I use the wheel of fortune by Roko C. Buljan from here: how to draw a wheel of fortune?
This is my first experience with JavaScipt and canvas, and I have two questions.
First:
How can I get the value after spinning? I tried using setTimeout for this, but I just don't understand when it stops.
Second:
I want to put long sentences in labels, but they go out of bounds.
I've tried using a flexible font, but that doesn't really work and isn't exactly what I need. I need the text inside each block to move to a new line and reduce the font if it goes out of bounds.
Can all of this be implemented in this code, or would I need to write everything from scratch?
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);
});
#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;
inset: 35%;
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>
I'll only answer your first question, as your second question of resizing font on a canvas is a big topic on its own and deserves its own question (though I'm sure it has been answered on StackOverflow before).
First: How can I get the value after spinning? I tried using setTimeout for this, but I just don't understand when it stops.
As I suggested in the comment, all you need to do is check if during the last frame update the wheel stopped spinning.
I've included the snippet below that accomplishes this, but note that I only changed the following:
frame
function, I'm now setting an isSpinning
variable.frame
function, I'm using this isSpinning
variable and the current velocity to determine if the wheel has just stopped. If it has, I'm calling a new finishedSpinning
function.finishedSpinning
function, I'm using the existing sectors
array and getIndex
to find the active sector. As an example, I'm then throwing an alert with the label, but you could replace this by whatever you need.I hope this helps! 😉
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>