スタイルと色の適用

// これらは全て fillStyle にオレンジ色を設定します

ctx.fillStyle = "orange";
ctx.fillStyle = "#FFA500";
ctx.fillStyle = "rgb(255 165 0)";
ctx.fillStyle = "rgb(255 165 0 / 100%)";

function draw() {
  const ctx = document.getElementById("canvas").getContext("2d");
  for (let i = 0; i < 6; i++) {
    for (let j = 0; j < 6; j++) {
      ctx.fillStyle = `rgb(${Math.floor(255 - 42.5 * i)} ${Math.floor(
        255 - 42.5 * j,
      )} 0)`;
      ctx.fillRect(j * 25, i * 25, 25, 25);
    }
  }
}

<canvas id="canvas" width="150" height="150"
  >6×6 の正方形のグリッドで、36 の色が表示されています。</canvas
>

draw();

function draw() {
  const ctx = document.getElementById("canvas").getContext("2d");
  for (let i = 0; i < 6; i++) {
    for (let j = 0; j < 6; j++) {
      ctx.strokeStyle = `rgb(0 ${Math.floor(255 - 42.5 * i)} ${Math.floor(
        255 - 42.5 * j,
      )})`;
      ctx.beginPath();
      ctx.arc(12.5 + j * 25, 12.5 + i * 25, 10, 0, 2 * Math.PI, true);
      ctx.stroke();
    }
  }
}

<canvas id="canvas" width="150" height="150" role="presentation"></canvas>

draw();

// 輪郭線と塗りつぶしの色に透明色を割り当てる

ctx.strokeStyle = "rgb(255 0 0 / 50%)";
ctx.fillStyle = "rgb(255 0 0 / 50%)";

function draw() {
  const ctx = document.getElementById("canvas").getContext("2d");
  // draw background
  ctx.fillStyle = "#FD0";
  ctx.fillRect(0, 0, 75, 75);
  ctx.fillStyle = "#6C0";
  ctx.fillRect(75, 0, 75, 75);
  ctx.fillStyle = "#09F";
  ctx.fillRect(0, 75, 75, 75);
  ctx.fillStyle = "#F30";
  ctx.fillRect(75, 75, 75, 75);
  ctx.fillStyle = "#FFF";

  // set transparency value
  ctx.globalAlpha = 0.2;

  // Draw semi transparent circles
  for (let i = 0; i < 7; i++) {
    ctx.beginPath();
    ctx.arc(75, 75, 10 + 10 * i, 0, Math.PI * 2, true);
    ctx.fill();
  }
}

<canvas id="canvas" width="150" height="150" role="presentation"></canvas>

draw();

function draw() {
  const ctx = document.getElementById("canvas").getContext("2d");

  // Draw background
  ctx.fillStyle = "rgb(255 221 0)";
  ctx.fillRect(0, 0, 150, 37.5);
  ctx.fillStyle = "rgb(102 204 0)";
  ctx.fillRect(0, 37.5, 150, 37.5);
  ctx.fillStyle = "rgb(0 153 255)";
  ctx.fillRect(0, 75, 150, 37.5);
  ctx.fillStyle = "rgb(255 51 0)";
  ctx.fillRect(0, 112.5, 150, 37.5);

  // 半透明の長方形を描画
  for (let i = 0; i < 10; i++) {
    ctx.fillStyle = `rgb(255 255 255 / ${(i + 1) / 10})`;
    for (let j = 0; j < 4; j++) {
      ctx.fillRect(5 + i * 14, 5 + j * 37.5, 14, 27.5);
    }
  }
}

<canvas id="canvas" width="150" height="150" role="presentation"></canvas>

draw();

function draw() {
  const ctx = document.getElementById("canvas").getContext("2d");
  for (let i = 0; i < 10; i++) {
    ctx.lineWidth = 1 + i;
    ctx.beginPath();
    ctx.moveTo(5 + i * 14, 5);
    ctx.lineTo(5 + i * 14, 140);
    ctx.stroke();
  }
}

<canvas id="canvas" width="150" height="150" role="presentation"></canvas>

draw();

function draw() {
  const ctx = document.getElementById("canvas").getContext("2d");

  // ガイドを描画
  ctx.strokeStyle = "#09f";
  ctx.beginPath();
  ctx.moveTo(10, 10);
  ctx.lineTo(140, 10);
  ctx.moveTo(10, 140);
  ctx.lineTo(140, 140);
  ctx.stroke();

  // 線を描画
  ctx.strokeStyle = "black";
  ["butt", "round", "square"].forEach((lineCap, i) => {
    ctx.lineWidth = 15;
    ctx.lineCap = lineCap;
    ctx.beginPath();
    ctx.moveTo(25 + i * 50, 10);
    ctx.lineTo(25 + i * 50, 140);
    ctx.stroke();
  });
}

<canvas id="canvas" width="150" height="150" role="presentation"></canvas>

draw();

function draw() {
  const ctx = document.getElementById("canvas").getContext("2d");
  ctx.lineWidth = 10;
  ["round", "bevel", "miter"].forEach((lineJoin, i) => {
    ctx.lineJoin = lineJoin;
    ctx.beginPath();
    ctx.moveTo(-5, 5 + i * 40);
    ctx.lineTo(35, 45 + i * 40);
    ctx.lineTo(75, 5 + i * 40);
    ctx.lineTo(115, 45 + i * 40);
    ctx.lineTo(155, 5 + i * 40);
    ctx.stroke();
  });
}

<canvas id="canvas" width="150" height="150" role="presentation"></canvas>

draw();

function draw() {
  const ctx = document.getElementById("canvas").getContext("2d");

  // キャンバスを消去
  ctx.clearRect(0, 0, 150, 150);

  // ガイドを描画
  ctx.strokeStyle = "#09f";
  ctx.lineWidth = 2;
  ctx.strokeRect(-5, 50, 160, 50);

  // 線のスタイルを設定
  ctx.strokeStyle = "#000";
  ctx.lineWidth = 10;

  // 入力をチェック
  if (document.getElementById("miterLimit").value.match(/\d+(\.\d+)?/)) {
    ctx.miterLimit = parseFloat(document.getElementById("miterLimit").value);
  } else {
    alert("Value must be a positive number");
  }

  // 線を描画
  ctx.beginPath();
  ctx.moveTo(0, 100);
  for (let i = 0; i < 24; i++) {
    const dy = i % 2 === 0 ? 25 : -25;
    ctx.lineTo(Math.pow(i, 1.5) * 2, 75 + dy);
  }
  ctx.stroke();
  return false;
}

<table>
  <tr>
    <td>
      <canvas id="canvas" width="150" height="150" role="presentation"></canvas>
    </td>
    <td>
      <code>miterLimit</code> を変更するには、下に新しい値を入力し、再描画ボタンをクリックしてください。<br /><br />
      <form onsubmit="return draw();">
        <label for="miterLimit">マイター制限</label>
        <input type="number" size="3" id="miterLimit" />
        <input type="submit" value="Redraw" />
      </form>
    </td>
  </tr>
</table>

document.getElementById("miterLimit").value = document
  .getElementById("canvas")
  .getContext("2d").miterLimit;
draw();

<canvas id="canvas" width="111" height="111" role="presentation"></canvas>

const ctx = document.getElementById("canvas").getContext("2d");
let offset = 0;

function draw() {
  ctx.clearRect(0, 0, canvas.width, canvas.height);
  ctx.setLineDash([4, 2]);
  ctx.lineDashOffset = -offset;
  ctx.strokeRect(10, 10, 100, 100);
}

function march() {
  offset++;
  if (offset > 5) {
    offset = 0;
  }
  draw();
  setTimeout(march, 20);
}

march();

const lineargradient = ctx.createLinearGradient(0, 0, 150, 150);
const radialgradient = ctx.createRadialGradient(75, 75, 0, 75, 75, 100);

const lineargradient = ctx.createLinearGradient(0, 0, 150, 150);
lineargradient.addColorStop(0, "white");
lineargradient.addColorStop(1, "black");

function draw() {
  const ctx = document.getElementById("canvas").getContext("2d");

  // グラデーションを生成
  const lingrad = ctx.createLinearGradient(0, 0, 0, 150);
  lingrad.addColorStop(0, "#00ABEB");
  lingrad.addColorStop(0.5, "#fff");
  lingrad.addColorStop(0.5, "#26C000");
  lingrad.addColorStop(1, "#fff");

  const lingrad2 = ctx.createLinearGradient(0, 50, 0, 95);
  lingrad2.addColorStop(0.5, "#000");
  lingrad2.addColorStop(1, "rgb(0 0 0 / 0%)");

  // グラデーションに塗りつぶしと輪郭のスタイルを割り当てる
  ctx.fillStyle = lingrad;
  ctx.strokeStyle = lingrad2;

  // 図形を描画
  ctx.fillRect(10, 10, 130, 130);
  ctx.strokeRect(50, 50, 50, 50);
}

<canvas id="canvas" width="150" height="150" role="presentation"></canvas>

draw();

function draw() {
  const ctx = document.getElementById("canvas").getContext("2d");

  // グラデーションを作成
  const radgrad = ctx.createRadialGradient(45, 45, 10, 52, 50, 30);
  radgrad.addColorStop(0, "#A7D30C");
  radgrad.addColorStop(0.9, "#019F62");
  radgrad.addColorStop(1, "rgb(1 159 98 / 0%)");

  const radgrad2 = ctx.createRadialGradient(105, 105, 20, 112, 120, 50);
  radgrad2.addColorStop(0, "#FF5F98");
  radgrad2.addColorStop(0.75, "#FF0188");
  radgrad2.addColorStop(1, "rgb(255 1 136 / 0%)");

  const radgrad3 = ctx.createRadialGradient(95, 15, 15, 102, 20, 40);
  radgrad3.addColorStop(0, "#00C9FF");
  radgrad3.addColorStop(0.8, "#00B5E2");
  radgrad3.addColorStop(1, "rgb(0 201 255 / 0%)");

  const radgrad4 = ctx.createRadialGradient(0, 150, 50, 0, 140, 90);
  radgrad4.addColorStop(0, "#F4F201");
  radgrad4.addColorStop(0.8, "#E4C700");
  radgrad4.addColorStop(1, "rgb(228 199 0 / 0%)");

  // 図形を描画
  ctx.fillStyle = radgrad4;
  ctx.fillRect(0, 0, 150, 150);
  ctx.fillStyle = radgrad3;
  ctx.fillRect(0, 0, 150, 150);
  ctx.fillStyle = radgrad2;
  ctx.fillRect(0, 0, 150, 150);
  ctx.fillStyle = radgrad;
  ctx.fillRect(0, 0, 150, 150);
}

<canvas id="canvas" width="150" height="150" role="presentation"></canvas>

draw();

function draw() {
  const ctx = document.getElementById("canvas").getContext("2d");

  // グラデーションの作成
  const conicGrad1 = ctx.createConicGradient(2, 62, 75);
  conicGrad1.addColorStop(0, "#A7D30C");
  conicGrad1.addColorStop(1, "#fff");

  const conicGrad2 = ctx.createConicGradient(0, 187, 75);
  // 値に Math.PI/180 を掛けて度数をラジアンに変換する
  conicGrad2.addColorStop(0, "black");
  conicGrad2.addColorStop(0.25, "black");
  conicGrad2.addColorStop(0.25, "white");
  conicGrad2.addColorStop(0.5, "white");
  conicGrad2.addColorStop(0.5, "black");
  conicGrad2.addColorStop(0.75, "black");
  conicGrad2.addColorStop(0.75, "white");
  conicGrad2.addColorStop(1, "white");

  // 図形を描画
  ctx.fillStyle = conicGrad1;
  ctx.fillRect(12, 25, 100, 100);
  ctx.fillStyle = conicGrad2;
  ctx.fillRect(137, 25, 100, 100);
}

<canvas id="canvas" width="250" height="150" role="presentation"
  >扇形グラデーション</canvas
>

draw();

const img = new Image();
img.src = "someimage.png";
const ptrn = ctx.createPattern(img, "repeat");

function draw() {
  const ctx = document.getElementById("canvas").getContext("2d");

  // 新しい画像オブジェクトを生成して、パターンとして使用する
  const img = new Image();
  img.src = "canvas_create_pattern.png";
  img.onload = () => {
    // パターンを作成
    const ptrn = ctx.createPattern(img, "repeat");
    ctx.fillStyle = ptrn;
    ctx.fillRect(0, 0, 150, 150);
  };
}

<canvas id="canvas" width="150" height="150" role="presentation"></canvas>

draw();

function draw() {
  const ctx = document.getElementById("canvas").getContext("2d");

  ctx.shadowOffsetX = 2;
  ctx.shadowOffsetY = 2;
  ctx.shadowBlur = 2;
  ctx.shadowColor = "rgb(0 0 0 / 50%)";

  ctx.font = "20px Times New Roman";
  ctx.fillStyle = "Black";
  ctx.fillText("Sample String", 5, 30);
}

<canvas id="canvas" width="150" height="80" role="presentation"></canvas>

draw();

function draw() {
  const ctx = document.getElementById("canvas").getContext("2d");
  ctx.beginPath();
  ctx.arc(50, 50, 30, 0, Math.PI * 2, true);
  ctx.arc(50, 50, 15, 0, Math.PI * 2, true);
  ctx.fill("evenodd");
}

<canvas id="canvas" width="100" height="100" role="presentation"></canvas>

draw();