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Created May 20, 2013 14:27
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A CodePen by Oscar Chinellato. JQuery KenBurns Effect with fade in - Based on Will MacGugan's jQuery kenBurns plugin, this adds a fade in to the first image displayed.
Raw
index.html
<html>
<head>
<title>KenBurns Test</title>
</head>
<body>
<canvas id="kenburns"></canvas>
</body>
</html>
Raw
script.js
/*
Ken Burns effect JQuery plugin
Copyright (C) 2011 Will McGugan http://www.willmcgugan.com
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
(function($){
$.fn.kenburns = function(options) {
var $canvas = $(this);
var ctx = this[0].getContext('2d');
var start_time = null;
var width = $canvas.width();
var height = $canvas.height();
var image_paths = options.images;
var display_time = options.display_time || 7000;
var fade_time = Math.min(display_time / 2, options.fade_time || 1000);
var solid_time = display_time - (fade_time * 2);
var fade_ratio = fade_time - display_time;
var frames_per_second = options.frames_per_second || 30;
var frame_time = (1 / frames_per_second) * 1000;
var zoom_level = 1 / (options.zoom || 2);
var clear_color = options.background_color || '#000000';
var load_counter = 0;
var images = [];
$(image_paths).each(function(i, image_path){
images.push({
path:image_path,
initialized:false,
loaded:false
});
});
function get_time() {
var d = new Date();
return d.getTime() - start_time;
}
function interpolate_point(x1, y1, x2, y2, i) {
// Finds a point between two other points
return {x: x1 + (x2 - x1) * i,
y: y1 + (y2 - y1) * i}
}
function interpolate_rect(r1, r2, i) {
// Blend one rect in to another
var p1 = interpolate_point(r1[0], r1[1], r2[0], r2[1], i);
var p2 = interpolate_point(r1[2], r1[3], r2[2], r2[3], i);
return [p1.x, p1.y, p2.x, p2.y];
}
function scale_rect(r, scale) {
// Scale a rect around its center
var w = r[2] - r[0];
var h = r[3] - r[1];
var cx = (r[2] + r[0]) / 2;
var cy = (r[3] + r[1]) / 2;
var scalew = w * scale;
var scaleh = h * scale;
return [cx - scalew/2,
cy - scaleh/2,
cx + scalew/2,
cy + scaleh/2];
}
function fit(src_w, src_h, dst_w, dst_h) {
// Finds the best-fit rect so that the destination can be covered
var src_a = src_w / src_h;
var dst_a = dst_w / dst_h;
var w = src_h * dst_a;
var h = src_h;
if (w > src_w)
{
var w = src_w;
var h = src_w / dst_a;
}
var x = (src_w - w) / 2;
var y = (src_h - h) / 2;
return [x, y, x+w, y+h];
}
function get_image_info(image_index, load_callback) {
// Gets information structure for a given index
// Also loads the image asynchronously, if required
var image_info = images[image_index];
if (!image_info.initialized) {
var image = new Image();
image_info.image = image;
image_info.loaded = false;
image.onload = function(){
image_info.loaded = true;
var iw = image.width;
var ih = image.height;
var r1 = fit(iw, ih, width, height);;
var r2 = scale_rect(r1, zoom_level);
var align_x = Math.floor(Math.random() * 3) - 1;
var align_y = Math.floor(Math.random() * 3) - 1;
align_x /= 2;
align_y /= 2;
var x = r2[0];
r2[0] += x * align_x;
r2[2] += x * align_x;
var y = r2[1];
r2[1] += y * align_y;
r2[3] += y * align_y;
if (image_index % 2) {
image_info.r1 = r1;
image_info.r2 = r2;
}
else {
image_info.r1 = r2;
image_info.r2 = r1;
}
if(load_callback) {
load_callback();
}
}
image_info.initialized = true;
image.src = image_info.path;
}
return image_info;
}
function render_image(image_index, anim, fade) {
// If rendering first image
if(++load_counter === 1) {
$canvas.hide().fadeIn(2000, function() {});
}
// Renders a frame of the effect
if (anim > 1) {
return;
}
var image_info = get_image_info(image_index);
if (image_info.loaded) {
var r = interpolate_rect(image_info.r1, image_info.r2, anim);
var transparency = Math.min(1, fade);
if (transparency > 0) {
ctx.save();
ctx.globalAlpha = Math.min(1, transparency);
ctx.drawImage(image_info.image, r[0], r[1], r[2] - r[0], r[3] - r[1], 0, 0, width, height);
ctx.restore();
}
}
}
function clear() {
// Clear the canvas
ctx.save();
ctx.globalAlpha = 1;
ctx.fillStyle = clear_color;
ctx.fillRect(0, 0, ctx.canvas.width, ctx.canvas.height);
ctx.restore();
}
function update() {
// Render the next frame
var update_time = get_time();
var top_frame = Math.floor(update_time / (display_time - fade_time));
var frame_start_time = top_frame * (display_time - fade_time);
var time_passed = update_time - frame_start_time;
function wrap_index(i) {
return (i + images.length) % images.length;
}
if (time_passed < fade_time)
{
var bottom_frame = top_frame - 1;
var bottom_frame_start_time = frame_start_time - display_time + fade_time;
var bottom_time_passed = update_time - bottom_frame_start_time;
if (update_time < fade_time) {
clear();
} else {
render_image(wrap_index(bottom_frame), bottom_time_passed / display_time, 1);
}
}
render_image(wrap_index(top_frame), time_passed / display_time, time_passed / fade_time);
if (options.post_render_callback) {
options.post_render_callback($canvas, ctx);
}
// Pre-load the next image in the sequence, so it has loaded
// by the time we get to it
var preload_image = wrap_index(top_frame + 1);
get_image_info(preload_image);
}
// Pre-load the first two images then start a timer
get_image_info(0, function(){
start_time = get_time();
setInterval(update, frame_time);
});
};
})( jQuery );
$(document).ready(function() {
var the_slides = new Array(
"http://coolsmswallpapers.files.wordpress.com/2011/03/wallpaper.jpg",
"http://3.bp.blogspot.com/-Nnv9R3vWzow/UGUemRaIJFI/AAAAAAAAHd4/zRW_IbFhb3A/s1600/Nature-wallpaper-85.jpg"
);
$('#kenburns').attr('width', $(window).width());
$('#kenburns').attr('height', $(window).height());
$('#kenburns').kenburns({
images: the_slides,
frames_per_second: 24,
display_time: 8000,
fade_time: 2000
});
});
Raw
style.css
html, body {
margin: 0;
padding: 0;
}
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