I'm studying canvas programming.
I'm try to make canvas draw through text array and input type text ..
How make this same photo ?
HTML Code:
<!DOCTYPE html>
<html>
<head>
<title>HTML5:Canvas</title>
</head>
<body>
<canvas id="myCanvas" width="800" height="600" style="border:2px solid#c3c3c3;">
Your browser does not support the canvas element.
</canvas>
<script type="text/javascript">
var c=document.getElementById("myCanvas");
var ctx=c.getContext("2d");
var Text_array = new Array("과자","모래","호두");
for( i=0; i<3; i++)
{
document.write(" " + Text_array[i]);
}
</script>
</body>
</html>
document.write writes text to the document. You need to write it to the canvas element. Canvas provides it's own methods for this: fillText and strokeText, so you'll need to use one of these.
You'll also need to call the javascript for when you want this to happen. In my code below I'm calling it from a click on a link, but it could equally be called from an onload event, a button click etc. I'm also providing x and y coordinates for where I want the text written on the canvas.
<!DOCTYPE html>
<html>
<head>
<title>HTML5:Canvas</title>
<script type="text/javascript">
function writeCanvas() {
var c=document.getElementById("myCanvas");
var ctx=c.getContext("2d");
ctx.font = "20px Arial";
var Text_array = new Array("과자","모래","호두");
for( i=0; i<3; i++)
{
ctx.fillText(Text_array[i], 10, (i+1) * 50);
}
}
</script>
</head>
<body>
<canvas id="myCanvas" width="800" height="600" style="border:2px solid#c3c3c3;">
Your browser does not support the canvas element.
</canvas><br>
Write
</body>
</html>
Related
this is my code, i use two canvas to drawimage to avoid flickering, but i cant get the full image when use this way, anyone can help please?
if i only use one canvas the image display fine, it seems the secondarycanvas that created by Javascript got some issue to display the image, but i can't find what's wrong. any help is appreciated!
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Decorate</title>
</head>
<body>
<div class="content-box">
<canvas id="canvas" width="360" height="740" style="border:1px solid #d3d3d3"></canvas>
</div>
<script>
var c=document.getElementById("canvas");
var ctx = c.getContext("2d");
var secondaryCanvas=document.createElement("canvas");
var secondaryCtx=secondaryCanvas.getContext("2d");
secondaryCanvas.weight=c.weight;
secondaryCanvas.height=c.height;
var bgimg=new Image();
bgimg.src=imageEncoder[24].background;
bgimg.onload=function() {
secondaryCtx.drawImage(bgimg, 0, 0);
ctx.drawImage(secondaryCanvas,0,0);
}
</script>
</body>
</html>
I change secondaryCanvas.weight=c.weight; to secondaryCanvas.width=c.width; and your code seems to work now.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Decorate</title>
</head>
<body>
<div class="content-box">
<canvas id="canvas" width="360" height="740" style="border:1px solid #d3d3d3"></canvas>
</div>
<script>
var c=document.getElementById("canvas");
var ctx = c.getContext("2d");
var secondaryCanvas=document.createElement("canvas");
var secondaryCtx=secondaryCanvas.getContext("2d");
secondaryCanvas.width=c.width;
secondaryCanvas.height=c.height;
var bgimg=new Image();
bgimg.src= "https://picsum.photos/360/740"
bgimg.onload=function() {
secondaryCtx.drawImage(bgimg, 0, 0);
ctx.drawImage(secondaryCanvas,0,0);
}
</script>
</body>
</html>
I am writing a code that takes in an image and pastes it into an HTML canvas. The code works when I declare my <img> in the HTML file, but this does not allow the user to input a new file.
Here is the html structure (the program works if the tag line is put back in:
<style type='text/css'>
canvas{
border: 10px solid black;
}
</style>
</head>
<body>
<canvas id='balls'>
</canvas>
<canvas id='hide' style:'border: 10px solid black;'>
<!-- <img id="taco" width="300" height="300" src="prime.png"> -->
</canvas>
<div>
<input id='url' placeholder="image url">
<button id='submit'>Submit</button>
</div>
<!--[if lt IE 7]>
<p class="browsehappy">You are using an <strong>outdated</strong> browser. Please upgrade your browser to improve your experience.</p>
<![endif]-->
<script src="client.js" async defer></script>
</body>
</html>
Here is the portion of JS code I am working on:
$(document).ready(onReady);
var canvas = document.querySelector('canvas');
canvas.width = 300;
canvas.height= 300;
let bounced = false;
let newPic = `id="taco" width="300" height="300" src="prime.png"`
function onReady(){
$('#submit').on('click', updateImage)
$('#hide').empty()
$('#hide').append(`<img ${newPic}>`)
makeCanvas();
setup();
animate();
}
function updateImage() {
newPic= `id="taco" width="300" height="300" src="${$('#url').val()}" alt="prime.png"`
//console.log(newPic)
$('#hide').empty()
$('#hide').append(`<img ${newPic}>`)
makeCanvas();
setup();
animate();
}
let c, can, ctx, img
function makeCanvas(){
c = canvas.getContext('2d');
can=document.getElementById("hide");
console.log(can)
can.width = 300;
can.height = 300;
ctx=can.getContext("2d");
img=document.getElementById("taco");
ctx.drawImage(img,10,10);
console.log(img)
console.log(ctx.drawImage(img,10,10))
}
My console.log statements for img are identical when the code in the HTML file is placed back in.
When you're setting up your canvas, your image isn't loaded at all. So your
ctx.drawImage(img,10,10);
call just draws... an unloaded image... an empty set of bytes... Nothing.
So you should first load your image. After that, drawing stuff will easily be done. Here's a little code example:
var canv, ctx, img;
function setup() {
//Setting up canvas
//Fetching Context
ctx = canv.getContext("2d");
//Now drawing our image
ctx.drawImage(img,10,10);
}
img = new Image();
img.onload = setup; //We'll setup the canvas after the image is fully loaded
img.src = "your/path/or/variable/pointing/to/your/image.ext";
Hope it helps!
I've read this and a few other questions, and it is clear I need to use destination-over to save the background and the sketch by display the new image over the old one.
I'm using Sketch.JS with my code as such:
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
$('#myCanvas').sketch({
defaultColor: "red"
});
$('#download').click(function() {
ctx.globalCompositeOperation = "destination-over";
img = new Image();
img.setAttribute('crossOrigin', 'anonymous');
img.src = 'http://lorempixel.com/400/200/';
ctx.drawImage(img, 0, 0);
$('#url').text(c.toDataURL('/image/png'));
window.open(c.toDataURL('/image/png'));
});
#myCanvas {
background: url(http://lorempixel.com/400/200/);
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://rawgit.com/intridea/sketch.js/gh-pages/lib/sketch.js"></script>
<canvas id="myCanvas"></canvas>
<input type='button' id='download' value='download'>
<span id='url'></span>
Fiddle
But that doesn't help. Clicking 'download' still only produces the sketch. Now, it seems I don't understand how I need to use destination-over properly. W3Schools doesn't seem to help.
Could anyone point me in the right direction please?
Assume you have a SketchJS canvas on top of an image containing a background:
#wrapper{positon:relative;}
#bk,#myCanvas{position:absolute;}
<div id='wrapper'>
<img crossOrigin='anonymous' id=bk src='yourImage.png'>
<canvas id="myCanvas" width=500 height=300></canvas>
</div>
Then when you want to combine the Sketch with the background and save it as an image you can use destination-over compositing to draw the background "under" the existing Sketch.
ctx.globalCompositeOperation='destination-over';
ctx.drawImage(bk, 0, 0);
Here's example code:
<!doctype html>
<html>
<head>
<script src="https://code.jquery.com/jquery-2.1.1.min.js"></script>
<script src="https://rawgit.com/intridea/sketch.js/gh-pages/lib/sketch.js"></script>
<style>
body{ background-color: ivory; }
#wrapper{positon:relative;}
#bk,#myCanvas{position:absolute;}
</style>
<script>
$(function(){
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
$('#myCanvas').sketch({ defaultColor: "red" });
$('#download').click(function() {
var img=document.getElementById('bk');
ctx.globalCompositeOperation='destination-over';
ctx.drawImage(bk, 0, 0);
ctx.globalCompositeOperation='source-over';
var html="<p>Right-click on image below and Save-Picture-As</p>";
html+="<img src='"+c.toDataURL()+"' alt='from canvas'/>";
var tab=window.open();
tab.document.write(html);
});
}); // end $(function(){});
</script>
</head>
<body>
<h4>Drag to sketch on the map.</h4>
<button id=download>Download</button>
<div id='wrapper'>
<img crossOrigin='anonymous' id=bk src='https://dl.dropboxusercontent.com/u/139992952/multple/googlemap1.png'>
<canvas id="myCanvas" width=459 height=459></canvas>
</div>
</body>
</html>
I've got code that looks like this (I've put the alerts in for testing purposes!):
<html>
<head>
</head>
<body>
<canvas width=750,height=860,id="maze">HTML5?</canvas>
<noscript>Javascript?</noscript>
<script>
alert("hello! (1)");
var canvas = document.getElementById("maze");
alert("hello! (2)");
var context = canvas.getContext("2d");
alert("hello! (3)");
</script>
</body>
The first and second alerts fire off. The third doesn't. Am I overlooking something obvious?
Change this:
<canvas width=750,height=860,id="maze">HTML5?</canvas>
to this:
<canvas width="750" height="860" id="maze">HTML5?</canvas>
Demonstration
Remove the commas from your HTML tag:
<canvas width=750 height=860 id="maze">HTML5?</canvas>
this is my first time here. I load a SVG with Javascript into an HTML document. I need to replace the color of this SVG (it's a black image with transparency), which is placed into a canvas; however, when I put the css (style), nothing happens.
This is my code:
<!DOCTYPE html>
<html>
<head>
<title>TEST CANVAS</title>
<script>
function draw_img(){
var img = document.getElementById("test");
test.width = 300;
test.height = 300;
var ctx = test.getContext('2d');
var source = new Image();
source.src = './field/image.svg';
source.onload = function(){
ctx.drawImage(source, 0, 0);
}
}
</script>
</head>
<style>
canvas#test {
fill:darkred;
}
</style>
<body onload = "draw_img();">
<h1>TEST</h1>
<canvas id="test"></canvas>
</body>
</html>
What's wrong with it? Sorry for my bad English and thanks in advance
Canvasses are bitmap images. You can't apply CSS styles to them and expect that to change their colour. Once the SVG is rendered into the Canvas, it's contents are fixed, and can't be changed (except by pixel manipulation).
If you want to manipulate the colours of your SVG, you should inline it.
<style>
svg#test {
fill:darkred;
}
</style>
<body>
<h1>TEST</h1>
<svg id="test">
<rect width="50" height="50"/>
</svg>
</body>
Demo here