命运之轮的麻烦

Question

我在这里使用 Roco K. Bullian 的命运之轮： how to draw a wheel of fortune?

这是我第一次接触js和canvas，我有两个问题。

首先：旋转后如何获取值？我尝试为此使用 setTimeout，但我只是不明白它何时停止。

第二个：我想在标签中放置长句子，但它们超出了范围。

我试过使用灵活的字体，但这并不奏效，也不是我所需要的。我需要每个块内的文本移动到新行并在超出范围时缩小字体。

所有这些都可以在此代码中实现吗，还是我需要从头开始编写所有内容？

代码

Js:

  const sectors = [
  {color:"#f82", label:"Stack"},
  {color:"#0bf", label:"10"},
  {color:"#fb0", label:"200"},
  {color:"#0fb", label:"50"},
  {color:"#b0f", label:"100"},
  {color:"#f0b", label:"5"},
  {color:"#bf0", label:"500"},
];

const rand = (m, M) => Math.random() * (M - m) + m;
const tot = sectors.length;
const EL_spin = document.querySelector("#spin");
const ctx = document.querySelector("#wheel").getContext('2d');
const dia = ctx.canvas.width;
const rad = dia / 2;
const PI = Math.PI;
const TAU = 2 * PI;
const arc = TAU / sectors.length;

const friction = 0.991; // 0.995=soft, 0.99=mid, 0.98=hard
let angVel = 0; // Angular velocity
let ang = 0; // Angle in radians

const getIndex = () => Math.floor(tot - ang / TAU * tot) % tot;

function drawSector(sector, i) {
  const ang = arc * i;
  ctx.save();
  // COLOR
  ctx.beginPath();
  ctx.fillStyle = sector.color;
  ctx.moveTo(rad, rad);
  ctx.arc(rad, rad, rad, ang, ang + arc);
  ctx.lineTo(rad, rad);
  ctx.fill();
  // TEXT
  ctx.translate(rad, rad);
  ctx.rotate(ang + arc / 2);
  ctx.textAlign = "right";
  ctx.fillStyle = "#fff";
  ctx.font = "bold 30px sans-serif";
  ctx.fillText(sector.label, rad - 10, 10);
  //
  ctx.restore();
};

function rotate() {
  const sector = sectors[getIndex()];
  ctx.canvas.style.transform = `rotate(${ang - PI / 2}rad)`;
  EL_spin.textContent = !angVel ? "SPIN" : sector.label;
  EL_spin.style.background = sector.color;
}

function frame() {
  if (!angVel) return;
  angVel *= friction; // Decrement velocity by friction
  if (angVel < 0.002) angVel = 0; // Bring to stop
  ang += angVel; // Update angle
  ang %= TAU; // Normalize angle
  rotate();
}

function engine() {
  frame();
  requestAnimationFrame(engine)
}

// INIT
sectors.forEach(drawSector);
rotate(); // Initial rotation
engine(); // Start engine
EL_spin.addEventListener("click", () => {
  if (!angVel) angVel = rand(0.25, 0.35);
});

Css:

    #wheelOfFortune {
  display: inline-block;
  position: relative;
  overflow: hidden;
}

#wheel {
  display: block;
}

#spin {
  font: 1.5em/0 sans-serif;
  user-select: none;
  cursor: pointer;
  display: flex;
  justify-content: center;
  align-items: center;
  position: absolute;
  top: 50%;
  left: 50%;
  width: 30%;
  height: 30%;
  margin: -15%;
  background: #fff;
  color: #fff;
  box-shadow: 0 0 0 8px currentColor, 0 0px 15px 5px rgba(0, 0, 0, 0.6);
  border-radius: 50%;
  transition: 0.8s;
}

#spin::after {
  content: "";
  position: absolute;
  top: -17px;
  border: 10px solid transparent;
  border-bottom-color: currentColor;
  border-top: none;
}

Answer 1

备注

我 只回答你的第一个问题 ，因为你的第二个问题 canvas 调整字体大小本身就是一个大话题，值得单独提问（虽然我确信它之前已经在 Whosebug 上得到了回答）。

旋转后如何获取数值

First: How can I get the value after spinning? I tried using setTimeout for this, but I just don't understand when it stops.

正如我在评论中建议的那样，您需要做的就是检查在最后一帧更新期间轮子是否停止旋转。

我在下面包含了完成此操作的代码片段，但请注意，我只更改了以下内容：

在 frame 函数的开头，我现在正在设置一个 isSpinning 变量。
在同一个 frame 函数的末尾，我使用这个 isSpinning 变量和当前速度来确定车轮是否刚刚停止。如果有，我将调用一个新的 finishedSpinning 函数。
在这个新的 finishedSpinning 函数中，我使用现有的 sectors 数组和 getIndex 来查找活动扇区。例如，我随后会发出带有标签的警报，但您可以将其替换为您需要的任何内容。

希望对您有所帮助！

const sectors = [
  {color:"#f82", label:"Stack"},
  {color:"#0bf", label:"10"},
  {color:"#fb0", label:"200"},
  {color:"#0fb", label:"50"},
  {color:"#b0f", label:"100"},
  {color:"#f0b", label:"5"},
  {color:"#bf0", label:"500"},
];

const rand = (m, M) => Math.random() * (M - m) + m;
const tot = sectors.length;
const EL_spin = document.querySelector("#spin");
const ctx = document.querySelector("#wheel").getContext('2d');
const dia = ctx.canvas.width;
const rad = dia / 2;
const PI = Math.PI;
const TAU = 2 * PI;
const arc = TAU / sectors.length;

const friction = 0.991; // 0.995=soft, 0.99=mid, 0.98=hard
let angVel = 0; // Angular velocity
let ang = 0; // Angle in radians

const getIndex = () => Math.floor(tot - ang / TAU * tot) % tot;

function drawSector(sector, i) {
  const ang = arc * i;
  ctx.save();
  // COLOR
  ctx.beginPath();
  ctx.fillStyle = sector.color;
  ctx.moveTo(rad, rad);
  ctx.arc(rad, rad, rad, ang, ang + arc);
  ctx.lineTo(rad, rad);
  ctx.fill();
  // TEXT
  ctx.translate(rad, rad);
  ctx.rotate(ang + arc / 2);
  ctx.textAlign = "right";
  ctx.fillStyle = "#fff";
  ctx.font = "bold 30px sans-serif";
  ctx.fillText(sector.label, rad - 10, 10);
  //
  ctx.restore();
};

function rotate() {
  const sector = sectors[getIndex()];
  ctx.canvas.style.transform = `rotate(${ang - PI / 2}rad)`;
  EL_spin.textContent = !angVel ? "SPIN" : sector.label;
  EL_spin.style.background = sector.color;
}

function finishedSpinning() { // Called when the wheel stops spinning
  const sector = sectors[getIndex()];
  alert(sector.label);
}

function frame() {
  if (!angVel) return;
  const isSpinning = angVel > 0; // Check if the wheel is currently spinning
  angVel *= friction; // Decrement velocity by friction
  if (angVel < 0.002) angVel = 0; // Bring to stop
  ang += angVel; // Update angle
  ang %= TAU; // Normalize angle
  rotate();
  
  if (isSpinning && angVel === 0) { // If the wheel was spinning, but isn't anymore, it has just stopped
    finishedSpinning();
  }
}

function engine() {
  frame();
  requestAnimationFrame(engine)
}

// INIT
sectors.forEach(drawSector);
rotate(); // Initial rotation
engine(); // Start engine
EL_spin.addEventListener("click", () => {
  if (!angVel) angVel = rand(0.25, 0.35);
});

    #wheelOfFortune {
  display: inline-block;
  position: relative;
  overflow: hidden;
}

#wheel {
  display: block;
}

#spin {
  font: 1.5em/0 sans-serif;
  user-select: none;
  cursor: pointer;
  display: flex;
  justify-content: center;
  align-items: center;
  position: absolute;
  top: 50%;
  left: 50%;
  width: 30%;
  height: 30%;
  margin: -15%;
  background: #fff;
  color: #fff;
  box-shadow: 0 0 0 8px currentColor, 0 0px 15px 5px rgba(0, 0, 0, 0.6);
  border-radius: 50%;
  transition: 0.8s;
}

#spin::after {
  content: "";
  position: absolute;
  top: -17px;
  border: 10px solid transparent;
  border-bottom-color: currentColor;
  border-top: none;
}

<div id="wheelOfFortune">
  <canvas id="wheel" width="300" height="300"></canvas>
  <div id="spin">SPIN</div>
</div>

命运之轮的麻烦

Troubles with wheel of fortune

javascript

html

canvas

备注

旋转后如何获取数值