How to achieve the rotation effect of web photos through front-end technology

With the development of mobile Internet, more and more attention is paid to the visual effects of websites, and the display methods of photos are becoming more and more diverse. Among them, photo rotation is a very common effect, which allows users to view photos more intuitively. This article will introduce how to achieve the rotation effect of web photos through front-end technology.

1. CSS3 to realize photo rotation

CSS3 is an indispensable technology in front-end development, and its powerful animation effects also provide a way to realize photo rotation. The implementation process is as follows:

1. Prepare photos

First, you need to prepare the pictures that need to be rotated and add them to the HTML page, for example:

<img  src="/static/imghwm/default1.png" data-src="photo.jpg" class="lazy" alt="How to achieve the rotation effect of web photos through front-end technology" >

2. CSS Style

In order to achieve photo rotation, you need to set the transform attribute of CSS3. The transform attribute can be used to achieve translation, scaling, rotation and other effects. Specifically, you can use the rotate(deg) function to rotate the photo. where deg represents the angle of rotation, positive values ​​represent clockwise rotation, and negative values ​​represent counterclockwise rotation.

img {
  transition: transform 0.5s ease-in-out;
}
img:hover {
  transform: rotate(90deg);  
}

The above code means that when the mouse hovers over the image, the image will be rotated 90 degrees clockwise. In addition, a transition effect is also set to make the rotation effect smoother.

2. JavaScript to realize photo rotation

If you need to control the photo rotation effect more flexibly, you can use JavaScript to achieve it. The implementation process is as follows:

1. Prepare photos

You also need to prepare the pictures that need to be rotated and add them to the HTML page.

2. JS code

Next, you can write the following JS code to achieve the rotation effect:

var img = document.querySelector('img');
var angle = 0;
function rotate() {
  angle += 90;
  img.style.transform = 'rotate(' + angle + 'deg)';
}
img.onclick = rotate;

The above code defines a rotate() function. When called this time, the photo is rotated 90 degrees clockwise and the angle of rotation is stored in the angle variable. For picture elements, the rotation function is performed through the onclick event.

It should be noted that the above method can only achieve clockwise rotation of the photo. If you need to rotate counterclockwise, just change the sign of the angle variable to a negative number.

3. Expansion: Other implementation methods of photo rotation

In addition to the above two implementation methods, there are other ways to achieve photo rotation effects, such as:

1. Using jQuery plug-ins

jQuery is a widely used JavaScript library with a rich plug-in library. Among them, jquery.rotate.js is a plug-in that implements photo rotation.

2. Using canvas

HTML5 adds a new canvas tag, which can achieve many animation effects. In canvas, you can rotate photos through the rotate() function.

var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var img = new Image();
img.src = 'photo.jpg';
img.onload = function() {
  ctx.rotate(Math.PI / 4);
  ctx.drawImage(img, 0, 0);
}

The above code rotates the photo 45 degrees and then uses the drawImage() function to draw it into the canvas.

In short, the rotation effect of photos can be achieved through a variety of front-end technologies, whether it is CSS3, JavaScript, jQuery plug-ins or canvas, and we can choose flexibly according to our needs.

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