SVG help

Scalable Vector Graphics is a commonly used file format for providing a geometrical description of an image using basic objects such as labels, circles, lines, curves and polygons. An image can be reduced or enlarged to an arbitrary size, and will not suffer image data loss, nor will it become pixelated. SVG makes an excellent format for artwork, diagrams and drawings. SVG images are defined in XML text files. This means that they can be searched, indexed, scripted, and compressed. Since they are XML files, SVG images can be edited with any text editor, but SVG-based drawing programs are also available.

However, the rendering engine used by wiki is not perfect, and may cause the image to be shown incorrectly, or differently from how it is displayed in your vector editor of choice. This page enables authors experiencing problems with SVG graphics to obtain some help in getting their images into wiki the way they intend.

Things we can help with

Understanding SVG

• Questions about the SVG format

Using SVG appropriately

• When to (or not to) use SVG

What you see is not what you get

• Missing objects from files
• Random filled boxes in the image
• Images that are the wrong size
• Font inconsistencies
• Other weird and wonderful bugs

Something new

• Questions that you can't find a better place for

There are two classes of problems with using tools to generate SVG files. The first is that tools may generate SVG files that are hard to localize or bloat SVG file size. The second is that the SVG files generated may not be rendered correctly by wikimedia software as PNGs for embedding in Wikipedia pages. This section includes guidance on using software to generate SVG files, including post processing cleanup in a text editor that may be necessary to get a good result.

SVG files are readily viewable in text editors. To alter a file without disrupting them on Wikimedia, download the file, open it in a text editor to experiment with your text changes, and review the changes in a browser before uploading a new version. For involved edits, you can use a non-destructive editor like Inkscape. Other editors may digest the code and produce outputs in their own SVG format, introducing bugs in the process.

There is a simple work-around for the scarcities of librsvg. The operation "Stroke to Path", to be found under Menu>Path in Inkscape or via Ctrl+Alt+C, can be applied to all of the objects that are not rendered correctly. To keep the SVGs editable, this should only be done to the files intended for upload, and these files can be deleted afterwards.

As of February 2014, the objects that must be modified to render correctly by librsvg include:

• Lines with arrow heads (the arrows need to be converted)
• Text, that has been transformed, e.g. "Text on Path"
• Compound objects created with the binary path tools (union, intersect etc.)

OpenOffice.org SVG files may require manual modification before being uploaded to Wikipedia. To achieve this:

• Change all fonts to Wikipedia supported fonts as mentioned before. (E.g. change "Sans embedded" to "DejaVu Sans".)
• Add "px" to all font-size references. (E.g. change "font-size:100" to "font-size:100px".)
• Remove all additional x coordinate references in tspan elements. (E.g. change <tspan x="17583 17917 " y="10943">to<tspan x="17583" y="10943">.)
• [Not required for OO 2.3.0] Explicitly colour all text (e.g. black) by replacing relevant "stroke:none;fill:none" instances with "stroke:none;fill:rgb(0,0,0)" (note that simply explicitly colouring text black in OpenOffice 3.2.1 does not appear to work).

NB: Vector graphics line widths may also need to be set explicitly in OpenOffice.org Draw.

This SVG export procedure has been tested using OO 2.3.0 and OO 3.2.1 with a simple .odg candidate.

It is easiest to save entire slides from Powerpoint as svg rather than saving multiselected objects with right click / save as picture, because for entire slides the boundaries will be cropped to the size of the slide and the background will be set to white. To save slides as svg, use file / save as / browse / save as type --> svg.

If your slide has text, open the exported svg into Notepad and replace all the existing font-family specifications with font-family="Liberation Sans,sans-serif". This specification will make Wikimedia render SVG fonts similarly to how browsers render Wikipedia fonts.

Text can also get chopped up on export, which causes rendering and localization bugs. To fix this, search for all </text> tags and make sure the tag isn't embedded in another text tag that's on the same line of text. Most embedded text tags can simply be deleted; however, but if content needs to be subscripted or subscripted, then replace the text tag with a tspan specifiction. For subscripts, use <tspan font-size="smaller" baseline-shift="sub">. For superscripts, use <tspan font-size="smaller" baseline-shift="super">.

Warming stripes
(five examples compared)

Warming stripes bar chart

Bar chart (vertical)

Line charts

I've uploaded .xlsx (Microsoft Excel) spreadsheets that automatically generate XML code for charts in SVG format.

You simply paste or enter your data into the spreadsheet, and specify image dimensions, number of grid lines, font sizes, etc. The spreadsheet instantly and automatically generates a column of XML code that you simply copy and paste into a text editor and save as an ".svg" file. The spreadsheets produce lean SVG code, avoiding the "extra stuff" that Inkscape inserts. They should save you time in creating SVG charts.

Feedback and suggestions on my talk page are welcome. RCraig09 (talk) 23:41, 19 February 2021 (UTC)Reply

1. Warming stripes — Accepts a single dataset and converts to SVG code portraying Ed Hawkins' warming stripes graphics. User chooses vertical or horizontal stripes; normal or reverse data ordering; or from a variety of geometric shapes (updated 17 May 2023). . . . . Click here to see examples of warming stripes embedded in different shapes.
2. Warming stripes bar chart — Accepts a single dataset and creates a conventional bar chart whose individual bars/columns are coloured according to Dr. Hawkins' warming stripes colour scheme. Alternate option: choose one colour for ascending bars and another colour for descending bars. (updated 28 August 2023)
3. Line charts — Accepts up to six datasets. (updated 30 August 2023)
4. Vertical bar charts (column charts) — Accepts up to six datasets. Toggle between clustered and stacked charts; user can adjust "Yfloor"—the Y level (usually=0) from which columns rise or fall; user chooses to keep or ignore negative input values. (updated 27 August 2023)
5. Horizontal bar charts — Accepts up to six datasets. Toggle between clustered and stacked charts; user can adjust "Yfloor"—the value (usually=0) from which bars extend; user chooses to keep or ignore negative input values. (updated 27 August 2023)
6. Scatter plots — Accepts up to five datasets. (updated 28 August 2023)
7. Pie charts — Accepts a single dataset of up to 36 items. (updated 17 May 2023)
8. Variable-width bar charts — Accepts up to six datasets; is like "Vertical bar charts", above, but user can choose different widths for different bars. (updated 27 August 2023)

Converting text in an SVG file into paths (shapes) increases file size and prevents localization and accessibility features like text to speech, and is therefore generally disfavored (except for text logos, etc.) The wikimedia text rendering engine can introduce bugs as its fonts may differ from browser fonts or SVG editor fonts, but following the guidance below should minimize them.

Due to copyright restrictions, MediaWiki cannot use proprietary fonts that are commonly found on several proprietary operating systems. Fonts such as Geneva require licensing fees to distribute. rsvg will not be able to locate such fonts, and the text will fail to appear in the rendered image. There are three solutions to this issue:

• One can substitute a font that is available on Wikipedia. This approach facilitates editability.
• One can specify a generic font-family such as "sans-serif", "serif", or "monospace", but this can lead to inconsistent rendering. It is better to specify a font available on Wikipedia (such as Liberation Sans) with fallback fonts such as: font-family="Liberation Sans,Arial,Helvetica,sans-serif", in which you define a font-list with similar fonts that at least contain one font for each Operating System such as Wikimedia (e.g. Liberation Sans), Windows (e.g. Arial), Linux (e.g. Liberation Sans), Mac (e.g. Helvetica).
• Since local rendering should be as close as possible to Wikipedia, it should use locally the same font as it will have on Wikipedia, if available. Therefore always define a Wikimedia-font first. Also, Wikimedia has synonyms for substituting fonts, such as "Arial" for "Liberation Sans"; therefore font-family="Arial,DejaVu Sans" will be rendered by "Liberation Sans" and not (as expected) by "DejaVu Sans". (This is because "Liberation Sans" has the same letter size as "Arial" [metric-compatible], so it is less likely to mess up the text flow.)
• Group the text, create a copy, and convert the copy to paths. Then either:
  1. move the original, editable non-path text into a separate editable text layer that you make transparent (warning: this might be removed by SVG optimizers), or
  2. move the original, editable non-path text outside the visible area (example: File:Essigsäuresynthesen.svg).

For ease of subsequent editing and significantly smaller file sizes, substituting the font with an available font is recommended. Many common fonts have non-proprietary alternatives that are similar in typographical style, resulting in minimal disruption to existing images during substitution. For a list of fonts available in Wikipedia, see available fonts on Meta.

Wikimedia has default fonts, and will use Liberation Serif for Times New Roman and Liberation Sans for Arial. For further fallbacks see c:Help:SVG#fallback.

Fonts that are available on Wikimedia servers may or may not be available on a visitor's machine. If the placement or appearance of text in the image is important and there is uncertainty about which fonts are installed on a visitor's machine, then converting text into path information may be necessary.

Fonts should be sized so that they look good as thumbnails on wikipedia pages and so they are easy to view on smartphones. Smartphones are how most people access wikipedia. Thumbnails are how most other people see images, as very few people click images and zoom them in to see them. Avoid using or creating images with fonts that are too small to be legible in thumbnail or smartphone views.

The font size that appears in a thumbnail is a combination of svg width, thumbnail width, and font size. To match wikipedia font size as a thumbnail, use font-size = (63/(your upright value))*((your svg width)/1000). For instance, if the thumbnail will be scaled up to thumb upright=1.35 and your image has svg width of 960, set font-size in the svg to (63/1.35)*(960/1000) = 44.8.

Transparent backgrounds are fine, but do not think your image will always be displayed on a light or white background. The wikipedia smartphone app, for instance, renders images on a black background, so if you show black text on a transparent background it will be invisible.

The following SVG checkers may help you to detect SVG problems before you upload:

• WMF Labs SVG check
• Commons SVG Checker
• w3.org validator

None of these checkers are foolproof, so it's wise to validate images. You can preliminarily validate images by uploading them to the shared, temporary-use location Test.svg, though other users may overwrite your image at any time.

To force refresh images in your browser use Ctrl+F5 (Shift-Reload on Mac), so that you see the latest upload and not cached image copies (this is necessary even on wikimedia upload pages).

On Wikipedia SVGs are interpreted by the librsvg-library to create PNG previews at different image sizes (torasterize them). That library only recognizes a subset of all valid SVG syntax, and may render your SVG without many features.

In order to bypass these deficiencies in the library, there are certain parameters that need to be formatted in specific ways or be assigned a workaround value in order for librsvg to accurately render views of your SVG file. Some issues are enumerated below, but be sure to test your SVG files before and after uploading them.

The librsvg-library does not interpret the value of "userSpaceOnUse" for the parameter maskUnits correctly. To bypass this issue, replace maskUnits="userSpaceOnUse" with maskUnits="-10% -10% 120% 120%", and the SVG mask will render properly on Wikipedia.

The librsvg-library does not acceptastroke-dasharray parameter with values separated by spaces. Replace all spaces with commas to bypass this issue: e.g. stroke-dasharray="2 3 2 4" → stroke-dasharray="2,3,2,4"

In Wikimedia projects, <use xlink:href="#myobjectname" transform="translate(10 10)" /> will render properly if you have specified xmlns:xlink="http://www.w3.org/1999/xlink". Be aware that href= by itself will not work on Wikimedia projects even though it might render properly if directly read by your browser.

http://w3.org/TR/css-syntax-3 states, "Property names and at-rule names are always identifiers, which have to start with a letter or a hyphen..."

The latest thumbnail-image-maker (named rsvg) unfortunately has a bug which misaligns centre- or right-aligned text tags containing tspan tags on the same line.

While developers work on a solution, here are some remedies in decreasing usefulness:

1. Left-align affected text tags with text-anchor="start"
2. Specify either the yordy attribute for affected tspan tags
3. If using multiple tspan tags on a line for:
   • word and character spacing, use:
     1.   (non-breaking space),   (thin space) and/or   (hair space) characters
     2. the letter-spacing attribute
     3. a monospaced font such as Liberation Mono (last resort)
   • subscripts or superscripts, use Unicode subscripts and superscripts
   • bolding or italicising variables etc in mathematics, use Unicode Mathematical Alphanumeric Symbols
4. Merge affected tspan tags, even unitalicising variables etc if above methods fail
5. Convert text into shapes (last resort, as the text can no longer be amended, copied or read by screen-readers)

If black box appear, read c:User:JoKalliauer/RepairFlowRoot how to solve this issue, but do not remove those objects since they might contain text. The workarounds that one can employ are either not to use flowed text (by using the text tool without creating a text field), or convert the text to normal text (byText-editor or sed-comand, or with Inkscape-GUI or with a Inkscape-batch), but to stroke the text using "object to path", since path-text is not recomended and increases file-size.

Normal image

When a raster graphic is embedded in an SVG it is encoded into base64 data. That data is then assigned a MIME type in the <image> element. In the case of an embedded JPEG, the MIME type is "image/jpeg". Older versions of Inkscape (and possibly other editors) assigned the MIME type "image/jpg". While Inkscape and most web browsers will display such an SVG image just fine, the MediaWiki software that rasterizes the SVG file will have trouble with it. Not recognizing the MIME type "image/jpg" there will simply be an empty space where the image is supposed to be. The fix is to open the SVG file in a text editor, find the <image> element, locate "image/jpg", change it to "image/jpeg" and re-save. At right is an example of this problem. The Commons SVG Checker looks for this problem; see Commons:Commons:Commons SVG Checker/KnownBugs#Checks for details.

Though Web browsers cope with image tags without width and height specified, librsvg ignores such images.

Further issues can be found at c:Librsvg_bugs or at Commons:Commons:Commons SVG Checker/KnownBugs, and examples can be found at c:Category:Pictures_demonstrating_a_librsvg_bug. However most issues (for files <1MB) can be fixed using https://svgworkaroundbot.toolforge.org/ (enable "run svgcleaner" and enable "run scour" before clicking convert), for a more detailed list check c:User:SVGWorkaroundBot.

• 1 Generating SVG files
  • 1.1 Changing SVG files
  • 1.2 Inkscape SVG files
  • 1.3 OpenOffice.org SVG files
    • 1.3.1 SVG code replacement guide (executing replace all using Nedit regular expressions)
  • 1.4 Microsoft Powerpoint SVG files
  • 1.5 Microsoft Visio SVG files
  • 1.6 Generating SVG charts from Microsoft Excel
• 2 Text guidance
  • 2.1 Use text over paths
  • 2.2 font-family property
  • 2.3 font-size property
  • 2.4 Background colors
  • 2.5 Testing for problems
• 3 Rendering SVG files
  • 3.1 <mask> parameter maskUnits="userSpaceOnUse"
  • 3.2 parameter stroke-dasharray
  • 3.3 Use xlink:href=, not href= alone, in <use ___/> statements
  • 3.4 CSS selectors or identifiers must start with a letter or hyphen
• 4 Common problems
  • 4.1 Misaligned text
  • 4.2 flowRoot does not appear
  • 4.3 Missing embedded JPEG images
  • 4.4 Further issues
• 5 Assistance
• 6 Current requests
  • 6.1 Move right side of text box
  • 6.2 Misaligned text
  • 6.3 mix-blend-mode not working?
  • 6.4 Non-breaking spaces at the start of text are ignored
  • 6.5 RFC on Commons re technical needs survey