copyright 2011 Google Inc.
	*
	* Licensed under the Apache License, Version 2.0 (the "License"); you may not
	* use this file except in compliance with the License. You may obtain a copy of
	* the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
	* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
	* License for the specific language governing permissions and limitations under
	* the License.
	*/
	package com.google.gwt.user.client.ui;

	import com.google.gwt.core.client.GWT;
	import com.google.gwt.core.client.Scheduler;
	import com.google.gwt.core.client.Scheduler.ScheduledCommand;
	import com.google.gwt.dom.client.Document;
	import com.google.gwt.dom.client.Style.Display;
	import com.google.gwt.dom.client.Style.Overflow;
	import com.google.gwt.dom.client.Style.Position;
	import com.google.gwt.dom.client.Style.Unit;
	import com.google.gwt.user.client.Element;
	import com.google.gwt.user.client.ui.FiniteWidgetIterator.WidgetProvider;

	import java.util.Iterator;

	/**
	* A panel that includes a header (top), footer (bottom), and content (middle)
	* area. The header and footer areas resize naturally. The content area is
	* allocated all of the remaining space between the header and footer area.
	*/
	public class HeaderPanel extends Panel implements RequiresResize {

	/**
	* The widget provider for this panel.
	*
	* <p>
	* Widgets are returned in the following order:
	* <ol>
	* <li>Header widget</li>
	* <li>Content widget</li>
	* <li>Footer widget</li>
	* </ol>
	*/
	private class WidgetProviderImpl implements WidgetProvider {

	public Widget get(int index) {
	switch (index) {
	case 0:
	return header;
	case 1:
	return content;
	case 2:
	return footer;
	}
	throw new ArrayIndexOutOfBoundsException(index);
	}
	}

	private Widget content;
	private final Element contentContainer;
	private Widget footer;
	private final Element footerContainer;
	private final ResizeLayoutPanel.Impl footerImpl = GWT.create(ResizeLayoutPanel.Impl.class);
	private Widget header;
	private final Element headerContainer;
	private final ResizeLayoutPanel.Impl headerImpl = GWT.create(ResizeLayoutPanel.Impl.class);
	private final ScheduledCommand layoutCmd = new ScheduledCommand() {
	public void execute() {
	layoutScheduled = false;
	forceLayout();
	}
	};
	private boolean layoutScheduled = false;

	public HeaderPanel() {
	// Create the outer element
	Element elem = Document.get().createDivElement().cast();
	elem.getStyle().setPosition(Position.RELATIVE);
	elem.getStyle().setOverflow(Overflow.HIDDEN);
	setElement(elem);

	// Create a delegate to handle resize from the header and footer.
	ResizeLayoutPanel.Impl.Delegate resizeDelegate = new ResizeLayoutPanel.Impl.Delegate() {
	public void onResize() {
	scheduledLayout();
	}
	};

	// Create the header container.
	headerContainer = createContainer();
	headerContainer.getStyle().setTop(0.0, Unit.PX);
	headerImpl.init(headerContainer, resizeDelegate);
	elem.appendChild(headerContainer);

	// Create the footer container.
	footerContainer = createContainer();
	footerContainer.getStyle().setBottom(0.0, Unit.PX);
	footerImpl.init(footerContainer, resizeDelegate);
	elem.appendChild(footerContainer);

	// Create the content container.
	contentContainer = createContainer();
	contentContainer.getStyle().setOverflow(Overflow.HIDDEN);
	contentContainer.getStyle().setTop(0.0, Unit.PX);
	contentContainer.getStyle().setHeight(0.0, Unit.PX);
	elem.appendChild(contentContainer);
	}

	/**
	* Adds a widget to this panel.
	*
	* @param w the child widget to be added
	*/
	@Override
	public void add(Widget w) {
	// Add widgets in the order that they appear.
	if (header == null) {
	setHeaderWidget(w);
	} else if (content == null) {
	setContentWidget(w);
	} else if (footer == null) {
	setFooterWidget(w);
	} else {
	throw new IllegalStateException(
	"HeaderPanel already contains header, content, and footer widgets.");
	}
	}

	/**
	* Get the content widget that appears between the header and footer.
	*
	* @return the content {@link Widget}
	*/
	public Widget getContentWidget() {
	return content;
	}

	/**
	* Get the footer widget at the bottom of the panel.
	*
	* @return the footer {@link Widget}
	*/
	public Widget getFooterWidget() {
	return footer;
	}

	/**
	* Get the header widget at the top of the panel.
	*
	* @return the header {@link Widget}
	*/
	public Widget getHeaderWidget() {
	return header;
	}

	public Iterator<Widget> iterator() {
	return new FiniteWidgetIterator(new WidgetProviderImpl(), 3);
	}

	@Override
	public void onAttach() {
	super.onAttach();
	headerImpl.onAttach();
	footerImpl.onAttach();
	scheduledLayout();
	}

	@Override
	public void onDetach() {
	super.onDetach();
	headerImpl.onDetach();
	footerImpl.onDetach();
	}

	public void onResize() {
	// Handle the outer element resizing.
	scheduledLayout();
	}

	@Override
	public boolean remove(Widget w) {
	// Validate.
	if (w.getParent() != this) {
	return false;
	}
	// Orphan.
	try {
	orphan(w);
	} finally {
	// Physical detach.
	w.getElement().removeFromParent();

	// Logical detach.
	if (w == content) {
	content = null;
	contentContainer.getStyle().setDisplay(Display.NONE);
	} else if (w == header) {
	header = null;
	headerContainer.getStyle().setDisplay(Display.NONE);
	} else if (w == footer) {
	footer = null;
	footerContainer.getStyle().setDisplay(Display.NONE);
	}
	}
	return true;
	}

	/**
	* Set the widget in the content portion between the header and footer.
	*
	* @param w the widget to use as the content
	*/
	public void setContentWidget(Widget w) {
	contentContainer.getStyle().clearDisplay();
	add(w, content, contentContainer);

	// Logical attach.
	content = w;
	scheduledLayout();
	}

	/**
	* Set the widget in the footer portion at the bottom of the panel.
	*
	* @param w the widget to use as the footer
	*/
	public void setFooterWidget(Widget w) {
	footerContainer.getStyle().clearDisplay();
	add(w, footer, footerContainer);

	// Logical attach.
	footer = w;
	scheduledLayout();
	}

	/**
	* Set the widget in the header portion at the top of the panel.
	*
	* @param w the widget to use as the header
	*/
	public void setHeaderWidget(Widget w) {
	headerContainer.getStyle().clearDisplay();
	add(w, header, headerContainer);

	// Logical attach.
	header = w;
	scheduledLayout();
	}

	/**
	* Add a widget to the panel in the specified container. Note that this method
	* does not do the logical attach.
	*
	* @param w the widget to add
	* @param toReplace the widget to replace
	* @param container the container in which to place the widget
	*/
	private void add(Widget w, Widget toReplace, Element container) {
	// Validate.
	if (w == toReplace) {
	return;
	}

	// Detach new child.
	if (w != null) {
	w.removeFromParent();
	}

	// Remove old child.
	if (toReplace != null) {
	remove(toReplace);
	}

	if (w != null) {
	// Physical attach.
	container.appendChild(w.getElement());

	adopt(w);
	}
	}

	private Element createContainer() {
	Element container = Document.get().createDivElement().cast();
	container.getStyle().setPosition(Position.ABSOLUTE);
	container.getStyle().setDisplay(Display.NONE);
	container.getStyle().setLeft(0.0, Unit.PX);
	container.getStyle().setWidth(100.0, Unit.PCT);
	return container;
	}

	/**
	* Update the layout.
	*/
	private void forceLayout() {
	// No sense in doing layout if we aren't attached or have no content.
	if (!isAttached() \|\| content == null) {
	return;
	}

	// Resize the content area to fit between the header and footer.
	int remainingHeight = getElement().getClientHeight();
	if (header != null) {
	int height = Math.max(0, headerContainer.getOffsetHeight());
	remainingHeight -= height;
	contentContainer.getStyle().setTop(height, Unit.PX);
	} else {
	contentContainer.getStyle().setTop(0.0, Unit.PX);
	}
	if (footer != null) {
	remainingHeight -= footerContainer.getOffsetHeight();
	}
	contentContainer.getStyle().setHeight(Math.max(0, remainingHeight), Unit.PX);

	// Provide resize to child.
	if (content instanceof RequiresResize) {
	((RequiresResize) content).onResize();
	}
	}

	/**
	* Schedule layout to adjust the height of the content area.
	*/
	private void scheduledLayout() {
	if (isAttached() && !layoutScheduled) {
	layoutScheduled = true;
	Scheduler.get().scheduleDeferred(layoutCmd);
	}
	}
	}