图片涂鸦、绘制、标注
1.画笔颜色 🎨
2.画笔粗细 ✏️
3.画布放大 🔍
4.画布缩小 🔍
5.清除画布 🧹
6.保存图片 🏔
7.回退一步 ↩️
8.前进一步 ↪️
1.画笔 ✏️
2.直线 📏
3.圆形 ⚪️
4.矩形 🔲
5.橡皮 🧽
6.文字 📝
创建三个不同作用的画布
// 用于绘制的画板
this.canvas_front = document.getElementById("ctx_front");
// 用于生成绘制后效果图的画板
this.canvas_back = document.getElementById("ctx_back");
// 底图画板，橡皮擦除时获取像素放到绘制画板中，达到不擦出底图的效果
this.canvas_base = document.getElementById("ctx_base");
鼠标按下判断工具类型，记录初始位置
let mousedown = (e) => {
this.ctx_front.strokeStyle = this.defaultColor;
this.ctx_front.lineWidth = this.slide;
e = e || window.event;
sx = e.clientX - this.canvas_front.offsetLeft;
sy = e.clientY - this.canvas_front.offsetTop;
this.ctx_front.moveTo(sx, sy);
this.canDraw = true;
...
若是输入文字则定位输入框到画布中，失焦或回车文字绘制到画布中
this.handleTextBlur();
this.text = "";
text.style.fontSize = 14 + this.slide * 10 + "px";
text.style.color = this.defaultColor;
text.style.left =
e.offsetX + this.canvas_front.offsetLeft - 20 + "px";
text.style.top =
e.offsetY + this.canvas_front.offsetTop - 10 + "px";
text.style.zIndex = 10;
text.style.display = "block";
this.tl = e.offsetX - 20;
this.tt = e.offsetY + 10;
break;
...
handleTextBlur() {
let text = document.getElementById("text");
this.ctx_front.font = `300 ${text.style.fontSize} sans-serif`;
this.ctx_front.fillStyle = this.defaultColor;
this.ctx_front.fillText(this.text, this.tl, this.tt);
text.style.display = "none";
this.handleSaveCanvasStore();
}
鼠标移动，根据工具类型绘制不同路径
let mousemove = (e) => {
e = e || window.event;
mx = e.clientX - this.canvas_front.offsetLeft;
my = e.clientY - this.canvas_front.offsetTop;
const cbx = this.ctx_base.getImageData(
e.offsetX - this.slide / 2,
e.offsetY - this.slide / 2,
this.slide * 2,
this.slide * 2
);
...
若工具类型是橡皮，则从 canvas_base 中获取底图像素放回 canvas_front 中
const cbx = this.ctx_base.getImageData(
e.offsetX - this.slide / 2,
e.offsetY - this.slide / 2,
this.slide * 2,
this.slide * 2
);
...
this.ctx_front.putImageData(
cbx,
e.offsetX - this.slide / 2,
e.offsetY - this.slide / 2
);
...
鼠标抬起，从绘制画布 canvas_front 生成绘制图并绘制到 canvas_back 中，然后再重绘 canvas_front
handleSaveCanvasStore() {
let url = this.canvas_front.toDataURL();
let image = new Image();
image.src = url;
image.onload = () => {
this.ctx_front.clearRect(
0,
0,
this.canvas_front.width,
this.canvas_front.height
);
this.ctx_front.drawImage(image, 0, 0, image.width, image.height);
this.ctx_back.drawImage(image, 0, 0, image.width, image.height);
const url2 = this.canvas_back.toDataURL();
this.currentImg.url = url2;
this.currentImg.index += 1;
this.canvasStore.push(url2);
this.prevDis = false;
console.log(this.canvasStore);
};
},
最终保存图片
let canvas = document.getElementById("ctx_back");
this.$refs.download.href = canvas.toDataURL();
this.$refs.download.click();
npm install
npm run serve
npm run build
npm run lint
开发不易，且用且珍惜 ，随手给个星，开心到起飞
React
Typescript
Django
Laravel
Facebook
Microsoft
Google
Alibaba
D3
Tencent