This article mainly introduces the example of HTML5 using html2canvas to implement browser screenshots. It is of great practical value. Friends who need it can refer to it.
In order to solve the global exception information record in a recent project, I studied browsing The full-screen screenshot function of the device allows users to quickly take screenshots and send them to the administrator when they find an abnormality. The final recorded exception information is as follows. The above [Screenshot Report to Administrator] is implemented using the html2canvas front-end plug-in.
html2canvas introduction
In the past, we could only capture images through other screenshot tools. The functions of modern browsers have become more and more powerful. With the gradual popularization of H5, the browser itself can take screenshots. html2canvas is such a front-end plug-in. Its principle is to draw Dom nodes in Canvas. Although it is very convenient, it has the following limitations:
iframe is not supported
cross-domain images are not supported
-
Cannot be used in browser plug-ins
SVG images are not supported on some browsers
Flash is not supported
Does not support ancient browsers and IE. If you want to confirm whether a certain browser is supported, you can use it to visit http://deerface.sinaapp.com/ and try:)
Since my usage scenario is very simple, record the exception information, and the exception page is also defined by myself, then html2canvas is enough to use.
Usage examples
Just reference jquery and html2canvas, and the code is also very simple. What I am using here is html2canvas version 0.5.0
html2canvas($("#tbl_exception"), { onrendered: function (canvas) { var url = canvas.toDataURL(); //以下代码为下载此图片功能 var triggerDownload = $("<a>").attr("href", url).attr("download", getNowFormatDate()+"异常信息.png").appendTo("body"); triggerDownload[0].click(); triggerDownload.remove(); } });
The first parameter is the Dom object to be screenshot, and the second parameter is the canvas object that is called back after rendering is completed.
Name | Type | Default | Description |
---|---|---|---|
allowTaint | boolean | false | Whether to allow cross-origin images to taint the canvas |
background | string | #fff | Canvas background color, if none is specified in DOM. Set undefined for transparent |
height | number | null | Define the heigt of the canvas in pixels. If null, renders with full height of the window. |
letterRendering | boolean | false | Whether to render each letter seperately. Necessary ifletter-spacing is used. |
logging | boolean | false | Whether to log events in the console. |
proxy | string | undefined | Url to the proxy which is to be used for loading cross-origin images. If left empty, cross-origin images won't be loaded. |
taintTest | boolean | true | Whether to test each image if it taints the canvas before drawing them |
timeout | number | 0 | Timeout for loading images, in milliseconds. Setting it to 0 will result in no timeout. |
width | number | null | Define the width of the canvas in pixels. If null, renders with full width of the window. |
useCORS | boolean | false | Whether to attempt to load cross-origin images as CORS served, before reverting back to proxy |
Problem Analysis
After introducing the use, talk about the problems you encountered during use. Screenshots can only capture the content of the current screen. After checking the plug-in source code and debugging, I found the solution. The source code and modified code are posted below
Source code:
return renderDocument(node.ownerDocument, options, node.ownerDocument.defaultView.innerWidth, node.ownerDocument.defaultView.innerHeight, index).then(function(canvas) { if (typeof(options.onrendered) === "function") { log("options.onrendered is deprecated, html2canvas returns a Promise containing the canvas"); options.onrendered(canvas); } return canvas; });
Modified code:
//2016-02-18修改源码,解决BUG 对于部分不能截屏不能全屏添加自定义宽高的参数以支持 var width = options.width != null ? options.width : node.ownerDocument.defaultView.innerWidth; var height = options.height != null ? options.height : node.ownerDocument.defaultView.innerHeight; return renderDocument(node.ownerDocument, options, width, height, index).then(function (canvas) { if (typeof(options.onrendered) === "function") { log("options.onrendered is deprecated, html2canvas returns a Promise containing the canvas"); options.onrendered(canvas); } return canvas; });
Mainly allows users to customize the width and height of the Dom object that needs to be intercepted when calling. The current calling method is as follows
$("#btn_screen").on("click", function () { html2canvas($("#tbl_exception"), { height: $("#tbl_exception").outerHeight() + 20, onrendered: function (canvas) { var url = canvas.toDataURL(); //以下代码为下载此图片功能 var triggerDownload = $("<a>").attr("href", url).attr("download", getNowFormatDate()+"异常信息.png").appendTo("body"); triggerDownload[0].click(); triggerDownload.remove(); } }); });
The above is the detailed content of Example of html5 browser screenshot. For more information, please follow other related articles on the PHP Chinese website!

The core purpose of HTML is to enable the browser to understand and display web content. 1. HTML defines the web page structure and content through tags, such as, to, etc. 2. HTML5 enhances multimedia support and introduces and tags. 3.HTML provides form elements to support user interaction. 4. Optimizing HTML code can improve web page performance, such as reducing HTTP requests and compressing HTML.

HTMLtagsareessentialforwebdevelopmentastheystructureandenhancewebpages.1)Theydefinelayout,semantics,andinteractivity.2)SemantictagsimproveaccessibilityandSEO.3)Properuseoftagscanoptimizeperformanceandensurecross-browsercompatibility.

A consistent HTML encoding style is important because it improves the readability, maintainability and efficiency of the code. 1) Use lowercase tags and attributes, 2) Keep consistent indentation, 3) Select and stick to single or double quotes, 4) Avoid mixing different styles in projects, 5) Use automation tools such as Prettier or ESLint to ensure consistency in styles.

Solution to implement multi-project carousel in Bootstrap4 Implementing multi-project carousel in Bootstrap4 is not an easy task. Although Bootstrap...

How to achieve the effect of mouse scrolling event penetration? When we browse the web, we often encounter some special interaction designs. For example, on deepseek official website, �...

The default playback control style of HTML video cannot be modified directly through CSS. 1. Create custom controls using JavaScript. 2. Beautify these controls through CSS. 3. Consider compatibility, user experience and performance, using libraries such as Video.js or Plyr can simplify the process.

Potential problems with using native select on mobile phones When developing mobile applications, we often encounter the need for selecting boxes. Normally, developers...

What are the disadvantages of using native select on your phone? When developing applications on mobile devices, it is very important to choose the right UI components. Many developers...


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

SublimeText3 Chinese version
Chinese version, very easy to use

MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.

Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

SecLists
SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.
