de.swm.commons.mobile.client.widgets.Slider.java Source code

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Here is the source code for de.swm.commons.mobile.client.widgets.Slider.java

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/*
 * 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.dom.client.Element;
import com.google.gwt.dom.client.Style.Unit;
import com.google.gwt.editor.client.IsEditor;
import com.google.gwt.editor.client.LeafValueEditor;
import com.google.gwt.editor.client.adapters.TakesValueEditor;
import com.google.gwt.event.dom.client.*;
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.FlowPanel;
import com.google.gwt.user.client.ui.HTML;
import com.google.gwt.user.client.ui.HasValue;
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;

/**
 * Integer value slider with data binding support.
 *  
 */
public class Slider extends SWMMobileWidgetBase implements DragEventsHandler, HasValueChangeHandlers<Integer>,
        IsEditor<LeafValueEditor<Integer>>, HasValue<Integer>, HasFocusHandlers, HasBlurHandlers {

    private static final int SCALE_FACTOR = 100;
    protected int myValue = 0;
    protected final FlowPanel contentPanel = new FlowPanel();
    protected final HTML myLabel = new HTML(myValue + "");
    protected final HTML mySlider = new HTML();
    private LeafValueEditor<Integer> editor;

    /**
     * Default constructor.
     */
    public Slider() {
        contentPanel.add(myLabel);
        mySlider.setHTML("<div></div><div></div><div></div>");
        contentPanel.add(mySlider);
        initWidget(contentPanel);
        setStyleName(SWMMobile.getTheme().getMGWTCssBundle().getSliderCss().slider());
    }

    @Override
    public void onLoad() {
        super.onLoad();
        DragController.get().addDragEventsHandler(this);
    }

    @Override
    public void onUnload() {
        DragController.get().removeDragEventsHandler(this);
    }

    @Override
    public void onDragStart(DragEvent e) {
        DragController.get().captureDragEvents(this);
        int value = computeNewValue(e);
        setValue(value);
    }

    @Override
    public void onDragMove(DragEvent e) {
        e.stopPropagation();
        int value = computeNewValue(e);
        setValue(value);
    }

    @Override
    public void onDragEnd(DragEvent e) {
        DragController.get().releaseDragCapture(this);
    }

    @Override
    public Integer getValue() {
        return myValue;
    }

    @Override
    public HandlerRegistration addValueChangeHandler(ValueChangeHandler<Integer> handler) {
        return this.addHandler(handler, ValueChangeEvent.getType());
    }

    /**
     * If the current value should be displayed.
     * 
     * @param display
     *            true if the value should be displayed
     */
    public void setDisplayValue(boolean display) {
        if (display) {
            myLabel.removeStyleName(SWMMobile.getTheme().getMGWTCssBundle().getSliderCss().hide());
        } else {
            myLabel.addStyleName(SWMMobile.getTheme().getMGWTCssBundle().getSliderCss().hide());
        }
    }

    /**
     * Computes the value after a Drag event (after the slider was moved)
     * 
     * @param event
     *            the event
     * @return the new value
     */
    private int computeNewValue(DragEvent event) {
        Element ele = getElement();
        int offset = (int) event.getX() - ele.getAbsoluteLeft();
        int width = ele.getClientWidth();
        int value = offset * SCALE_FACTOR / width;
        if (value > SCALE_FACTOR) {
            value = SCALE_FACTOR;
        } else if (value < 0) {
            value = 0;
        }
        return value;
    }

    /**
     * Enforce the slider position update.
     */
    private void updateSliderPosition() {
        myLabel.setHTML(myValue + "");
        Element slider = getSliderElement();
        slider.getStyle().setWidth(myValue, Unit.PCT);
    }

    private Element getSliderElement() {
        return (Element) mySlider.getElement().getChild(1);
    }

    @Override
    public LeafValueEditor<Integer> asEditor() {
        if (editor == null) {
            editor = TakesValueEditor.of(this);
        }
        return editor;
    }

    /**
     * Sets the value.
     * 
     * @param value
     *            the value
     */
    public void setValue(Integer value) {
        if (value != null && myValue != value) {
            myValue = value;
            updateSliderPosition();
            ValueChangeEvent.fire(this, myValue);
        }
    }

    @Override
    public void setValue(Integer value, boolean fireEvents) {
        setValue(value);
    }

    @Override
    public HandlerRegistration addBlurHandler(BlurHandler handler) {
        return mySlider.addDomHandler(handler, BlurEvent.getType());
    }

    @Override
    public HandlerRegistration addFocusHandler(FocusHandler handler) {
        return mySlider.addDomHandler(handler, FocusEvent.getType());
    }
}