html2canvas/src/lineargradientcontainer.js

var GradientContainer = require('./gradientcontainer');
var Color = require('./color');

var COLOR_STOP_REGEXP = /^(.*)\s*(\d{1,3})?(%|px)?$/;

function LinearGradientContainer(imageData) {
    GradientContainer.apply(this, arguments);
    this.type = this.TYPES.LINEAR;

    var hasDirection = imageData.args[0].match(this.stepRegExp) === null;

    if (hasDirection) {
        imageData.args[0].split(" ").reverse().forEach(function(position) {
            switch(position) {
            case "left":
                this.x0 = 0;
                this.x1 = 1;
                break;
            case "top":
                this.y0 = 0;
                this.y1 = 1;
                break;
            case "right":
                this.x0 = 1;
                this.x1 = 0;
                break;
            case "bottom":
                this.y0 = 1;
                this.y1 = 0;
                break;
            case "to":
                var y0 = this.y0;
                var x0 = this.x0;
                this.y0 = this.y1;
                this.x0 = this.x1;
                this.x1 = x0;
                this.y1 = y0;
                break;
            }
        }, this);
    } else {
        this.y0 = 0;
        this.y1 = 1;
    }


    this.colorStops = imageData.args.slice(hasDirection ? 1 : 0)
        .map(function(colorStop) { return colorStop.match(COLOR_STOP_REGEXP);})
        .filter(function(colorStopMatch) { return !!colorStopMatch;})
        .map(function(colorStopMatch) {
            return {
                color: new Color(colorStopMatch[1]),
                stop: colorStopMatch[3] === "%" ? colorStopMatch[2] / 100 : null
            };
        });

    if (this.colorStops[0].stop === null) {
        this.colorStops[0].stop = 0;
    }

    if (this.colorStops[this.colorStops.length - 1].stop === null) {
        this.colorStops[this.colorStops.length - 1].stop = 1;
    }

    this.colorStops.forEach(function(colorStop, index) {
        if (colorStop.stop === null) {
            this.colorStops.slice(index).some(function(find, count) {
                if (find.stop !== null) {
                    colorStop.stop = ((find.stop - this.colorStops[index - 1].stop) / (count + 1)) + this.colorStops[index - 1].stop;
                    return true;
                } else {
                    return false;
                }
            }, this);
        }
    }, this);
}

LinearGradientContainer.prototype = Object.create(GradientContainer.prototype);

LinearGradientContainer.prototype.stepRegExp = /((?:rgb|rgba)\(\d{1,3},\s\d{1,3},\s\d{1,3}(?:,\s[0-9\.]+)?\))\s*(\d{1,3})?(%|px)?/;

module.exports = LinearGradientContainer;