画布不会清除 [英] Canvas will not clear

问题描述

我已经尝试了所有可以找到的清晰画布代码，但是当我单击回到画布上时，旧的图形重新出现。我需要它，这样当你按下清除按钮时，图纸不会再回来了。我正在使用paper.js如果有帮助

I have tried every clear canvas code I can find but when I click back onto the canvas, the old drawings reappear. I need it so that when you press the clear button the drawings don't come back on a new draw. I'm using paper.js if that helps

Html

<canvas id="myCanvas" height="400px" width="400px;"></canvas>    

JS（Clearcanvas是一个按钮功能）

JS (Clearcanvas is a function from a button)

function clearcanvas(){

    var c=document.getElementById("myCanvas");
    var ctx=c.getContext("2d");
    ctx.clearRect(0,0,400,400);

    }

绘图功能的JS适用于paper.js

JS for the drawing function works with paper.js

<script type="text/paperscript" canvas="myCanvas">
tool.minDistance = 5;

var path;

function onMouseDown(event) {
path = new Path();
path.strokeColor = 'red';
path.strokeWidth= 3;
path.opacity="0.4";

path.add(event.point, event.point);
}

function onMouseDrag(event) {
path.add(event.point, event.point);
}

function onMouseDrag(event) {
if(event.modifiers.shift) {
    path.lastSegment.point = event.point;
    path.strokeColor = 'blue';

} else {
    path.add(event.point);
}
}    
</script>

推荐答案

你试过这个吗？

 canvas.width = canvas.width;

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