Canvas Test FADE

Testing some stuff

by joquery

HTML

<canvas id="myCanvas" width="300" height="200"></canvas>

<div>
    <button id="start">Start</button>
    <button id="stop">Stop</button>
    <button id="next">Next</button>
    <button id="reset">Reset</button>
</div>

CSS

#myCanvas {
    background: #fafaee;
}

JavaScript

var context;
var canvas;
var drawInterval = 1000.0 / 60.0; // 60Hz
var duration = 5;
var stepping = 1 / (duration * drawInterval);
var intervalId;

var alpha = 0.0;



var draw = function() {
    
    if (alpha + stepping > 1) {
        alpha = 1;
    } else {
        alpha += stepping;
    }
        
    context.globalAlpha = alpha;
    
    context.clearRect(0,0,canvas.width,canvas.height);
    
    context.rect(0,0,canvas.width,canvas.height);
    context.fillStyle="red";
    context.fillRect(0,0,canvas.width,canvas.height);
    
    if (alpha === 1) {
        clearInterval(intervalId);
    }
};




var startAnimation = function() {
    alpha = 0;
    context.save();
    intervalId = setInterval(draw, drawInterval);
    //draw();
};

var resetAnimation = function() {
    clearInterval(intervalId);
    alpha = 0;
    context.restore();
    canvas.width = canvas.width;
    canvas.height = canvas.height;
};
var stopAnimation = function() {
    clearInterval(intervalId);
};



jQuery(document).ready(function(){

    canvas = $("#myCanvas")[0];
    context = canvas.getContext("2d");
    
    $("#start").on("click", function(){
        startAnimation();
    });
    
    $("#stop").on("click", function(){
        stopAnimation();
    });
    
    $("#next").on("click", function(){
        draw();
    });
    
    $("#reset").on("click", function(){
        resetAnimation();
    });
    
    
});