HTML Canvas displaying over my main content
Question
I am trying to work a christmas Javascript overlay onto a website and the tag I am using is displaying over the rest of my websites content.
window.onload = function(){ //canvas init var canvas = document.getElementById("canvas"); var ctx = canvas.getContext("2d"); //canvas dimensions var W = window.innerWidth; var H = window.innerHeight; canvas.width = W; canvas.height = H; //snowflake particles var mp = 25; //max particles var particles = []; for(var i = 0; i < mp; i++) { particles.push({ x: Math.random()*W, //x-coordinate y: Math.random()*H, //y-coordinate r: Math.random()*4+1, //radius d: Math.random()*mp //density }) } //Lets draw the flakes function draw() { ctx.clearRect(0, 0, W, H); ctx.fillStyle = "rgba(255, 255, 255, 0.8)"; ctx.beginPath(); for(var i = 0; i < mp; i++) { var p = particles[i]; ctx.moveTo(px, py); ctx.arc(px, py, pr, 0, Math.PI*2, true); } ctx.fill(); update(); } //Function to move the snowflakes //angle will be an ongoing incremental flag. Sin and Cos functions will be applied to it to create vertical and horizontal movements of the flakes var angle = 0; function update() { angle += 0.01; for(var i = 0; i < mp; i++) { var p = particles[i]; //Updating X and Y coordinates //We will add 1 to the cos function to prevent negative values which will lead flakes to move upwards //Every particle has its own density which can be used to make the downward movement different for each flake //Lets make it more random by adding in the radius py += Math.cos(angle+pd) + 1 + pr/2; px += Math.sin(angle) * 2; //Sending flakes back from the top when it exits //Lets make it a bit more organic and let flakes enter from the left and right also. if(px > W+5 || px < -5 || py > H) { if(i%3 > 0) //66.67% of the flakes { particles[i] = {x: Math.random()*W, y: -10, r: pr, d: pd}; } else { //If the flake is exitting from the right if(Math.sin(angle) > 0) { //Enter from the left particles[i] = {x: -5, y: Math.random()*H, r: pr, d: pd}; } else { //Enter from the right particles[i] = {x: W+5, y: Math.random()*H, r: pr, d: pd}; } } } } } //animation loop setInterval(draw, 33); }
* {margin: 0; padding: 0;} body { /*You can use any kind of background here.*/ background: #6b92b9; } canvas { display: block; position: absolute; }
<canvas id="canvas"> <header> <a href = "/games/"><img id="headerimg" src="http://hosted-it.co.uk/img/logo-colour.svg" alt="Hosted-IT" height="150px" width="250px" /> </a></header> <nav class="navbar"><form method="get" action="/games/questions"> <button type="onclick">Questions</button> </form> </nav> <body> {% block content %} {% endblock %} </body> </canvas>
If it helps, this is all inline script/html/css. It uses DJango templating to use a main html file to store the main formatting and then any other tweaks are made in the individual files. I was hoping if anyone could help me figure out why the canvas tag is overriding absolutely everything on the pages themselves ?
1 answers
solution1
1 ACCPTED 2016-12-09 12:29:32
You should provide a plunker, but for now you can try below css
canvas {
display: block;
position: relative;
}
change position to 'relative'. May be it will work. And in HTML close canvas tag on first line
<canvas id="canvas"></canvas>
<header> <a href = "/games/"><img id="headerimg" src="http://hosted-it.co.uk/img/logo-colour.svg" alt="Hosted-IT" height="150px" width="250px" /></a></header>
<nav class="navbar"><form method="get" action="/games/questions">
<button type="onclick">Questions</button>
</form> </nav>
<body>
{% block content %}
{% endblock %}
</body>
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.