Java tutorial
/* * Copyright (c) 2010 Zhihua (Dennis) Jiang * * 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.gwtmobile.ui.client.widgets; import java.beans.Beans; import java.util.Iterator; import com.google.gwt.dom.client.Style; import com.google.gwt.dom.client.Style.Unit; import com.google.gwt.user.client.DOM; import com.google.gwt.user.client.Element; import com.google.gwt.user.client.Event; import com.google.gwt.user.client.EventListener; import com.google.gwt.user.client.ui.HTMLPanel; import com.google.gwt.user.client.ui.Label; import com.google.gwt.user.client.ui.Widget; import com.gwtmobile.ui.client.CSS.StyleNames.Primary; import com.gwtmobile.ui.client.CSS.StyleNames.Secondary; import com.gwtmobile.ui.client.event.DragController; import com.gwtmobile.ui.client.event.DragEvent; import com.gwtmobile.ui.client.event.DragEventsHandler; import com.gwtmobile.ui.client.event.SwipeEvent; import com.gwtmobile.ui.client.event.SwipeEventsHandler; import com.gwtmobile.ui.client.utils.Utils; public class ScrollPanel extends PanelBase implements DragEventsHandler, SwipeEventsHandler { private boolean _withPadding = true; private boolean _hasTextBox = false; private boolean _fullHeight = false; private Element _scrollbar; protected HTMLPanel _intPanel = new HTMLPanel(""); public ScrollPanel() { super.add(_intPanel); setStyleName(Primary.ScrollPanel); setWithPadding(_withPadding); this.initScrollbar(); if (Beans.isDesignTime()) { _intPanel.add(new Label("Empty ScrollPanel. " + getDesignTimeMessage())); } } public boolean isWithPadding() { return _withPadding; } public void setWithPadding(boolean withPadding) { this._withPadding = withPadding; if (withPadding) { addStyleName(Secondary.WithPadding); } else { removeStyleName(Secondary.WithPadding); } } private void initScrollbar() { _scrollbar = DOM.createDiv(); _scrollbar.appendChild(DOM.createDiv()); _scrollbar.setClassName(Primary.ScrollBar); this.getElement().insertFirst(_scrollbar); this.hideScrollBar(); } private void adjustScrollbar(double scrollPannerPos) { Element widgetEle = getWidget().getElement(); int scrollPannelHeight = widgetEle.getOffsetHeight(); double scrollHeight = Utils.getHeight(this._scrollbar); double scrollbarHeight = (scrollHeight * scrollHeight) / scrollPannelHeight; if (scrollbarHeight >= scrollHeight) { this.hideScrollBar(); return; } else { this.showScrollBar(); } double scrollbarPos = -scrollHeight * scrollPannerPos / scrollPannelHeight; if (scrollPannerPos > 0) { scrollbarHeight = (scrollbarHeight - scrollPannerPos); scrollbarPos = 0; if (scrollbarHeight < 8) scrollbarHeight = 8; } else if ((-scrollPannerPos + scrollHeight) > (scrollPannelHeight)) { double outScroll = (-scrollPannerPos + scrollHeight) - scrollPannelHeight; scrollbarHeight = scrollbarHeight - outScroll; if (scrollbarHeight < 8) { scrollbarHeight = 8; } else { scrollbarPos = scrollbarPos + outScroll; } scrollbarPos = (scrollbarPos + scrollHeight) > scrollHeight ? scrollHeight - scrollbarHeight : scrollbarPos; } Utils.setHeight(this._scrollbar.getFirstChildElement(), scrollbarHeight); Utils.setTranslateY(this._scrollbar.getFirstChildElement(), scrollbarPos); } private void showScrollBar() { this._scrollbar.setAttribute("style", "opacity:1"); } private void hideScrollBar() { this._scrollbar.setAttribute("style", "opacity:0"); } public void setHasTextBox(boolean hasTextBox) { hasTextBox = hasTextBox && Utils.isAndroid(); } public boolean getHasTextBox() { return _hasTextBox; } public boolean isFullHeight() { return _fullHeight; } public void setFullHeight(boolean fullHeight) { this._fullHeight = fullHeight; if (fullHeight) { addStyleName(Secondary.FullHeight); } else { removeStyleName(Secondary.FullHeight); } } @Override public void onLoad() { DragController.get().addDragEventsHandler(this); DragController.get().addSwipeEventsHandler(this); } @Override public void onUnload() { DragController.get().removeDragEventsHandler(this); DragController.get().removeSwipeEventHandler(this); } public Widget getWidget() { //if (Beans.isDesignTime() an return getIntPanel(); //return super.getWidget(0); } public void reset() { Utils.setTransitionDuration(getWidget().getElement(), 0); Utils.setTranslateY(getWidget().getElement(), 0); } public void setPostionToTop() { Utils.setTransitionDuration(getWidget().getElement(), 0); Utils.setTranslateY(getWidget().getElement(), 0); } public void setPositionToBottom() { Utils.setTransitionDuration(getWidget().getElement(), 0); Utils.setTranslateY(getWidget().getElement(), this.getElement().getClientHeight() - this.getElement().getScrollHeight()); } public void setScrollPosition(int pos) { if (_hasTextBox) { setStyleTop(pos); } else { Element element = getWidget().getElement(); Utils.setTranslateY(element, pos); } this.adjustScrollbar(pos); } public int getScrollPosition() { if (_hasTextBox) { return getStyleTop(); } else { Element element = getWidget().getElement(); return Utils.getTranslateY(element); } } public int getScrollToPosition() { if (_hasTextBox) { return getStyleTop(); } else { Element element = getWidget().getElement(); return Utils.getMatrixY(element); } } @Override public void onDragStart(DragEvent e) { int matrix = getScrollToPosition(); int current = getScrollPosition(); Utils.setTransitionDuration(getWidget().getElement(), 0); Utils.setTransitionDuration(this._scrollbar.getFirstChildElement(), 0); if (current != matrix) { //scroll on going int diff = current - matrix; int offset = diff > 2 ? 2 : diff > -2 ? diff : -2; setScrollPosition(matrix + offset); DragController.get().suppressNextClick(); } } @Override public void onDragMove(DragEvent e) { Element widgetEle = getWidget().getElement(); int panelHeight = Utils.getHeight(this.getElement()); int widgetHeight = widgetEle.getOffsetHeight(); int current = getScrollPosition(); if (current > 0) {//exceed top boundary if (e.OffsetY > 0) { //resist scroll down. current += (int) (e.OffsetY / 2); // need the cast for production mode. } else { current += e.OffsetY * 2; } } else if (-current + panelHeight > widgetHeight) { //exceed bottom boundary if (e.OffsetY < 0) { //resist scroll up. current += (int) (e.OffsetY / 2); } else { current += e.OffsetY * 2; } } else { current += e.OffsetY; } setScrollPosition(current); } @Override public void onDragEnd(DragEvent e) { Element widgetEle = getWidget().getElement(); int current = getScrollPosition(); if (current == 0) { return; } int panelHeight = Utils.getHeight(this.getElement()); int widgetHeight = widgetEle.getOffsetHeight(); if (current > 0 //exceed top boundary || panelHeight > widgetHeight) { Utils.setTransitionDuration(widgetEle, 500); Utils.setTransitionDuration(this._scrollbar.getFirstChildElement(), 500); setScrollPosition(0); } else if (-current + panelHeight > widgetHeight) { //exceed bottom boundary Utils.setTransitionDuration(widgetEle, 500); Utils.setTransitionDuration(this._scrollbar.getFirstChildElement(), 500); setScrollPosition(panelHeight - widgetHeight); } this.hideScrollBar(); } @Override public void onSwipeVertical(SwipeEvent e) { Element widgetEle = getWidget().getElement(); int panelHeight = Utils.getHeight(this.getElement()); int widgetHeight = widgetEle.getOffsetHeight(); long current = getScrollPosition(); if ((current >= 0) // exceed top boundary || (-current + panelHeight >= widgetHeight)) { // exceed bottom boundary return; } double speed = e.getSpeed(); double timeFactor = 3000; long time = (long) Math.abs(speed * timeFactor); double dicstanceFactor = 0.25; long distance = (long) (speed * time * dicstanceFactor); //Utils.Console("speed " + speed + " time " + time + " distance " + distance + " current " + current); current += distance; if (current > 0) {//exceed top boundary double timeAdj = 1 - (double) current / distance; time = (long) (time * timeAdj); current = 0; } else if (-current + panelHeight > widgetHeight) { //exceed bottom boundary long bottom = panelHeight - widgetHeight; double timeAdj = 1 - (double) (current - bottom) / distance; time = (long) (time * timeAdj); current = bottom; } Utils.setTransitionDuration(widgetEle, time); Utils.setTransitionDuration(this._scrollbar.getFirstChildElement(), time); Utils.addEventListenerOnce(this._scrollbar.getFirstChildElement(), "webkitTransitionEnd", false, new EventListener() { @Override public void onBrowserEvent(Event event) { hideScrollBar(); } }); setScrollPosition((int) current); } @Override public void onSwipeHorizontal(SwipeEvent e) { } @Override public void add(Widget w) { if (Beans.isDesignTime()) { if (getWidgetCount() == 1 && isDesignTimeEmptyLabel(getWidget(0))) { clear(); } } _intPanel.add(w); if (Utils.isIOS()) { Utils.setTranslateY(w.getElement(), 0); //anti-flickering on iOS. } } private int getStyleTop() { Style style = getWidget().getElement().getStyle(); String top = style.getTop(); if (top.isEmpty()) { return 0; } else { return Integer.parseInt(top.replace("px", "")); } } private void setStyleTop(int top) { Style style = getWidget().getElement().getStyle(); style.setTop(top, Unit.PX); } public Widget getIntPanel() { return _intPanel; } @Override public void clear() { _intPanel.clear(); } @Override public Iterator<Widget> iterator() { return _intPanel.iterator(); } @Override public boolean remove(Widget w) { return _intPanel.remove(w); } @Override public Widget getWidget(int index) { return _intPanel.getWidget(index); } @Override public int getWidgetCount() { return _intPanel.getWidgetCount(); } }