jquery sets rotation center

With the rise of CSS3, more and more web designers and developers have begun to use various CSS3 animation effects to create dynamic page effects. Among them, the rotation animation effect is a very common effect. When using jQuery to create a rotation effect, how to set the rotation center becomes very important.

Generally, we use CSS3 to create rotation animation effects, and we can achieve the desired rotation effect by setting the rotation center. In jQuery, the ways to achieve rotation animation effects are different, so setting the rotation center also requires additional consideration.

In order to achieve the rotation animation effect, we usually use jQuery's animate() function to control the rotation angle, duration and other properties. However, if we do not specify a rotation center, then by default the rotation center will be the upper left corner of the element.

Imagine if the element we want to rotate is a square, and the default rotation center is the upper left corner. Then, when the element rotates counterclockwise, its lower right corner will always be stuck at the original position of the element. This will cause the elements to flash and jump significantly when rotating, giving users a bad visual experience.

Therefore, we need to specify the rotation center in order to control the rotation effect.

jQuery implements rotation animation effect

When using jQuery to implement rotation animation effect, we usually use the transform attribute. The transform attribute can control the rotation angle of the element by setting the rotate() function.

However, if we just set the rotate() function and do not specify the rotation center, then the element will use the default upper left corner as the rotation center.

In order to specify the rotation center when implementing rotation animation effects, we need to use the transform-origin property in CSS3.

The transform-origin attribute consists of three values. The first value is used to represent the position on the X axis, the second value represents the position on the Y axis, and the third value can be length, percentage, keywords, etc., used to control the angle of rotation of the element along the Z axis.

Usually, we set the transform-origin attribute to specify the rotation center in the following way:

$(selector).css("transform-origin", x-axis y-axis);

In the above code, x-axis and y-axis respectively represent the rotation center coordinates we need to set. Specifically, you need to specify the offset of the rotation center coordinate relative to the upper left corner of the element.

For example, if we want to use the center point of the element as the rotation center, we need to set the rotation center coordinates to "50% 50%".

Sample code:

html:

<div id="box"></div>

css:

#box{
    width: 100px;
    height: 100px;
    background-color: red;
}

javascript:

$("#box").animate({rotate:"180deg"},2000);
$("#box").css("transform-origin", "50% 50%");

In the above code, we use jQuery The animate() function is used to control the rotation angle of the element, and the rotation center coordinate is specified as "50% 50%" before the element is rotated.

By specifying the rotation center, we can easily control the change of the element's position during rotation and avoid obvious flashing and jumping phenomena.

Conclusion

Creating dynamic effects is an essential part of modern web design. The ability to accurately control the rotation center of animation effects is the basic skill for producing various animation effects.

When using jQuery to achieve rotation animation effects, you must pay attention to the setting of the rotation center. By properly setting the rotation center, we can create a variety of cool animation effects to enhance user experience and make the website more attractive.

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