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What does the html5 canvas tag mean? Introduction to how to use the canvas tag

寻∝梦
寻∝梦Original
2018-08-30 11:06:158639browse

This article mainly introduces the drawing of canvas tag in HTML5, explains the definition and basic usage process of html5 canvas tag, and adds some basic knowledge of css style and js to make the whole article more interesting. The difficulty has increased, but it is always correct to follow the code. Next, let’s take a look at this article

First of all, let’s talk about the meaning of the canvas tag in HTML5:

tag defines graphics, Such as charts and other images.

The tag is just a graphics container. You can use canvas to draw paths, boxes, circles, characters, and add images in a variety of ways.

Now let’s talk about how to use html5 markup for drawing:

Most of the Canvas drawing API is not defined on the element itself, but defined on On a "drawing context" object obtained through the canvas's getContext() method.

The Canvas API also uses path representation. However, a path is defined by a series of method calls, such as calls to the beginPath() and arc() methods, rather than being described as a string of letters and numbers.

Once the path is defined, other methods, such as fill(), operate on this path. Various properties of the drawing environment, such as fillStyle, describe how these operations are used.

Note: One reason the Canvas API is very compact is that it does not provide any support for drawing text. To add text to a graphic, you must either draw it yourself and merge it with a bitmap image, or use CSS positioning to overlay the HTML text above the .

html5Use of tag:

Define graphics, such as charts and other images. But the tag is just a graphics container, and a script must be used to draw graphics. Tags usually need to specify an id attribute (often referenced in scripts), width and height attributes to define the size of the canvas, and use the style attribute to add borders.

For example, create a rectangle or square.

<!doctype html>
<html >
<head>
    <meta charset="UTF-8">
    <script type="js/index.js"></script>
    <title>php中文网之画图</title>
</head>
<body >
<canvas id="rectangular" width="200" height="100" style="border:3px solid #adadad;">
</canvas>
<canvas id="square" width="200" height="200" style="border:5px solid #ff88c2;"></canvas>
</body>
</html>

The effect is shown in the figure:

What does the html5 canvas tag mean? Introduction to how to use the canvas tag

Summary of the canvas tag in html5:

HTML5 canvas In layman's terms, this thing is a piece of cloth used for painting, but this is not an ordinary cloth, this is a magical thing similar to the magic pen Ma Liang's magic pen, which can draw many exquisite and wonderful things. This article shows two cool effects based on canvas, which can give us a more intuitive understanding of the potential of canvas.

Personally, I feel that canvas has a lot of room for development. It can be predicted that if the country's Internet speed can keep up without pressure, it cannot be doubted that this will be the world of HTML. . Because in canvas, as far as his imagination is unlimited, his development space will be as far as possible. Of course, the premise is that the technology must be excellent. Of course, it is a conjecture of mine, but it is undeniable that HTML is powerful, but the biggest problem at present is Compatibility issues, and network speed is also a major limitation

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