javascript - 如何只清除矩形边框？ (JS， Canvas )

Question

我试图只清除 strokeRect() 并将内容保留在该矩形中。 在此示例中，如何在不影响红色矩形的情况下清除绿色矩形？

 var cut = [50, 70, 100, 100]
 var cut1 = [60, 85, 60, 60]
 var c = document.getElementById("canvas");
 var ctx = c.getContext("2d");
 ctx.beginPath();
 ctx.rect(cut[0], cut[1], cut[2], cut[3]);
 ctx.lineWidth = 3;
 ctx.strokeStyle = 'green';
 ctx.stroke();
 ctx.closePath();
 
 ctx.beginPath();
 ctx.rect(cut1[0], cut1[1], cut1[2], cut1[3]);
 ctx.lineWidth = 3;
 ctx.strokeStyle = 'red';
 ctx.stroke();
 ctx.closePath();

<canvas id="canvas" width=400px height=200px></canvas>

不知道怎么办 提前致谢!

Answer 1

您需要清除 Canvas 并重新绘制红色矩形。

var c = document.getElementById("canvas");
 c.width=400;
 c.height=200;
 var ctx = c.getContext("2d");

 var cut = [50, 70, 100, 100]
 var cut1 = [60, 85, 60, 60]
 
 function drawRectangle(cut,fill){
 ctx.beginPath();
 ctx.rect(cut[0], cut[1], cut[2], cut[3]);
 ctx.lineWidth = 3;
 ctx.strokeStyle = fill;
 ctx.stroke();
 ctx.closePath();
 }

drawRectangle(cut,"green");
drawRectangle(cut1,"red");



clear.addEventListener("click",()=>{
ctx.clearRect(0,0, c.width, c.height);
drawRectangle(cut1,"red");
});

canvas{display:block;}

<button id="clear">clear</button>
<canvas id="canvas" width=400px height=200px></canvas>