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JavaScript - Setting User-pasted Image Url As Canvas Background
Okay, so I have a canvas, and I want the user to be able to copy an image url and paste it into an input box, that will then set it as the canvas background image.
Does anyone know how I can do this? I was thinking about using the OnChange method in the text input, but I cannot find any help with that online. My current Canvas Background is (In <head><script>) Code: var imgObg = new Image(); imageObj.src = "images/bg.png"; And my text input is Code: <form name="input" action="" method="get"> <input type="text" id="textboxBG" onchange="??" /> <input type="submit" value="Submit" /> </form> If you need more code, or would like to help me out more in depth, I would gladly paypal you a little money. I know this can't be too difficult! I REALLY want this done! Similar TutorialsI found a great little starfield script made with javascript and canvas3d. however i can't for the life of me figure out how to implement a background image inside the canvas. is there some command that tells it to use some feature of canvas, that if otherwise not called, won't allow normal graphics? his whole starfield is generated with a search engine form , and appears to just use a text period to represent stars. here's a link to his script: http://seb.ly/demos/canvas3d/canvas3d2.html how do i get a background image in that? or is it impossible? i tried putting it in the body tag, but it just flashed the background image on the screen for a half a second and then went back to showing only the black background. i tried removing the background body color and replacing it with only background-image ccs, same problem. i tried div positioning it, but the div just covered up the starfield. I already asked that question on Stack Overflow, however so far I haven't gotten any answers there, so I thought maybe somebody here could help me. Below is the question, copied from Stack Overflow. I've got this problem that I've been trying to solve for a week and I'm at wit's end (which, well, most likely means my wit's not so great, since it doesn't seem to be a very hard problem; nonetheless I'm very new to Javascript and am trying to look at this as a learning experience). I wanted to have a fixed position element that would rotate as a user scrolls the page. Doing so in CSS is trivially easy, however it doesn't work all that great, especially across browsers (works fine in Chrome, but is janky in Firefox) and under stress (when I turn on FPS meter or some other stuff in Chrome Developer Tools it stops working correctly ― I assume it would also behave similarly if there was another CPU-extensive app open etc.). So I figured that animating in the canvas would be a more stable technique. Doing the basic animation in the canvas is, again, rather easy. However I started having problems while trying to emulate the CSS transition effect. In short, I'm trying to emulate a code like this: Code: <!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
<style>
body {
height: 3000px;
}
#square {
margin: 50px;
width: 150px;
height: 150px;
position: fixed;
background-color: black;
transition: transform linear 0.3s;
}
</style>
<script>
window.onload = function() {
var deg = 0;
var pos = window.pageYOffset;
var square = document.getElementById('square');
window.onscroll = function() {
var npos = window.pageYOffset;
deg += (npos - pos) / 10;
pos = npos;
square.style.transform = 'rotate(' + deg + 'deg)';
}
}
</script>
</head>
<body>
<div id='square'></div>
</body>
</html>
And what I've got currently is below. This is, like, fifteenth try, and if you run it, you'll see that it kind of works but is very ugly and totally not how it should look. I have had better results before, but still not what I was looking for. Code: <!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
<style>
body {
height: 3000px;
}
canvas {
position: fixed;
}
</style>
</head>
<body>
<canvas id='canvas' width='250' height='250'></canvas>
<script>
window.onload = function() {
// some canvas geometry stuff
var canvas = document.getElementById('canvas');
var c = canvas.getContext('2d');
c.translate(125,125);
var deg = Math.PI / 180;
// initializing variables
var request = null;
var deg = 0;
var ndeg = 0;
var base_degree;
var pos = window.pageYOffset;
var time = 0;
var duration = 300; // in milliseconds
draw();
document.addEventListener('scroll', rotateStart, false);
function rotateStart() {
// at the beggining of the scroll, set the time variable and start the loop.
// if scroll continues, only set the time (thus resetting the animation),
// but don't call loop, since it's already set as a callback to requestAnimationFrame.
if (request == null) {
time = (new Date()).getTime();
loop();
}
else {
time = (new Date()).getTime();
}
}
function loop() {
// time passed as a fraction of total duration of animation. Describes our progress
var fraction = ((new Date()).getTime() - time) / duration;
if (fraction == 0) {
// if current time and old time are the same, skip this frame
request = window.requestAnimationFrame(loop);
}
else if (fraction < 1) {
base_degree = (window.pageYOffset - pos) / 10;
ndeg = deg + base_degree * fraction;
// we operate on ndeg, and preserve deg as a reference point
request = window.requestAnimationFrame(loop);
draw();
}
else {
// clean up code.
// we draw one last time at a definitive degree of rotation because
// in my experience with similar scripts it sometimes doesn't go all the way there,
// e.g. maybe it stops at fraction == 0.95 or something like that.
ndeg = deg + base_degree;
draw();
deg = ndeg;
pos = window.pageYOffset;
request = null;
}
}
function draw() {
c.save();
c.clearRect(-125,-125,250,250);
c.rotate(ndeg * deg);
c.fillRect(-75,-75,150,150);
c.restore();
}
};
</script>
</body>
</html>
Could somebody point out errors in what I'm doing, post a solution, give a hint as to what method would be preferred here, whatever? I am trying to make the date that is entered by the user within the pickDate text box be +2 days ahead of the current date. Code: function reserveDate(){
var mydate = new Date();
var theyear = mydate.getFullYear();
var themonth = mydate.getMonth()+1;
var thetoday = mydate.getDate()+2;
if (document.forms[0].pickDate.value <= thetoday)
window.alert("Reservations need to be two days in advance.");
}
input type="text" name="pickDate" onblur="return reserveDate(this.value);">
So I'm creating a game and decided to use a canvas for the map. The map is a big pictures 500kb+ (6400x6400px) and the canvas size is 320x320 so I am displaying only part of the image at a time and have the page reload on button click for database purposes. What I'd like help with is performance. Currently it's taking a few secs to reload every time and it seems that it causes some cpu strain (can't switch tabs while loading). Could I stop the canvas from reloading the image each time the page is reloaded and if so then how? Can I make the canvas only load a part of the image, if so then how? If neither is possible any tips, solutions how to solve the performance issues? i want to transfrom image like the picture below using canvas,it seems simple but i find no way to do , can anyone give me some ideas? ( left side is the source) I am very new to javascript(and these forums) and I am teaching my self to use the canvas element. I am trying to draw an image to the canvas but nothing is appearing. And I am getting no error in the chrome console. Can anyone see why? Code:
function RPGanimation(options)
{
this.initcanvas(options);
this.initbackground(options);
};
RPGanimation.prototype = {
initbackground: function(options){
this.background = new Image();
this.background.src = options.backsource;
this.background.onload = this.drawbackground();
},
initcanvas:function(options){
this.canvas = document.getElementById(options.canvasid);
this.context = this.canvas.getContext('2d');
this.dimensions = {width:this.canvas.width,height:this.canvas.height};
},
drawbackground:function(){
//document.write('<IMG SRC="Chrysanthemum.jpg">');
this.context.drawImage(this.background,0,0,this.dimensions.width,this.dimensions.height);
}
};
I create the object in a webpage with the canvas element created just before that script tag... Hello all; I am trying to load four images into a canvas using an array. The images load fine and all, however they are resizing weird. I haven't specified what I want them to resize to, as the actual image are already the sizes I want. However when loaded into the canvas they are sizing differently then their actual sizes. Even when I specify their actual size in the code, they still resize weirdly. Here is my code: Code: <body>
<canvas id="worldscreen" class="map"></canvas><br />
<script type="text/javascript">
function loadImages(arrow, call) {
var images = {};
var loaded = 0;
var num = 0;
for (var src in arrow) {
num++;
}
for (var src in arrow) {
images[src] = new Image();
images[src].onload = function(){
if (++loaded >= num) {
call(images);
}
};
images[src].src = arrow[src];
}
}
window.onload = function(images) {
var canvas = document.getElementById("worldscreen").getContext("2d");
var arrow = {
top: "sideQUEST/images/arrow-top.png",
right: "sideQUEST/images/arrow-right.png",
bottom: "sideQUEST/images/arrow-bottom.png",
left: "sideQUEST/images/arrow-left.png",
};
loadImages(arrow, function(images) {
canvas.drawImage(images.top, 100, 18);
canvas.drawImage(images.right, 215, 36);
canvas.drawImage(images.bottom, 100, 115);
canvas.drawImage(images.left, 36, 36);
});
};
</script>
</body>
You can see the code in action he http://myrmidon16.x10.mx/test.php. This is very frustrating and if you have any suggestions it would be greatly appreciated. Thank you. Hi everyone, I am trying to make an image mask using javascript. The basic idea is that the image on the canvas will appear as a black box. When the user hovers over the image a small part of it is revealed. I have attached a picture as an example because its quite hard to explain! Any help would be appreciated! Thanks, Luke This works; Code: document.body.style.backgroundColor="#FF00aa"; these do not work Code: document.bgColor="#FF00aa"; document.body.bgColor="#FF00aa"; But all three work in a normal window. I'm clueless? Ok guys, I am finally not being lazy anymore and going through my images and writing better code. But unfortunately it is proving to be slightly more difficult then what I thought. Basically, I cannot find a way to set a element ID using javascript. Right now I am preloading my images through JavaScript and setting them like this Code: goodAfternoon = new Image(400,200) goodAfternoon.src = "Good Afternoon.gif" But I cannot find out how to setElementId() to the picture I am setting in JavaScript, I can do it in HTML by Code: <img src="Good Afternoon.gif" id = "pic_afternoon" name="goodAfternoon"> but this code displays the image which I do not want to do with all of my pictures right away. So how can I preload images and set the Ids of them without displaying them? This is really annyoing. I'm trying to set up an image's source from a function within the document's head, but to no avail. The code is something like this: ------------------------------------------------------- <head> .....js code..... function updatePieChart() { document.pie_chart.src = "piechart.php?p1&p2"; // php-generated image, with parameters } // A FUNCTION WHICH SUCCESSFULLY RUNS EVERY 2-3 SECONDS function ajax() { ....stuff..... // THE NEXT LINE DOESN'T WORK!!! // updatePieChart(); ...stuff..... } ....js code...... // THE NEXT LINE DOESN'T WORK!!! // updatePieChart(); </head> //THIS LINE WORKS LIKE A CHARM <body onload="updatePieChart();"> ....bla bla bla... <img src="#" name="pie_chart" /> ...bla bla bla.... </body> ------------------------------------------------------- As you can see, the function updatePieChart works wonderfully from the <body> tag of the function, but any attempt to call it from within the <head> tags fails. Also, I've tried to change the function updatePieChart so that it wouldn't call any php code and changed it to a simple document.pie_chart.src = "#"; but that still causes errors on the page when called from inside the <head> tags. On the other hand, if the function updatePieChart merely made an alert() call, then the ajax element works fine, and every so and so seconds I get an alert. Anyone, help? An explanation how come I can't set the image from within the <head> tags? Hi, I'm faced with a problem trying to set background color under IE7. I have the following Javascript: Code: function showLayer793BKColor(id)
{
var txtObj = document.all(id);
if (txtObj.style.display == 'none')
{
txtObj.style.display = ''
txtObj.style.backgroundColor = 'grey';
}
}
function hideLayer793BKColor(id)
{
var txtObj = document.all(id);
if ( txtObj.style.backgroundColor == 'grey' )
txtObj.style.display = 'none';
}
These functions are used to show or hide div blocks. These blocks are, for example, specified in the following way: Code: <div id="l_gct5tekst" style="display:none"> <b>GCT 5. Eerste verkenning problematiek</b> and, for example, Code: <div id="l_Keuze" style="display:none"> <br/> <b>GCT 5</b> <br/> </div> The whole configuration works smoothly when using IE8. However, when using IE7 I get an error msg like "Invalid value for property". When I use the Color propert iso the BackgroundColor property I get no error anymore but of course I don't have a background color anymore then. In what way can I specify the use of a background color under IE7 ? Or is just not possible in one way or the other. Furthermore, what more differences between JS under IE7 and IE8 do I have to take into account ? Do I also have to rewrite my div block in some way (using some attribs ?) to cope with IE7 ? Thanks in advance, Diederick van Elst Hello, I've just finished my website. But my random background images load properly sometimes, and sometimes they load as a half. Here is my website: http://www.finnhaverkamp.com/ Here is the relevant HTML: Code: <!--open random background script-->
<script type="text/javascript">
var randnum = Math.random();
var inum = 7;
var rand1 = Math.round(randnum * (inum-1)) + 1;
var images = new Array;
images[1] = "background1.jpg";
images[2] = "background2.jpg";
images[3] = "background3.jpg";
images[4] = "background4.jpg";
images[5] = "background5.jpg";
images[6] = "background6.jpg";
images[7] = "background7.jpg";
var image = images[rand1];
function chBackgr()
{
document.body.style.backgroundImage = 'url(' + image + ')';
}
onload = chBackgr;
<!--close random background script-->
It's weird. Because my background image is certainly random. It's just that sometimes only half of the image loads. Really strange. Any help is appreciated. Thank You. After you click on the last button 3 times it should change the background to the zombies image however it isn't working. I haven't found tutorials for doing it exactly as I am attempting it but I don't see why this isn't working. It runs through the code just fine and the button works as intended except for the fact that the background image isn't changing. I am still pretty new to JavaScript however so I feel I may just being calling the image incorrectly. Code: <html>
<title>Welcome :D</title>
<head>
<style type="text/css">
body {
background-color:E6E6E6;
}
</style>
<script type="text/javascript">
//Pre loading images to be used with check boxes.
function preLoad(){
Eyeball= new Image(400,200)
Eyeball.src = "Eyeball.jpg"
Smileys = new Image(400,200)
Smileys.src = "Smileys.gif"
goodAfternoon = new Image(400,200)
goodAfternoon.src = "Good Afternoon.gif"
goodAfternoonFinal = new Image(400,200)
goodAfternoonFinal.src = "Good Afternoon.gif"
zombies=new Image()
zombies.src = "Zombies.jpg"
}
function validate(){
if(document.getElementById("cb1").checked){
document.goodAfternoon.src=Eyeball.src;
}else{
document.goodAfternoon.src=Smileys.src;
}
}
function reset(){
cb1.checked=false;
document.goodAfternoon.src=goodAfternoonFinal.src;
}
var i=0;
function myalert(){
i++
if(i == 1){
alert("I dare you to press me again....");
}
if(i == 2){
}
if(i == 3){
i = 0;
document.body.background = "zombies.src";
}
}
</script>
</head>
<body onLoad="javascript:preLoad()">
This is where I learn a lot of my coding for Java, JavaScript, and HTML
<a href="http://www.thenewboston.com/"><img src="theNewBoston.gif"></a>
</br>
"Check" me out;) <input type="checkbox" id="cb1" onClick="validate()" />
<img src="Good Afternoon.gif" name="goodAfternoon">
<input type="button" id="cb2" value="RESET" onClick="reset()"/>
</BR></br></br></br></br>
Hello, thank you for visiting my webpage I hope you like it.
<input type="button" onClick="myalert()"value="CLICK me"/>
</body>
</html>
Hey, everyone! I found this script that works great for what it's for. However, I would like to use it for background images. Can someone tell me how to adjust this script so it can be used for backgrounds? Thanks in advance! Web Page Code Code: <html> <head> <title>slayeroffice | code | image cross fade redux</title> <link rel="stylesheet" type="text/css" href="xfade2_o.css"> <script type="text/javascript" src="xfade2.js"></script> </head> </div> <body background="id=imageContainer"> <div id="imageContainer"> <img src="http://slayeroffice.com/code/imageCrossFade/img1.jpg"> <img src="http://slayeroffice.com/code/imageCrossFade/img2.jpg"> <img src="http://slayeroffice.com/code/imageCrossFade/img3.jpg"> <img src="http://slayeroffice.com/code/imageCrossFade/img4.jpg"> <img src="http://slayeroffice.com/code/imageCrossFade/img5.jpg"> <img src="http://slayeroffice.com/code/imageCrossFade/img6.jpg"> </div> </body> </html> Style Sheet 1 Code: #imageContainer {
height:309px;
}
#imageContainer img {
display:none;
position:absolute;
top:0; left:0;
}
Style Sheet 2 Code: #imageContainer {
position:relative;
margin:auto;
width:500px;
border:1px solid #000;
}
JavaScript Code: window.addEventListener?window.addEventListener("load",so_init,false):window.attachEvent("onload",so_init);
var d=document, imgs = new Array(), zInterval = null, current=0, pause=false;
function so_init() {
if(!d.getElementById || !d.createElement)return;
css = d.createElement("link");
css.setAttribute("href","xfade2.css");
css.setAttribute("rel","stylesheet");
css.setAttribute("type","text/css");
d.getElementsByTagName("head")[0].appendChild(css);
imgs = d.getElementById("imageContainer").getElementsByTagName("img");
for(i=1;i<imgs.length;i++) imgs[i].xOpacity = 0;
imgs[0].style.display = "block";
imgs[0].xOpacity = .99;
setTimeout(so_xfade,1000);
}
function so_xfade() {
cOpacity = imgs[current].xOpacity;
nIndex = imgs[current+1]?current+1:0;
nOpacity = imgs[nIndex].xOpacity;
cOpacity-=.05;
nOpacity+=.05;
imgs[nIndex].style.display = "block";
imgs[current].xOpacity = cOpacity;
imgs[nIndex].xOpacity = nOpacity;
setOpacity(imgs[current]);
setOpacity(imgs[nIndex]);
if(cOpacity<=0) {
imgs[current].style.display = "none";
current = nIndex;
setTimeout(so_xfade,1000);
} else {
setTimeout(so_xfade,50);
}
function setOpacity(obj) {
if(obj.xOpacity>.99) {
obj.xOpacity = .99;
return;
}
obj.style.opacity = obj.xOpacity;
obj.style.MozOpacity = obj.xOpacity;
obj.style.filter = "alpha(opacity=" + (obj.xOpacity*100) + ")";
}
}
Hello, I have recently been working on a website which will have rotating background images. I have found a useful javascript code (i don't know who the author is) which rotates different background images neatly after x milliseconds. here is the code: ==== <script language="JavaScript1.2"> var bgimages=new Array() bgimages[0]="../gfx/bgs/bg1.jpg" bgimages[1]="../gfx/bgs/bg2.jpg" //preload images var pathToImg=new Array() for (i=0;i<bgimages.length;i++){ pathToImg[i]=new Image() pathToImg[i].src=bgimages[i] } var inc=-1 function bgSlide(){ if (inc<bgimages.length-1) inc++ else inc=0 document.body.background=pathToImg[inc].src } if (document.all||document.getElementById) window.onload=new Function('setInterval("bgSlide()",6000)') </script> ==== The script works, and the background images rotate. However, currently the rotation of the images have no effect. I would like to add the effect of the images blending into each other when they rotate. How would this be possible? Thanks a bunch! -Captainel I have a 16x16 solid color yellow image - .gif type. I'm using it as a background for a div. I'd like to make it transparent but can't figure out how to do. I have Paint.net and follow its instructions to make the image 50% transparent but afterwards, it's completely clear with no hint of yellow. How can I make a transparent solid image? I'd like it about 50% transparent. Thanks... PHP Code: .xstooltip { visibility: hidden; position: absolute; top: 0; left: 0; z-index: 2; font: normal 8pt sans-serif; padding: 3px; border: solid 1px; /*background-color: #DBDBDB;*/ /*background-color: #FFFF77;*/ background-repeat:repeat; background-image:url(/yellow_help.gif); } How am I able to have a gallery of images fading in and out as the background of a DIV? It's currently just a static background using CSS. You can view the HTML page in question he http://aksdesigns.co.uk/temp/template.html The DIV container is the one with the ID of #MainContent Code: #MainContent {
width: 980px;
height: 550px;
margin: 0 auto;
padding: 0px;
background-image: url(images/Content-bg-1.jpg);
background-repeat: no-repeat;
background-position: top center;
border-left: 2px solid #153365;
border-right: 1px solid #FFF;
}
It probably couldn't be done using CSS be how could I achieve this with Javascript? Hi Guys, I would like to be able to change my webpage background image according to the screen resolution the user uses so: if screen resolution is greater than or equals to 1200*600 then background = mybackground.jpg no-repeat else background = #000000 THANKS A MILLION! Im going nuts with this, first im starting of by just putting a background image in the tb using JavaScript, but it won't work! Heres what i got in my 'name.js' file i got var name=new Array() name='name.jpg' and in my HTML i got <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> </head> <body> <div> <table> <script type="text/javascript" language="JavaScript" src="name.js"> document.write('<td id="name2" background="' + name + '">'); </script> </td> </table> </div> </body> </html> Where have a gone wrong?? If I type Hello World into the name.js file and put it in a tb it works fine, im confused thanks, Paul |
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