Improving performance with responsive (and responsible!) images [CSSConf]

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David Newton, St. Michael’s Hospital 1 Improving performance with responsive (and responsible!) images CSSConf, 2015-06-18 Twitter: @newtron Github: @nwtn Email: david@davidnewton.ca Slides: http://nwtn.ca/b

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2 Web performance

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“ 3 Many of us are fortunate to live in high bandwidth regions, but there are still large portions of the world that do not. By keeping your client side code small and lightweight, you can literally open your product up to new markets. —Chris Zacharias, Page Weight Matters (emphasis mine)

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“ 4 Good performance is good design. —Brad Frost

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5 Why images?

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6 —Marc Andreessen, www-talk, February 1993

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7 Fonts 98 KB Stylesheets 63 KB Video 208 KB HTML 55 KB Scripts 334 KB Other 4 KB Images 1,312 KB Total: 2,061 KB

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“ 9 More human beings today have access to a cellphone than…a clean toilet. –Anand Giridharadas, New York Times April 10 2010

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11 — OpenSignal, Android Fragmentation Visualized (August 2014)

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12 —https://twitter.com/lukew/status/507880029737328640/photo/1

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13 A problem: We want images to look good e’rywhere

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14 img { max-width: 100%; }

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18 A solution: Serve one big image and let the browser scale it

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21 Bullet 1 Bullet 2 Bullet 3

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22 Bullet 1 Bullet 2 Bullet 3

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24 more pixels = more energy more pixels = more memory more pixels = more time

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25 A problem: We want images to look good e’rywhere

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26 A harder problem: We want images to look good e’rywhere, without hurting the user experience

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27 Responsive images

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28 A solution: Serve one big image and let the browser scale it

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29 A better solution: Serve an appropriate image to each user

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33 SVG WebP JPEG XR JPEG 2000

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35 Using CSS is a bad idea.

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36 Using JavaScript is a bad idea.

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37 http://whatwg.org/html#the-picture-element Responsive images speciﬁcation

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38 Resolution switching Markup

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38 Resolution switching Markup

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46 Viewport (and resolution!) switching Markup

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60 File type switching Markup

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68 Art direction Markup

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69 —Adventure Time

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78 All the things! Markup a.k.a. the scary slide

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78 All the things! Markup a.k.a. the scary slide

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81 http://whatwg.org/html#the-picture-element Responsive images speciﬁcation

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82 http://codepen.io/Tigt/blog/when-responsive-images-get-ugly When responsive images get ugly

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83 You can use this now!

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84 Firefox (Gecko) Chrome/Opera (Blink) Safari (WebKit) Internet Explorer/ Edge srcset + sizes Works now! Firefox 38 Works now! Chrome 34 Opera 21 Works now! * Safari 6.2 Safari 7.1 iOS 8 In development picture Works now! Firefox 38 Works now! Chrome 38 Opera 25 In development Under consideration

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85 http://picturefill.responsiveimages.org/ Picturefill by Scott Jehl & others http://filamentgroup.com/lab/to-picturefill.html To Picturefill, or not to Picturefill

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86 Responsive images are a pain in the butt

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88 https://www.npmjs.com/package/grunt-respimg grunt-respimg

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89 https://github.com/nwtn/php-respimg/ php-respimg

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90 https://www.npmjs.com/package/grunt- responsive-images-extender/ grunt-responsive-images-extender

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91 https://wordpress.org/plugins/ricg-responsive-images/ WP RICG Responsive Images plugin

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92 Responsible images

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93 1. Responsive images

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94 1. Responsive images 2. Image optimization

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95 https://imageoptim.com/ ImageOptim https://github.com/toy/image_optim image_optim https://github.com/svg/svgo-gui SVGO-GUI https://github.com/svg/svgo SVGO

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96 SetOutputFilter DEFLATE AddOutputFilterByType DEFLATE "image/svg+xml"

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97 1. Responsive images 2. Image optimization 3. Deferred image loading (a.k.a. “lazy loading”)

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100 http://afarkas.github.io/lazysizes/ LazyLoad JS scripts and plugins, e.g.:

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101 1. Responsive images 2. Image optimization 3. Deferred image loading (a.k.a. “lazy loading”) 4. CDNs & Caching

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102 1. Responsive images 2. Image optimization 3. Deferred image loading (a.k.a. “lazy loading”) 4. CDNs & Caching 5. Appropriate contrast and colour

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103 7% 8% 10% 11% 29% 35% April May June July August September

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104 7% 8% 10% 11% 29% 35% April May June July August September

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105

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106 http://colororacle.org/ Color Oracle

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107 September 7% August 8% July 10% June 11% May 29% April 35%

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108 1. Responsive images 2. Image optimization 3. Deferred image loading (a.k.a. “lazy loading”) 4. CDNs & Caching 5. Appropriate contrast and colour 6. Text-based alternatives

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109 [alt] [aria-describedby], [aria-labelledby] [longdesc] SVG elements and attributes

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110 http://www.w3.org/TR/html-alt-techniques/ HTML5: Techniques for providing useful text alternatives http://www.w3.org/WAI/GL/wiki/Using_aria-describedby_to_provide_descriptions_of_images Using aria-describedby to provide descriptions of images http://w3c.github.io/test-results/html-longdesc/cr-report.html longdesc Implementation Report http://www.paciellogroup.com/blog/2013/12/using-aria-enhance-svg-accessibility/ Using ARIA to enhance SVG accessibility http://www.w3.org/WAI/GL/wiki/Using_aria-labelledby_to_provide_a_text_alternative_for_non- text_content Using aria-labelledby to provide a text alternative for non-text content

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111 1. Responsive images 2. Image optimization 3. Deferred image loading (a.k.a. “lazy loading”) 4. CDNs & Caching 5. Appropriate contrast and colour 6. Text-based alternatives 7. Fewer images!

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“ 112 Good performance is good design. —Brad Frost

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David Newton, St. Michael’s Hospital 113 Improving performance with responsive (and responsible!) images CSSConf, 2015-06-18 Twitter: @newtron Github: @nwtn Email: david@davidnewton.ca Slides: http://nwtn.ca/b