Free Custom Calculator and Firework Gadget Code for Blogger

<!– setup our canvas element shipmethis.com–>
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Get the code here</h4>
<div>
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<style>/* basic styles for black background and crosshair cursor */
canvas {
background-color: #000;
 cursor: crosshair;
 display: block;
width: 800px;
}</style>
<script>// when animating on canvas, it is best to use requestAnimationFrame instead of setTimeout or setInterval
// not supported in all browsers though and sometimes needs a prefix, so we need a shim
window.requestAnimFrame = ( function() {
 return window.requestAnimationFrame ||
    window.webkitRequestAnimationFrame ||
    window.mozRequestAnimationFrame ||
    function( callback ) {
     window.setTimeout( callback, 1000 / 60 );
    };
})();
// now we will setup our basic variables for the demo
var canvas = document.getElementById( ‘canvas’ ),
  ctx = canvas.getContext( ‘2d’ ),
  // full screen dimensions
  cw = window.innerWidth,
  ch = window.innerHeight,
  // firework collection
  fireworks = [],
  // particle collection
  particles = [],
  // starting hue
  hue = 120,
  // when launching fireworks with a click, too many get launched at once without a limiter, one launch per 5 loop ticks
  limiterTotal = 5,
  limiterTick = 0,
  // this will time the auto launches of fireworks, one launch per 80 loop ticks
  timerTotal = 80,
  timerTick = 0,
  mousedown = false,
  // mouse x coordinate,
  mx,
  // mouse y coordinate
  my;

// set canvas dimensions
canvas.width = cw;
canvas.height = ch;
// now we are going to setup our function placeholders for the entire demo
// get a random number within a range
function random( min, max ) {
 return Math.random() * ( max – min ) + min;
}
// calculate the distance between two points
function calculateDistance( p1x, p1y, p2x, p2y ) {
 var xDistance = p1x – p2x,
   yDistance = p1y – p2y;
 return Math.sqrt( Math.pow( xDistance, 2 ) + Math.pow( yDistance, 2 ) );
}
// create firework
function Firework( sx, sy, tx, ty ) {
 // actual coordinates
 this.x = sx;
 this.y = sy;
 // starting coordinates
 this.sx = sx;
 this.sy = sy;
 // target coordinates
 this.tx = tx;
 this.ty = ty;
 // distance from starting point to target
 this.distanceToTarget = calculateDistance( sx, sy, tx, ty );
 this.distanceTraveled = 0;
 // track the past coordinates of each firework to create a trail effect, increase the coordinate count to create more prominent trails
 this.coordinates = [];
 this.coordinateCount = 3;
 // populate initial coordinate collection with the current coordinates
 while( this.coordinateCount– ) {
  this.coordinates.push( [ this.x, this.y ] );
 }
 this.angle = Math.atan2( ty – sy, tx – sx );
 this.speed = 2;
 this.acceleration = 1.05;
 this.brightness = random( 50, 70 );
 // circle target indicator radius
 this.targetRadius = 1;
}
// update firework
Firework.prototype.update = function( index ) {
 // remove last item in coordinates array
 this.coordinates.pop();
 // add current coordinates to the start of the array
 this.coordinates.unshift( [ this.x, this.y ] );

 // cycle the circle target indicator radius
 if( this.targetRadius < 8 ) {
  this.targetRadius += 0.3;
 } else {
  this.targetRadius = 1;
 }

 // speed up the firework
 this.speed *= this.acceleration;

 // get the current velocities based on angle and speed
 var vx = Math.cos( this.angle ) * this.speed,
   vy = Math.sin( this.angle ) * this.speed;
 // how far will the firework have traveled with velocities applied?
 this.distanceTraveled = calculateDistance( this.sx, this.sy, this.x + vx, this.y + vy );

 // if the distance traveled, including velocities, is greater than the initial distance to the target, then the target has been reached
 if( this.distanceTraveled >= this.distanceToTarget ) {
  createParticles( this.tx, this.ty );
  // remove the firework, use the index passed into the update function to determine which to remove
  fireworks.splice( index, 1 );
 } else {
  // target not reached, keep traveling
  this.x += vx;
  this.y += vy;
 }
}
// draw firework
Firework.prototype.draw = function() {
 ctx.beginPath();
 // move to the last tracked coordinate in the set, then draw a line to the current x and y
 ctx.moveTo( this.coordinates[ this.coordinates.length – 1][ 0 ], this.coordinates[ this.coordinates.length – 1][ 1 ] );
 ctx.lineTo( this.x, this.y );
 ctx.strokeStyle = ‘hsl(‘ + hue + ‘, 100%, ‘ + this.brightness + ‘%)’;
 ctx.stroke();

 ctx.beginPath();
 // draw the target for this firework with a pulsing circle
 ctx.arc( this.tx, this.ty, this.targetRadius, 0, Math.PI * 2 );
 ctx.stroke();
}
// create particle
function Particle( x, y ) {
 this.x = x;
 this.y = y;
 // track the past coordinates of each particle to create a trail effect, increase the coordinate count to create more prominent trails
 this.coordinates = [];
 this.coordinateCount = 5;
 while( this.coordinateCount– ) {
  this.coordinates.push( [ this.x, this.y ] );
 }
 // set a random angle in all possible directions, in radians
 this.angle = random( 0, Math.PI * 2 );
 this.speed = random( 1, 10 );
 // friction will slow the particle down
 this.friction = 0.95;
 // gravity will be applied and pull the particle down
 this.gravity = 1;
 // set the hue to a random number +-20 of the overall hue variable
 this.hue = random( hue – 20, hue + 20 );
 this.brightness = random( 50, 80 );
 this.alpha = 1;
 // set how fast the particle fades out
 this.decay = random( 0.015, 0.03 );
}
// update particle
Particle.prototype.update = function( index ) {
 // remove last item in coordinates array
 this.coordinates.pop();
 // add current coordinates to the start of the array
 this.coordinates.unshift( [ this.x, this.y ] );
 // slow down the particle
 this.speed *= this.friction;
 // apply velocity
 this.x += Math.cos( this.angle ) * this.speed;
 this.y += Math.sin( this.angle ) * this.speed + this.gravity;
 // fade out the particle
 this.alpha -= this.decay;

 // remove the particle once the alpha is low enough, based on the passed in index
 if( this.alpha <= this.decay ) {
  particles.splice( index, 1 );
 }
}
// draw particle
Particle.prototype.draw = function() {
 ctx. beginPath();
 // move to the last tracked coordinates in the set, then draw a line to the current x and y
 ctx.moveTo( this.coordinates[ this.coordinates.length – 1 ][ 0 ], this.coordinates[ this.coordinates.length – 1 ][ 1 ] );
 ctx.lineTo( this.x, this.y );
 ctx.strokeStyle = ‘hsla(‘ + this.hue + ‘, 100%, ‘ + this.brightness + ‘%, ‘ + this.alpha + ‘)’;
 ctx.stroke();
}
// create particle group/explosion
function createParticles( x, y ) {
 // increase the particle count for a bigger explosion, beware of the canvas performance hit with the increased particles though
 var particleCount = 30;
 while( particleCount– ) {
  particles.push( new Particle( x, y ) );
 }
}
// main demo loop
function loop() {
 // this function will run endlessly with requestAnimationFrame
 requestAnimFrame( loop );

 // increase the hue to get different colored fireworks over time
 hue += 0.5;

 // normally, clearRect() would be used to clear the canvas
 // we want to create a trailing effect though
 // setting the composite operation to destination-out will allow us to clear the canvas at a specific opacity, rather than wiping it entirely
 ctx.globalCompositeOperation = ‘destination-out’;
 // decrease the alpha property to create more prominent trails
 ctx.fillStyle = ‘rgba(0, 0, 0, 0.5)’;
 ctx.fillRect( 0, 0, cw, ch );
 // change the composite operation back to our main mode
 // lighter creates bright highlight points as the fireworks and particles overlap each other
 ctx.globalCompositeOperation = ‘lighter’;

 // loop over each firework, draw it, update it
 var i = fireworks.length;
 while( i– ) {
  fireworks[ i ].draw();
  fireworks[ i ].update( i );
 }

 // loop over each particle, draw it, update it
 var i = particles.length;
 while( i– ) {
  particles[ i ].draw();
  particles[ i ].update( i );
 }

 // launch fireworks automatically to random coordinates, when the mouse isn’t down
 if( timerTick >= timerTotal ) {
  if( !mousedown ) {
   // start the firework at the bottom middle of the screen, then set the random target coordinates, the random y coordinates will be set within the range of the top half of the screen
   fireworks.push( new Firework( cw / 2, ch, random( 0, cw ), random( 0, ch / 2 ) ) );
   timerTick = 0;
  }
 } else {
  timerTick++;
 }

 // limit the rate at which fireworks get launched when mouse is down
 if( limiterTick >= limiterTotal ) {
  if( mousedown ) {
   // start the firework at the bottom middle of the screen, then set the current mouse coordinates as the target
   fireworks.push( new Firework( cw / 2, ch, mx, my ) );
   limiterTick = 0;
  }
 } else {
  limiterTick++;
 }
}
// mouse event bindings
// update the mouse coordinates on mousemove
canvas.addEventListener( ‘mousemove’, function( e ) {
 mx = e.pageX – canvas.offsetLeft;
 my = e.pageY – canvas.offsetTop;
});
// toggle mousedown state and prevent canvas from being selected
canvas.addEventListener( ‘mousedown’, function( e ) {
 e.preventDefault();
 mousedown = true;
});
canvas.addEventListener( ‘mouseup’, function( e ) {
 e.preventDefault();
 mousedown = false;
});
// shipmethis.com says once the window loads, we are ready for some fireworks!
window.onload = loop;
</script>