/**
 * Radial gradient.
 *
 *     @example
 *     Ext.create({
 *        xtype: 'draw', 
 *        renderTo: document.body,
 *        width: 600,
 *        height: 400,
 *        sprites: [{
 *            type: 'circle',
 *            cx: 100,
 *            cy: 100,
 *            r: 100,
 *            fillStyle: {
 *                type: 'radial',
 *                start: {
 *                    x: 0,
 *                    y: 0,
 *                    r: 0
 *                },
 *                end: {
 *                    x: 0,
 *                    y: 0,
 *                    r: 1
 *                },
 *                stops: [{
 *                    offset: 0,
 *                    color: '#90BCC9'
 *                }, {
 *                    offset: 1,
 *                    color: '#1F6D91'
 *                }]
 *            }
 *        }]
 *     });
 */
Ext.define('Ext.draw.gradient.Radial', {
    extend: 'Ext.draw.gradient.Gradient',
    type: 'radial',
    config: {
        /**
         * @cfg {Object} start
         * The starting circle of the gradient.
         */
        start: {
            x: 0,
            y: 0,
            r: 0
        },
        /**
         * @cfg {Object} end
         * The ending circle of the gradient.
         */
        end: {
            x: 0,
            y: 0,
            r: 1
        }
    },

    applyStart: function(newStart, oldStart) {
        var circle;

        if (!oldStart) {
            return newStart;
        }

        circle = {
            x: oldStart.x,
            y: oldStart.y,
            r: oldStart.r
        };

        if ('x' in newStart) {
            circle.x = newStart.x;
        }
        else if ('centerX' in newStart) {
            circle.x = newStart.centerX;
        }

        if ('y' in newStart) {
            circle.y = newStart.y;
        }
        else if ('centerY' in newStart) {
            circle.y = newStart.centerY;
        }

        if ('r' in newStart) {
            circle.r = newStart.r;
        }
        else if ('radius' in newStart) {
            circle.r = newStart.radius;
        }

        return circle;
    },

    applyEnd: function(newEnd, oldEnd) {
        var circle;

        if (!oldEnd) {
            return newEnd;
        }

        circle = {
            x: oldEnd.x,
            y: oldEnd.y,
            r: oldEnd.r
        };

        if ('x' in newEnd) {
            circle.x = newEnd.x;
        }
        else if ('centerX' in newEnd) {
            circle.x = newEnd.centerX;
        }

        if ('y' in newEnd) {
            circle.y = newEnd.y;
        }
        else if ('centerY' in newEnd) {
            circle.y = newEnd.centerY;
        }

        if ('r' in newEnd) {
            circle.r = newEnd.r;
        }
        else if ('radius' in newEnd) {
            circle.r = newEnd.radius;
        }

        return circle;
    },

    /**
     * @method generateGradient
     * @inheritdoc
     */
    generateGradient: function(ctx, bbox) {
        var start = this.getStart(),
            end = this.getEnd(),
            w = bbox.width * 0.5,
            h = bbox.height * 0.5,
            x = bbox.x + w,
            y = bbox.y + h,
            gradient = ctx.createRadialGradient(
                x + start.x * w, y + start.y * h, start.r * Math.max(w, h),
                x + end.x * w, y + end.y * h, end.r * Math.max(w, h)
            ),
            stops = this.getStops(),
            ln = stops.length,
            i;

        for (i = 0; i < ln; i++) {
            gradient.addColorStop(stops[i].offset, stops[i].color);
        }

        return gradient;
    }
});