Canvas---折线图---绘制网格

折线图---绘制网格

布置好canvas

<canvas width="600" height="400"></canvas>

    <style>
        canvas {
            border: 1px solid #ccc;
        }
    </style>

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

画网格大小

var gridSize = 10;

 

画多少条X轴方向的线，横线的条数取决于画布高度，同理纵线条数=>画布宽度

        var canvasHeight = ctx.canvas.height;
        var canvasWidth = ctx.canvas.width;
        console.log(ctx.canvas.height);
        console.log(ctx.canvas.width);

遍历的形式去画

X轴

        var xLineTotal = Math.floor(canvasHeight / gridSize);
        for (var i = 0; i <= xLineTotal; i++) {
            ctx.beginPath();
            ctx.moveTo(0, i * gridSize - 0.5); //canvasHeight=xlineTotal(也就是i)*gridSize
            ctx.lineTo(canvasWidth, i * gridSize - 0.5);
            ctx.strokeStyle = '#eee';
            ctx.stroke();
        }

Y轴

        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();
        }