canvas 颜色绘制

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>canvas 颜色</title>
    <style>
      #canvas {
        background-color: #f9f9f9;
      }
    </style>
  </head>

  <body>
    <canvas id="canvas">浏览器不支持 canvas </canvas>
  </body>
  <script>
    var canvas = document.getElementById("canvas");
    var ctx = canvas.getContext("2d");
    canvas.height = 500;
    canvas.width = 500;

    // 填充 描边 - 纯色
    ctx.fillStyle = "red";
    ctx.strokeStyle = "green";
    ctx.lineWidth = 5;
    ctx.fillRect(20, 20, 100, 100);
    ctx.strokeRect(20, 20, 100, 100);

    // 填充 描边 - 渐变色
    // 圆形渐变：ctx.createRadialGradient(x0, y0, r0, x1, y1, r1) // 开始和结束圆的 横、纵、半径
    var radial = ctx.createRadialGradient(320, 70, 0, 320, 70, 60);
    radial.addColorStop(0, "red");
    radial.addColorStop(1, "green");
    ctx.fillStyle = radial;
    // 线性渐变：ctx.createRadialGradient(x0, y0, x1, y1) // 开始和结束点的 横、纵
    var linear = ctx.createLinearGradient(200, 70, 420, 70);
    linear.addColorStop(0, "red");
    linear.addColorStop(1, "green");
    ctx.strokeStyle = linear;
    ctx.lineWidth = 10;
    ctx.fillRect(220, 20, 200, 100);
    ctx.strokeRect(220, 20, 200, 100);
  </script>
</html>
canvas 颜色 绘制

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canvas 颜色绘制
