HTML Canvas Quadratic curve with control points

Description

HTML Canvas Quadratic curve with control points

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<!DOCTYPE HTML>
<html>
<head>
<script>
  // SUMMARY: Draws a quadratic curve on a canvas.

  window.onload = function() {/*from   w w  w.  j a va2  s.c o m*/
    // CANVAS definition variables.            
    canvas = document.getElementById("canvasArea");
    context = canvas.getContext("2d");

    // LAYOUT parameters.
    let xStart = 50;
    let yStart = 25;
    let xControl1 = 175;
    let yControl1 = 50;
    let xEnd = 125;
    let yEnd = 175;

    // ATTRIBUTES of curve.
    context.strokeStyle = "orange";
    context.lineWidth = 7;
    context.shadowOffsetX = 3;
    context.shadowOffsetY = 3;
    context.shadowBlur = 5;
    context.shadowColor = "gray";

    // STARTING point.
    context.beginPath();
    context.moveTo(xStart, yStart);

    // QUADRATIC curve.
    context.quadraticCurveTo(xControl1, yControl1, xEnd, yEnd);

    // DRAW curve.
    context.stroke();

    // DISPLAY control points.
    displayPoint(xStart, yStart, "S");
    displayPoint(xControl1, yControl1, "1");
    displayPoint(xEnd, yEnd, "E");

    // DISPLAY POINT function.
    function displayPoint(xPos, yPos, text) {
      // ATTRIBUTES.
      context.font = "10pt Arial";
      context.fillStyle = "black";
      context.textAlign = "center";
      context.textBaseline = "middle";
      context.shadowColor = "white";

      // DISPLAY text.
      context.fillText(text, xPos, yPos);
    }
  }
</script>
</head>
<body>
  <div style="width: 200px; height: 200px; margin: 0 auto; padding: 5px;">
    <canvas id="canvasArea" width="200" height="200"
      style="border: 2px solid black">
Your browser doesn't currently support HTML5 Canvas.
</canvas>
  </div>
</body>
</html>



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