vue中使用canvas實現手寫簽名功能

效果圖

代碼

<template>
    <div class="sign-canvas">
        <canvas
                id="canvas"
                width="400"
                height="600"
                @mousedown="canvasDown($event)"
                @mousemove="canvasMove($event)"
                @mouseup="canvasUp()"
                @mouseleave="canvasLeave()"
                ref="canvas"
        >
            抱歉，您的瀏覽器暫不支持canvas元素
        </canvas>
        <div class="sign-btn">
            <div class="clear" @click="clear">
                清空
            </div>
            <div class="save" @click="save">
                保存
            </div>
        </div>
    </div>
</template>

<script>
    export default {
        mounted() {
            this.show();
        },
        methods:{
            show(){
                this.canvas = this.$refs.canvas;// 指定canvas
                this.ctx = this.canvas.getContext("2d") // 設置2D渲染區域
                this.ctx.lineWidth = 5; // 設置線的寬度
            },
            canvasDown(e) {
                this.canvasMoveUse = true;
                const canvasX = e.clientX - e.target.offsetLeft + document.documentElement.scrollLeft
                const canvasY = e.clientY - e.target.offsetTop + document.documentElement.scrollTop
                this.ctx.beginPath()  // 移動的起點
                this.ctx.moveTo(canvasX, canvasY)
            },
            canvasMove(e) {
                // 只在移動是進行繪製圖線
                if (this.canvasMoveUse) {
                    const t = e.target;
                    let canvasX;
                    let canvasY;
                    canvasX = e.clientX - t.offsetLeft + document.documentElement.scrollLeft
                    canvasY = e.clientY - t.offsetTop + document.documentElement.scrollTop
                    this.ctx.lineTo(canvasX, canvasY)
                    this.ctx.stroke()
                }
            },
            canvasUp() {
                this.canvasMoveUse = false;
            },
            canvasLeave() {
                this.canvasMoveUse = false;
            },
            clear(){
                this.ctx.clearRect(0, 0, this.ctx.canvas.width, this.ctx.canvas.height)
            },
            save() {
                const imgBase64 = this.$refs.canvas.toDataURL();
                console.log(imgBase64);
            }
        }
    }
</script>

<style scoped>
    .sign-canvas{
        display: flex;
        flex-direction: column;
        align-items: center;
        width: 100%;
        height: 100%;
        padding: 20px 30px;
    }
    .sign-canvas canvas{
        background-color: #e0e3e5;
    }
    .sign-btn {
        display: flex;
        margin:20px 0;
    }
    .sign-btn div {
        width: 175px;
        text-align: center;
        height: 70px;
        line-height: 70px;
        color: #FFFFFF;
    }
    .sign-btn div:active {
        background-color: #CCCCCC;
        color: #333333;
    }
    .sign-btn .clear {
        background-color: #FF8F58;
    }
    .sign-btn .save {
        background-color: #0599D7;
    }
</style>