This is my code:
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.arc(55, 95, 30, 0, 2 * Math.PI);
var ctx1 = c.getContext("2d");
ctx1.rect(0, 0, 200, 300);
ctx.clip();
ctx.stroke();
var canvas = document.getElementById('myCanvas'),
context = canvas.getContext('2d');
make_base();
function make_base() {
base_image = new Image();
base_image.src = 'https://www.gravatar.com/avatar/4af2cdbaf02d97ba88d5d6daff94fbae/default=&s=80';
base_image.onload = function() {
context.drawImage(base_image, 15, 55);
}
}
canvas {
border: 1px solid #000000;
position: absolute;
top: 66px;
left: 22px;
}
<canvas id="myCanvas" width="236" height="413"></canvas>
From my code above I try to add image in to the circle and rectangle
I have done with add image in circle I try to add one more image in to the rectangle for the background but it seem not works.
You just need to create a second image and position it accordingly. Also use only one context, there is no need to declare it multiple times. Modified your code. I hope this will help you:
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.arc(55, 95, 30, 0, 2 * Math.PI);
ctx.rect(18, 150, 200, 250);
ctx.clip();
ctx.stroke();
make_base();
function make_base() {
base_image = new Image();
base_image.src = 'https://www.gravatar.com/avatar/4af2cdbaf02d97ba88d5d6daff94fbae/?default=&s=80';
base_image.onload = function() {
ctx.drawImage(base_image, 15, 55);
}
second_image = new Image();
second_image.src = 'https://www.gravatar.com/avatar/4af2cdbaf02d97ba88d5d6daff94fbae/?default=&s=80';
second_image.onload = function() {
ctx.drawImage(second_image, 19, 151);
}
}
<canvas id="myCanvas" width="236" height="413" style="border:1px solid #000000; position:absolute; top:66px; left:22px;"></canvas>
Related
I wrote the following code on my text editor:
!DOCTYPE html><html><head><script>
window.onload = function()
{
canvas = document.getElementById("canvasArea");
context = canvas.getContext("2d");
var smallIMage = new Image();
smallImage.src = "https://vignette.wikia.nocookie.net/cardfight/images/8/89/De.jpg/revision/latest?cb=20130414214050";
smallImage.onload = function()
{
context.shadowOffsetX = 4;
context.shadowOffsetY = 4;
context.shadowBlur = 20;
context.shadowColor = "lavender";
context.strokestyle = "gray";
context.lineWidth = 1;
var repeatPattern = context.createPattern(smallImage, "repeat");
var noRepeatPattern = context.createPattern(smallImage, "no-repeat");
var repeatXPattern = context.createPattern(smallImage, "repeat-x");
var repeatYPattern = context.createPattern(smallImage, "repeat-y");
context.fillStyle = repeatPattern;
context.fillRect (125, 125, 325, 325);
context.strokeRect (125, 125, 325, 325);
context.fillStyle = noRepeatPattern;
context.fillRect (0, 0, 100, 100);
context.strokeRect (0, 0, 100, 100);
context.fillStyle = repeatXPattern;
context.fillRect (125, 0, 350, 100);
context.strokeRect (125, 0, 350, 100);
context.fillStyle = repeatYPattern;
context.fillRect (0, 125, 100, 350);
context.strokeRect (0, 125, 100, 350);
}
}
</script></head><body>
<div style = "width:500px; height:500px;
margin:0 auto; padding:5px;">
<canvas id = "canvasArea"
width = "500" height = "500"
style = "border:2px solid black">
Your browser doesn't currently support HTML5 canvas.
</canvas>
</div>
</body>
</html>
This code s supposed to create a pattern from an online image, but it's not showing as the canvas is completely blank. Can you please tell me what I did wrong.
There wasn't much wrong with your code apart from correcting a few spelling inconsistencies and defining the new Image() event handler before assigning it's .src property. Also, remember to declare the charset of the document in the head section of the file. E.G...
<head>
<meta charset="utf-8">
... etc ...
</head>
Anyway, after a little editing the major components of your page look like this.
document.addEventListener('DOMContentLoaded', function() {
var canvas = document.getElementById("canvasArea"),
ctx = canvas.getContext("2d"),
smallImage = new Image();
/* set canvas dimensions */
canvas.width = canvas.height = 500;
smallImage.addEventListener("load", function() {
/* the image is bound to the
function's 'this' property */
var repeatPattern = ctx.createPattern(this, "repeat"),
noRepeatPattern = ctx.createPattern(this, "no-repeat"),
repeatXPattern = ctx.createPattern(this, "repeat-x"),
repeatYPattern = ctx.createPattern(this, "repeat-y");
ctx.shadowOffsetX = 4;
ctx.shadowOffsetY = 4;
ctx.shadowBlur = 20;
ctx.shadowColor = "rgb(230,230,250)";
ctx.strokestyle = "rgb(128,128,128)";
ctx.lineWidth = 1;
ctx.fillStyle = repeatPattern;
ctx.fillRect (125, 125, 325, 325);
ctx.strokeRect (125, 125, 325, 325);
ctx.fillStyle = noRepeatPattern;
ctx.fillRect (0, 0, 100, 100);
ctx.strokeRect (0, 0, 100, 100);
ctx.fillStyle = repeatXPattern;
ctx.fillRect (125, 0, 350, 100);
ctx.strokeRect (125, 0, 350, 100);
ctx.fillStyle = repeatYPattern;
ctx.fillRect (0, 125, 100, 350);
ctx.strokeRect (0, 125, 100, 350);
}, !1);
/* define Image.onload event handler
before assigning Image.src */
smallImage.src = "https://vignette.wikia.nocookie.net/cardfight/images/8/89/De.jpg/revision/latest?cb=20130414214050";
}, !1);
body {
background:rgb(90,90,110);
padding:33px 0 }
#box {
width:500px;
height:500px;
background:rgb(50,50,70);
margin:0 auto;
box-shadow:0 0 0.25em 0.5em rgba(0,0,0,0.25) }
#canvasArea {
width:100%;
height:100%;
border:2px solid rgb(22,22,22) }
<div id="box">
<canvas id="canvasArea">
Your browser doesn't currently support HTML5 canvas.
</canvas>
</div>
BP ;)
I am trying to separate canvas context from the actual draw functions but not working. As part of the context I wish to include the ability to resize the canvas which isn't working. The HTML works fine as this is evident with the getElementbyID working. The draw function which works fine is included for reference.
window.onload = function() {
'use strict';
var ctx = getCanvas();
draw(ctx);
}
function getCanvas() {
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var w = canvas.width = 200;
var h = canvas.height = 150;
return ctx;
}
function draw(ctx) {
ctx.fillStyle = 'rgb(200, 0, 0)';
ctx.fillRect(10, 10, 50, 50);
ctx.fillStyle = 'rgba(0, 0, 200, 0.5)';
ctx.fillRect(30, 30, 50, 50);
}
I see no issues with your code. It works as expected.
window.onload = function() {
'use strict';
var ctx = getCanvas();
draw(ctx);
};
function getCanvas() {
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var w = canvas.width = 200;
var h = canvas.height = 150;
return ctx;
}
function draw(ctx) {
ctx.fillStyle = 'rgb(200, 0, 0)';
ctx.fillRect(10, 10, 50, 50);
ctx.fillStyle = 'rgba(0, 0, 200, 0.5)';
ctx.fillRect(30, 30, 50, 50);
}
canvas{border: 1px solid black}
<canvas id="canvas" width="1000" height="1000"></canvas>
note: do not set canvas's width and height using css (in first place).
Hi I already created a round shaped form for the first image in the first canvas, but I didn't succeed to use the dataURL of the first canvas and add it in the second canvas.
Here is my fiddle : http://jsfiddle.net/acbo6m6o/2/
var ctx = document.getElementById('canvas').getContext("2d");
var ctx2 = document.getElementById('canvas2').getContext("2d");
ctx.arc(150,150, 130, 0, Math.PI*2,true); // you can use any shape
ctx.clip();
var img = new Image();
img.addEventListener('load', function(e) {
ctx.drawImage(this, 0, 0, 300, 300);
img2.src=canvas.toDataURL();
}, true);
img.src="https://scontent-mad1-1.xx.fbcdn.net/v/t1.0-9/10400072_76198580294_2746326_n.jpg?oh=b8cc93c35d6badfffb65ab5c9cbfce28&oe=5941AAB6";
img2.src=canvas.toDataURL();
Thank you.
No need to grab the dataURL of first canvas. You can draw the first canvas itself into the second canvas using the drawImage() method :
var ctx = document.getElementById('canvas').getContext("2d");
var ctx2 = document.getElementById('canvas2').getContext("2d");
var img = new Image();
img.src = "https://scontent-mad1-1.xx.fbcdn.net/v/t1.0-9/10400072_76198580294_2746326_n.jpg?oh=b8cc93c35d6badfffb65ab5c9cbfce28&oe=5941AAB6";
img.addEventListener('load', function(e) {
ctx.arc(150, 150, 130, 0, Math.PI * 2, true);
ctx.save();
ctx.clip();
ctx.drawImage(this, 0, 0, 300, 300);
ctx.restore();
ctx2.drawImage(ctx.canvas, 0, 0);
}, true);
#canvas2 {
background-color: lightgrey;
}
<canvas width="300" height="300" id="canvas"></canvas>
<canvas width="300" height="300" id="canvas2"></canvas>
In HTML5 canvas, I have a wheel, that I'm trying to spin, however the wheel is acting really crazy. It's being swung around the screen, out of it and into it again.
var canvas = document.getElementById("my-canvas");
var ctx = canvas.getContext("2d");
var img = new Image();
img.src = "http://www.roulette30.com/wp-content/uploads/americanroulette.png";
ctx.drawImage(img, 70, 70, 200, 200);
function spinWheel() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.translate(0, 0, canvas.width, canvas.height);
ctx.rotate(1 * Math.PI / 180);
ctx.drawImage(img, 70, 70, 200, 200);
}
setInterval(spinWheel, 0);
#my-canvas {
border: 1px solid black;
}
<!--<img id="my-image" height="200" width="200" src="http://www.roulette30.com/wp-content/uploads/americanroulette.png">
-->
<canvas id="my-canvas" width="400" height="400"></canvas>
I was certain that if I called the translate method, I could always have the wheel positioned in the center of the screen. Along with rotate, this was sure to work.
Any insights will be welcomed.
You need to translate outside of your spin code, to half width/height for dead center.
var canvas = document.getElementById("my-canvas");
var ctx = canvas.getContext("2d");
var img = new Image();
img.src = "http://www.roulette30.com/wp-content/uploads/americanroulette.png";
var speed = 1; // adding increases speed
var loop = true;
ctx.translate(canvas.width/2, canvas.height/2);
function spinWheel() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.rotate(speed * Math.PI / 180);
ctx.drawImage(img, -(img.width/2), -(img.height/2));
if (loop) requestAnimationFrame(spinWheel);
}
spinWheel();
#my-canvas {
border: 1px solid black;
}
<canvas id="my-canvas" width="400" height="400"></canvas>
Is it possible to show / hide part of canvas image like Image Sprite ?
Example Case:
I have a canvas of 200 X 200 dimension.
On One button click i want to show part of canvas from point (100, 100) to (120, 120).
On another i want to show entire canvas.
Any help in how to do this?
As sprite are usually shown within another element as a background, perhaps hiding the parent element would take care of your problem?
<style>
#sprite {
width: 100px;
height: 100px;
background-image: src(sprite.png);
background-position: 100px 100px;
}
</style>
<script>
var hide = false;
function show() {
if(!hide) {
document.getElementById("sprite").style.width="200px";
hide = true;
}
else {
document.getElementById("sprite").style.width="100px";
hide = false;
}
}
</script>
<div id="button" onclick="show();">button</div>
<div id="sprite"></div>
This is if the sprite's position is 100px to the right. You could also use document.getElementById('#sprite').style.backgroundPosition="200px 200px"; to change position of the sprite background entirely.
You can use the clipping form of drawImage to display your desired portion of the full image:
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var cw=canvas.width;
var ch=canvas.height;
var img=new Image();
img.onload=start;
img.src="https://dl.dropboxusercontent.com/u/139992952/stackoverflow/cats.png";
function start(){
ctx.drawImage(img, 0,0,78,86, 0,0,78,86);
document.getElementById('partial').onclick=function(){
ctx.clearRect(0,0,cw,ch);
ctx.drawImage(img, 0,0,78,86, 0,0,78,86);
}
document.getElementById('full').onclick=function(){
ctx.clearRect(0,0,cw,ch);
ctx.drawImage(img, 0,0);
}
}
body{ background-color: ivory; }
#canvas{border:1px solid red;}
<button id='partial'>Show partial canvas</button>
<button id='full'>Show full canvas</button>
<br><canvas id="canvas" width=300 height=300></canvas>
You can clip the image this way.
var canvas = document.getElementById('canvas');
var context = canvas.getContext('2d');
var btn = document.getElementById('btn');
var c = 0;
var img = new Image();
img.src = 'http://placehold.it/200/200';
img.onload = function() {
canvas.width = img.width;
canvas.height = img.height;
context.drawImage(img, 0, 0)
}
btn.onclick = function() {
if (c++ % 2 == 0) {
context.clearRect(0, 0, canvas.width, canvas.height);
context.drawImage(img, 100, 100, 20, 20, 100, 100, 20, 20);
btn.value = 'Unclip';
}
else {
context.drawImage(img, 0, 0);
btn.value = 'Clip';
}
}
<input id="btn" type="button" value="Clip" /><br />
<canvas id="canvas"></canvas>
EDIT
When a user clicks on the canvas, you can get the exact co-ordinates of where the event happened and if the co-ordinates lies inside of the middle circle, you can toggle the whole image by using the same clipping method.
var canvas = document.getElementById('canvas');
var context = canvas.getContext('2d');
var c = 0;
var img = new Image();
img.src = 'http://s25.postimg.org/cv29exevj/index.png';
img.onload = function() {
canvas.width = img.width;
canvas.height = img.height;
context.drawImage(img, 80, 80, 40, 40, 80, 80, 40, 40);
}
canvas.onclick = function(e) {
var x = e.clientX - canvas.getBoundingClientRect().left;
var y = e.clientY - canvas.getBoundingClientRect().top;
if (x >= 80 && x <= 120 && y >= 80 && y <= 120) {
if (c++ % 2 == 0) {
context.clearRect(0, 0, canvas.width, canvas.height);
context.drawImage(img, 0, 0);
} else {
context.clearRect(0, 0, canvas.width, canvas.height);
context.drawImage(img, 80, 80, 40, 40, 80, 80, 40, 40);
}
}
}
<canvas id="canvas"></canvas>