559day(绘制网格.html)

《2019年4月16日》【连续 55天】

标题：绘制网格.html；
内容：

var myCanvas = document.querySelector('canvas');
    var ctx = myCanvas.getContext('2d');

    /*1.绘制网格*/
    /*2.网格的大小*/
    var gridSize = 10;
    var canvasHeight = ctx.canvas.height;
    var canvasWidth = ctx.canvas.width;
    /*3.画多少条X轴方向的线 横线的条数  画布高度*/
    /*var canvasHeight = myCanvas.height;
    var canvasWidth = myCanvas.width;
    console.log(canvasHeight);
    console.log(canvasWidth);*/
    /*console.log(ctx.canvas.width);
    console.log(ctx.canvas.height);*/
    var xLineTotal = Math.floor(canvasHeight / gridSize);
    for (var i = 0; i <= xLineTotal; i++) {
        ctx.beginPath();
        ctx.moveTo(0, i * gridSize - 0.5 );
        ctx.lineTo(canvasWidth, i * gridSize - 0.5);
        ctx.strokeStyle = '#eee';
        ctx.stroke();
    }
    /*4.画多少条Y轴方向的线*/
    var yLineTotal = Math.floor(canvasWidth / gridSize);
    for (var i = 0; i <= yLineTotal; i++) {
        ctx.beginPath();
        ctx.moveTo(i*gridSize - 0.5 ,0);
        ctx.lineTo(i*gridSize - 0.5 ,canvasHeight);
        ctx.strokeStyle = '#eee';
        ctx.stroke();
    }
    /*5.遍历的形式去画*/