画布触觉JS

Question

我有一个项目，我需要建立一个自行车预订网站。我需要创建一个画布，以允许人们签署的东西。我创建了我的画布，它与鼠标工作得很好，但我需要知道如何在移动设备上做它。我尝试了几种方法(使用touchmove/touchstart)，但是我不能让它工作。这是我在ES6中的对象画布(我不使用jQuery)。我不被允许使用任何库，我只想使用JS (我会在某个时候学习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

• pointerdown
• pointerup

用于触控设备。