echarts/src/component/helper/roamHelper.js

A powerful charting and visualization library for browser

define(function (require) {

    var helper = {};

    /**
     * For geo and graph.
     *
     * @param {Object} controllerHost
     * @param {module:zrender/Element} controllerHost.target
     */
    helper.updateViewOnPan = function (controllerHost, dx, dy) {
        var target = controllerHost.target;
        var pos = target.position;
        pos[0] += dx;
        pos[1] += dy;
        target.dirty();
    };

    /**
     * For geo and graph.
     *
     * @param {Object} controllerHost
     * @param {module:zrender/Element} controllerHost.target
     * @param {number} controllerHost.zoom
     * @param {number} controllerHost.zoomLimit like: {min: 1, max: 2}
     */
    helper.updateViewOnZoom = function (controllerHost, zoomDelta, zoomX, zoomY) {
        var target = controllerHost.target;
        var zoomLimit = controllerHost.zoomLimit;
        var pos = target.position;
        var scale = target.scale;

        var newZoom = controllerHost.zoom = controllerHost.zoom || 1;
        newZoom *= zoomDelta;
        if (zoomLimit) {
            var zoomMin = zoomLimit.min || 0;
            var zoomMax = zoomLimit.max || Infinity;
            newZoom = Math.max(
                Math.min(zoomMax, newZoom),
                zoomMin
            );
        }
        var zoomScale = newZoom / controllerHost.zoom;
        controllerHost.zoom = newZoom;
        // Keep the mouse center when scaling
        pos[0] -= (zoomX - pos[0]) * (zoomScale - 1);
        pos[1] -= (zoomY - pos[1]) * (zoomScale - 1);
        scale[0] *= zoomScale;
        scale[1] *= zoomScale;

        target.dirty();
    };

    return helper;
});