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How to lie,
cheat and steal
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@polarblau
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How to lie,
cheat and steal
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Ruby 2.0
Rails 4.0
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http://blog.airbrake.io/guest-post/exploring-everything/
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How does it work?
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Not well …
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ctx = $($canvas).get(0).getContext('2d')
preview = $($preview).get(0)
localMediaStream = null
start = null
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start: ->
start = (new Date).getTime()
started = true
isStarted: ->
started? and started
stop: ->
started = false
isStopped: ->
started == false
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success = (stream) =>
preview.src = window.URL.createObjectURL(stream)
localMediaStream = stream
preview.addEventListener 'loadeddata', capture
error = ->
console.error arguments
navigator.getUserMedia video: true, success, error
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capture: =>
ctx.drawImage(preview, 0, 0) if localMediaStream?
now = (new Date).getTime()
pixels = ctx.getImageData(0, 0, WIDTH, HEIGHT).data
timestamp = now - start
createFrame(pixels, timestamp)
requestAnimationFrame capture unless isStopped()
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v
[red, green, blue, alpha]
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createFrame = (pixels, timestamp) ->
intensity = 0
intensity += pixel for pixel in pixels by 4 when pixel?
{ intensity: intensity, timestamp: timestamp }
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v
[red, green, blue, alpha]
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86
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window.URL ?= window.webkitURL
window.requestAnimationFrame ?=
window.webkitRequestAnimationFrame
navigator.getUserMedia ?= navigator.webkitGetUserMedia
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Server
Client
Request
Response
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Server
Request
Response
Browser
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Server
Request
Response
Browser
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Can it run Crysis?
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crack = (hash, maxLength = 10, charset) ->
charset ?= (
'abcdefghijklmnopqrstuvwxyz' +
'ABCDEFGHIJKLMNOPQRSTUVWXYZ' +
'0123456789'
).split('')
stack = ['']
for [1..maxLength]
buffer = []
for item in stack
for character in charset
word = item + character
if md5(word) == hash
return word
else
buffer.push word
stack = stack.concat buffer
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hash = '3858f62230ac3c915f300c664312c63f' # "foobar"
crack(hash)
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def crack(hash, max_length = 10, charset = nil)
charset ||= (
'abcdefghijklmnopqrstuvwxyz' +
'ABCDEFGHIJKLMNOPQRSTUVWXYZ' +
'0123456789'
).split('')
stack = ['']
max_length.times do
buffer = []
for item in stack
for character in charset
word = item + character
if Digest::MD5.hexdigest(word) == hash
return word
else
buffer << word
end
end
end
stack = stack + buffer
end
end
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Javascript Ruby
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v
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Square one
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Try to solve problems
closer to the GUI
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url = window.URL || window.webkitURL
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# Creates a new object URL.
window.URL.createObjectURL()
# Revokes an object URL previously created
window.URL.revokeObjectURL()
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video = document.createElement 'video')
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$('#source').on 'change', ->
src = url.createObjectURL(@files[0])
video.src = src
video.autoplay = false
video.load()
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THUMBNAILSIZE = 0.25
$(video).on 'canplaythrough', ->
width = video.videoWidth * THUMBNAILSIZE
height = video.videoHeight * THUMBNAILSIZE
extractFrame(video, width, height)
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step = 1 # extract a frame every on second
extractFrame = (video, width, height, time = 0) ->
video.currentTime = time
$(video).one 'seeked', ->
ctx = createAndInsertCanvas(width, height)
ctx.drawImage(video, 0, 0, width, height)
time += step
if time < video.duration
extractFrame(video, width, height, time)
else
$('#output')
.show()
.on('mousemove', scrub)
.find('canvas:not(:last)')
.hide()
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$output = $('#output')
outputOffset = $output.offset().left
outputWidth = $output.width()
pages = $output.find('canvas')
pageCount = pages.length
stepSize = outputWidth / (pageCount - 1)
scrub = (e) ->
page = Math.round((e.pageX - outputOffset) / stepSize)
pages.hide().eq(page).show()
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Potential issues —
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Potential issues —
Video format
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Potential issues —
Video format
Canvas support
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Potential issues —
Video format
Canvas support
Javascript support
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width = $image.data('width')
height = $image.data('height')
src = $image.attr('src')
$canvas = $('')
$canvas.attr(width: width, height: height)
ctx = $canvas.get(0).getContext('2d')
image = new Image()
image.onload = ->
ratio = if width > height then height / width
else height / height
[sWidth, sHeight] = if width > height
[@width, @width * ratio]
else
[@height * ratio, @height]
ctx.drawImage(@, 0, 0, sWidth, sHeight,
0, 0, width, height)
$image.replaceWith $canvas
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ctx.drawImage(
image, # image object
sx, # crop positition
sy, #
sWidth, # crop size
sHeight, #
dx, # target position
dy, #
dWidth, # target size
dHeight #
)
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$('img.resize').resize()
$('img.resize').resize(gravity: 'ne', zoom: false)
# resize, crop if necessary to maintain aspect ratio
# north-east gravity
$('img.resize').resize('400x300#ne')
# resize only if the image is smaller than this
$('img.resize').resize('400x300<')
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Potential issues —
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Potential issues —
Canvas support
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Potential issues —
Canvas support
Javascript support
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But, can it run Crysis?
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ORANGE
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v
[red, green, blue, alpha]
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createFrame = (pixels, timestamp) ->
intensity = 0
intensity += pixel for pixel in pixels by 4 when pixel?
{ intensity: intensity, timestamp: timestamp }
&
requestAnimationFrame capture unless isStopped()
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Web Workers
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ORANGE
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Orange = require 'orange'
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set = new Orange.JobSet
set.on 'complete', ->
console.log 'All done'
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job = new Orange.Job 'calculate_intensity',
pixels : pixels
timestamp: timestamp
job.on 'complete', (data) =>
console.log data.intensity
job.perform()
# or run whole set at once
set.push(job)
set.perform()
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self.onmessage = (event) ->
[type, data] = [event.data.type, event.data.data]
switch type
when 'perform'
intensity = 0
intensity += pixel for pixel in data.pixels by 4 ↵
when pixel?
self.postMessage
type: 'complete'
data:
intensity: intensity
timestamp: data.timestamp
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The Future —
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The Future —
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The Future —
Worker API
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The Future —
Worker API
Persistent jobs (?)
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The Future —
Worker API
Persistent jobs (?)
Worker class shim
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The Future —
Worker API
Persistent jobs (?)
Worker class shim
Queue interface
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The Future —
Worker API
Persistent jobs (?)
Worker class shim
Queue interface
Custom events
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The Future —
Worker API
Persistent jobs (?)
Worker class shim
Queue interface
Custom events
Job retry
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The Future —
Worker API
Persistent jobs (?)
Worker class shim
Queue interface
Custom events
Job retry
Error handling
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Why not?
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Fundamental lack of trust
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window.onbeforeunload = ->
'Are you sure you want to leave?'
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Local storage
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Shims / Shivs
https://github.com/Modernizr/Modernizr/wiki/
HTML5-Cross-Browser-Polyfills
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Dziękuję!
Thanks!