book

Creating Web Animations

by Kirupa Chinnathambi

March 2017

Beginner

210 pages

English

O'Reilly Media, Inc.

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Know Your Basic HTML, CSS, and JavaScriptAbout Authoring ToolsUsing the Code ExamplesO’Reilly SafariGetting Help/Contacting the AuthorContacting O’ReillyAcknowledgments
What Is an Animation?The Start and End StatesInterpolationAnimations on the WebConclusion
Creating a Simple AnimationWhat Just HappenedThe NameDuration and KeyframesLoopingThe Longhand VersionConclusion
Creating a Simple TransitionWhat Just HappenedThe Longhand VersionConclusion
What Is a Timing Function?Timing Functions in CSSTiming Functions in CSS AnimationsTiming Functions in CSS TransitionsMeet the Timing Function CurveThe cubic-bezier Timing FunctionThe step Timing FunctionConclusion
What Is a Smooth Animation?Creating Responsive 60 fps AnimationsMeet the Animation-Friendly PropertiesPush Element Rendering to the GPUConclusion
It’s Just Property ChangesThe ExampleInitial State Using CSS, Changes Using JSWhat Just Happened?A Tale of Two Styling ApproachesSetting the Style DirectlyAdding and Removing Classes Using JavaScriptAnimating with requestAnimationFrameConclusion
SimilaritiesDifferencesTriggeringLoopingDefining Intermediate Points/KeyframesSpecifying Properties Up FrontInteraction with JavaScriptConclusion

The Starting PointAnimated UnderlineSimple Background Color ChangeCooler Background Color ChangeConclusion
The ExampleThe CSS AnimationThe Easing FunctionConclusion
How the Sliding Menu WorksCreating the Sliding MenuThe Initial PageAdding the MenuMaking the Menu WorkAdding Some Finishing TouchesConclusion
The Basic IdeaThe ContentIt’s Scrolling TimeIdentifying the ElementsModifying the ElementsBuilding It All OutListening to the Scroll EventDetecting When Elements Are VisiblePutting It All TogetherSome Performance ConsiderationsConclusion
The Full HTML and CSSDeconstructing This EffectLooking at the CSSFaking RandomnessSlightly Different Variants of Style Rules + KeyframesAltering Some CSS Properties and Their Values…Inline!Conclusion
Overview of How the Parallax Effect WorksGetting StartedAdding Our Background ElementsThe JavaScriptConclusion
Creating the Sprite SheetThe Actual ImplementationIt’s Animation TimeThe Steps Easing Function in ActionConclusion
Overview of How It WorksThe ContentThe Content (For Realz This Time)What You Just DidClipping the ContentThe Navigation LinksMaking the Content Actually SlideAdding the JavaScriptAdding the TransitionUnderstanding the Code (and More!)What’s Really Going OnThe Role of the data-pos AttributeIt’s All About the JavaScriptConclusion
Until Next Time

Content preview from Creating Web Animations

Chapter 5. Ensuring Your Animations Run Really Smoothly

For the longest time, creating smooth and highly performant animations using only web technologies was very difficult. The browsers were slow, CSS properties weren’t optimized for rapid updates, the graphics card didn’t do much work, you had to walk 15 miles in the snow to get to school, and so on (see Figure 5-1).

You remember those days, right?

Fortunately, nowadays those problems have mostly gone away. While you still might have to walk 15 miles to get to school (in the snow, barefoot, wolves chasing you, etc.), our browsers have gotten really good about helping ensure our animations don’t jitter, lag, tear, or exhibit any other unwanted visual side effects that are jarring to see.

Now, this doesn’t mean we can pack our bags and go home. Our browsers provide you with all the controls to create animations that run well, but you need to know which controls to fiddle with. Don’t worry—that’s where this chapter comes in! In the following sections, you’ll learn how to ensure your animations run really really well.

What Is a Smooth Animation?

Before we start digging into the code, let’s step back for a moment and clarify what we mean by a smooth animation. At a high level, there are three major things smooth animations have going for them: