跳转到帖子
在手机APP中查看

一个更好的浏览方法。了解更多。
OKCCN - XenForo & IPS Plugin Marketplace

主屏幕上的全屏APP，带有推送通知、徽章等。

在iOS和iPadOS上安装此APP
  1. 在Safari中轻敲分享图标
  2. 滚动菜单并轻敲添加到主屏幕。
  3. 轻敲右上角的添加按钮。
在安卓上安装此APP
  1. 轻敲浏览器右上角的三个点菜单 (⋮) 。
  2. 轻敲添加到主屏幕或安装APP。
  3. 轻敲安装进行确认。
  • 选择语言

HTML Canvas Graphics

Cavalry
在 教程

推荐的帖子

  • 行政经理

HTML Canvas Graphics

Your browser does not support the <canvas> element.

The HTML <canvas> element is used to draw graphics on a web page.

The graphic to the left is created with <canvas>. It shows four elements: a red rectangle, a gradient rectangle, a multicolor rectangle, and a multicolor text.

What is HTML Canvas?

The HTML <canvas> element is used to draw graphics, on the fly, via JavaScript.

The <canvas> element is only a container for graphics. You must use JavaScript to actually draw the graphics.

Canvas has several methods for drawing paths, boxes, circles, text, and adding images.

Canvas is supported by all major browsers.

Canvas Examples

A canvas is a rectangular area on an HTML page. By default, a canvas has no border and no content.

The markup looks like this:

<canvas id="myCanvas" width="200" height="100"></canvas>

Note: Always specify an id attribute (to be referred to in a script), and a width and height attribute to define the size of the canvas. To add a border, use the style attribute.

Here is an example of a basic, empty canvas:

Your browser does not support the canvas element.

Example

<canvas id="myCanvas" width="200" height="100" style="border:1px solid #000000;">
</canvas>

Add a JavaScript

After creating the rectangular canvas area, you must add a JavaScript to do the drawing.

Here are some examples:

Draw a Line

Your browser does not support the canvas element

Example

<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.moveTo(0, 0);
ctx.lineTo(200, 100);
ctx.stroke();
</script>

Draw a Circle

Your browser does not support the canvas element

Example

<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.arc(95, 50, 40, 0, 2 * Math.PI);
ctx.stroke();
</script>

Draw a Text

Your browser does not support the canvas element

Example

<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.font = "30px Arial";
ctx.fillText("Hello World", 10, 50);
</script>

Stroke Text

Your browser does not support the canvas element

Example

<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.font = "30px Arial";
ctx.strokeText("Hello World", 10, 50);
</script>

Draw Linear Gradient

Your browser does not support the canvas element

Example

<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");

// Create gradient
var grd = ctx.createLinearGradient(0, 0, 200, 0);
grd.addColorStop(0, "red");
grd.addColorStop(1, "white");

// Fill with gradient
ctx.fillStyle = grd;
ctx.fillRect(10, 10, 150, 80);
</script>

Draw Circular Gradient

Your browser does not support the canvas element

Example

<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");

// Create gradient
var grd = ctx.createRadialGradient(75, 50, 5, 90, 60, 100);
grd.addColorStop(0, "red");
grd.addColorStop(1, "white");

// Fill with gradient
ctx.fillStyle = grd;
ctx.fillRect(10, 10, 150, 80);
</script>

Draw Image

Example

<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
var img = document.getElementById("scream");
ctx.drawImage(img, 10, 10);
</script>

HTML Canvas Tutorial

To learn more about <canvas>, please read our HTML Canvas Tutorial.


  • 引用

    • 参与讨论

    你可立刻发布并稍后注册。 如果你有帐户，立刻登录发布帖子。

    游客
    回帖…
    转到主题列表

    帐户

    导航

    搜索

    搜索

    配置浏览器推送通知
    Chrome (安卓)
    1. 轻敲地址栏旁的锁形图标。
    2. 轻敲权限 → 通知。
    3. 调整你的偏好。
    Chrome (台式电脑)
    1. 点击地址栏中的挂锁图标。
    2. 选择网站设置。
    3. 找到通知选项并调整你的偏好。