Create Canvas element with image and append to parent - javascript

I need to create Canvas element with image and need to append to parent for this i have done this
<html>
<head>
<script>
window.onload = function() {
var canvas = document.createElement('canvas');
var context = canvas.getContext("2d");
canvas.id = "canvas_id";
canvas.setAttribute("class" ,"canvas");
canvas.height = "400";
canvas.width = "800";
var image = new Image();
image.src = "http://localhost/tile.png";
image.onload = function(){
context.drawImage(image, canvas.width, canvas.height);
}
document.body.appendChild(canvas);
}
</script>
</head>
<body>
</body>
</html>
it give blank canvas
can somebody guide me ?

You are using drawImage() the wrong way. Instead of drawing the image at (0,0) you are drawing it just outside the canvas area as width and height is where position normally goes.
The valid signatures are:
context.drawImage(image, dx, dy)
context.drawImage(image, dx, dy, dw, dh)
context.drawImage(image, sx, sy, sw, sh, dx, dy, dw, dh)
Where dx and dy are delta position (relative to origin, normally (0,0) when untranslated). Without width and height specified drawImage() will by default use the image's natural width and height.
The second version allows to override the default size, and the third will allow you to draw from one region to another.
Source
Corrected example:
window.onload = function() {
var canvas = document.createElement('canvas');
var context = canvas.getContext("2d");
canvas.id = "canvas_id";
canvas.className = "canvas"; // should be className
canvas.height = 400; // should be numbers
canvas.width = 800;
var image = new Image();
image.onload = function() {
// or set canvas size = image, here: (this = currently loaded image)
// canvas.width = this.width;
// canvas.height = this.height;
context.drawImage(this, 0, 0); // draw at (0,0), size = image size
// or, if you want to fill the canvas independent on image size:
// context.drawImage(this, 0, 0, canvas.width, canvas.height);
}
// set src last (recommend to use relative paths where possible)
image.src = "http://lorempixel.com/output/fashion-q-c-800-400-7.jpg";
document.body.appendChild(canvas);
}
That being said, if you only need the image appended there is no need to go via canvas. Just add the image to DOM directly (I assume this is not you want, but just in case..):
var image = new Image();
image.src = "tile.png";
document.body.appendChild(image);

This is my take on it... You need to indicate the coordinates where you want to start drawing (i.e. 0, 0) and - optionally - you can specify how big (wide, height) the canvas is to be.
In my case, I make the canvas to be as big as the image (instead of an arbitrary 400x800) you may need to update that your suit your requirements.
I added some css to show how big the canvas is in relation to the image. You can update/remove that as well depending on your needs.
UPDATED
It uses an hidden image as the source.
I hope this will work for you.
window.onload = function() {
var canvas = document.createElement('canvas');
var ctx = canvas.getContext("2d");
canvas.id = 'canvas_id';
canvas.setAttribute("class", "canvas");
var image = new Image();
image.src = 'http://placekitten.com/g/200/300';
canvas.width = image.width;
canvas.height = image.height;
ctx.drawImage(image, 0, 0, image.width, image.height);
document.body.appendChild(canvas);
}
.canvas {
border: solid red 1px;
}
<html>
<body>
</body>
</html>

Related

drawing a cropped version of an image onto a canvas

I have the following html file which draws an image on the canvas.
<canvas id="canvas"width="800"height="800"></canvas>
<script>
var canvas = document.getElementById('canvas')
let ctx = canvas.getContext('2d')
let img = new Image()
img.src = 'https://clipartspub.com/images/circle-clipart-blue-1.jpg'
img.onload = function(){
ctx.drawImage(img,300,300,300,300)
}
</script>
It works fine, however I would like to instead draw a cropped version of this image, for example, the bottom right quarter of the image. Is this possible?
You have to use the below implementation of drawImage to achieve that
void ctx.drawImage(image, sx, sy, sWidth, sHeight, dx, dy, dWidth, dHeight);
Check the docs here
var canvas = document.getElementById("canvas");
let ctx = canvas.getContext("2d");
let img = new Image();
img.src = "https://clipartspub.com/images/circle-clipart-blue-1.jpg";
img.onload = function () {
const width = img.width;
const height = img.height;
ctx.drawImage(
img, // Source image
width / 2, // Start at this x of image
height / 2, // Start at this y of image
width / 2, // Till this width of image
height / 2, // Till this height of image
0, // Start at this x of canvas
0, // Start at this y of image
300, // Till this width of canvas
300 // // Till this height of canvas
);
};
<canvas id="canvas"width="800"height="800"></canvas>
You can also use canvas.width and canvas.height in the canvas values used above for a better scaled result.

How to draw a photo then a shape on top of the photo using a canvas in Ionic?

There are numerous examples out there showing how to draw things onto a canvas, however, my problem is slightly different - I want to load a photo into memory, draw a shape onto exact coordinates over the photo, THEN draw/scale the photo onto a canvas. Not sure where to start with this. Are there any relevant libraries out there I can use with ionic that will allow you to do this?
Edit 1 ~ I now have this mostly working:
private properties:
#ViewChild('mainCanvas') canvasEl: ElementRef;
private _CANVAS: any;
private _CONTEXT: any;
ionViewDidEnter():
this._CANVAS = this.canvasEl.nativeElement;
this._CONTEXT = this._CANVAS.getContext('2d');
updateCanvas():
var img = new Image();
const ctx = this._CONTEXT;
const canvas = this._CANVAS;
ctx.clearRect(0, 0, this._CANVAS.width, this._CANVAS.height);
ctx.fillStyle = "#ff0000";
img.onload = (() => {
img.width = img.width;
img.height = img.height;
canvas.width = img.width;
canvas.height = img.height;
ctx.drawImage(img, 0, 0);
ctx.lineWidth = 8;
ctx.strokeStyle = "#FF0000";
ctx.strokeRect(100, 100, 400, 400);
ctx.scale(0.5, 0.5); // this does nothing
});
img.src = (<any>window).Ionic.WebView.convertFileSrc(path);
This draws the photo then the rectangle onto the canvas, however, the resulting image is too large to fit onto the screen, so I need to scale the canvas after all drawing is complete. I tried this with ctx.scale but the canvas remains the same size regardless of which values I specify.
You cannot draw straight onto a photo, but what you can do is create an offscreen canvas that is the same size as the photo, draw the photo to it, and then draw your shapes on top.
The result can then be drawn to your main canvas e.g.
// Empty image for example purposes
const img = new Image(100, 100);
// Creating a canvas for example purposes
const mainCanvas = document.createElement('canvas');
const mainCtx = mainCanvas.getContext('2d');
// Create an offscreen buffer
const bufferCanvas = document.createElement('canvas');
const bufferCtx = bufferCanvas.getContext('2d');
// Scale the buffer canvas to match our image
bufferCanvas.width = img.width;
bufferCanvas.height = img.height;
if (bufferCtx && mainCtx) {
// Draw image to canvas
bufferCtx.drawImage(img, 0, 0);
// Draw a rectangle in the center
bufferCtx.fillRect(img.width / 2 - 5, img.height / 2 - 5, 10, 10);
// Draw the buffer to the main canvas
mainCtx.drawImage(bufferCanvas, 0, 0);
}

HTML flexible canvas scale

I am making a website which will load some blueprint images on a canvas.
but the images are vary in height and width.i Would like to make the canvas scaling equal to the uploaded image scale. How do i code to make the canvas width and height changeble respective to uploaded image.
This done in html5
If I understand you correctly, you want to load images with various dimensions. According to the dimension, set the width / height of the canvas and draw the image?
In that case you could add an eventListener to the image. Once it's loaded, get the width and height. Use those to set the dimensions of the canvas. After that, draw the image on the canvas.
var image = new Image();
image.addEventListener('load', function(e) {
var width = image.width;
var height = image.height;
var canvas = document.querySelector('canvas');
canvas.width = width;
canvas.height = height;
canvas.getContext('2d').drawImage(image, 0, 0, width, height);
});
image.src = 'https://upload.wikimedia.org/wikipedia/commons/c/c4/PM5544_with_non-PAL_signals.png';
<canvas></canvas>
Fiddle
var canvas = document.getElementById('myCanvas');
var ctx = canvas.getContext('2d');
var imageObj = new Image();
imageObj.src = 'images/e1.jpg';
canvas.width = imageObj.naturalWidth;
canvas.height = imageObj.naturalHeight;
this also works

Canvas resize image object and repeat pattern

My canvas is 500px x 500px.
I have a png image that is 500px x 500px:
I want to re-size the image to be say... 100px x 100px, and then use that re-sized image as part of defining a repeat pattern and then using that as a fillStyle to repeat across the whole canvas. This is what I do...
//...define canvas, ctx, width and height above
var image = new Image();
image.onload = function() {
_self = this;
drawBG();
}
image.src = 'img.png';
function drawBG() {
var space = ctx.createPattern(_self, 'repeat');
ctx.fillStyle = space;
ctx.fillRect(0, 0, width, height);
}
Now, this is all well and good if I want to waste my own time. See, the space image is the same size as the canvas. My question is... How do you first resize the original image(in javascript) to then later create a pattern with it?
P.S. How do you re-size an image on stack overflow? This image I have showing here is to big for it's purpose.
You can draw your image on a second offscreen canvas, with drawImage(img, x, y, resizedWidth, resizedHeight) and then use this canvas as pattern.
var ctx = canvas.getContext('2d');
var image = new Image();
image.onload = function() {
// create an off-screen canvas
var patt = document.createElement('canvas');
// set the resized width and height
patt.width = 50;
patt.height = 50;
patt.getContext('2d').drawImage(this, 0,0, patt.width, patt.height);
// pass the resized canvas to your createPattern
drawBG(patt);
}
image.src = 'http://lorempixel.com/500/500';
function drawBG(patternCanvas) {
var space = ctx.createPattern(patternCanvas, 'repeat');
ctx.fillStyle = space;
ctx.fillRect(0, 0, 400, 200);
}
<canvas id="canvas" width="500" height="250"></canvas>

fill the image within the canvas

I have a base64 image string, I have created a canvas and put the base64 with the image and have given canvas height as 481 and width as 650, when I tried to display the image in html, image is coming but it is not completely filling the canvas,
Can anyone please tell me some solution to fill the image within the entire canvas, no matter what the quality of the picture.
My code is as given below
JSFiddle
var base64 = "data:image/jpeg;base64,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";
var canvas = document.createElement('canvas');
canvas.width = 650;
canvas.height = 481;
var ctx = canvas.getContext("2d");
var image = new Image();
image.onload = function () {
ctx.drawImage(image, 0, 0);
};
image.src = base64;
$('#showImage').html(canvas);
Change your onload function body to
ctx.drawImage(image, 0, 0, 650, 481);
Set the size of the canvas using natural width/height after the image has loaded:
var base64 = "data:image/jpeg;base64,/9j/4AAQSkZJ.....";
var canvas = document.createElement('canvas');
var ctx = canvas.getContext("2d");
var image = new Image();
image.onload = function () {
canvas.width = this.naturalWidth;
canvas.height = this.naturalHeight;
ctx.drawImage(this, 0, 0);
};
image.src = base64;
$('#showImage').html(canvas);

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