Table of content

|Read No. | Name of chapter| |:———: |:————–:| |14a|Transforms| |14a|Transitions & Animations|

# Transforms

Transform Syntax

The actual syntax for the transform property is quite simple, including the transform property followed by the value. The value specifies the transform type followed by a specific amount inside parentheses.

2D Transforms

Elements may be distorted, or transformed, on both a two-dimensional plane or a three-dimensional plane. Two-dimensional transforms work on the x and y axes, known as horizontal and vertical axes. Three-dimensional transforms work on both the x and y axes, as well as the z axis. These three-dimensional transforms help define not only the length and width of an element.

2D Rotate

The transform property accepts a handful of different values. The rotate value provides the ability to rotate an element from 0 to 360 degrees. Using a positive value will rotate an element clockwise, and using a negative value will rotate the element counterclockwise. The default point of rotation is the center of the element, 50% 50%, both horizontally and vertically.

2D Scale

Using the scale value within the transform property allows you to change the appeared size of an element. The default scale value is 1, therefore any value between .99 and .01 makes an element appear smaller while any value greater than or equal to 1.01 makes an element appear larger.

It is possible to scale only the height or width of an element using the scaleX and scaleY values. The scaleX value will scale the width of an element while the scaleY value will scale the height of an element. To scale both the height and width of an element but at different sizes, the x and y axis values may be set simultaneously. To do so, use the scale transform declaring the x axis value first, followed by a comma, and then the y axis value.

2D Translate

The translate value works a bit like that of relative positioning, pushing and pulling an element in different directions without interrupting the normal flow of the document. Using the translateX value will change the position of an element on the horizontal axis while using the translateY value will change the position of an element on the vertical axis.As with the scale value, to set both the x and y axis values at once, use the translate value and declare the x axis value first, followed by a comma, and then the y axis value.

2D Skew

The last transform value in the group, skew, is used to distort elements on the horizontal axis, vertical axis, or both. The syntax is very similar to that of the scale and translate values. Using the skewX value distorts an element on the horizontal axis while the skewY value distorts an element on the vertical axis. To distort an element on both axes the skew value is used, declaring the x axis value first, followed by a comma, and then the y axis value.

Combining Transforms

It is common for multiple transforms to be used at once, rotating and scaling the size of an element at the same time for example. In this event multiple transforms can be combined together. To combine transforms, list the transform values within the transform property one after the other without the use of commas.

Transform Origin

The transform-origin property can accept one or two values. When only one value is specified, that value is used for both the horizontal and vertical axes. If two values are specified, the first is used for the horizontal axis and the second is used for the vertical axis. Individually the values are treated like that of a background image position, using either a length or keyword value. That said, 0 0 is the same value as top left, and 100% 100% is the same value as bottom right. More specific values can also be set, for example 20px 50px would set the origin to 20 pixels across and 50 pixels down the element.

Perspective

The perspective of an element can be set in two different ways. One way includes using the perspective value within the transform property on individual elements, while the other includes using the perspective property on the parent element residing over child elements being transformed.

Perspective Depth Value

The perspective value can be set as none or a length measurement. The none value turns off any perspective, while the length value will set the depth of the perspective. The higher the value, the further away the perspective appears, thus creating a fairly low intensity perspective and a small three-dimensional change. The lower the value the closer the perspective appears, thus creating a high intensity perspective and a large three-dimensional change.

3D Transforms

Working with two-dimensional transforms we are able to alter elements on the horizontal and vertical axes, however there is another axis along which we can transform elements. Using three-dimensional transforms we can change elements on the z axis, giving us control of depth as well as length and width.

3D Rotate

So far we’ve discussed how to rotate an object either clockwise or counterclockwise on a flat plane. With three-dimensional transforms we can rotate an element around any axes. To do so, we use three new transform values, including rotateX, rotateY, and rotateZ.

3D Scale

By using the scaleZ three-dimensional transform elements may be scaled on the z axis. This isn’t extremely exciting when no other three-dimensional transforms are in place, as there is nothing in particular to scale. In the demonstration below the elements are being scaled up and down on the z axis, however the rotateX value is added in order to see the behavior of the scaleZ value. When removing the rotateX in this case, the elements will appear to be unchanged.

Transform Style

On occasion three-dimensional transforms will be applied on an element that is nested within a parent element which is also being transformed. In this event, the nested, transformed elements will not appear in their own three-dimensional space. To allow nested elements to transform in their own three-dimensional plane use the transform-style property with the preserve-3d value.The transform-style property needs to be placed on the parent element, above any nested transforms. The preserve-3d value allows the transformed children elements to appear in their own three-dimensional plane while the flat value forces the transformed children elements to lie flat on the two-dimensional plane.

Backface Visibility

When working with three-dimensional transforms, elements will occasionally be transformed in a way that causes them to face away from the screen. This may be caused by setting the rotateY(180deg) value for example. By default these elements are shown from the back. So if you prefer not to see these elements at all, set the backface-visibility property to hidden, and you will hide the element whenever it is facing away from the screen. The other value to backface-visibility is visible which is the default value, always displaying an element, no matter which direction it faces.

Transitions & Animations

Transitions

There are four transition related properties in total, including transition-property, transition-duration, transition-timing-function, and transition-delay. Not all of these are required to build a transition, with the first three are the most popular.

Transitional Property

The transition-property property determines exactly what properties will be altered in conjunction with the other transitional properties. By default, all of the properties within an element’s different states will be altered upon change. However, only the properties identified within the transition-property value will be affected by any transitions.

Transition Duration

The duration in which a transition takes place is set using the transition-duration property. The value of this property can be set using general timing values, including seconds (s) and milliseconds (ms). These timing values may also come in fractional measurements, .2s for example.

Transition Timing

The transition-timing-function property is used to set the speed in which a transition will move. Knowing the duration from the transition-duration property a transition can have multiple speeds within a single duration. A few of the more popular keyword values for the transition-timing-function property include linear, ease-in, ease-out, and ease-in-out. The linear keyword value identifies a transition moving in a constant speed from one state to another. The ease-in value identifies a transition that starts slowly and speeds up throughout the transition, while the ease-out value identifies a transition that starts quickly and slows down throughout the transition. The ease-in-out value identifies a transition that starts slowly, speeds up in the middle, then slows down again before ending.

Transition Delay

On top of declaring the transition property, duration, and timing function, you can also set a delay with the transition-delay property. The delay sets a time value, seconds or milliseconds, that determines how long a transition should be stalled before executing. As with all other transition properties, to delay numerous transitions, each delay can be declared as comma separated values.

Animations

Transitions do a great job of building out visual interactions from one state to another, and are perfect for these kinds of single state changes. However, when more control is required, transitions need to have multiple states. In return, this is where animations pick up where transitions leave off.

Animations Keyframes

To set multiple points at which an element should undergo a transition, use the @keyframes rule. The @keyframes rule includes the animation name, any animation breakpoints, and the properties intended to be animated.

The animation is named slide, stated directly after the opening @keyframes rule. The different keyframe breakpoints are set using percentages, starting at 0% and working to 100% with an intermediate breakpoint at 50%. The keywords from and to could be used in place of 0% and 100% if wished. Additional breakpoints, besides 50%, may also be stated. The element properties to be animated are listed inside each of the breakpoints, left and top .

It is important to note, as with transitions only individual properties may be animated. Consider how you might move an element from top to bottom for example. Trying to animate from top: 0; to bottom: 0; will not work, because animations can only apply a transition within a single property, not from one property to another. In this case, the element will need to be animated from top: 0; to top: 100%;.

Animation Name

Once the keyframes for an animation have been declared they need to be assigned to an element. To do so, the animation-name property is used with the animation name, identified from the @keyframes rule, as the property value. The animation-name declaration is applied to the element in which the animation is to be applied to.

Animation Duration, Timing Function, & Delay

Once you have declared the animation-name property on an element, animations behave similarly to transitions. They include a duration, timing function, and delay if desired. To start, animations need a duration declared using the animation-duration property. As with transitions, the duration may be set in seconds or milliseconds.

A timing function and delay can be declared using the animation-timing-function and animation-delay properties respectively. The values for these properties mimic and behave just as they do with transitions.

Customizing Animations

nimations also provide the ability to further customize an element’s behavior, including the ability to declare the number of times an animation runs, as well as the direction in which an animation completes.

Animation Iteration

By default, animations run their cycle once from beginning to end and then stop. To have an animation repeat itself numerous times the animation-iteration-count property may be used. Values for the animation-iteration-count property include either an integer or the infinite keyword. Using an integer will repeat the animation as many times as specified, while the infinite keyword will repeat the animation indefinitely in a never ending fashion.

Animation Direction

On top of being able to set the number of times an animation repeats, you may also declare the direction an animation completes using the animation-direction property. Values for the animation-direction property include normal, reverse, alternate, and alternate-reverse.

The normal value plays an animation as intended from beginning to end. The reverse value will play the animation exactly opposite as identified within the @keyframes rule, thus starting at 100% and working backwards to 0%.

The alternate value will play an animation forwards then backwards. Within the keyframes that includes running forward from 0% to 100% and then backwards from 100% to 0%. Using the animation-iteration-count property may limit the number of times an animation runs both forwards and backwards. The count starts at 1 running an animation forwards from 0% to 100%, then adds 1 running an animation backwards from 100% to 0%. Combining for a total of 2 iterations. The alternate value also inverses any timing functions when playing in reverse. If an animation uses the ease-in value going from 0% to 100%, it then uses the ease-out value going from 100% to 0%.

Lastly, the alternate-reverse value combines both the alternate and reverse values, running an animation backwards then forwards. The alternate-reverse value starts at 100% running to 0% and then back to 100% again.

Animation Play State

The animation-play-state property allows an animation to be played or paused using the running and paused keyword values respectively. When you play a paused animation, it will resume running from its current state rather than starting from the very beginning again.

Animation Fill Mode

The animation-fill-mode property identifies how an element should be styled either before, after, or before and after an animation is run. The animation-fill-mode property accepts four keyword values, including none, forwards, backwards, and both.

The none value will not apply any styles to an element before or after an animation has been run.

The forwards value will keep the styles declared within the last specified keyframe. These styles may, however, be affected by the animation-direction and animation-iteration-count property values, changing exactly where an animation ends.

The backwards value will apply the styles within the first specified keyframe as soon as being identified, before the animation has been run. This does include applying those styles during any time that may be set within an animation delay. The backwards value may also be affected by the animation-direction property value.

Lastly, the both value will apply the behaviors from both the forwards and backwards values.