Java tutorial
/* * This library is part of Geranium - * an open source UI library for GWT. * * Copyright (c) Alkacon Software GmbH (http://www.alkacon.com)- * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * For further information about Alkacon Software, please see the * company website: http://www.alkacon.com * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ package com.alkacon.geranium.client.ui.input; import com.alkacon.geranium.client.I_HasInit; import com.alkacon.geranium.client.ui.I_AutoHider; import com.alkacon.geranium.client.ui.I_Button.ButtonStyle; import com.alkacon.geranium.client.ui.ToggleButton; import com.alkacon.geranium.client.ui.css.I_InputCss; import com.alkacon.geranium.client.ui.css.I_InputLayoutBundle; import com.google.gwt.core.client.Scheduler; import com.google.gwt.core.client.Scheduler.ScheduledCommand; import com.google.gwt.event.dom.client.ClickEvent; import com.google.gwt.event.dom.client.ClickHandler; import com.google.gwt.event.dom.client.HasClickHandlers; import com.google.gwt.event.logical.shared.HasValueChangeHandlers; import com.google.gwt.event.logical.shared.ValueChangeEvent; import com.google.gwt.event.logical.shared.ValueChangeHandler; import com.google.gwt.event.shared.HandlerRegistration; import com.google.gwt.user.client.ui.Composite; import com.google.gwt.user.client.ui.FlowPanel; import com.google.gwt.user.client.ui.HasHorizontalAlignment; /** * This class represents a labeled checkbox which is not represented as an INPUT element in * the DOM, but is displayed as an image.<p> * * It can be checked/unchecked and enabled/disabled, which means 4 combinations in total. * So you need to supply 4 images, one for each of the combinations.<p> */ public class CheckBox extends Composite implements HasClickHandlers, I_FormWidget, I_HasInit, HasHorizontalAlignment, HasValueChangeHandlers<Boolean> { /** Type string for this widget. */ public static final String WIDGET_TYPE = "checkbox"; /** CSS bundle for this widget. */ private static final I_InputCss CSS = I_InputLayoutBundle.INSTANCE.inputCss(); /** The current horizontal alignment. */ private HorizontalAlignmentConstant m_align; /** Toggle button which actually displays the checkbox. */ private final ToggleButton m_button; /** The error display for this widget. */ private final ErrorWidget m_error; /** Internal root widget to which all other components of this widget are attached. */ private final FlowPanel m_root; /** * Default constructor which creates a checkbox without a label.<p> */ public CheckBox() { this(null); } /** * Public constructor for a checkbox.<p> * * The label text passed will be displayed to the right of the checkbox. If * it is null, no label is displayed.<p> * * @param labelText the label text */ public CheckBox(String labelText) { m_button = new ToggleButton(); m_button.setUseMinWidth(false); m_button.setButtonStyle(ButtonStyle.TRANSPARENT, null); m_button.setImageClass(CSS.checkBoxImage()); if (labelText != null) { m_button.setText(labelText); } setHorizontalAlignment(ALIGN_RIGHT); m_root = new FlowPanel(); m_error = new ErrorWidget(); m_root.add(m_button); m_root.add(m_error); initWidget(m_root); addStyleName(CSS.checkBox()); addStyleName(CSS.inlineBlock()); addClickHandler(new ClickHandler() { /** * @see com.google.gwt.event.dom.client.ClickHandler#onClick(com.google.gwt.event.dom.client.ClickEvent) */ public void onClick(ClickEvent event) { Scheduler.get().scheduleDeferred(new ScheduledCommand() { public void execute() { fireValueChangedEvent(); } }); } }); } /** * Adds a click handler to the checkbox.<p> * * @see com.google.gwt.event.dom.client.HasClickHandlers#addClickHandler(com.google.gwt.event.dom.client.ClickHandler) */ public HandlerRegistration addClickHandler(ClickHandler handler) { return addDomHandler(handler, ClickEvent.getType()); } /** * @see com.google.gwt.event.logical.shared.HasValueChangeHandlers#addValueChangeHandler(com.google.gwt.event.logical.shared.ValueChangeHandler) */ public HandlerRegistration addValueChangeHandler(ValueChangeHandler<Boolean> handler) { return addHandler(handler, ValueChangeEvent.getType()); } /** * Disables the checkbox and changes the checkbox title attribute to the disabled reason.<p> * * @param disabledReason the disabled reason */ public void disable(String disabledReason) { m_button.disable(disabledReason); } /** * Enables the checkbox, switching the checkbox title attribute from the disabled reason to the original title.<p> */ public void enable() { m_button.enable(); } /** * @see com.alkacon.geranium.client.ui.input.I_FormWidget#getApparentValue() */ public String getApparentValue() { return getFormValueAsString(); } /** * @see com.alkacon.geranium.client.ui.input.I_FormWidget#getFieldType() */ public FieldType getFieldType() { return I_FormWidget.FieldType.BOOLEAN; } /** * @see com.alkacon.geranium.client.ui.input.I_FormWidget#getFormValue() */ public Boolean getFormValue() { return isChecked() ? Boolean.TRUE : Boolean.FALSE; } /** * @see com.alkacon.geranium.client.ui.input.I_FormWidget#getFormValueAsString() */ public String getFormValueAsString() { return "" + isChecked(); } /** * This is the alignment of the text in reference to the checkbox, possible values are left or right.<p> * * @see com.google.gwt.user.client.ui.HasHorizontalAlignment#getHorizontalAlignment() */ public HorizontalAlignmentConstant getHorizontalAlignment() { return m_align; } /** * Returns true if the checkbox is checked.<p> * * @return true if the checkbox is checked */ public boolean isChecked() { return m_button.isDown(); } /** * Returns true if the checkbox is enabled.<p> * * @return true if the checkbox is enabled */ public boolean isEnabled() { return m_button.isEnabled(); } /** * @see com.alkacon.geranium.client.ui.input.I_FormWidget#reset() */ public void reset() { setChecked(false); } /** * @see com.alkacon.geranium.client.ui.input.I_FormWidget#setAutoHideParent(com.alkacon.geranium.client.ui.I_AutoHider) */ public void setAutoHideParent(I_AutoHider autoHideParent) { // do nothing } /** * Checks or unchecks the checkbox.<p> * * @param checked if true, check the checkbox else uncheck it */ public void setChecked(boolean checked) { m_button.setDown(checked); } /** * Enables or disables the checkbox.<p> * * @param enabled if true, enable the checkbox, else disable it */ public void setEnabled(boolean enabled) { m_button.setEnabled(enabled); } /** * @see com.alkacon.geranium.client.ui.input.I_FormWidget#setErrorMessage(java.lang.String) */ public void setErrorMessage(String errorMessage) { m_error.setText(errorMessage); } /** * Sets the value of the widget.<p> * * @param value the new value */ public void setFormValue(Object value) { if (value instanceof Boolean) { Boolean boolValue = (Boolean) value; setChecked(boolValue.booleanValue()); } } /** * @see com.alkacon.geranium.client.ui.input.I_FormWidget#setFormValueAsString(java.lang.String) */ public void setFormValueAsString(String value) { setChecked(Boolean.parseBoolean(value) || "checked".equalsIgnoreCase(value)); } /** * This is the alignment of the text in reference to the checkbox, possible values are left or right.<p> * * @see com.google.gwt.user.client.ui.HasHorizontalAlignment#setHorizontalAlignment(com.google.gwt.user.client.ui.HasHorizontalAlignment.HorizontalAlignmentConstant) */ public void setHorizontalAlignment(HorizontalAlignmentConstant align) { if (align.equals(HasHorizontalAlignment.ALIGN_CENTER)) { // ignore center alignment return; } m_button.setHorizontalAlignment(align); m_align = align; } /** * Sets the text.<p> * * @param text the text to set */ public void setText(String text) { m_button.setText(text); } /** * Helper method for firing a 'value changed' event.<p> */ protected void fireValueChangedEvent() { ValueChangeEvent.fire(this, getFormValue()); } }