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html5 settings picture

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2023-05-15 16:07:381247browse

HTML5 is a new generation of web standards that includes many new features and tags, making web development more convenient, flexible, and rich. In web development, pictures are an indispensable element. HTML5 provides some new image setting methods. This article will introduce some common image setting methods.

1. Img tag setting image

In HTML4, we use the following method to add images to the web page: 

<img src="image.jpg" alt="This is an image">

In HTML5, this method still applies, but There are also some new options available. Here are some common img tag attributes:

  1. src attribute

The src attribute is used to specify the URL of the image file, and it is the most basic img attribute. If this attribute is not specified, the image element will not be displayed.

  1. alt attribute

The alt attribute is used to provide alternative text for images. When the image cannot be displayed, the text of the alt attribute is displayed as a replacement. If your image is an essential component of your web page, you should provide some additional specific information.

For example: 

<img src="image.jpg" alt="This is an image of a flower">
  1. title attribute

The title attribute is used to provide additional description for the image. When the mouse is hovered over the image, the text of the title attribute will be displayed as tooltip text.

For example: 

<img src="image.jpg" alt="This is an image" title="This image is taken by me">
  1. width and height attributes

The width and height attributes are used to specify the width and height of the image. Specifying width and height can help the browser render the web page faster and can also make the web page layout more intuitive.

For example: 

<img src="image.jpg" alt="This is an image" width="500" height="300">

2. Canvas tag draws pictures

canvas is an HTML5 tag used to draw images or other paintings on web pages. Canvas allows developers to draw pictures and graphics directly, so that pictures in web pages are no longer restricted by front-end tools and can be drawn and edited freely.

The following is an example of using canvas to draw an image: 

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Canvas Example</title>
  </head>
  <body>
    <canvas id="myCanvas"></canvas>
    <script>
      var canvas = document.getElementById('myCanvas');
      var context = canvas.getContext('2d');
      var image = new Image();

      image.onload = function() {
        context.drawImage(image, 0, 0, canvas.width, canvas.height);
      };

      image.src = 'image.jpg';
    </script>
  </body>
</html>

In the above example, we first created a canvas element and assigned an ID. We then use JavaScript to get the canvas element and set its context to 2D (getContext('2d')). Next, we create an image object and use the drawImage() method to draw it on the canvas after the image is loaded.

3. svg tag to draw vector graphics

SVG (Scalable Vector Graphics) is an XML-based markup language used to describe two-dimensional graphics and animations. HTML5 allows us to draw vector graphics using the SVG tag.

Here is an example of using SVG tags to draw vector graphics: 

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>SVG Example</title>
  </head>
  <body>
    <svg width="500" height="500">
      <image x="0" y="0" width="100%" height="100%" href="image.svg"></image>
    </svg>
  </body>
</html>

In the above example, we created an SVG element and specified the width and height. Next, we create an image element and specify the URL of the image using the href attribute. Add an image to an SVG element and it will adapt to the size of the SVG element and can be further adjusted and decorated via CSS styles.

Summary

The above are the common ways to set images in HTML5. The img tag is the most common way. It provides basic image display functions and also supports some custom attributes. The canvas tag allows us to use JavaScript to draw and manipulate images directly, making the drawing process more flexible. The SVG tag is used for drawing vector graphics and animations. Choosing the right way to add pictures to a web page can make the page more colorful.

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