Question

我有一个项目，需要建立一个自行车预定网站。我需要创建一个画布以允许人们签名。我创建了画布，它可以很好地与鼠标配合使用，但是我需要知道如何在移动设备上进行操作。我尝试了几种方法（使用touchmove / touchstart），但无法正常工作。这是我在ES6中使用的对象画布（我不使用jQuery）。我不允许使用任何库，我只想使用JS（有时我会学习jQuery）。

class Canvas {

    constructor(canvasId, clearBtnId) {
        this.canvas = document.getElementById(canvasId);
        this.idBtnClear = clearBtnId;
        this.ctx = this.canvas.getContext("2d");
        this.painting = false;
        this.isEmpty = true;

        this.canvas.addEventListener("mousedown", this.mouseDown.bind(this));
        this.canvas.addEventListener("mouseup", this.mouseUp.bind(this));
        this.canvas.addEventListener("mousemove", this.draw.bind(this));
        this.canvas.addEventListener("mouseout", this.mouseUp.bind(this));

        document.getElementById(this.idBtnClear).addEventListener("click", this.clearCanvas.bind(this));

    }

    mouseDown(e) {
        this.painting = true;
    }

    mouseUp() {
        this.painting = false;
        this.ctx.beginPath();
    }

    draw(e) {
        if (!this.painting) return;
        this.ctx.lineWidth = 5;
        this.ctx.lineCap = "round";
        this.ctx.lineJoin = "round";

        let topPos = e.pageY - this.canvas.offsetTop;
        let leftPos = e.pageX - this.canvas.offsetLeft;

        this.ctx.lineTo(leftPos, topPos);
        this.ctx.stroke();
        this.ctx.beginPath();
        this.ctx.moveTo(leftPos, topPos);

        this.isEmpty = false;
    }

    clearCanvas() {
        this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height);
        this.isEmpty = true;
    }

}

Answer 1

您可以使用事件

用于触摸设备。

帆布手感JS

1 个答案: