/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.waveprotocol.wave.client.scroll;
import com.google.common.base.Preconditions;
import com.google.gwt.dom.client.Element;
import org.waveprotocol.wave.client.common.util.DomHelper;
import org.waveprotocol.wave.client.common.util.Measurer;
import org.waveprotocol.wave.client.common.util.MeasurerInstance;
/**
* Reveals the scrolling capabilities of a DOM element.
*
*/
public final class DomScrollPanel implements ScrollPanel<Element> {
private final Element element;
private final Measurer measurer;
DomScrollPanel(Element element, Measurer measurer) {
this.element = element;
this.measurer = measurer;
}
/**
* Reveals {@code e} as a scroll panel. It is assumed that the given element
* has appropriate CSS constraints that make it scrollable.
*/
public static DomScrollPanel create(Element e) {
return new DomScrollPanel(e, MeasurerInstance.get());
}
@Override
public Extent getViewport() {
int top = element.getScrollTop();
return Extent.of(top, top + measurer.height(element));
}
@Override
public Extent getContent() {
Element first = element.getFirstChildElement();
Element last = DomHelper.getLastChildElement(element);
Preconditions.checkNotNull(first, "No content");
int top = element.getScrollTop();
return Extent.of(measurer.top(element, first) + top, measurer.bottom(element, last) + top);
}
@Override
public Extent extentOf(Element target) {
int top = element.getScrollTop();
return Extent.of(measurer.top(element, target) + top, measurer.bottom(element, target) + top);
}
@Override
public void moveTo(double location) {
element.setScrollTop((int) location);
}
}