Java tutorial
/* * Copyright 2011 SWM Services GmbH. * * 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 de.swm.commons.mobile.client.widgets; import com.google.gwt.core.client.Scheduler; import com.google.gwt.core.client.Scheduler.ScheduledCommand; import com.google.gwt.dom.client.Style.Unit; import com.google.gwt.user.client.ui.Label; import de.swm.commons.mobile.client.SWMMobile; import de.swm.commons.mobile.client.event.DragController; import de.swm.commons.mobile.client.event.DragEvent; import de.swm.commons.mobile.client.event.DragEventsHandler; import de.swm.commons.mobile.client.utils.IsSWMMobileWidgetHelper; import de.swm.commons.mobile.client.widgets.scroll.ScrollPanel; import java.util.List; /** * Indes scroll panel is a address book like widget that orders his entries alphabetically including a selection index * displayed on the right. */ public class IndexedScrollPanelWithPager extends HorizontalPanel { private static final double INNER_HEIGHT = 90.0; private static final double OUTER_HEIGHT = 100.0; private static final String[] letters = { "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" }; /** * Inner class that represents the alphabetical selection index. */ public class IndexPanel extends VerticalPanel implements DragEventsHandler { private static final int PADDING = 4; private static final int NO_OF_LETTERS = 26; private final IsSWMMobileWidgetHelper myWidgetHelper = new IsSWMMobileWidgetHelper(); private final int[] sectionHeight = new int[NO_OF_LETTERS]; private int absY, letterHeight; private final ScrollPanel scroller; /** * Default constructor. * * @param scroller the indexed scroller. */ public IndexPanel(final ScrollPanel scroller) { this.scroller = scroller; addStyleName(SWMMobile.getTheme().getMGWTCssBundle().getIndexPanelCss().indexPanel()); for (int i = 0; i < NO_OF_LETTERS; i++) { add(new Label(letters[i])); sectionHeight[i] = -1; } Scheduler.get().scheduleDeferred(new ScheduledCommand() { @Override public void execute() { absY = getAbsoluteTop() + PADDING; // include padding letterHeight = getWidget(0).getElement().getClientHeight(); } }); } /** * Updates the positions. */ void updateSectionPositions() { for (int i = 0; i < NO_OF_LETTERS; i++) { sectionHeight[i] = -1; } ListPanel list = (ListPanel) scroller.getWidget(); int s = 0; for (int i = 0; i < list.getWidgetCount(); i++) { ListItem item = list.getItem(i); if (item.getElement().getClassName().contains( SWMMobile.getTheme().getMGWTCssBundle().getIndexPanelCss().indexHeaderListItem())) { sectionHeight[s++] = item.getElement().getOffsetTop(); } } } @Override public void onLoad() { super.onLoad(); DragController.get().addDragEventsHandler(this); myWidgetHelper.checkInitialLoad(this); } @Override public void onUnload() { DragController.get().removeDragEventsHandler(this); } @Override public void onDragStart(DragEvent e) { // do nothing } @Override public void onDragMove(DragEvent e) { int index = (((int) e.getY()) - absY) / letterHeight; index = Math.max(0, index); index = Math.min(NO_OF_LETTERS - 1, index); if (sectionHeight[index] >= 0) { scroller.setScrollPosition(-sectionHeight[index]); } } @Override public void onDragEnd(DragEvent e) { int index = (((int) e.getY()) - absY) / letterHeight; index = Math.max(0, index); index = Math.min(NO_OF_LETTERS - 1, index); if (sectionHeight[index] >= 0) { scroller.setScrollPosition(-sectionHeight[index]); } } } private final IndexPanel indexPanel; private final ScrollPanel scroller; private final ListPanel list; /** * Default constructor. */ public IndexedScrollPanelWithPager() { addStyleName(SWMMobile.getTheme().getMGWTCssBundle().getIndexPanelCss().indexedScrollPanel()); getElement().getStyle().setHeight(INNER_HEIGHT, Unit.PCT); // compensation for height of header panel scroller = new ScrollPanel(); scroller.getElement().getStyle().setHeight(OUTER_HEIGHT, Unit.PCT); list = new ListPanel(); createAlphabeticalIndex(); scroller.add(list); add(scroller); indexPanel = new IndexPanel(scroller); add(indexPanel); } /** * Create the basic index structure,. */ private void createAlphabeticalIndex() { for (int i = 0; i < letters.length; i++) { ListItem item = new ListItem(); item.addStyleName(SWMMobile.getTheme().getMGWTCssBundle().getIndexPanelCss().indexHeaderListItem()); item.add(new Label(letters[i])); item.setDisabled(true); list.add(item); } } /** * Adds the items to the pannel. * * @param sectionIndex the selection index * @param items the items */ public void setIndexedItems(int sectionIndex, List<ListItem> items) { int pos = findIndexedSectionPosition(sectionIndex); if (pos >= 0) { for (int j = items.size(); j > 0; j--) { list.insert(items.get(j - 1), (pos + 1)); } } } /** * Clears all entries. * * @see de.swm.commons.mobile.client.base.PanelBase#clear() */ @Override public void clear() { list.clear(); createAlphabeticalIndex(); } /** * Updated the index. */ public void updateIndex() { Scheduler.get().scheduleDeferred(new ScheduledCommand() { @Override public void execute() { indexPanel.updateSectionPositions(); } }); } /** * Finds the screen position of an concrete index * * @param sectionIndex the index * @return the screen position. */ private int findIndexedSectionPosition(int sectionIndex) { ListPanel list = (ListPanel) scroller.getWidget(); int s = 0; for (int i = 0; i < list.getWidgetCount(); i++) { ListItem item = list.getItem(i); if (item.getElement().getClassName() .contains(SWMMobile.getTheme().getMGWTCssBundle().getIndexPanelCss().indexHeaderListItem())) { if (s == sectionIndex) { return i; } s++; } } return -1; } }