I'm trying to load the image on canvas but it's not working:(
I checked functions and variables much time but I couldn't find any errors.
Help me to find the reasons why it can't be loaded.
When I run it on the tomcat server, only the canvas with aliceblue color is shown.
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Print image and text</title>
<script>
function drawPicture(ctx) {
var img = new Image();
img.addEventListener('load', function() {
ctx.drawImage(img, 20, 20, 100, 100);
ctx.font = "50px forte";
ctx.strokeStyle="blue";
ctx.fillStyle = "violet";
ctx.strokeText("Spongebob", 20, 100);
ctx.fillText("Spongebob", 20, 100);
}, false);
img.src = "spongebob.png";
}
</script>
</head>
<body>
<h3>Print image and text</h3>
<hr>
<canvas id="myCanvas" width="300" height="130"
style="background-color:aliceblue"></canvas>
<script>
var canvas = document.getElementById("myCanvas");
var context = canvas.getContext("2d");
drawPicture(context);
</script>
</body>
</html>
Your code is fine, here is an example with a different image...
<!DOCTYPE html>
<html>
<body>
<canvas id="myCanvas" width="300" height="130"></canvas>
<script>
function drawPicture(ctx) {
var img = new Image();
img.addEventListener('load', function() {
ctx.drawImage(img, 20, 20, 100, 100);
ctx.font = "50px forte";
ctx.strokeStyle = "blue";
ctx.fillStyle = "violet";
ctx.strokeText("Spongebob", 20, 100);
ctx.fillText("Spongebob", 20, 100);
}, false);
img.src = "http://i.stack.imgur.com/UFBxY.png";
}
var canvas = document.getElementById("myCanvas");
var context = canvas.getContext("2d");
drawPicture(context);
</script>
</body>
</html>
Only thing could be that the image you are trying to load does not exist...
As #Kaiido mentioned in the comments you need to debug this, check in your browser developer tools see if the image is loading correctly.
You should see something like:
instead of image.addEventListener, try doing image.onload?
You can instead of using the load event in the image, try adding the image directly on the canvas.
function drawPicture(ctx) {
var img = new Image();
img.src = "spongebob.png";
ctx.drawImage(img, 20, 20, 100, 100);
ctx.font = "50px forte";
ctx.strokeStyle="blue";
ctx.fillStyle = "violet";
ctx.strokeText("Spongebob", 20, 100);
ctx.fillText("Spongebob", 20, 100);
}
var canvas = document.getElementById("myCanvas");
var context = canvas.getContext("2d");
drawPicture(context);
<h3>Print image and text</h3>
<hr>
<canvas id="myCanvas" width="300" height="130"
style="background-color:aliceblue"></canvas>
Related
I tried canvas but can't find if there is any way to get all data, there is only single pixel information.
<!DOCTYPE html>
<html>
<body>
<canvas id="myCanvas" width="300" height="150" style="border:1px solid #3f3939;">
Your browser does not support the HTML5 canvas tag.</canvas>
<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.fillStyle = "red";
ctx.fillRect(10, 10, 100, 100);
function copy() {
var imgData = ctx.getImageData(10, 10, 50, 50);
ctx.putImageData(imgData, 20, 20);
}
</script>
<button onclick="copy()">Copy</button>
</body>
</html>
I'm working on image Decryption/Encryption methods, but first I want to get all image data at once, please anyone help.
Extending on my comment...
I'm not sure what you mean by "get all image data at once" the getImageData can return as much or little as you need, and it certainly is at once, we don't need to make multiple calls, we just change the parameters.
read more:
https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/getImageData
If you need the entire canvas you can do:
ctx.getImageData(0, 0, c.width, c.height)
var output = document.getElementById("output");
var ctx_output = output.getContext("2d");
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.fillStyle = "red";
ctx.fillRect(10, 10, 80, 80);
ctx.fillRect(99, 20, 20, 20);
function copy() {
var imgData = ctx.getImageData(0, 0, c.width, c.height);
ctx_output.putImageData(imgData, 0, 0);
}
<canvas id="myCanvas" width="200" height="100" style="border:1px solid #3f3939;">
Your browser does not support the HTML5 canvas tag.</canvas>
<br>
<button onclick="copy()">Copy</button>
<br>
<canvas id="output" width="200" height="100" style="border:1px solid #0000ff;">
Your browser does not support the HTML5 canvas tag.</canvas>
I am trying to load an image of me on my html canvas.....
The image is in the right folder...... I just get a weird error (as shown above) im not sure what is going on if you know please let me know.
Here is the code:
<!DOCTYPE html>
<html>
<body>
<canvas id="myCanvas" width="800" height="500"></canvas>
<script>
var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
ctx.fillStyle = "black";
ctx.fillRect(0,0,800,500)
var img = new Image();
img.src = "science.PNG";
img.onload = function() {
context.drawImage(img, 145, 145);
};
</script>
</body>
</html>
context.drawImage(img, 145, 145);
Try changing 'context' to 'ctx'.
I am trying to draw an image on a canvas, in HTML5. For some reason, the image simply isn't drawn onto the canvas, and there are no errors in the console. Here is my code:
<!DOCTYPE html>
<html>
<body>
<img id="image" src="Images/player.png"></img>
<canvas id="canvas" width="1000" height="750"></canvas>
<script>
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
var image = document.getElementById("image");
context.fillStyle = "lightblue";
context.fillRect(0, 0, 1000, 750);
context.drawImage(image, 0, 0);
</script>
</body>
</html>
Can somebody help? Thanks.
You need to add an event listener to the img tag called load. Then in the callback you can call drawImage with the provided img element.
You can do something like this - I have added one stackoverflow image for representation:
const canvas = document.getElementById("canvas");
const context = canvas.getContext("2d");
const image = document.getElementById("image");
context.fillStyle = "lightblue";
context.fillRect(0, 0, 1000, 750);
image.addEventListener('load', e => context.drawImage(image, 0, 0));
<img id="image" src="https://stackoverflow.blog/wp-content/themes/stackoverflow-oct-19/images2/header-podcast.svg" height="100px"></img>
<canvas id="canvas" width="1000" height="750"></canvas>
From the documentation: Drawing an image to the canvas
I hope this helps!
hi i am trying to draw image with a button in canvas. But i can not draw in the clear canvas. so;
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Başlıksız Belge</title>
</head>
<body>
<input type="button" id="b1" value="ciz">
<canvas id="canvas" height="300" width="600" style="border: solid;background-color: brown; " >Eski Sürüm Tarayıcı . </canvas>
<script>
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var b1 =document.getElementById("b1");
var image = new Image(60, 45); // using optional size for image
var kontrol;
image.src = '/pika.png'; //it is in my pc
image.onload = function(){ // i don't want draw the image on load
kontrol=true;}
b1.onclick=function(){ // i want draw with button
if(kontrol=true){
ctx.drawImage(image, 0, 0);
}
}
</script>
</body>
</html>
when i try with image on load function it is working but i want draw with the button
No problem i get it. thanks...
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var b1 =document.getElementById("b1");
var image = new Image(60, 45);
b1.onclick=function(){
image.src = 'https://i.hizliresim.com/nWdGrR.png';
image.onload = function(){
ctx.drawImage(image, 0, 0);
}
}
If pika.png is located in same directory as your html file then just remove the forward slash before your image's name: image.src = 'pika.png';
I want to draw multiple canvases on a single canvas using drawImage() method but it is not working
Code
<html>
<head>
<script>
window.onload = function() {
var context1= document.getElementById("canvas1").getContext("2d");
var context2 = document.getElementById("canvas2").getContext("2d");
var context3 = document.getElementById("canvas3").getContext("2d");
context1.font = "20pt Calibri";
context1.fillStyle = "blue";
context1.fillText("Hello ", 50, 25);
context2.font = "20pt Calibri";
context2.fillStyle = "red";
context2.fillText("World!", 100, 25);
var imageObj = new Image();
imageObj.onload = function() {
context3.drawImage(context1.canvas, 50, 25);
context3.drawImage(context2.canvas, 100, 25);
};
};
</script>
</head>
<body>
<canvas id="canvas1" class="canvas" width="200" height="50"></canvas>
<canvas id="canvas2" class="canvas" width="200" height="50"></canvas>
<canvas id="canvas3" class="canvas" width="200" height="50"></canvas>
</body>
</html>
JS Fiddle
http://jsfiddle.net/4xT2j/2/
Your images have no source. Add one if you want to see something.
The onload function cannot be called as long as you don't have a src.
And you must provide the image to the drawImage function :
var imageObj = new Image();
imageObj.onload = function() {
context3.drawImage(imageObj, 50, 25);
context3.drawImage(imageObj, 100, 25);
};
imageObj.src = "someFile.png";
If what you're trying to do is draw canvas1 and canva2 on context3, simply do all this outside the imageObj.onload function which is never called : http://jsfiddle.net/KCyvE/
A precision following a question in comment :
My code in the fiddle uses context1.canvas. This works because The context is an instance of CanvasRenderingContext2D and thus has a property named canvas which is a "Back-reference to the canvas element for which this context was created".
Your imageObj.onload function is somewhat wrong. This is what you want: http://jsfiddle.net/4xT2j/3/
Please observe there isn't necessarily a reason to write canvas3 to an image object since it already is an image object.