I am trying to implement this post, which draws and animates a stick figure, into Vue.
draw(timestamp, wave) {
if(Date.now() < (timestamp+900)) return requestAnimationFrame(this.draw);
context.clearRect(0, 0, window.innerWidth, window.innerHeight);
context.beginPath();
context.fillStyle = "black"; // #000000
context.arc(200, 50, 30, 0, Math.PI * 2, true);
context.fill(); //fill the circle
context.beginPath();
context.lineWidth = 6;
context.stroke();
//body
context.beginPath();
context.moveTo(200, 80);
context.lineTo(200, 180);
context.strokeStyle = "black";
context.stroke();
//arms
context.beginPath();
context.strokeStyle = "black";
context.moveTo(200, 100);
context.lineTo(150, 130);
if(wave) {
context.moveTo(200, 100);
context.lineTo(250, 130);
wave = false;
}
else {
context.moveTo(200, 100);
context.lineTo(250, 70);
wave = true;
}
context.stroke();
//legs
context.beginPath();
context.strokeStyle = "black";
context.moveTo(200, 180);
context.lineTo(150, 280);
context.moveTo(200, 180);
context.lineTo(250, 280);
context.stroke();
timestamp = Date.now();
requestAnimationFrame(this.draw);
}
},
mounted: function () {
var canvas = document.getElementById("canvas");
context = canvas.getContext("2d"); // get Canvas Context object
let timestamp = Date.now();
let wave = false;
this.draw(timestamp, wave);
}
If I do the entire draw method inside of my mounted method, it works. But when I move draw to it's own method, as shown above, it fails.
I know it's failing because the line if(Date.now() < (timestamp+900)) is always returning false when running the code above. But I'm not sure why that's happening, or what the difference is.
How can I get this canvas to animate?
Here's an example of how this might look in a component.
Vue.component('canvas-demo', {
data: function () {
return {
timestamp: Date.now(),
wave: false
}
},
mounted: function(){
this.startDrawing(this.$el.getContext("2d"));
},
template: '<canvas></canvas>',
methods: {
startDrawing: function(context) {
var draw = () => {
if (Date.now() < (this.timestamp + 900)) return requestAnimationFrame(draw);
context.clearRect(0, 0, window.innerWidth, window.innerHeight);
context.beginPath();
context.fillStyle = "black"; // #000000
context.arc(200, 50, 30, 0, Math.PI * 2, true);
context.fill(); //fill the circle
context.beginPath();
context.lineWidth = 6;
context.stroke();
//body
context.beginPath();
context.moveTo(200, 80);
context.lineTo(200, 180);
context.strokeStyle = "black";
context.stroke();
//arms
context.beginPath();
context.strokeStyle = "black";
context.moveTo(200, 100);
context.lineTo(150, 130);
if (this.wave) {
context.moveTo(200, 100);
context.lineTo(250, 130);
this.wave = false;
}
else {
context.moveTo(200, 100);
context.lineTo(250, 70);
this.wave = true;
}
context.stroke();
//legs
context.beginPath();
context.strokeStyle = "black";
context.moveTo(200, 180);
context.lineTo(150, 280);
context.moveTo(200, 180);
context.lineTo(250, 280);
context.stroke();
this.timestamp = Date.now();
requestAnimationFrame(draw);
}
draw();
}
}
});
new Vue({
el: '#app'
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
<canvas-demo></canvas-demo>
</div>
Related
I'm looking for a solution to freehand draw a line with a gradient in canvas like this:
I already found this, but the gradient seems to be 'locked' on the background and is not following the line.
window.addEventListener('load', ()=>{
resize(); // Resizes the canvas once the window loads
document.addEventListener('mousedown', startPainting);
document.addEventListener('mouseup', stopPainting);
document.addEventListener('mousemove', sketch);
window.addEventListener('resize', resize);
});
const canvas = document.querySelector('#canvas');
const ctx = canvas.getContext('2d');
function resize(){
ctx.canvas.width = window.innerWidth;
ctx.canvas.height = window.innerHeight;
}
let coord = {x:0 , y:0};
let paint = false;
function getPosition(event){
coord.x = event.clientX - canvas.offsetLeft;
coord.y = event.clientY - canvas.offsetTop;
}
function startPainting(event){
paint = true;
getPosition(event);
}
function stopPainting(){
paint = false;
}
function sketch(event){
if (!paint) return;
ctx.beginPath();
ctx.lineWidth = 5;
ctx.lineCap = 'round';
var gradient = ctx.createLinearGradient(0, 0, 200, 0);
gradient.addColorStop(0.00, 'grey');
gradient.addColorStop(1 / 2, 'white');
gradient.addColorStop(1.00, 'grey');
ctx.strokeStyle = gradient;
ctx.moveTo(coord.x, coord.y);
getPosition(event);
ctx.lineTo(coord.x , coord.y);
ctx.stroke();
}
Can somebody help me please?
I found a way to do it:
var context = canvas.getContext("2d");
context.strokeStyle = '#000000';
context.fillStyle = '#000000';
context.beginPath();
context.moveTo(10, 10);
context.lineTo(50, 10);
context.lineWidth = 2;
context.stroke();
context.beginPath();
context.lineWidth = 15;
context.moveTo(10, 30);
context.lineTo(50, 30);
context.stroke();
context.beginPath();
context.moveTo(10, 50);
context.lineTo(50, 50);
context.lineWidth = 2;
context.stroke();
Where I reconstructed the gradient with multiple lines and a blur on those lines.
I'm programming on JavaScript and basically what I'm supposed to do is to draw a face on a canvas and those faces have certain effects.
One of the effects I'm supposed to do is to click on the nose and it will change the face to an angry face. I have created objects for all the face parts (nose, eyes, etc.) and what I'm trying to do is that I want the function "angryFace" to be called when the nose is clicked. The nose is already an object.
Been stuck for a long time on this. Would appreciate it if someone could help! Uploaded the whole code down here. Thanks guys!
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>COM1008 Assignment 2</title>
<link rel="stylesheet" href="main1.css">
</head>
<main>
<h1>COM 1008 Assignment 2</h1>
<p>By Samuel Fung Chi Lun</p>
</main>
<body>
<canvas id="canvasFrame" width="600" height="600"></canvas>
<p>
<button name="sadbutton" id="sadFace">Sad</button>
<button name="angrybutton" id="angryFace">Angry</button>
<button name="surprisedbutton" id="surprisedFace">Surprised</button>
<button name="neutralbutton" id="neutralFace">Neutral</button>
</p>
<script>
var canvas = document.getElementById('canvasFrame');
var context = canvas.getContext('2d');
//Function to obtain x and y coordinates of mouse positions - Obtained from 20/11/2017 lecture slides
function getMouseXY(e) {
var boundingRect = canvas.getBoundingClientRect();
var offsetX = boundingRect.left;
var offsetY = boundingRect.top;
var w = (boundingRect.width - canvas.width);
var h = (boundingRect.height - canvas.height);
offsetX += w;
offsetY += h;
var mx = Math.round(e.clientX - offsetX);
var my = Math.round(e.clientY - offsetY);
return { x: mx, y: my };
}
const BROWS_UP = 190;
const BROWS_DOWN = 170;
//Creating an object for left eye brow
var leftEyeB = {
draw: function (x1,brows_direction1,x2,brows_direction2) {
context.beginPath();
context.lineWidth = 18;
context.moveTo(x1, brows_direction1);
context.lineTo(x2, brows_direction2)
context.stroke();
}
};
//Creating an object for right eye brow
var rightEyeB = {
draw: function (x1,brows_direction1,x2,brows_direction2) {
context.beginPath();
context.lineWidth = 18;
context.moveTo(x1, brows_direction1);
context.lineTo(x2, brows_direction2)
context.stroke();
}
};
//Creating an object for the head
var faceShape = {
draw: function() {
context.beginPath();
context.fillStyle = "rgb(255,255,0)"
context.lineWidth = 3;
context.arc(300, 300, 200, 0, Math.PI * 2, true);
context.fill();
context.stroke();
}
}
//Creating an object for the eyes
var eyes = {
draw: function() {
context.beginPath();
context.fillStyle = "rgb(0,0,0)";
context.moveTo(255, 250); //LeftEye
context.arc(220, 250, 40, 0, Math.PI * 2, true);
context.moveTo(415, 250);//Right Eye
context.arc(380, 250, 40, 0, Math.PI * 2, true);
context.fill();
context.fill();
context.stroke();
context.beginPath();
context.fillStyle = "rgb(255,255,255)";
context.moveTo(240, 250); //LeftPupil
context.arc(220, 250, 15, 0, Math.PI * 2, true);
context.moveTo(400, 250); //Right Pupil
context.arc(380, 250, 15, 0, Math.PI * 2, true);
context.fill();
context.stroke();
}
}
//Creating an object for the nose
var nose = {
draw: function() {
context.beginPath();
context.fillStyle = "rgb(0,0,0)";
context.moveTo(300, 275);
context.lineTo(275, 325);
context.lineTo(325, 325);
context.fill();
context.closePath();
context.stroke();
}
}
//Creating an object for the mouth
var mouth = {
frown: function() {
context.beginPath();
context.fillStyle = "rgb(0,0,0)";
context.moveTo(305, 427);//Mouth
context.arc(305, 427, 80, 0, Math.PI, true);
context.fill();
context.closePath();
context.stroke();
},
circle: function() {
context.beginPath();
context.fillStyle = "rgb(0,0,0)";
context.arc(300, 400, 50, 0, Math.PI * 2, true);
context.fill();
context.stroke();
},
straight: function() {
context.beginPath();
context.fillStyle = "rgb(0,0,0)";
context.rect(225, 390, 150, 20);//Mouth
context.fill();
context.stroke();
}
}
//Drawing the sad face
function sadFace() {
faceShape.draw();
eyes.draw();
nose.draw();
mouth.frown();
leftEyeB.draw(175,BROWS_DOWN,265,BROWS_DOWN);
rightEyeB.draw(335,BROWS_DOWN,425,BROWS_DOWN);
}
//Drawing the angry face
function angryFace() {
faceShape.draw();
eyes.draw();
nose.draw();
mouth.frown();
leftEyeB.draw(175,BROWS_DOWN,265,BROWS_UP);
rightEyeB.draw(335,BROWS_UP,425,BROWS_DOWN);
}
//Drawing the surprised face
function surprisedFace() {
faceShape.draw();
eyes.draw();
nose.draw();
mouth.circle();
leftEyeB.draw(175,BROWS_UP,265,BROWS_DOWN);
rightEyeB.draw(335,BROWS_DOWN,425,BROWS_UP);
}
//Drawing the neutral face
function neutralFace() {
faceShape.draw();
eyes.draw();
nose.draw();
mouth.circle();
leftEyeB.draw(175,BROWS_DOWN,265,BROWS_DOWN);
rightEyeB.draw(335,BROWS_DOWN,425,BROWS_DOWN);
}
//Not sure how to properly do the bottom part. It does not work at all for the eyebrows one so please help!
function effects() {
//Click on the eyebrows to raise them
if (mousePosition.x > x1 && mousePosition.x < x2 && mousePosition.y < BROWS_UP && mousePosition.y > BROWS_DOWN) {
BROWS_UP += 20;
}
//Click on eye to show angry face
if (mousePosition = on coordinates of the eye) {
angryFace();
}
//Click on nose to show happy face
if (mousePosition = on coordinates of the nose) {
smileFace();
}
}
canvas.addEventListener('click', function(evt) {
effects(evt);
});
neutralFace();
//Linking the face functions to the buttons
var angryButton = document.getElementById("angryFace");
var sadButton = document.getElementById("sadFace");
var surprisedButton = document.getElementById("surprisedFace");
var neutralButton = document.getElementById("neutralFace");
sadButton.addEventListener("click", sadFace);
angryButton.addEventListener("click", angryFace);
surprisedButton.addEventListener("click", surprisedFace);
neutralButton.addEventListener("click", neutralFace);
</script>
</body>
</html>
When you make face, for you, there are different objects(say nose, eyes etc). For DOM, there is only 1 object i.e. Canvas. So when you click, you are clicking on canvas and not nose.
So to achieve this, you will have to play with coordinates. You have to assume the position of every container and on click of canvas, check the coordinates. If the coordinates are within range of some object, fire necessary function.
canvas.addEventListener('click', function(event){
var x = event.clientX, y = event.clientY;
if(x> 280 && x <335 && y > 280 && y <335) {
// nose is clicked.
angryFace();
}
else {
neutralFace();
}
})
Following is a partial sample:
var canvas = document.getElementById('canvasFrame');
var context = canvas.getContext('2d');
//Function to obtain x and y coordinates of mouse positions - Obtained from 20/11/2017 lecture slides
function getMouseXY(e) {
var boundingRect = canvas.getBoundingClientRect();
var offsetX = boundingRect.left;
var offsetY = boundingRect.top;
var w = (boundingRect.width - canvas.width);
var h = (boundingRect.height - canvas.height);
offsetX += w;
offsetY += h;
var mx = Math.round(e.clientX - offsetX);
var my = Math.round(e.clientY - offsetY);
return {
x: mx,
y: my
};
}
const BROWS_UP = 190;
const BROWS_DOWN = 170;
//Creating an object for left eye brow
var leftEyeB = {
draw: function(x1, brows_direction1, x2, brows_direction2) {
context.beginPath();
context.lineWidth = 18;
context.moveTo(x1, brows_direction1);
context.lineTo(x2, brows_direction2)
context.stroke();
}
};
//Creating an object for right eye brow
var rightEyeB = {
draw: function(x1, brows_direction1, x2, brows_direction2) {
context.beginPath();
context.lineWidth = 18;
context.moveTo(x1, brows_direction1);
context.lineTo(x2, brows_direction2)
context.stroke();
}
};
//Creating an object for the head
var faceShape = {
draw: function() {
context.beginPath();
context.fillStyle = "rgb(255,255,0)"
context.lineWidth = 3;
context.arc(300, 300, 200, 0, Math.PI * 2, true);
context.fill();
context.stroke();
}
}
//Creating an object for the eyes
var eyes = {
draw: function() {
context.beginPath();
context.fillStyle = "rgb(0,0,0)";
context.moveTo(255, 250); //LeftEye
context.arc(220, 250, 40, 0, Math.PI * 2, true);
context.moveTo(415, 250); //Right Eye
context.arc(380, 250, 40, 0, Math.PI * 2, true);
context.fill();
context.fill();
context.stroke();
context.beginPath();
context.fillStyle = "rgb(255,255,255)";
context.moveTo(240, 250); //LeftPupil
context.arc(220, 250, 15, 0, Math.PI * 2, true);
context.moveTo(400, 250); //Right Pupil
context.arc(380, 250, 15, 0, Math.PI * 2, true);
context.fill();
context.stroke();
}
}
//Creating an object for the nose
var nose = {
draw: function() {
context.beginPath();
context.fillStyle = "rgb(0,0,0)";
context.moveTo(300, 275);
context.lineTo(275, 325);
context.lineTo(325, 325);
context.fill();
context.closePath();
context.stroke();
}
}
//Creating an object for the mouth
var mouth = {
frown: function() {
context.beginPath();
context.fillStyle = "rgb(0,0,0)";
context.moveTo(305, 427); //Mouth
context.arc(305, 427, 80, 0, Math.PI, true);
context.fill();
context.closePath();
context.stroke();
},
circle: function() {
context.beginPath();
context.fillStyle = "rgb(0,0,0)";
context.arc(300, 400, 50, 0, Math.PI * 2, true);
context.fill();
context.stroke();
},
straight: function() {
context.beginPath();
context.fillStyle = "rgb(0,0,0)";
context.rect(225, 390, 150, 20); //Mouth
context.fill();
context.stroke();
}
}
//Drawing the sad face
function sadFace() {
faceShape.draw();
eyes.draw();
nose.draw();
mouth.frown();
leftEyeB.draw(175, BROWS_DOWN, 265, BROWS_DOWN);
rightEyeB.draw(335, BROWS_DOWN, 425, BROWS_DOWN);
}
//Drawing the angry face
function angryFace() {
faceShape.draw();
eyes.draw();
nose.draw();
mouth.frown();
leftEyeB.draw(175, BROWS_DOWN, 265, BROWS_UP);
rightEyeB.draw(335, BROWS_UP, 425, BROWS_DOWN);
}
//Drawing the surprised face
function surprisedFace() {
faceShape.draw();
eyes.draw();
nose.draw();
mouth.circle();
leftEyeB.draw(175, BROWS_UP, 265, BROWS_DOWN);
rightEyeB.draw(335, BROWS_DOWN, 425, BROWS_UP);
}
//Drawing the neutral face
function neutralFace() {
faceShape.draw();
eyes.draw();
nose.draw();
mouth.circle();
leftEyeB.draw(175, BROWS_DOWN, 265, BROWS_DOWN);
rightEyeB.draw(335, BROWS_DOWN, 425, BROWS_DOWN);
}
function effects() {
mousePosition = getMouseXY(e);
console.log(mousePosition);
}
neutralFace();
canvas.addEventListener('click', function(event){
var x = event.clientX, y = event.clientY;
if(x> 280 && x <335 && y > 280 && y <335) {
// nose is clicked.
angryFace();
}
else {
neutralFace();
}
})
//Linking the face functions to the buttons
var angryButton = document.getElementById("angryFace");
var sadButton = document.getElementById("sadFace");
var surprisedButton = document.getElementById("surprisedFace");
var neutralButton = document.getElementById("neutralFace");
sadButton.addEventListener("click", sadFace);
angryButton.addEventListener("click", angryFace);
surprisedButton.addEventListener("click", surprisedFace);
neutralButton.addEventListener("click", neutralFace);
<!-- This is not the original markup. This is a part of an edit to make the code executable. -->
<canvas id='canvasFrame' width=600 height=600></canvas>
<div>
<button id="angryFace">Angry Face</button>
<button id="sadFace">Sad Face</button>
<button id="surprisedFace">Surprised Face</button>
<button id="neutralFace">Neutral Face</button>
</div>
i've been working on trying to animate the stars but i'm not sure how. I've tried using on multiple different techniques but at the end its still not working. it doesn't matter if you move that stars to much i just want them to move. any help would be appreciated thanks.
var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
ctx.fillStyle = "rgb(0, 102, 204)";
ctx.strokeStyle = "rgb(0, 0, 0)";
ctx.linewidth = 3;
//making the background
ctx.fillRect(0, 0, 1000, 900);
//making the grass
ctx.fillStyle = "rgb(178, 255, 102)";
ctx.fillRect(0, 620, 1000, 280);
// draw the stars
ctx.fillStyle = "rgb(255, 255, 153)";
ctx.beginPath();
ctx.moveTo(80, 120);
ctx.lineTo(100, 100);
ctx.lineTo(80, 80);
ctx.lineTo(60, 100);
ctx.lineTo(80, 120);
ctx.fill();
ctx.beginPath(); //star 2
ctx.moveTo(120, 220);
ctx.lineTo(140, 200);
ctx.lineTo(120, 180);
ctx.lineTo(100, 200);
ctx.lineTo(120, 220);
ctx.fill();
ctx.beginPath();// star 3
ctx.moveTo(60, 160);
ctx.lineTo(180, 40);
ctx.lineTo(160, 20);
ctx.lineTo(140, 40);
ctx.lineTo(160, 60);
ctx.fill();
ctx.beginPath();//star 4
ctx.moveTo(240, 140);
ctx.lineTo(260, 120);
ctx.lineTo(240, 100);
ctx.lineTo(220, 120);
ctx.lineTo(240, 140);
ctx.fill();
ctx.beginPath();//star 5
ctx.moveTo(300, 260);
ctx.lineTo(320, 240);
ctx.lineTo(300, 220);
ctx.lineTo(280, 240);
ctx.lineTo(300, 260);
ctx.fill();
ctx.beginPath();//star 6
ctx.moveTo(380, 180);
ctx.lineTo(400, 160);
ctx.lineTo(380, 140);
ctx.lineTo(360, 160);
ctx.lineTo(380, 180);
ctx.fill();
ctx.beginPath();//star 7
ctx.moveTo(460, 80);
ctx.lineTo(480, 60);
ctx.lineTo(460, 40);
ctx.lineTo(440, 60);
ctx.lineTo(460, 80);
ctx.fill();
ctx.beginPath();//star 8
ctx.moveTo(520, 160);
ctx.lineTo(540, 140);
ctx.lineTo(520, 120);
ctx.lineTo(500, 140);
ctx.lineTo(520, 160);
ctx.fill();
ctx.beginPath();//star 9
ctx.moveTo(620, 60);
ctx.lineTo(640, 40);
ctx.lineTo(620, 20);
ctx.lineTo(600, 40);
ctx.lineTo(620, 60);
ctx.fill();
ctx.beginPath();//star 10
ctx.moveTo(660, 180);
ctx.lineTo(680, 160);
ctx.lineTo(660, 140);
ctx.lineTo(640, 160);
ctx.lineTo(660, 180);
ctx.fill();
ctx.beginPath();//star 11
ctx.moveTo(600, 240);
ctx.lineTo(620, 220);
ctx.lineTo(600, 200);
ctx.lineTo(580, 220);
ctx.lineTo(600, 240);
ctx.fill();
ctx.beginPath();//star 12
ctx.moveTo(740, 80);
ctx.lineTo(760, 60);
ctx.lineTo(740, 40);
ctx.lineTo(720, 60);
ctx.lineTo(740, 80);
ctx.fill();
ctx.beginPath();//star 13
ctx.moveTo(820, 160);
ctx.lineTo(840, 140);
ctx.lineTo(820, 120);
ctx.lineTo(800, 140);
ctx.lineTo(820, 160);
ctx.fill();
</script>
</body>
</html>
Take a look at window.requestAnimationFrame.
var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
var i = 0;
var speed = 500;
var drawStar = function (x, y) {
ctx.beginPath();
ctx.moveTo(80 + x, 120 + y);
ctx.lineTo(100 + x, 100 + y);
ctx.lineTo(80 + x, 80 + y);
ctx.lineTo(60 + x, 100 + y);
ctx.closePath();
ctx.fill();
};
var render = function () {
i += 1;
var offset = i % speed; // calculate how much the stars moved
ctx.fillStyle = "rgb(0, 102, 204)";
//making the background
ctx.fillRect(0, 0, 400, 300);
//making the grass
ctx.fillStyle = "rgb(178, 255, 102)";
ctx.fillRect(0, 200, 400, 100);
// draw the stars
ctx.fillStyle = "rgb(255, 255, 153)";
drawStar(offset, 0);
drawStar(offset + 100, 50);
drawStar(offset + 160, 20);
window.requestAnimationFrame(render); // call render again in about 33ms
};
render(); // call render for the first time
<canvas id="myCanvas" width="400" height="300"></canvas>
I just wanted to clip image in a curve .. but not happening this..
Only image is showing and but not with clip.
var canvas = document.getElementById('leaf');
var context = canvas.getContext('2d');
/*
* save() allows us to save the canvas context before
* defining the clipping region so that we can return
* to the default state later on
*/
context.save();
context.beginPath();
context.moveTo(188, 150);
context.quadraticCurveTo(288, 0, 388, 150);
context.lineWidth = 10;
context.quadraticCurveTo(288, 288, 188, 150);
context.lineWidth = 10;
context.clip();
context.beginPath();
var imageObj = new Image();
imageObj.onload = function() {
context.drawImage(imageObj, 10, 50);
};
imageObj.src = 'http://www.html5canvastutorials.com/demos/assets/darth-vader.jpg';
/* context.beginPath();
context.arc(x - offset, y - offset, radius, 0, 2 * Math.PI, false);
context.fillStyle = 'yello';
context.fill();
*/
/*
* restore() restores the canvas context to its original state
* before we defined the clipping region
*/
context.restore();
context.beginPath();
context.moveTo(188, 150);
context.quadraticCurveTo(288, 0, 388, 150);
context.lineWidth = 10;
context.quadraticCurveTo(288, 288, 188, 150);
context.lineWidth = 10;
context.strokeStyle = 'blue';
context.stroke();
<canvas id="leaf" width="500" height="500" style='left: 0;
position: absolute; top: 0;'></canvas>
You have to move everything from the line context.save(); to context.clip(); inside the function object of your imgObj's onload handler:
imageObj.onload = function()
{
context.save();
context.beginPath();
context.moveTo(188, 150);
context.quadraticCurveTo(288, 0, 388, 150);
context.lineWidth = 10;
context.quadraticCurveTo(288, 288, 188, 150);
context.lineWidth = 10;
context.clip();
context.drawImage(imageObj, 10, 50);
};
See http://jsfiddle.net/CSkP6/1/ for an example.
When, a few time after your script is launched, your image gets loaded, you have no more a clipped Canvas since you restore it afterwise.
You need to do a drawClipped function, and call it in your onload function for instance :
function drawClipped(context, myImage) = {
context.save();
context.beginPath();
context.moveTo(188, 150);
context.quadraticCurveTo(288, 0, 388, 150);
context.lineWidth = 10;
context.quadraticCurveTo(288, 288, 188, 150);
context.lineWidth = 10;
context.clip();
context.drawImage(myImage, 10, 50);
context.restore();
};
var imageObj = new Image();
imageObj.onload = function() {
drawClipped(context, imageObj);
};
imageObj.src = 'http://www.html5canvastutorials.com/demos/assets/darth-vader.jpg';
I want my rectangle to rotate in place. But currently it is rotating as though there is one object at center and my object is revolving around it i.e much like what we see in solar system. I want my object to rotate in place not revolve around something. How can I do that?
This is my code so far:
<script type="text/javascript">
var context;
var radian = 0.01;
var w, h;
$(document).ready(function () {
w = document.width;
h = document.height;
var canvas = $('#canvas');
context = canvas[0].getContext('2d');
canvas[0].width = w;
canvas[0].height = h;
setInterval(startAnim, 10);
});
function startAnim() {
context.save();
context.strokeStyle = 'rgb(0,0,0)';
context.fillStyle = 'rgb(0,0,0)';
context.fillRect(0, 0, w, h);
context.strokeStyle = 'rgb(0,0,0)';
context.fillStyle = 'rgb(255,255,0)';
context.strokeRect(0, 0, 200, 200);
context.fillRect(0, 0, 200, 200);
context.restore();
context.fillStyle = 'rgb(0,255,255)';
context.fillRect(500, 400, 200, 200);
radian += 0.01;
}
</script>
UPDATE: Sorry I was experimenting before I posted and I forgot to add rotate function while posting here. This is the actual code:
function startAnim() {
context.save();
context.strokeStyle = 'rgb(0,0,0)';
context.fillStyle = 'rgb(0,0,0)';
context.fillRect(0, 0, w, h);
context.translate(350, 300);
context.rotate(radian);
context.translate(-350, -300);
context.strokeStyle = 'rgb(0,0,0)';
context.fillStyle = 'rgb(255,255,0)';
context.strokeRect(0, 0, 200, 200);
context.fillRect(0, 0, 200, 200);
context.restore();
context.fillStyle = 'rgb(0,255,255)';
context.fillRect(500, 400, 200, 200);
radian += 0.01;
}
Use translate(x, y), rotate(r), and then draw your rectangle.
function startAnim() {
context.save();
context.strokeStyle = 'rgb(0,0,0)';
context.fillStyle = 'rgb(0,0,0)';
context.fillRect(0, 0, w, h);
//^Shouldn't clearRect() be better here?
//Draw translated, rotated rectangle at (250, 250)
var x = 250;
var y = 250;
context.save();
context.translate(x, y);
context.rotate(radian);
context.fillStyle = 'rgb(255,255,0)';
context.fillRect(0, 0, 200, 200);
context.restore();
//Restore context (to reverse translation and rotation)
context.strokeStyle = 'rgb(0,0,0)';
context.fillStyle = 'rgb(255,255,0)';
context.strokeRect(0, 0, 200, 200);
context.fillRect(0, 0, 200, 200);
context.restore();
context.fillStyle = 'rgb(0,255,255)';
context.fillRect(500, 400, 200, 200);
radian += 0.01;
}
jsFiddle demo and Simple jsFiddle demo with one rotating rectangle
You have to translate your context to the center of the rectangle before you rotate it:
context.translate(RECT_CENTER_X, RECT_CENTER_Y);
context.rotate(radian);
context.fillRect(-RECT_CENTER_X, -RECT_CENTER_Y, w, h);