Java tutorial
/* Copyright 2014 URL IS/IT * 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.urlisit.siteswrapper.cloud.widgets; import java.math.BigDecimal; import java.math.MathContext; import com.google.gwt.dom.client.Document; import com.google.gwt.dom.client.Element; import com.google.gwt.dom.client.ImageElement; import com.google.gwt.user.client.DOM; import com.google.gwt.user.client.Event; import com.google.gwt.user.client.EventListener; import com.google.gwt.user.client.Timer; import com.google.gwt.user.client.Window; import com.google.gwt.user.client.ui.Composite; import com.google.gwt.user.client.ui.Image; import com.google.gwt.user.client.ui.RequiresResize; import com.urlisit.siteswrapper.cloud.presenter.Presenter; import com.urlisit.siteswrapper.cloud.view.View; /** * @author Todd Url * */ public class BackgroundImage extends Composite implements EventListener, RequiresResize { private View view; private String url; private Image image; private ImageElement img; private Element div; private Timer timer; private boolean isLoaded; private BigDecimal windowWidth; private BigDecimal windowHeight; private BigDecimal imageWidth; private BigDecimal imageHeight; private BigDecimal widthRatio; private BigDecimal heightRatio; private BigDecimal scaledWidth; private BigDecimal scaledHeight; /** * */ public BackgroundImage(View view) { this.view = view; div = DOM.createDiv(); div.getStyle().setProperty("visibility", "hidden"); div.getStyle().setProperty("position", "absolute"); div.getStyle().setProperty("width", "1px"); div.getStyle().setProperty("height", "1px"); div.getStyle().setProperty("overflow", "hidden"); Document.get().getBody().appendChild(div); img = DOM.createImg().cast(); div.appendChild(img); Event.sinkEvents(img, Event.ONLOAD | Event.ONERROR); Event.setEventListener(div, this); img.setSrc(view.getPage().getBackgroundImageUrls(view.getLiterals().zero())); image = new Image(); image.setVisible(false); initWidget(image); view.getPanel().insert(this.asWidget(), 0, 0, 0); } @Override public void onBrowserEvent(Event event) { if (event.getTypeInt() == Event.ONLOAD) { isLoaded = true; img.removeFromParent(); div.removeFromParent(); image.setUrl(view.getPage().getBackgroundImageUrls(view.getLiterals().zero())); onResize(); } else if (event.getTypeInt() == Event.ONERROR) { Window.alert(view.getLiterals().imageErrorMessage() + url); } } @Override public void onResize() { if (isLoaded) { windowWidth = BigDecimal.valueOf(Window.getClientWidth()); windowHeight = BigDecimal.valueOf(Window.getClientHeight()); imageWidth = BigDecimal.valueOf(image.getWidth()); imageHeight = BigDecimal.valueOf(image.getHeight()); widthRatio = windowWidth.divide(imageWidth, 4, BigDecimal.ROUND_HALF_EVEN); heightRatio = windowHeight.divide(imageHeight, 4, BigDecimal.ROUND_HALF_EVEN); int left = 0; int top = 0; if (widthRatio.compareTo(heightRatio) >= 0) { scaledWidth = widthRatio.multiply(imageWidth); scaledHeight = widthRatio.multiply(imageHeight); top = scaledHeight.subtract(windowHeight).divide(new BigDecimal(2)).intValue(); image.setWidth(scaledWidth.intValue() + "px"); image.setHeight(scaledHeight.intValue() + "px"); view.getPanel().setWidgetPosition(this, left, -top); } else { scaledWidth = heightRatio.multiply(imageWidth); scaledHeight = heightRatio.multiply(imageHeight); left = scaledWidth.subtract(windowWidth).divide(new BigDecimal(2)).intValue(); image.setWidth(scaledWidth.intValue() + "px"); image.setHeight(scaledHeight.intValue() + "px"); view.getPanel().setWidgetPosition(this, -left, top); } } } public void fadeIn() { onResize(); image.getElement().getStyle().setOpacity(0); image.setVisible(true); int interval = 15; timer = new Timer() { BigDecimal current = new BigDecimal(0.0, MathContext.DECIMAL32); BigDecimal increment = new BigDecimal(0.1, MathContext.DECIMAL32); @Override public void run() { if (current.doubleValue() <= BigDecimal.ONE.doubleValue()) { image.getElement().getStyle().setOpacity(current.doubleValue()); current = current.add(increment, MathContext.DECIMAL32); } else { timer.cancel(); } } }; timer.scheduleRepeating(interval); } public void fadeOut(final Presenter presenter, final View view) { int stepInterval = 15; timer = new Timer() { BigDecimal current = new BigDecimal(1.0, MathContext.DECIMAL32); BigDecimal decrement = new BigDecimal(0.1, MathContext.DECIMAL32); @Override public void run() { if (current.doubleValue() >= BigDecimal.ZERO.doubleValue()) { image.getElement().getStyle().setOpacity(current.doubleValue()); current = current.subtract(decrement, MathContext.DECIMAL32); } else { timer.cancel(); presenter.loadView(view); } } }; timer.scheduleRepeating(stepInterval); } public void fadeOut() { int stepInterval = 15; timer = new Timer() { BigDecimal current = new BigDecimal(1.0, MathContext.DECIMAL32); BigDecimal decrement = new BigDecimal(0.1, MathContext.DECIMAL32); @Override public void run() { if (current.doubleValue() >= BigDecimal.ZERO.doubleValue()) { image.getElement().getStyle().setOpacity(current.doubleValue()); current = current.subtract(decrement, MathContext.DECIMAL32); } else { timer.cancel(); } } }; timer.scheduleRepeating(stepInterval); } public void setTitle(String title) { image.setTitle(title); } }