1 Introduction
CSS animations can add vivid interactive effects to websites. In CSS3, the @keyframes rule was introduced to define keyframes and property values for CSS animations. @keyframes rules provide a very powerful and flexible tool, allowing developers to control the details of animation to create various types of animation effects. In this article, we’ll take a deep dive into the @keyframes rule and see how you can use it to create various types of animations.
2: What are @keyframes rules?
In CSS, the @keyframes rule is used to define animation keyframes and property values. Keyframes are important points in time in an animation that define the state of an element and how long that state should last. In a @keyframes rule, you can define any number of keyframes, and each keyframe can set any number of CSS properties.
The @keyframes rule is a CSS rule that allows you to define animations and apply them to HTML elements. Like other CSS rules, @keyframes rules also follow the cascading and inheritance properties of CSS. This means you can use multiple @keyframes rules in your CSS code and combine them with other CSS rules to create complex animation effects.
3: How to use @keyframes rules
To create animations you need to use two keywords: @keyframes and animation. @keyframes is used to define the keyframes and attribute values of the animation, while animation is used to apply animation to HTML elements.
Here is an example of using @keyframes and animation to create animations:
@keyframes myAnimation {
from {
background-color: red; }
to {
background-color: yellow; }
}
.element {
animation: myAnimation 2s linear infinite;
}
In the code above, we define a @keyframes rule called myAnimation. This rule defines a background color change from red to yellow. We apply this animation to an HTML element named .element, set the animation duration to 2 seconds, the animation speed to linear, and play in an infinite loop.
In a @keyframes rule, you can define any number of keyframes. Keyframes are defined by percentage values or keywords that represent points in time in the animation. For example, 0% represents the beginning of the animation, and 100% represents the end of the animation.
Here is an example @keyframes rule defining four keyframes:
@keyframes myAnimation {
0% {
transform: scale(1); }
25% {
transform: scale(1.2); }
50% {
transform: scale(0.8); }
100% {
transform: scale(1); }
}
In the code above, we define a @keyframes rule called myAnimation. This rule defines four keyframes, which apply different transform attributes at different time points of the animation.
4: Syntax of @keyframes rules
-
Syntax of @keyframes rule:
- keyword@keyframes
- Animation name
- A set of keyframes defined by percentage values or keywords
- Each keyframe contains the CSS properties and property values to be set.
Here is the basic syntax of the @keyframes rule:
@keyframes animationName {
0% {
/* CSS属性和属性值 */
}
50% {
/* CSS属性和属性值 */
}
100% {
/* CSS属性和属性值 */
}
}
In the above code, we define an animation named animationName. The animation has different CSS properties and property values at 0%, 50% and 100% of the time. In actual development, you can define any number of keyframes and any number of CSS properties and property values in each keyframe.
5: Apply animation using animation attribute
After defining the @keyframes rules, we can apply animations to HTML elements using the animation attribute. The animation property contains multiple sub-properties, as shown below:
- animation-name: Specifies the name of the animation to be applied
- animation-duration: Specify the duration of the animation
- animation-timing-function: Specify the speed curve of the animation
- animation-delay: Specify the delay time before the animation starts
- animation-iteration-count: Specifies the number of times the animation is played
- animation-direction: Specify the direction of animation playback
- animation-fill-mode: Specify the element style before and after animation playback
- animation-play-state: Specify the playback state of animation
Here's an example of using the animation attribute to apply animation to an HTML element:
.element {
animation-name: myAnimation;
animation-duration: 2s;
animation-timing-function: linear;
animation-delay: 1s;
animation-iteration-count: infinite;
animation-direction: alternate;
animation-fill-mode: both;
animation-play-state: running;
}
In the code above, we apply an animation named myAnimation to an HTML element named .element. We set the duration of the animation to 2 seconds, the animation speed to linear, a delay of 1 second to start playing, and an infinite loop. The animation direction is set to alternate playback, that is, forward playback and then reverse playback. The fill mode is set to both, retaining the element style before and after animation. The playback status is set to running, which means the animation is playing.
6: Attention
When using @keyframes rules and animation attributes, you need to pay attention to the following points:
1: Consider browser compatibility: Different browsers may have different levels of support for CSS animations. When using @keyframes rules and animation attributes, you need to test the performance of your code on different browsers and devices to ensure that the animation effect is normal.
2: Consider performance issues: CSS animation may have a certain impact on web page performance. When working with CSS animations, you need to take into account the complexity of the animation and the resources required at runtime. You can improve animation performance through some optimization techniques, such as using hardware acceleration, reducing the number of animated elements, etc.
3: Consider user experience: Animation can add a certain degree of interactivity and vividness to the web page, but too many animation effects may affect the user experience. When using CSS animations, you need to choose animation effects carefully to ensure that they do not have a negative impact on the user experience.
By in-depth understanding of @keyframes rules and animation properties, you can better master the use of CSS animations and create more vivid and rich user interface effects.
7: Summary
In this article, we take a deep dive into the @keyframes rules in CSS. The @keyframes rule is a CSS rule used to define animation keyframes and property values. Using @keyframes rules, developers can create various types of animation effects. In a @keyframes rule, you can define any number of keyframes and set any number of CSS properties and property values in each keyframe.
To apply animation to an HTML element, you need to use the animation attribute and set multiple sub-properties to control the playback of the animation. The animation property contains multiple sub-properties, including animation name, duration, speed curve, delay time, play times, play direction, fill mode and play status. By adjusting these properties, you can create a variety of different types of animation effects.