I've found mixed evidence about whether it's feasible to create a dynamic background with the HTML5 canvas element. Here's a guy who seems to have successfully done it:
http://radikalfx.com/files/anibg/
I have successfully positioned my canvas element as a background, but it has rendered my links unclickable. Here's the situation:
HTML:
<div id='container'>
... other header stuff ...
<canvas id='background'>
</canvas>
<!-- Can't touch this *MC Hammer Shuffle* -->
<a href='#'>test</a>
... footer stuff ...
</div>
CSS:
/* Everything's z-index is now 1 */
#container
{
position: relative;
min-height:100%;
width:100%;
z-index:1;
}
/* Make the canvas z-index 0 */
#background
{
position: absolute;
top: 0;
width:100%;
height:100%;
z-index: 0;
}
JavaScript:
// Onload Draw an ellipse
// I've got jCanvas installed (jQuery plugin) to use the drawArc() method
// This bit can be replaced with whatever test code you want.
function load()
{
init_canvas();
$("canvas").drawArc({
fillStyle: "black",
x: 100, y: 100,
radius: 50
});
}
// Make the canvas the appropriate size
function init_canvas()
{
canvas = document.getElementById("background");
canvas.width = document.width;
canvas.height = document.height;
canvasW = canvas.width;
canvasH = canvas.height;
}
Cheers!
You use #container in your CSS to give everything else a z-index of 1, yet you never put an element #container on the page.
Change your HTML to the following and it will work as expected:
<canvas id='background'></canvas>
<div id="container">
<a href='#'>test</a>
</div>
JSFiddle: http://jsfiddle.net/ht6c8/
every element with the position: absolute is being placed over other not positioned item, even if other elements are placed in DOM after. So you can just set position: relative for your anchor element
Related
I'm using a full screen canvas as background of the first section of my page. But as soon as I add the second section and vertical scrollbar appears, the height of canvas reduces a little bit and a gap appears. here's my code:
P.S: Sorry, my code contained bugs, I fixed them. now you can see the red gap.
var canvas = document.getElementById('canvas')
var c = canvas.getContext('2d')
scaleCanvas()
window.addEventListener("resize", scaleCanvas)
function scaleCanvas() {
canvas.width = window.innerWidth
canvas.height = window.innerHeight
c.fillStyle = 'black'
c.fillRect(0, 0, canvas.width, canvas.height)
}
* {
box-sizing: border-box;
max-width: 100%;
}
body {
margin: 0;
padding: 0;
}
#first-section {
position: relative;
min-height: 100vh;
background-color: red; /* to see the gap */
}
#content {
position: relative;
z-index: 2;
}
#second-section {
min-height: 100vh;
background-color: blue;
}
#canvas {
display: block;
padding: 0;
margin: 0;
border: none;
position: absolute;
top: 0;
left: 0;
z-index: 1;
}
<div id="first-section">
<canvas id="canvas"></canvas>
<div id="content">content</div>
</div>
<div id="second-section"></div>
Assuming you mean full screen, and not full page. The two are very different.
If you mean full page then the link to the Screen API will also give you details on obtaining the page size.
Size full screen canvas.
The problem is that you have content that extends outside the page width and height (innerWidth, innerHeight)
The elements with ids first-section, content, and second-section must be inside the display area or else you will get a scroll bar. The scroll bar will change the innerWidth, innerHeight values subtracting the scrollbar width or height depending on which is visible.
To prevent scroll bars the best option is to keep all content inside innerWidth, and innerHeight
Full screen with scroll bars.
If you want have the scroll bars and you are using full screen you can use the Screen API to get the width and height of the display in pixels. You can set the canvas size to match the screen without the scroll bars effecting its size.
Note Do read the provided link to Screen as what defines the screen may not be as expected. EG more than one monitor, or device orientation will effect how you use the API.
Basic example
Thus when in full-screen mode you can set the canvas size and ignore scroll bars with
function sizeFullScreenCanvas() {
canvas.width = screen.width;
canvas.height= screen.height;
}
Requirements:
The HTML: The iframe HAS to be inside of a containing div. See code down below.
The CSS: The container should be able to have ANY valid width and height using the vw and vh viewport units. Se code down below.
Yes, the width and height HAS to be in vw and vh.
The static video preview image should NEVER be cropped.
The static video preview image should NOT have any black bars above and below (letterboxing).
The static video preview image should NOT have any black bars to the left or to the right (pillarboxing).
The static video preview image should use as much space estate as possible inside the div that contains it.
The static video preview image should ALWAYS keep its aspect ratio of 16:9.
Scrollbars should NEVER appear.
The static video preview image should be centered vertically as well as horizontally inside the div that contains it.
Responsive Web Design.
When resizing the browser or viewport all of the above requirements should be fulfilled.
HTML:
<div class="container">
<iframe></iframe>
</div>
CSS:
.container {
width:90vw;
height:50vh;
}
Same solution, but no extra markup for keeping the ratio.
JsFiddle with same comments totally not needed.
<!DOCTYPE html><html lang="en"><head><meta charset="utf-8">
<title>Fully Container Centred Iframe</title>
<meta name="generator" content="PSPad editor, www.pspad.com">
<style>
.container {
display:table-cell; /* (specs: omitted table parts, the browser will insert mandatory elements in the dom tree) */
position:relative;
padding:; /* optional, margins ignored */
width:100vw; /* any value */
height:1vh; /* will expand by the :before element */
overflow:hidden; /* hide eventual black bars */
background:tan; /* bg-colors just for demo testing */
vertical-align:middle;
text-align:center;
}
.container:before {
display:block;
padding-top:56%; /* keeps the 16/9 ratio for the AP */
height:0;
background:red;
content:"\a0";
}
.container iframe {
position:absolute; /* to be ratio consistent */
top:-.5%;
left:-.5%; /* overflow eventual black bars */
border:0;
width:101%; /* grow some to avoid thinner black bars */
height:101%;
overflow:hidden; /* for html5 browsers the html attribute is depreciated */
background:gold;
}
</style>
</head><body>
<div class="container">
<iframe scrolling="no" src=""></iframe>
</div>
</body></html>
Using JavaScript, you can listen for the resize event, which fires whenever the browser's window changes shape. Then, with some simple algebra you can calculate the dimensions of the iframe based on the dimensions of the container. Here is a demo that shows all of the requirements.
"use strict";
var container = document.querySelector('.container');
var frame = container.querySelector('iframe');
function resizeVideo() {
frame.width = frame.height = 0;
var width = container.offsetWidth;
var height = container.offsetHeight;
if (height * (16 / 9) <= width) {
frame.height = height;
frame.width = height * (16 / 9);
} else {
frame.width = width;
frame.height = width * (9 / 16);
}
}
window.addEventListener('load', resizeVideo);
window.addEventListener('resize', resizeVideo);
.container {
width: 90vw;
height: 50vh;
display: table-cell;
text-align: center;
vertical-align: middle;
}
<div class="container">
<iframe src="https://www.youtube.com/embed/BKhZvubRYy8" frameborder="0" allowfullscreen></iframe>
</div>
if you want Responsive use
.container, iframe {
width:100%;
height:auto;
}
.container {
width:90vw;
height:50vh;
}
.container iframe {
width: 100%;
height: 100%;
}
Seems to work quite nicely in this fiddle https://jsfiddle.net/1q10L7hj/
why don't you just use the calc method to get the aspect ratio width you are wanting?
HTML
<div class="container">
<iframe src="" frameborder="0"></iframe>
</div>
SCSS
<style>
$width = 80vw;
.container {
width: $width;
height: calc(($width/16) * 9);
position: relative;
}
iframe {
position: absolute;
width: 100%;
height: 100%;
top: 50%;
left: 50%;
-webkit-transform: translate(+50%, -50%);
transform: translate(+50%, -50%);
}
</style>
then you can change the width of it anywhere and apply whatever positioning you want on the container div and the iframe with follow suit
I think the table-cell display could solve this. Just apply it on the container so the iframe is the content
According to specs the browser will insert dummy elements where it needs to render the cell correctly and fully centre and to contain its content and if it need, grow with it.
The requirements: I think some of them is beyond the scope of your question, they will also depend on what is loaded in the iframe, out of control of this container document. My suggested code is simple, but I believe it meets all requirements possible for the iframe parent and still be crossbrowser friendly.
The forbidden black bars and the mandatory aspect ratio could still be at fault in the loaded document. If you can't control whats loaded, the last option might be the "srcdoc" and "seamless" attributes, but that would exclude e.g. all IE versions.
JsFiddle with some comments totally not needed. Hope the edit below solves the case.
Anyway, I had fun! Thanks! :)
<!DOCTYPE html><html lang="en"><head><meta charset="utf-8">
<title>Fully Container Centred Iframe</title>
<meta name="generator" content="PSPad editor, www.pspad.com">
<style>
.container {
display:table-cell;
padding:;
width:100vw;
height:20vh;
background:tan;
vertical-align:middle;
text-align:center;
}
.container .ratio{
display:inline-block;
position:relative;
padding-bottom:56%;
width:100%;
height:0;
overflow:hidden;
vertical-align:middle;
}
.container iframe {
position:absolute;
top:-1%;
left:-1%;
border:0;
width:102%;
height:102%;
overflow:hidden;
vertical-align:middle;
}
</style>
</head><body>
<div class="container">
<div class="ratio">
<iframe scrolling="no" src=""></iframe>
</div>
</div>
</body></html>
I have gotten the result you wanted, I however had to add an extra div as the parent of the .container class. This JSFiddle should work for users on chrome (Windows desktop version) however when I tried to use the same fiddle on Edge and IE11 I found that it would create the undesired letter-box effect due to the image cover zooming too far out.
HTML
<div id="wrapper">
<div class="container">
<iframe scrolling="no" src="https://www.youtube.com/embed/YL9RetC0ook" frameborder="0" allowfullscreen>
</iframe>
</div>
</div>
CSS
body {
margin: 0;
}
#wrapper {
width: 90vw;
height: 50vh;
}
.container,iframe {
width: 100%;
height: 100%;
}
I am not sure if this works for Firefox, so perhaps if you have Firefox you can try it on my JSFiddle. However for Chrome (at the very least) this should be the solution you where looking for as stated by the requirements you listed.
I would recommend using a JavaScript window.resize listener to solve this kind of an issue. Cannot write code today cause I have a pretty tight schedule, but I'll try writing an algo:
On window resize, compute window width (wW) and window height (wH);
Determine container width (cW) as per wW (say cW = wW-10 to get almost all the width available - you can omit the -10 if you want);
Determine container height (cH) as per cW computed above: cH = cW * 9 / 16;
Now, if cH > wH (i.e. the container is not fitting into the screen vertically because it is too wide), we should revise cW as per available window height. In this case, cH = wH-10 (to get almost all the vertical space available - again, you can omit the -10 if you want) and then cW = wH * 16 / 9;
You should have a valid cW and cH now to make you container fit into the window without going out of the screen and you can apply it to the container.
To center the container to the screen, use position: absolute, left: 50%; top: 50%; in your CSS. When you update the cW and cH, also update margin-left: -(cW/2); margin-top: -(cH/2);
This is the concept - you can improvise as per your needs. I hope it helps.
I need the contents of an iframe which has height of 100px(displays only part of iframe) to expand like an animation on read more button click,and fill up the entire screen(expands in all directions), and on clicking close button positioned on top of it, it needs to animate and shrink to it original size.
I found a fiddle that dooes something similar
http://jsfiddle.net/FP2DZ/.
But my issue is that my div cannot be absolutely positioned as I have contents underneath that and that gets affected if I make this one absolutely positioned.
Absolutely positioning rest of the contents also does not seem to me like a good solution
Code
<html>
<head>
<script type="text/javascript">
var isFullscreen = false;
function fullscreen(){
//var d = document.getElementById('controls').style;
var d = {};
var speed = 900;
if(!isFullscreen){ // MAXIMIZATION
/*comment to have smooth transition from centre but loose covering the header*/
//document.getElementById('controls').style.position= "absolute";
d.width = "100%";
d.height="100%";
//d.left="0%";
d.top="0px";
//d.margin="0 0 0 0";
$("#header").animate({
height: 0
}, speed);
$("#controls2").animate(d,speed);
isFullscreen = true;
}else{ // MINIMIZATION
d.width="300px";
d.height="100px";
d.margin="0 auto";
d.position="relative";
//d.top="+=30px";
/* comment to have smooth minimze transition but not be placed below header */
// document.getElementById('controls').style.position= "relative";
$("#header").animate({
height: 30
}, speed);
$("#controls2").animate(d,speed);
isFullscreen = false;
}
}
</script>
<style>
* { margin: 0 }
#controls {
width:100%;
height:100%;
margin: 0 auto;
display:block;
position:absolute;
left: 50%;
z-index:5;
}
#controls2 {
overflow:visible;
width: 300px;
height: 100px;
position: relative;
left: -50%;
background-color: green;
z-index:10;
}
</style>
</head>
<body>
<h1 id="header" align=center> Header (To be covered on Fullscreen) </h1>
<div id='controls' style="" align="center">
<div id='controls2'>
<input type='button' value='fullscreen' onclick='fullscreen();' /><br>
I am some centered shrink-to-fit content! <br />
tum te tum
</div>
</div>
</body>
Probably the easiest way is to utilize the .animate({}) method in Jquery.
Check out this fiddle: http://jsfiddle.net/cm6v7bca/2/
$("#clickhere").on("click", function () {
$("#myframe").animate({
width: "200px",
height: "200px"
}, 1000);
});
.animate({}) allows you to change the css properties and then smoothly animates the changes onto the element. There are several different parameters you can pass. In the fiddle you'll see that I passed "1000" - that's the duration for the animation to complete in ms.
You can read more about the parameters and the method here: https://api.jquery.com/animate/
That really helps. But then the iframe needs to cover rest of the contents in the page and overlay them, Thats seems possible only if iframe is absolutely positioned. But there is so much dynamic content in the page, I do not want to absolute position the iframe.
http://jsfiddle.net/CvhkM/2833/
this is like what I want just that am not able to absolute position.
JS:
$(this).stop().animate({
left: parseInt(this.style.left)-100,
top: parseInt(this.style.top)-100,
width: parseInt(this.style.width)+200,
height: parseInt(this.style.height)+200
}, 300);
I have an HTML video player with Javascript generated controls(with background images of SVG graphics). I'm having an issue using the css calc() function, and need to resize the div's based on the video controls bar. So when the window is expanded/contracted, the controls need to adjust accordingly.
The controls div:
//Controls Wrapper
videoObj.controlsWrapper = document.createElement("div");
videoObj.controlsWrapper.className = "video-controls";
The controls are generated dynamically, so for instance, the play button is generated by this:
videoObj.playBtn = document.createElement("button");
videoObj.playBtn.className = "play btn";
So the question is how to adjust the size of the play button(which is a background of an SVG graphic), to a percentage(about 25%) of the height of the controls wrapper div.
jsfiddle
This is the easiest way... try resizing the box :)
The parent is relative. The child is absolute. Setting the top, left, right and bottom all to 0 will actually create a spider web effect ( or stretch effect ). I used different pixels so you could see the reaction. otherwise the child will cover the parent. Hope this helps.
http://jsfiddle.net/m5wm1rLs/
.parent{
position: relative;
width: 100px;
height: 100px;
background-color: red;
}
.child{
position: absolute;
top: 3px;
bottom: 20px;
left: 3px;
right: 20px;
background-color: green;
}
<div class="parent">
<div class="child"></div>
</div>
To test that this works, you can make parent resizable:
$('.parent').resizable();
Resizing it to 25% of the parent div height is relatively easy, but only doable with a scripting language. As far as CSS has come by allow calc(), it has no support for pulling the sizes of designated elements.
Here's a simple script I threw together for you:
window.onload = function() {
resize();
}
window.onresize = function() {
resize();
}
function resize() {
document.getElementsByClassName('play')[0].style.width = (document.getElementsByClassName('timeline')[0].offsetHeight * .25) + 'px';
}
JSFiddle: http://jsfiddle.net/zq2vzkk5/
I recommend you use ids to identify the elements you want to pull the values from, but if the positions of the elements won't change on the page, then classes are fine. You just have to update which instance of the class you want to pull the value from if it does change.
If you want a jQuery variation, I can supply that, too.
I hope this helps.
Edit:
Here's the jQuery variation:
$(function() {
resize();
$(window).resize(function() {
resize();
});
});
function resize() {
$('.play').first().width($('.timeline').first().outerHeight() * .25);
}
JSFiddle: http://jsfiddle.net/s51vrca2/
You can do this without JS :
.play {
height: 25%;
}
I have a problem to get my window size, I try this code:
Javascript
var game;
function game() {
this.canvas = document.getElementById('canvas');
this.canvasWidth = window.innerWidth;
this.canvasHeight = window.innerHeight;
this.initCanvas = function() {
this.canvas.style.width = this.canvasWidth + "px";
this.canvas.style.height = this.canvasHeight + "px";
}
this.run = function() {
this.initCanvas();
}
}
game = new game();
game.run();
I also have
CSS
html, body {
padding: 0;
margin: 0;
}
I only have a canvas in my body.
Problem is, that I have a vertical and horizontal scroll bar. This means the size of canvas is too large. How to make it of the window size without the scroll bars appearing?
It looks like you're just trying to make your canvas have a width and height of 100%. You can do this with just css:
HTML
<body>
<canvas id="canvas"></canvas>
</body>
CSS
body, html {
height: 100%;
width: 100%;
margin: 0px;
}
canvas {
background: #ffcccc;
height: 100%;
width: 100%;
display: block;
}
Demo
Or if you want to use your code but get rid of the scroll bars on the window, you need to specify block on the canvas tag.
CSS
canvas {
display: block;
}
Demo
When you use CSS to style your <canvas> element it will get scaled instead of sized. Be sure to set the .width and .height properties on the canvas element instead (ie canvas.width not canvas.style.width).
jsfiddle example
In the example the first canvas element is scaled correctly, the second (using CSS) is not scaled properly. This has to do with a default canvas element size (300x150) that CSS scales.
To prevent getting scrollbars when setting the <canvas> to the full window width/height set the body to overflow:hidden; as used in the jsfiddle above.