Manual:Coding conventions/SVG/cs

Tato stránka popisuje kódovací konvence používané v souborech MediaWiki codebase napsané v SVG. Viz také obecné konvence, které platí pro všechny programovací a značkovací jazyky, včetně SVG.

Jako optimalizační nástroj používáme SVGO, viz automatizovaná optimalizace níže.



Struktura kódu
Předpokladem je co nejjednodušší kód s ohledem na čitelnost.

Příklad jednoduchého optimalizovaného souboru – subtract.svg od OOUI:

Pro minimalisty lze kreslit úplně stejně

Příklad trochu složitějšího, optimalizovaného souboru – BetaFeatures šablona snímku obrazovky:

V následující části vysvětlíme různé konvence kódování.



Automatická optimalizace (SVGO)


Jak používat
Je doporučeno instalovat  z https://github.com/svg/svgo nebo z   pro příkazový řádek. K dispozici je také demo v prohlížeči, které vám pomůže s náhledem a obecným pochopením nástroje na https://jakearchibald.github.io/svgomg/. Toto by se však nemělo používat k vytváření produkčních souborů.



Bezpečné pluginy:
Protože některé výchozí zásuvné moduly (možnosti) SVGO mohou mít za následek neočekávaný vzhled u složitějších zásuvných modulů SVG, rozlišujeme mezi bezpečnými, podstatně méně bezpečnými a nebezpečnými zásuvnými moduly. Nastavte "transformPrecision" alespoň na 7, abyste snížili riziko poškození souborů. Při používání nebezpečných zásuvných modulů se doporučuje ověřit před a po rozdílu na soubor, aby byla zajištěna vizuální kvalita.

Uvádíme pouze pluginy, které jsou změněny z výchozího nastavení nebo které mohou být neintuitivní:

Viz SVGO Readme pro další povolené, bezpečné pluginy.
 * Atributy řazení . Povolit nastavením na . Ve výchozím nastavení zakázáno
 * Pokud je to možné, odstraňte nebo vyčistěte atribut . Deprecated attribute, only supported by IE/Edge; enabled by default

Pluginy, které je třeba pečlivě zvážit:


 * Odstraňte nepoužívaná a minifikujte použitá ID
 * As general rule dangerous, could cause data loss, some raster-images are difficult to spot ; disabled by default
 * - some users prefer to use CSS than inlineStyles, can reduce editability
 * - for SVG 1.1 there is not reason to remove it, however for the upcommong SVG2-draft it will be deapreciated

 Unsafe rules to disable (don't use!): 


 * 'convertPathData' Might cause (i) imprecise rendering, (ii) wrong rendering by librsvg, (iii) breaking files  ; enabled by default
 * Round/rewrite number lists cleanupListOfValues breaks Wikimedia-renderin
 * convertShapeToPath can reduce readability and breaks files
 * Remove XML processing instructions 'removeXMLProcInst', aka XML declaration   Issues when viewed as standalone file in some editors, also possible issues with MIME type interpretation Example: If the SVG doesn't start with an XML declaration, then it's MIME type will be detected as   rather than   by libmagic and consequently, MediaWiki's CSSMin CSS minifier. libmagic's default database currently requires that SVGs contain an XML declaration; disable by setting to ; enabled by default
 * Remove 'removeTitle' Problematic for accessibility reasons ; set to ; enabled by default
 * Remove 'removeDesc' Problematic for accessibility reasons; set to ; enabled by default
 * Remove  attribute 'removeViewBox' Results in troublesome appearance in some browsers, therefore both,  /  and   should be featured; set to ; enabled by default
 * Remove dimensions /  when   is available 'removeDimensions' As above; set to ; disabled by default
 * removeMetadata Possible Copyright-Information
 * removeHiddenElems Possible reference lines, editor data, real text before convertion, Copyright-informations
 * removeUnknownsAndDefaults removes Flow-Text
 * cleanupNumericValues breaks some files
 * minifyStyles breaks some files
 * removeComments reduces readability and possible removes reference lines, editor data, real text before convertion, Copyright-informations
 * removeEditorsNSData reduces editability with GUI-SVG-Editors
 * collapseGroups reduced readabilty and editability and breaks some files
 * removeStyleElement breaks some files
 * removeOffCanvasPaths breaks some files
 * removeEmptyContainers breaks some files
 * removeElementsByAttr breaks some files
 * convertStyleToAttrs breaks some files
 * convertTransform breaks some files
 * cleanupNumericValues breaks some files
 * inlineStyles breaks some CSS-features
 * reusePaths breaks some files



Příklad bezpečné konfigurace
Všimněte si, že toto je pro svgo v1.x; v2.x přebírá různé argumenty CLI:

Použijte výstup  pro kód čitelný pro člověka a v procesu odsazení kódu po tabulátorech.



Příklad bezpečné konfigurace (.svgo.config.js)
Update 2023-06: SVGO v3.0.0+ compatibility, amending to new  plugin name (phab:T324899).

Update 2022-01: NPM run scripts enabled SVGO configuration (T246321).



Příklad bezpečné konfigurace (Gruntfile.js)
svgmin: { options: { js2svg: { indent: '\t', pretty: true },		plugins: [ { cleanupIDs: false }, {			removeDesc: false }, {			removeRasterImages: true }, {			removeTitle: false }, {			removeViewBox: false }, {			removeXMLProcInst: false }, {			sortAttrs: true }, {			convertPathData: false // https://github.com/svg/svgo/issues/880 }, {			removeMetadata: false // Copyright-Violation }, {			removeHiddenElems: false // source for converted text2path }, {			removeUnknownsAndDefaults: false // removes Flow-Text }, {			cleanupNumericValues: false // https://github.com/svg/svgo/issues/1080 }, {			minifyStyles: false //https://github.com/svg/svgo/issues/888 }, {			removeComments: false //reduces readability }, {			removeEditorsNSData: false // https://github.com/svg/svgo/issues/1096 }, {			collapseGroups: false // https://github.com/svg/svgo/issues/1057 }, {			removeOffCanvasPaths: false //https://github.com/svg/svgo/issues/1732 }, {			removeEmptyContainers:false // https://github.com/svg/svgo/issues/1194 https://github.com/svg/svgo/issues/1618 }, {			convertTransform: fasle // https://github.com/svg/svgo/issues/988 https://github.com/svg/svgo/issues/1021 }, {			cleanupNumericValues: false // https://github.com/svg/svgo/issues/1080 }, {			inlineStyles: false // https://github.com/svg/svgo/issues/1486 } ]	} }



Ruční optimalizace
Beyond automated optimising SVGs there are further steps to consider:


 * retain the following code,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  , ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  , see c:Help:SVG guideline
 * Remove  from XML processing instruction, as it's default
 * Lowercase (for better gzipping) and shorten hex color values, if possible, e.g.  instead of.
 * Attributes that are the same for a group of elements can be applied to a common parent instead, or sometimes even specified by the   statement (see an example: CHE Bettens COA.svg). This might reduce the editability or readability
 * Rely on defaults like  and.
 * The  syntax is almost always shorter than the syntax of basic shapes like  or even, however , ,  are generally more easy to read&edit, therfore there is generally prefered to use more specific ones.
 * Merge  elements where applicable. Do not do that if the both path should be edited speratly.
 * Do not remove redundant  attribute when identical to   it get's more difficult to read&edit.
 * Remove not needed  and  . These rules only have an effect on certain paths, e.g. when a path intersects itself.
 * Look for IEEE rounding errors like  or  . Such numbers take up space without providing any additional information. They can almost always be cut off without visually changing anything.
 * Work with a non-fractional pixel grid while drawing, and align as much points as possible on this grid. These points have a much higher chance of being represented as short integer numbers in the resulting code.
 * Pick a non-fractional grid so that it matches the features of an existing image, and scale or redraw shapes so that as many points as possible fall on the grid. The result might be misaligned and can be cropped using.

If you want to dig even deeper, there are more optimisations to compress delivery, such as:


 * auto-closing paths (aka removing  for certain shapes),
 * use relative commands when creating paths (instead of absolute commands, e.g. "m" for "move by", instead of "M" for "move to"),
 * optimising for compression backreferences

Other tools
Další nástroje, které mohou být užitečné:


 * 1) SvgWorkAroundBot
 * 2) SVGOMG
 * 3) scour
 * 4) svgcleaner
 * 5) další možnosti naleznete na stránce Nápověda:Pokyny pro SVG#Jak optimalizovat.

Description&History
This opimizer was one of the first optimizers: Since 2009 it included with the installation of Inkscape, it can be used by saving Inkscape-files with "Optimized Inkscape SVG", and in 2013 seperated into an self-contained project available at https://github.com/scour-project/scour. It is maintained by the Inscape-Developer Patrick Storz (Ede123).

How to use
You can use in the browser at https://svgworkaroundbot.toolforge.org/ or install it via  from the command line (Linux-PC/Mac-PC/Windows).

safe plugins
Scour is a very cautious optimizer, however some plugins can still be break the file or remove important non-visible parts, to be on the safe side you can use

Description&History
This optimizer was developed from Jan 2012 to 2022 by Yevhenii Reizner. It focusses on following the current w3c-Standards (SVG1.1). Compared to scour or svgo it breaks less files, reduces the file size more and the performance is magnitues faster.

How to use
You can use in the browser at https://svgworkaroundbot.toolforge.org/ or download it from https://github.com/RazrFalcon/svgcleaner-gui/releases.

safe plugins
Files will be treated according to the standards, however sometimes file non-svg-elements which are importante for reading and/or editing the file, to be on the safe side you can use