strokeRect (0, 0, canvasWidth, canvasHeight);绘制了一个完整的矩形,但线条宽度被减半,下面是一个示例: var canvas = document.getElementsByTagName ("canvas");
var canvasWidth = canvas[0].width;
va
DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml