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问题:
I know with that an image can be placed in a MD with the MD syntax of either  or , but I am having difficulty placing an SVG in MD where the code is hosted on Github.
Ultimately using rails3, and changing the model frequently right now, so I am using RailRoady to generate an SVG of the schema diagram of the models. I would like for that SVG to then be placed in the ReadMe.md, and be displayed. When I open the SVG file locally, it does work, so how do I get the browser to render the SVG in the MD file? Given that the code will be dynamic until it is finalized (seemingly never), hosting the SVG in a separate place seems overkill and that I am missing an approach to accomplish this.
The SVG I am trying to include is here on Github: https://github.com/specialorange/FDXCM/blob/master/Rails/fdxcm/doc/models_brief.svg
I have tried the following, with an actual image as well to verify the syntax is working, just that the SVG code isn't being rendered:
![Overview][1]
[1]: https://github.com/specialorange/FDXCM/blob/master/doc/controllers_brief.svg "Overview"
<img src="https://raw.github.com/specialorange/FDXCM/master/doc/controllers_brief.svg">
[Google Doc](https://docs.google.com/drawings/d/1B95ajItJTAImL2WXISX0fkBLYk3nldea4Vm9eo-VyE4/edit) :
<img src="https://docs.google.com/drawings/pub?id=117XsJ1kDyaY-n8AdPS3_8jTgMyITqaoT3-ah_BSc9YQ&w=960&h=720">
<img src="https://raw.github.com/specialorange/FDXCM/master/doc/controllers_brief.svg">
<img src="https://docs.google.com/drawings/d/1B95ajItJTAImL2WXISX0fkBLYk3nldea4Vm9eo-VyE4/edit">
to get the results of :
Google Doc :
回答1:
The purpose of raw.github.com is to allow users to view the contents of a file, so for text based files (SVG, JS, CSS, etc) this means you get the wrong headers and things break in the browser.
Update:
Github has implemented a feature which makes it possible for SVG's to be used with the Markdown image syntax. The SVG image will be sanitized and displayed with the correct HTTP header. Certain tags (like <script>) are removed.
To view the sanitized SVG or to achieve this effect from other places (i.e. from markdown files not hosted in repos on http://github.com/) simply append ?sanitize=true to the SVG's raw URL.
See the examples below for rendering details.
Although you cannot link directly to SVG images from raw.github.com you could put the SVG files on the gh-pages branch (or configure master as source for Github Pages) and link to the files from github.io
As the file you are trying to get to display seems to part of your projects documentation this might be a win-win situation
If using Github Pages is not your thing, rawgithub.com could be an option. RawGit retrieves your files and sets the correct headers for you.
As stated by AdamKatz in the comments, using a source other than github.io can introduce potentially privacy and security risks. See the answer by CiroSantilli and the answer by DavidChambers for more details.
As stated by MonsieurDart
in the comments, RawGit does not work for private repos.
The issue to resolve this was opened on Github on October 13th 2015 and was resolved on August 31th 2017
Examples
I copied the SVG image from the question to a repo on github in order to create the examples below:
Linking to relative files (Works, but obviously only https://github.com/)
Code
<img src="./controllers_brief.svg">
Result
See the working example on github.com.
Linking to RAW files (Does not work)
Code
<img src="https://raw.github.com/potherca-blog/StackOverflow/master/question.13808020.include-an-svg-hosted-on-github-in-markdown/controllers_brief.svg">
Result
Linking to RAW files using ?sanitize=true (Works)
Code
<img src="https://raw.github.com/potherca-blog/StackOverflow/master/question.13808020.include-an-svg-hosted-on-github-in-markdown/controllers_brief.svg?sanitize=true">
Result
Linking to files hosted on github.io (Works)
Code
<img src="https://potherca-blog.github.io/StackOverflow/question.13808020.include-an-svg-hosted-on-github-in-markdown/controllers_brief.svg">
Result
Linking to RAW files using rawgithub.com (Also Works)
Note: Sometimes the RawGithub service is down/doesn't work. If you don't see an image below, that is probably the case.
Code
<img src="https://rawgithub.com/potherca-blog/StackOverflow/master/question.13808020.include-an-svg-hosted-on-github-in-markdown/controllers_brief.svg">
Result
回答2:
I contacted GitHub to say that github.io-hosted SVGs are no longer displayed in GitHub READMEs. I received this reply:
We have had to disable svg image rendering on GitHub.com due to potential cross site scripting vulnerabilities.
回答3:
rawgit.com solves this problem nicely. For each request, it retrieves the appropriate document from GitHub and, crucially, serves it with the correct Content-Type header.
回答4:
This will work. Link to your SVG using the following pattern:
https://cdn.rawgit.com/<repo-owner>/<repo>/<branch>/path/to.svg
The downside is hardcoding the owner and repo in the path, meaning the svg will break if either of those are renamed.
回答5:
Update 2017
A GitHub dev is currently looking into this: https://github.com/github/markup/issues/556#issuecomment-306103203
Update 2014-12: GitHub now renders SVG on blob show, so I don't see any reason why not to render on README renderings:
- https://github.com/blog/1902-svg-viewing-diffing
- https://github.com/cirosantilli/test/blob/2144a93333be144152e8b0d4144b77b211afce63/svg.svg
Also note that that SVG does have an XSS attempt but it does not run: https://raw.githubusercontent.com/cirosantilli/test/2144a93333be144152e8b0d4144b77b211afce63/svg.svg
The billion laugh SVG does make Firefox 44 Freeze, but Chromium 48 is OK: https://github.com/cirosantilli/web-cheat/blob/master/svg-billion-laughs.svg
Petah mentioned that blobs are fine because the SVG is inside an iframe.
Possible rationale for GitHub not serving SVG images
general XML vulnerabilities. E.g. opening a billion laughs exploit just made Firefox crash my system. Firefox bug with exploit attached: https://bugzilla.mozilla.org/page.cgi?id=voting/user.html. Same on Chromium: https://code.google.com/p/chromium/issues/detail?id=231562
SVG XSS scripting: while most browsers don't run scripts when the SVG is embedded with img, it seems that this is not required by the standards, so maybe GitHub is playing it safe.
Browsers do run it if you open the SVG directly (but it appears that GitHub never shows images directly on the github.com domain) or if it is inline (which are currently completely removed by GitHub), so those cases shouldn't be a security concern. Relevant links:
- spec: http://www.w3.org/TR/SVG/script.html
- interactive SVG demo: http://www.w3.org/TR/SVG/images/script/script01.svg
The following questions asks about the risks of SVG in general: https://security.stackexchange.com/questions/11384/exploits-or-other-security-risks-with-svg-upload
回答6:
Use this site: https://rawgit.com , it works for me as I don't have permission issue with the svg file.
Please pay attention that RawGit is not a service of github, as mentioned in Rawgit FAQ :
RawGit is not associated with GitHub in any way. Please don't contact GitHub asking for help with RawGit
Enter the url of svg you need, such as :
https://github.com/sel-fish/redis-experiments/blob/master/dat/memDistrib-jemalloc-4.0.3.svg
Then, you can get the url bellow which can be used to display:
https://cdn.rawgit.com/sel-fish/redis-experiments/master/dat/memDistrib-jemalloc-4.0.3.svg
回答7:
I have a working example with an img-tag, but your images won't display.
The difference I see is the content-type.
I checked the github image from your post (the google doc images don't load at all because of connection failures). The image from github is delivered as content-type: text/plain, which won't get rendered as an image by your browser.
The correct content-type value for svg is image/svg+xml. So you have to make sure that svg files set the correct mime type, but that's a server issue.
Try it with http://svg.tutorial.aptico.de/grafik_svg/dummy3.svg and don't forget to specify width and height in the tag.
