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waterfall_new.html
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<!-- TODO kreslit pngcka do canvas namiesto do tabulky
drawing = new Image();
drawing.src = "draw.png";
context.drawImage(drawing,0,0);
!-->
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
<html> <head>
<title></title>
</head>
<style>
h1 {
text-align: center;
}
ul#spectrum {
list-style: none;
text-align: center;
margin: 0px auto;
padding: 0px;
overflow: hidden;
font-size:0;
}
li {
display: block;
margin: 0px;
padding: 0px;
line-height: 0px;
font-size:0;
}
img {
margin: 0px;
padding: 0px;
}
ul { border: 2px solid #000; position:absolute; top:150;left:150; }
</style>
<script>
var resolution = 128;
var samples = 64;
var waterfall = new Array();
var sqsize;
var speed;
var oldSpeed = 0;
var updateTimer = "";
var c = document.createElement('canvas');
// shortcut
function _(element) {
return document.getElementById(element);
}
// return random number between min and max
function getRandom (min, max) {
return Math.floor(Math.random() * (max - min + 1)) + min;
}
// insert new random value to array
function insertWF() {
if (waterfall.length < samples) {
var insert = [];
for (var i = 0; i < resolution; i++) insert[i] = getRandom(1, 255);
waterfall.unshift(insert);
}
else {
waterfall.pop();
insertWF();
}
}
// draw waterfall
function displayWF() {
sqsize = _("sqsizeSlider").value;
speed = _("speedSlider").value;
resolution = _("resolutionSlider").value;
samples = _("samplesSlider").value;
_("sqsize").innerHTML = "Sqsize: " + sqsize;
_("speed").innerHTML = "Speed: " + 1000/(1000 - speed) + " Hz";
_("resolution").innerHTML = "Resolution: " + resolution;
_("samples").innerHTML = "samples: " + samples;
// set speed of waterfall
if(speed != oldSpeed) {
clearInterval(updateTimer);
updateTimer = setInterval(function() { updateWF()}, 1000 - speed);
oldSpeed = speed;
}
// c is globally defined context
var ctx = c.getContext("2d");
c.width = resolution * sqsize;
c.height = sqsize;
ctx.clearRect(0, 0, ctx.width, ctx.height);
for (var j = 0; j < resolution; j++) {
ctx.fillStyle="rgb(" + waterfall[0][j] + ",50,50)";
ctx.fillRect(j * sqsize, 0, sqsize, sqsize);
}
// create png from canvas
var img = c.toDataURL("image/png");
// create li entry with image
var li = document.createElement("li");
var liImg = document.createElement("img");
liImg.setAttribute('src', img);
li.appendChild(liImg);
// append li to spectrum
spectrum = _("spectrum");
spectrum.appendChild(li);
spectrum.insertBefore(li, spectrum.firstChild);
// delete last entry, if spectrum is full
var children = spectrum.childNodes.length;
while (children > samples) {
spectrum.removeChild(spectrum.lastChild);
children = spectrum.childNodes.length;
}
}
// periodically called function which inserts new value
// and redraw the waterfall
function updateWF() {
insertWF();
displayWF();
}
window.onload = function ()
{
// populate array with values
for (var i = 0; i < samples; i++) {
insertWF();
}
// start waterfall
toggleWF();
}
// start / stop waterfall
function toggleWF() {
if(updateTimer == "")
{
updateTimer = setInterval( function() { updateWF() }, speed);
_("toggleButton").innerHTML = "Pause";
}
else
{
clearInterval(updateTimer);
updateTimer = "";
_("toggleButton").innerHTML = "Resume";
}
}
// save screenshot as png in "screenshots" div
function saveImg() {
var now = new Date();
// create hidden canvas
var buffer = document.createElement('canvas');
buffer.width = sqsize * resolution;
buffer.height = sqsize * samples;
context = buffer.getContext('2d');
// draw all data from array
for (var i = 0; i < samples; i++) {
for (var j = 0; j < resolution; j++) {
context.fillStyle="rgb(" + waterfall[i][j] + ",50,50)";
context.fillRect(j * sqsize, i * sqsize, sqsize, sqsize);
}
}
// convert canvas to png
var img = buffer.toDataURL("image/png");
_("screenshots").innerHTML += '<img alt="' + now + '" src="' + img + '"/> ' + now + '<br>';
}
</script>
<body>
<div>
square size <input id="sqsizeSlider" type ="range" min ="1" max="20" step ="1" value ="2"/>
<div id="sqsize"></div>
speed <input id="speedSlider" type ="range" min ="0" max="1000" step ="50" value ="750"/>
<div id="speed"></div>
resolution <input id="resolutionSlider" type ="range" min ="1" max="1000" step ="1" value ="128"/>
<div id="samples"></div>
samples <input id="samplesSlider" type ="range" min ="0" max="1000" step ="1" value ="64"/>
<div id="resolution"></div>
<button autofocus="autofocus" id="toggleButton" onclick="JavaScript:toggleWF()">Pause</button>
<button id="capture" onclick="JavaScript:saveImg()">Capture</button>
</div>
<div id="graf"></div>
<ul id="spectrum">
</ul>
<br>
<br>
<div id="screenshots"></div>
</body> </html>