svg.setAttribute('height', height);
// 绘制网格
drawGrid(gridSvg, width, height, gridLength...网格大小
*/
function drawGrid(svgBackground, winWidth, winHeight, gridLength) {...); j < len; j++){
var attrs = {
x1 : j * gridLength,...y1 : 0,
x2 : j * gridLength,
y2 : winHeight,...,
x2 : winWidth,
y2 : k * gridLength,
stroke