ColumnLayout.java

/*
 Copyright (c) 2014 Ahomé Innovation Technologies. All rights reserved.

 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.ait.toolkit.sencha.ext.client.layout;

import com.google.gwt.core.client.JavaScriptObject;

/**
 * This is the layout style of choice for creating structural layouts in a
 * multi-column format where the width of each column can be specified as a
 * percentage or fixed width, but the height is allowed to vary based on the
 * content. This class is intended to be extended or created via the
 * layout:'column' Ext.container.Container.layout config, and should generally
 * not need to be created directly via the new keyword.
 * 
 * ColumnLayout does not have any direct config options (other than inherited
 * ones), but it does support a specific config property of columnWidth that can
 * be included in the config of any panel added to it. The layout will use the
 * columnWidth (if present) or width of each panel during layout to determine
 * how to size each panel. If width or columnWidth is not specified for a given
 * panel, its width will default to the panel's width (or auto).
 * 
 * The width property is always evaluated as pixels, and must be a number
 * greater than or equal to 1. The columnWidth property is always evaluated as a
 * percentage, and must be a decimal value greater than 0 and less than 1 (e.g.,
 * .25).
 * 
 * The basic rules for specifying column widths are pretty simple. The logic
 * makes two passes through the set of contained panels. During the first layout
 * pass, all panels that either have a fixed width or none specified (auto) are
 * skipped, but their widths are subtracted from the overall container width.
 * 
 * During the second pass, all panels with columnWidths are assigned pixel
 * widths in proportion to their percentages based on the total remaining
 * container width. In other words, percentage width panels are designed to fill
 * the space left over by all the fixed-width and/or auto-width panels. Because
 * of this, while you can specify any number of columns with different
 * percentages, the columnWidths must always add up to 1 (or 100%) when added
 * together, otherwise your layout may not render as expected.
 */
public class ColumnLayout extends ContainerLayout {

    public ColumnLayout() {
    }

    protected ColumnLayout(JavaScriptObject obj) {
        jsObj = obj;
    }

    protected native JavaScriptObject create(JavaScriptObject config) /*-{
		return {
			type : 'column'
		};
    }-*/;

    @Override
    protected native void create() /*-{
		var jso = {
			type : 'column'
		};
		this.@com.ait.toolkit.sencha.ext.client.layout.ContainerLayout::jsObj = jso;
    }-*/;

    public static ColumnLayout cast(ContainerLayout layout) {
        return new ColumnLayout(layout.getJsObj());
    }

}