/*
 * Ext JS Library 2.0
 * Copyright(c) 2006-2007, Ext JS, LLC.
 * licensing@extjs.com
 * 
 * http://extjs.com/license
 */

/**
 * @class Ext.layout.ColumnLayout
 * @extends Ext.layout.ContainerLayout
 * <p>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' {@link Ext.Container#layout} config,
 * and should generally not need to be created directly via the new keyword.</p>
 * <p>ColumnLayout does not have any direct config options (other than inherited ones), but it does support a
 * specific config property of <b>columnWidth</b> that can be included in the config of any panel added to it.  The
 * layout will use the width (if pixels) or columnWidth (if percent) 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).</p>
 * <p>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).</p>
 * <p>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 <b>remaining</b> container width.  In other words, percentage width panels are designed to fill the space
 * left over by all the fixed-width 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.  Example usage:</p>
 * <pre><code>
// All columns are percentages -- they must add up to 1
var p = new Ext.Panel({
    title: 'Column Layout - Percentage Only',
    layout:'column',
    items: [{
        title: 'Column 1',
        columnWidth: .25 
    },{
        title: 'Column 2',
        columnWidth: .6
    },{
        title: 'Column 3',
        columnWidth: .15
    }]
});

// Mix of width and columnWidth -- all columnWidth values values must add
// up to 1. The first column will take up exactly 120px, and the last two
// columns will fill the remaining container width.
var p = new Ext.Panel({
    title: 'Column Layout - Mixed',
    layout:'column',
    items: [{
        title: 'Column 1',
        width: 120
    },{
        title: 'Column 2',
        columnWidth: .8
    },{
        title: 'Column 3',
        columnWidth: .2
    }]
});
</code></pre>
 */
Ext.layout.ColumnLayout = Ext.extend(Ext.layout.ContainerLayout, {
    // private
    monitorResize:true,
    // private
    extraCls: 'x-column',

    scrollOffset : 0,

    // private
    isValidParent : function(c, target){
        return c.getEl().dom.parentNode == this.innerCt.dom;
    },

    // private
    onLayout : function(ct, target){
        var cs = ct.items.items, len = cs.length, c, i;

        if(!this.innerCt){
            target.addClass('x-column-layout-ct');

            // the innerCt prevents wrapping and shuffling while
            // the container is resizing
            this.innerCt = target.createChild({cls:'x-column-inner'});

            this.renderAll(ct, this.innerCt);

            this.innerCt.createChild({cls:'x-clear'});

        }

        var size = target.getViewSize();

        if(size.width < 1 && size.height < 1){ // display none?
            return;
        }

        var w = size.width - target.getPadding('lr') - this.scrollOffset,
            h = size.height - target.getPadding('tb'),
            pw = w;

        this.innerCt.setWidth(w);
        
        // some columns can be percentages while others are fixed
        // so we need to make 2 passes

        for(i = 0; i < len; i++){
            c = cs[i];
            if(!c.columnWidth){
                pw -= (c.getSize().width + c.getEl().getMargins('lr'));
            }
        }

        pw = pw < 0 ? 0 : pw;

        for(i = 0; i < len; i++){
            c = cs[i];
            if(c.columnWidth){
                c.setSize(Math.floor(c.columnWidth*pw) - c.getEl().getMargins('lr'));
            }
        }
    }
    
    /**
     * @property activeItem
     * @hide
     */
});

Ext.Container.LAYOUTS['column'] = Ext.layout.ColumnLayout;