HTMLCanvasElement

HTMLCanvasElement接口提供用于操纵<canvas>元素的布局和表示的属性和方法。 HTMLCanvasElement接口还继承了HTMLElement接口的属性和方法。

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属性

从其父项HTMLElement继承属性。

HTMLCanvasElement.height: 是一个正整数，反映了<canvas> 元素的height HTML属性，以CSS像素表示。如果未指定属性，或者将其设置为无效值（例如负数），则使用默认值150。
HTMLCanvasElement.width: 是一个正整数，反映了<canvas> 元素的width HTML属性，以CSS像素表示。如果未指定属性，或者将其设置为无效值（例如负数），则使用默认值300。
HTMLCanvasElement.mozOpaque: 是反映 <canvas>元素的moz-opaque 属性的Boolean。它让画布知道半透明性是否会成为一个因素。如果画布知道没有透明感，则可以优化绘画性能。仅基于Mozilla的浏览器支持此功能，可以使用标准化的canvas.getContext('2d', { alpha: false }) 代替。
HTMLCanvasElement.mozPrintCallback: 是最初为空的函数。 Web内容可以将其设置为JavaScript函数，该函数将在打印页面时重新绘制画布时调用。调用时，回调将传递一个实现了MozCanvasPrintState接口的“ printState”对象。回调可以从printState对象获取要绘制的上下文，然后必须在完成时在其上调用done() 。 mozPrintCallback 的目的是在所使用打印机的分辨率下获得较高分辨率的画布渲染。请参阅此博客文章。

方法

从其父项HTMLElement继承方法。

HTMLCanvasElement.captureStream(): 返回CanvasCaptureMediaStream ，它是对画布表面的实时视频捕获。
HTMLCanvasElement.getContext(): 返回画布上的绘图上下文；如果不支持上下文ID，则返回null。绘图上下文可让您在画布上绘图。调用getContext传入"2d" 可以返回一个CanvasRenderingContext2D对象，也可以传入"webgl"（或"experimental-webgl"）返回一个WebGLRenderingContext 对象。此上下文仅在实现WebGL的浏览器上可用。
HTMLCanvasElement.toDataURL(): 返回一个数据URL，该URL包含由类型参数指定的格式的图像（默认为png）。返回的图像分辨率为96dpi。
HTMLCanvasElement.toBlob(): 创建一个Blob 对象，表示canvas中包含的图像；该文件可以由用户代理决定是否缓存在磁盘上或存储在内存中。
HTMLCanvasElement.transferControlToOffscreen(): 将控制权转移到主线程或辅助线程上的 OffscreenCanvas对象。
过时的方法
HTMLCanvasElement.mozGetAsFile(): 返回代表画布中包含的图像的File 对象；该文件是基于内存的文件，具有指定的名称。如果未指定类型，则图像类型为image / png。

事件

使用addEventListener()监听这些事件。

webglcontextcreationerror: 如果用户代理无法创建WebGLRenderingContext 或WebGL2RenderingContext 上下文，则触发该事件。
webglcontextlost: 如果用户代理检测到与WebGLRenderingContext 或WebGL2RenderingContext 对象关联的绘图缓冲区已丢失，则触发此事件。
webglcontextrestored: 如果用户代理为WebGLRenderingContext 或WebGL2RenderingContext 对象恢复绘图缓冲区，则触发该事件。

规范

Specification	Status	Comment
HTML Living Standard HTMLCanvasElement	Living Standard	Primary definition of `HTMLCanvasElement`.
Media Capture from DOM Elements HTMLCanvasElement	Working Draft	Adds the method `captureStream()`.

浏览器支持

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`HTMLCanvasElement`	Chrome Full support 1	Edge Full support 12	Firefox Full support 1.5	IE Full support 9	Opera Full support 9 Notes Full support 9 Notes Notes Opera Mini 5.0 and later has partial support.	Safari Full support 2	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1 Notes Full support 10.1 Notes Notes Opera Mini 5.0 and later has partial support.	Safari iOS Full support 1	Samsung Internet Android Full support 1.0
`captureStream` Experimental	Chrome Full support 51	Edge Full support ≤79	Firefox Full support 43	IE No support No	Opera Full support 36	Safari Full support 11	WebView Android Full support 51	Chrome Android Full support 51	Firefox Android Full support 43	Opera Android Full support 36	Safari iOS Full support 11	Samsung Internet Android Full support 5.0
`getContext`	Chrome Full support 1	Edge Full support 12	Firefox Full support 1.5	IE Full support 9	Opera Full support 9	Safari Full support 2	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 1	Samsung Internet Android Full support 1.0
`height`	Chrome Full support 1	Edge Full support 12	Firefox Full support 1.5	IE Full support 9	Opera Full support 9	Safari Full support 3	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 1	Samsung Internet Android Full support 1.0
`mozFetchAsStream` DeprecatedNon-standard	Chrome No support No	Edge No support No	Firefox No support 13 — 43	IE No support No	Opera No support No	Safari No support No	WebView Android No support No	Chrome Android No support No	Firefox Android No support No	Opera Android No support No	Safari iOS No support No	Samsung Internet Android No support No
`mozGetAsFile` DeprecatedNon-standard	Chrome No support No	Edge No support No	Firefox No support 4 — 74 Notes No support 4 — 74 Notes Notes `mozGetAsFile()` was deprecated in Firefox 26 (in 2013) and was removed entirely in Firefox 74.	IE No support No	Opera No support No	Safari No support No	WebView Android No support No	Chrome Android No support No	Firefox Android Full support 4	Opera Android No support No	Safari iOS No support No	Samsung Internet Android No support No
`mozOpaque` Non-standard	Chrome No support No	Edge No support No	Firefox Full support 3	IE No support No	Opera No support No	Safari No support No	WebView Android No support No	Chrome Android No support No	Firefox Android Full support 4	Opera Android No support No	Safari iOS No support No	Samsung Internet Android No support No
`toBlob`	Chrome Full support 50	Edge Full support 79 Full support 79 No support 12 — 79 Prefixed Prefixed Implemented with the vendor prefix: ms	Firefox Full support 19	IE Full support 10 Prefixed Full support 10 Prefixed Prefixed Implemented with the vendor prefix: ms	Opera Full support 37	Safari Full support 11	WebView Android Full support 50	Chrome Android Full support 50	Firefox Android Full support 4	Opera Android Full support 37	Safari iOS Full support 11	Samsung Internet Android Full support 5.0
`toDataURL`	Chrome Full support 1	Edge Full support 12	Firefox Full support 2	IE Full support 9	Opera Full support 9	Safari Full support 4	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 3.2	Samsung Internet Android Full support 1.0
`transferControlToOffscreen` Experimental	Chrome Full support 69	Edge Full support 79	Firefox Full support 44 Disabled Full support 44 Disabled Disabled From version 44: this feature is behind the `gfx.offscreencanvas.enabled` preference. To change preferences in Firefox, visit about:config.	IE No support No	Opera No support No	Safari No support No	WebView Android No support No	Chrome Android Full support 69	Firefox Android Full support 44 Disabled Full support 44 Disabled Disabled From version 44: this feature is behind the `gfx.offscreencanvas.enabled` preference. To change preferences in Firefox, visit about:config.	Opera Android No support No	Safari iOS No support No	Samsung Internet Android Full support 10.0
`webglcontextcreationerror` event	Chrome Full support 9	Edge Full support 12	Firefox Full support 49	IE Full support 11	Opera Full support 12	Safari Full support 5.1	WebView Android Full support Yes	Chrome Android Full support 25	Firefox Android Full support 49	Opera Android Full support 12	Safari iOS Full support 8	Samsung Internet Android Full support 1.5
`webglcontextlost` event	Chrome Full support 9	Edge Full support 12	Firefox Full support 4	IE Full support 11	Opera Full support 12	Safari Full support 5.1	WebView Android Full support Yes	Chrome Android Full support 25	Firefox Android Full support 4	Opera Android Full support 12	Safari iOS Full support 8	Samsung Internet Android Full support 1.5
`webglcontextrestored` event	Chrome Full support 9	Edge Full support 12	Firefox Full support 4	IE Full support 11	Opera Full support 12	Safari Full support 5.1	WebView Android Full support Yes	Chrome Android Full support 25	Firefox Android Full support 4	Opera Android Full support 12	Safari iOS Full support 8	Samsung Internet Android Full support 1.5
`width`	Chrome Full support 1	Edge Full support 12	Firefox Full support 1.5	IE Full support 9	Opera Full support 9	Safari Full support 3	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 1	Samsung Internet Android Full support 1.0

Legend

Full support: Full support
No support: No support
Experimental. Expect behavior to change in the future.: Experimental. Expect behavior to change in the future.
Non-standard. Expect poor cross-browser support.: Non-standard. Expect poor cross-browser support.
Deprecated. Not for use in new websites.: Deprecated. Not for use in new websites.
See implementation notes.: See implementation notes.
User must explicitly enable this feature.: User must explicitly enable this feature.
Requires a vendor prefix or different name for use.: Requires a vendor prefix or different name for use.

属性

方法

过时的方法

事件

规范

浏览器支持

Legend

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