HTML5 Canvas 기초 (6)

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<!DOCTYPE html>
<html>
  <head>
    <title>Canvas</title>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <style>
      canvas {
        background: #eee;
      }
    </style>
  </head>

  <body>
    <h1>Interaction</h1>
    <canvas class="canvas" width="600" height="400"></canvas>

    <script src="utils.js"></script>
    <script src="Box.js"></script>
    <script src="Panel.js"></script>
    <script>
      const canvas = document.querySelector(".canvas");
      const context = canvas.getContext("2d");
      const boxes = [];
      const mousePos = { x: 0, y: 0 };
      let panel;
      let selectedBox; // 클릭된 box
      let oX;
      let oY;
      let step; // 애플리케이션의 상태(단계)를 저장 1 ~ 4
      let rafId;

      context.font = "bold 30px sans-serif";

      function render() {
        context.clearRect(0, 0, canvas.width, canvas.height);

        let box;
        for (let i = 0; i < boxes.length; i++) {
          box = boxes[i];
          // box.x += box.speed;
          // if (box.x > canvas.width) {
          //   box.x = -box.width;
          // }
          box.draw();
        }

        switch (step) {
          case 1:
            for (let i = 0; i < boxes.length; i++) {
              box = boxes[i];
              box.x += box.speed;
              if (box.x > canvas.width) {
                box.x = -box.width;
              }
            }
            break;

          case 2:
            // panel.scale += 0.05;
            // 현재크기 = 현재크기 + (목표크기 - 현재크기)*0.1
            // 감속
            panel.scale = panel.scale + (1 - panel.scale) * 0.1;
            // 가속
            // panel.scale = panel.scale + panel.scale*0.02;
            // 각도 = 스케일(0~1) * 720;
            panel.angle = panel.scale * 720;
            panel.draw();
            if (panel.scale >= 0.999) {
              panel.scale = 1;
              panel.angle = 720;
              step = 3;
            }
            break;

          case 3:
            panel.draw();
            break;
        }

        // console.log('render!');

        rafId = requestAnimationFrame(render);
        if (step === 3) {
          panel.showContent();
          cancelAnimationFrame(rafId);
        }
      }

      let tempX, tempY, tempSpeed;

      function init() {
        step = 1;
        oX = canvas.width / 2;
        oY = canvas.height / 2;
        for (let i = 0; i < 10; i++) {
          tempX = Math.random() * canvas.width * 0.8;
          tempY = Math.random() * canvas.height * 0.8;
          tempSpeed = Math.random() * 4 + 1;
          boxes.push(new Box(i, tempX, tempY, tempSpeed));
        }

        panel = new Panel();

        render();
      }

      canvas.addEventListener("click", (e) => {
        mousePos.x = e.layerX;
        mousePos.y = e.layerY;

        let box;
        for (let i = 0; i < boxes.length; i++) {
          box = boxes[i];
          if (
            mousePos.x > box.x &&
            mousePos.x < box.x + box.width &&
            mousePos.y > box.y &&
            mousePos.y < box.y + box.height
          ) {
            selectedBox = box;
          }
        }

        if (step === 1 && selectedBox) {
          // console.log(selectedBox.index);
          step = 2;
        } else if (step === 3) {
          step = 1;
          panel.scale = 0.01;
          selectedBox = null;
          render();
        }
      });

      init();
    </script>
  </body>
</html>
  • Box.js
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class Box {
  constructor(index, x, y, speed) {
    this.index = index;
    this.x = x;
    this.y = y;
    this.speed = speed;
    this.width = 100;
    this.height = 100;
    this.draw();
  }

  draw() {
    context.fillStyle = "rgba(0,0,0,0.5)";
    context.fillRect(this.x, this.y, 100, 100);
    context.fillStyle = "#fff";
    context.fillText(this.index, this.x + 30, this.y + 30);
  }
}
  • Panel.js
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class Panel {
  constructor() {
    this.scale = 0.01;
    this.angle = 0;
  }

  draw() {
    context.fillStyle = "rgba(255,0,0,0.8)";
    // 변환 초기화;
    context.resetTransform();
    // context.setTransform(1,0,0,1,0,0);
    context.translate(oX, oY);
    context.scale(this.scale, this.scale);
    context.rotate(canUtil.toRadian(this.angle));
    context.translate(-oX, -oY);
    context.fillRect(oX - 150, oY - 150, 300, 300);
    context.resetTransform();
  }

  showContent() {
    console.log("showContent 실행");
    context.fillStyle = "#fff";
    context.fillText(selectedBox.index, oX, oY);
  }
}
  • utils.js
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const canUtil = {
  toRadian: function (degree) {
    return (degree * Math.PI) / 180;
  },
};