gentelella/vendors/jquery-sparkline/src/vcanvas-base.js

    // Setup a very simple "virtual canvas" to make drawing the few shapes we need easier
    // This is accessible as $(foo).simpledraw()

    VShape = createClass({
        init: function (target, id, type, args) {
            this.target = target;
            this.id = id;
            this.type = type;
            this.args = args;
        },
        append: function () {
            this.target.appendShape(this);
            return this;
        }
    });

    VCanvas_base = createClass({
        _pxregex: /(\d+)(px)?\s*$/i,

        init: function (width, height, target) {
            if (!width) {
                return;
            }
            this.width = width;
            this.height = height;
            this.target = target;
            this.lastShapeId = null;
            if (target[0]) {
                target = target[0];
            }
            $.data(target, '_jqs_vcanvas', this);
        },

        drawLine: function (x1, y1, x2, y2, lineColor, lineWidth) {
            return this.drawShape([[x1, y1], [x2, y2]], lineColor, lineWidth);
        },

        drawShape: function (path, lineColor, fillColor, lineWidth) {
            return this._genShape('Shape', [path, lineColor, fillColor, lineWidth]);
        },

        drawCircle: function (x, y, radius, lineColor, fillColor, lineWidth) {
            return this._genShape('Circle', [x, y, radius, lineColor, fillColor, lineWidth]);
        },

        drawPieSlice: function (x, y, radius, startAngle, endAngle, lineColor, fillColor) {
            return this._genShape('PieSlice', [x, y, radius, startAngle, endAngle, lineColor, fillColor]);
        },

        drawRect: function (x, y, width, height, lineColor, fillColor) {
            return this._genShape('Rect', [x, y, width, height, lineColor, fillColor]);
        },

        getElement: function () {
            return this.canvas;
        },

        /**
         * Return the most recently inserted shape id
         */
        getLastShapeId: function () {
            return this.lastShapeId;
        },

        /**
         * Clear and reset the canvas
         */
        reset: function () {
            alert('reset not implemented');
        },

        _insert: function (el, target) {
            $(target).html(el);
        },

        /**
         * Calculate the pixel dimensions of the canvas
         */
        _calculatePixelDims: function (width, height, canvas) {
            // XXX This should probably be a configurable option
            var match;
            match = this._pxregex.exec(height);
            if (match) {
                this.pixelHeight = match[1];
            } else {
                this.pixelHeight = $(canvas).height();
            }
            match = this._pxregex.exec(width);
            if (match) {
                this.pixelWidth = match[1];
            } else {
                this.pixelWidth = $(canvas).width();
            }
        },

        /**
         * Generate a shape object and id for later rendering
         */
        _genShape: function (shapetype, shapeargs) {
            var id = shapeCount++;
            shapeargs.unshift(id);
            return new VShape(this, id, shapetype, shapeargs);
        },

        /**
         * Add a shape to the end of the render queue
         */
        appendShape: function (shape) {
            alert('appendShape not implemented');
        },

        /**
         * Replace one shape with another
         */
        replaceWithShape: function (shapeid, shape) {
            alert('replaceWithShape not implemented');
        },

        /**
         * Insert one shape after another in the render queue
         */
        insertAfterShape: function (shapeid, shape) {
            alert('insertAfterShape not implemented');
        },

        /**
         * Remove a shape from the queue
         */
        removeShapeId: function (shapeid) {
            alert('removeShapeId not implemented');
        },

        /**
         * Find a shape at the specified x/y co-ordinates
         */
        getShapeAt: function (el, x, y) {
            alert('getShapeAt not implemented');
        },

        /**
         * Render all queued shapes onto the canvas
         */
        render: function () {
            alert('render not implemented');
        }
    });