/*
* Copyright 2008 Google Inc.
*
* 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.google.gwt.user.client.ui;
import com.google.gwt.core.client.GWT;
import com.google.gwt.i18n.client.HasDirection.Direction;
import com.google.gwt.i18n.client.LocaleInfo;
/**
* Characteristic interface which indicates that a widget can be aligned
* horizontally.
*
* <h3>Use in UiBinder Templates</h3>
*
* <p>
* The names of the static members of {@link HorizontalAlignmentConstant}, as
* well as simple alignment names (<code>left</code>, <code>center</code>,
* <code>right</code>, <code>justify</code>), can be used as values for a
* <code>horizontalAlignment</code> attribute of any widget that implements this
* interface. (In fact, this will work for any widget method that takes a single
* HorizontalAlignmentConstant value.)
* <p>
* For example,
*
* <pre>
* <g:Label horizontalAlignment='ALIGN_RIGHT'>Hi there.</g:Label>
* <g:Label horizontalAlignment='right'>Hi there.</g:Label>
* </pre>
*/
public interface HasHorizontalAlignment {
/**
* Type for values defined and used in {@link HasAutoHorizontalAlignment}.
* Defined here so that HorizontalAlignmentConstant can be derived from it,
* thus allowing HasAutoHorizontalAlignment methods to accept and return both
* AutoHorizontalAlignmentConstant and HorizontalAlignmentConstant values -
* without allowing the methods defined here to accept or return
* AutoHorizontalAlignmentConstant values.
*/
public static class AutoHorizontalAlignmentConstant {
// The constructor is package-private to prevent uncontrolled inheritance
// and instantiation of this class.
AutoHorizontalAlignmentConstant() {
}
}
/**
* Possible return values for {@link #getHorizontalAlignment}, and parameter
* values for {@link #setHorizontalAlignment}.
*/
public static class HorizontalAlignmentConstant extends
AutoHorizontalAlignmentConstant {
public static HorizontalAlignmentConstant endOf(Direction direction) {
return direction == Direction.LTR ? ALIGN_RIGHT :
direction == Direction.RTL ? ALIGN_LEFT : ALIGN_LOCALE_END;
}
public static HorizontalAlignmentConstant startOf(Direction direction) {
return direction == Direction.LTR ? ALIGN_LEFT :
direction == Direction.RTL ? ALIGN_RIGHT : ALIGN_LOCALE_START;
}
private final String textAlignString;
private HorizontalAlignmentConstant(String textAlignString) {
this.textAlignString = textAlignString;
}
/**
* Gets the CSS 'text-align' string associated with this constant.
*
* @return the CSS 'text-align' value
*/
public String getTextAlignString() {
return textAlignString;
}
}
/**
* Specifies that the widget's contents should be aligned in the center.
*/
HorizontalAlignmentConstant ALIGN_CENTER = new HorizontalAlignmentConstant(
"center");
/**
* Specifies that the widget's contents should be aligned as justify.
*/
HorizontalAlignmentConstant ALIGN_JUSTIFY = new HorizontalAlignmentConstant(
"justify");
/**
* Specifies that the widget's contents should be aligned to the left.
*/
HorizontalAlignmentConstant ALIGN_LEFT = new HorizontalAlignmentConstant(
"left");
/**
* Specifies that the widget's contents should be aligned to the right.
*/
HorizontalAlignmentConstant ALIGN_RIGHT = new HorizontalAlignmentConstant(
"right");
/**
* In a RTL layout, specifies that the widget's contents should be aligned to
* the right. In a LTR layout, specifies that the widget's constants should be
* aligned to the left.
*/
HorizontalAlignmentConstant ALIGN_LOCALE_START = GWT.isClient()
&& LocaleInfo.getCurrentLocale().isRTL() ? ALIGN_RIGHT : ALIGN_LEFT;
/**
* In a RTL layout, specifies that the widget's contents should be aligned to
* the left. In a LTR layout, specifies that the widget's constants should be
* aligned to the right.
*/
HorizontalAlignmentConstant ALIGN_LOCALE_END = GWT.isClient()
&& LocaleInfo.getCurrentLocale().isRTL() ? ALIGN_LEFT : ALIGN_RIGHT;
/**
* Synonym of {@link #ALIGN_LOCALE_START}.
*/
HorizontalAlignmentConstant ALIGN_DEFAULT = ALIGN_LOCALE_START;
/**
* Gets the horizontal alignment.
*
* @return the current horizontal alignment (
* {@link HasHorizontalAlignment#ALIGN_LEFT},
* {@link HasHorizontalAlignment#ALIGN_CENTER},
* {@link HasHorizontalAlignment#ALIGN_RIGHT},
* {@link HasHorizontalAlignment#ALIGN_JUSTIFY}, or
* null).
*/
HorizontalAlignmentConstant getHorizontalAlignment();
/**
* Sets the horizontal alignment.
* <p> Use {@code null} to clear horizontal alignment, allowing it to be
* determined by the standard HTML mechanisms such as inheritance and CSS
* rules.
*
* @param align the horizontal alignment (
* {@link HasHorizontalAlignment#ALIGN_LEFT},
* {@link HasHorizontalAlignment#ALIGN_CENTER},
* {@link HasHorizontalAlignment#ALIGN_RIGHT},
* {@link HasHorizontalAlignment#ALIGN_JUSTIFY},
* {@link HasHorizontalAlignment#ALIGN_LOCALE_START}, or
* {@link HasHorizontalAlignment#ALIGN_LOCALE_END}).
*/
void setHorizontalAlignment(HorizontalAlignmentConstant align);
}