I've read a bunch of topics here about this but I can't figure out what my problem is.
I have this :
function init() {
canvas = document.getElementById("Canvas");
canvas.width = document.body.clientWidth;
canvas.height = window.innerHeight-30;
var stage = new createjs.Stage(canvas);
createjs.Ticker.addEventListener("tick", tick);
createjs.Ticker.framerate = 65;
var image = new Image();
image.src = "Pics/tipeee-logo-pointcom-RVB.png";
image.onload = function(){
var bitmap = new createjs.Bitmap(image);
stage.addChild(bitmap)
;};
}
function tick(event){
init();
stage.update();
}
There's more code within the functions, but nothing to do with the image, and no image is dispayed.
Can you help me ?
Thanks !
Related
I want to get an image scaled correctly after loading it with a dummy click on a <input type='file'> and compressing it via drawing it onto a canvas. When calling a console.log() inside the img.onload I discovered it was being run in a loop. Putting the img.src = canvas.toDataURL("image/png") outside of the onload results in a blank image but no loop. Moving things around by trial and error has not been effective as I don't get the dynamics at play here (even though I can get images redrawn when rescaling a canvas). Thanks!
$('button.picture').on('click',function(){
var outerWrapper = $(this).closest('.outerWrapper')
$(this).siblings('.imageLoad').on('change', function(e){
var loadedImage = e.target.files[0]
var img = new Image();
img.src = window.URL.createObjectURL(loadedImage);
var canvas = document.createElement("canvas");
canvas.width = outerWrapper.width()
canvas.height = outerWrapper.height()
img.onload = function(e){
//still here the img.width returns the canvas width and not the original image's width
console.log(img.width)
var context = canvas.getContext("2d");
context.drawImage(img,0,0, canvas.width, canvas.height )
img.src = canvas.toDataURL("image/png")
}
$(this).closest('.outerWrapper').children('.imageWrapper').append(img)
})
$(this).siblings('.imageLoad').trigger('click')
})
To answer my own question I want to make clear what my aims were:
Load in image through a dummy click on an <input type="file">
Keeps the aspect ratio of the original image
Compress it
What worked was not setting img.src = canvas.toDataURL("image/png") as you would when resizing a canvas but by loading the original again image with URL.createObjectURL(loadedImage). To preserve the aspect ration I had to create two separate images, one to get the img.naturalWidth and img.naturalHeight for calculation and the next to load the image onto the canvas. Works a charm. Would be interested to learn where it can be refined.
$('button.picture').on('click',function(){
var outerWrapper = $(this).closest('.outerWrapper')
$(this).siblings('.imageLoad').on('change', function(e){
var loadedImage = e.target.files[0]
var img = new Image();
img.src = window.URL.createObjectURL(loadedImage);
var canvasPic = $('<canvas class="canvasPic"></canvas>')
canvasPic.prependTo(outerWrapper)
var canvas = canvasPic[0]
canvas.width = outerWrapper.width()
canvas.height = outerWrapper.height()
var context = canvas.getContext("2d");
var image = new Image();
image.onload = function(){
var w = img.naturalWidth
var h = img.naturalHeight
var ratio = h/w
var newWidth = canvas.height/ratio
context.drawImage(img,0,0,newWidth,canvas.height)
}
image.src = URL.createObjectURL(loadedImage);
})
$(this).siblings('.imageLoad').trigger('click')
})
I try to build a javascript code, to draw a image on canvas, but I don't know where go wrong.
That is my code:
<body>
<canvas id = "my_canvas"></canvas>
<script>
function setup(){
var canvas = document.getElementById('my_canvas');
var ctx = canvas.getContext('2d');
canvas.width = 800;
canvas.height = 600;
var image = new Image();
image.src = 'a.png';
ctx.drawImage(image,5,5);
};
window.onload = setup;
setup();
</script>
The question is, if I put a line of code setup(); at end then the image is correctly draw, I don't know why.
Thanks.
The problem is that image is loaded asynchronously, so if you set the source and draw it immediately then the image bits are not yet available and nothing is drawn.
You have to wait for the image to load before being able to draw it on a canvas.
Changing the code to
image.onload = function() {
ctx.drawImage(image, 5, 5);
};
image.src = "a.png";
should work as expected.
The image is loading asynchronously. This code will work:
JavaScript:
function setup(){
var canvas = document.getElementById('myCanvas');
var ctx = canvas.getContext('2d');
canvas.width = 800;
canvas.height = 600;
var image = new Image();
image.onload = function () {
ctx.drawImage(image,5,5);
};
image.src = 'a.png';
}
window.onload = setup;
I have a big canvas (5000x5000) and I want to take a picture of it and create a thumbnail on client side. I can capture the image using canvas.toDataURL but how do i re-size it? Do i have to create an new $("<canvas></canvas>") element and then put that image inside and run the canvas2.toDataURL(); Can anyone help me with this? I can't get my head around it how to do it.
var canvas = document.getElementById("main");
var ctx = canvas.getContext("2d");
var tumbnail64 = null;
var image = new Image();
image.src = canvas.toDataURL();
image.onload = function() {
$c2 = $("<canvas></canvas>");
$c2[0].width=100;
$c2[0].height=100;
$c2[0].getContext("2d");
$c2[0].drawImage(image, 0, 0,100,100);
tumbnail64 = $c2[0].toDataURL();
};
Something like this should work, given you don't have security restrictions on the original canvas element:
var resizedCanvas = document.createElement("canvas");
var resizedContext = resizedCanvas.getContext("2d");
resizedCanvas.height = "100";
resizedCanvas.width = "200";
var canvas = document.getElementById("original-canvas");
resizedContext.drawImage(canvas, 0, 0, 200, 100);
var myResizedData = resizedCanvas.toDataURL();
I try to build a javascript code, to draw a image on canvas, but I don't know where go wrong.
That is my code:
<body>
<canvas id = "my_canvas"></canvas>
<script>
function setup(){
var canvas = document.getElementById('my_canvas');
var ctx = canvas.getContext('2d');
canvas.width = 800;
canvas.height = 600;
var image = new Image();
image.src = 'a.png';
ctx.drawImage(image,5,5);
};
window.onload = setup;
setup();
</script>
The question is, if I put a line of code setup(); at end then the image is correctly draw, I don't know why.
Thanks.
The problem is that image is loaded asynchronously, so if you set the source and draw it immediately then the image bits are not yet available and nothing is drawn.
You have to wait for the image to load before being able to draw it on a canvas.
Changing the code to
image.onload = function() {
ctx.drawImage(image, 5, 5);
};
image.src = "a.png";
should work as expected.
The image is loading asynchronously. This code will work:
JavaScript:
function setup(){
var canvas = document.getElementById('myCanvas');
var ctx = canvas.getContext('2d');
canvas.width = 800;
canvas.height = 600;
var image = new Image();
image.onload = function () {
ctx.drawImage(image,5,5);
};
image.src = 'a.png';
}
window.onload = setup;
I'm attempting to pull an image (in this case, /camera/frame, which is a known-good JPG), and load it as the background of my document.body.
Here's my code thus far:
var backgroundImage = new Image();
backgroundImage.onload = function ()
{
console.log("onload");
document.body.style.backgroundImage = this.src;
};
backgroundImage.src = 'camera/frame';
"onload" prints as expected, and this.src prints out the full URL to /camera/frame, however document.body.style.backgroundImage remains "".
I believe you may be missing two things.
var path = 'path/to/image.jpg';
document.body.style.background='url('+path+')';
Canvas 2D to the rescue!
var backgroundImage = new Image();
backgroundImage.onload = function ()
{
var canvas = document.getElementById('canvas');
canvas.width = this.width;
canvas.height = this.height;
var canvasContext = canvas.getContext('2d');
canvasContext.drawImage(this, 0, 0, this.width, this.height);
};
backgroundImage.src = 'camera/frame';
backgroundImage.width = $(window).width();
backgroundImage.height = $(window).height();
Loads the image in the background, then draws it into the canvas seamlessly!