Units In Inkscape - Revision history

Vanzandtj: /* Page Size/Scale Changes */

2019-12-22T16:54:31Z

Page Size/Scale Changes

← Older revision		Revision as of 16:54, 22 December 2019
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	* Page size is determined by SVG root 'width' and 'height'.		* Page size is determined by SVG root 'width' and 'height'.
	* 'viewBox' defined in 'user units' with the values: (x offset,y-offset, width, height).		* 'viewBox' defined in 'user units' with the values: (x offset, y-offset, width, height).
	* Document scale is determined by ratio of 'width'/'height' to 'viewBox'.		* Document scale is determined by ratio of 'width'/'height' to 'viewBox'.

Vanzandtj: grammar: if -> of

2019-12-22T16:53:49Z

grammar: if -> of

← Older revision		Revision as of 16:53, 22 December 2019
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	=== Editing Aides ===		=== Editing Aides ===

	Guides, grids, and other ''editing aides'' should be defined in terms if 'user units'. These will then behave as a user would expect when the document size or scale is changed. To see how this behavior should work, draw a rectangle, duplicate it, and then use the duplicate to create a set of guides. As the document size or scale is changed, the guides should follow along the edges of the rectangle.		Guides, grids, and other ''editing aides'' should be defined in terms of 'user units'. These will then behave as a user would expect when the document size or scale is changed. To see how this behavior should work, draw a rectangle, duplicate it, and then use the duplicate to create a set of guides. As the document size or scale is changed, the guides should follow along the edges of the rectangle.

Tavmjong: /* Page Size/Scale Changes */

2014-12-05T15:22:59Z

Page Size/Scale Changes

← Older revision		Revision as of 15:22, 5 December 2014
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	* Document scale is determined by ratio of 'width'/'height' to 'viewBox'.		* Document scale is determined by ratio of 'width'/'height' to 'viewBox'.

	Operations:		=== Operations ===

	; Change page size		; Change page size
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	=== ~~Notes~~ ===		=== Editing Aides ===

	Guides, grids, and other ''editing'' ~~aides~~ should be defined in terms if 'user units'. These will then behave as a user would expect when the document size or scale is changed. To see how this behavior should work, draw a rectangle, duplicate it, and then use the duplicate to create a set of guides. As the document size or scale is changed, the guides should follow along the edges of the rectangle.		Guides, grids, and other ''editing aides'' should be defined in terms if 'user units'. These will then behave as a user would expect when the document size or scale is changed. To see how this behavior should work, draw a rectangle, duplicate it, and then use the duplicate to create a set of guides. As the document size or scale is changed, the guides should follow along the edges of the rectangle.


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	; Other		; Other
	: ?		: ?


	== Test Files ==		== Test Files ==

	See [http://tavmjong.free.fr/INKSCAPE/UNITS/ Test Files]		See [http://tavmjong.free.fr/INKSCAPE/UNITS/ Test Files]

Tavmjong at 14:58, 5 December 2014

2014-12-05T14:58:54Z

← Older revision		Revision as of 14:58, 5 December 2014
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	Consider an SVG with the following SVG root element:		Consider an SVG with the following SVG root element:

			<pre>
	<svg width="10in" height="6in" viewBox="0 0 50 30">		<svg width="10in" height="6in" viewBox="0 0 50 30">
			</pre>

	; Drawing size		; Drawing size
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	one "mm".		one "mm".

	The ''SVG scale'' would be 1mm/1 user-unit.		The ''SVG scale factor'' would be 1mm/1 user-unit.

	If the ''GUI display unit'' ('inkscape:document-units') identifier is set to "mm" then the GUI would show a width of '25.4' for a rectangle 25.4 ''user-units'' wide. If the ''GUI display unit'' identifier is set to "in", the GUI would show '1.0'.		If the ''GUI display unit'' ('inkscape:document-units') identifier is set to "mm" then the GUI would show a width of '25.4' for a rectangle 25.4 ''user-units'' wide. If the ''GUI display unit'' identifier is set to "in", the GUI would show '1.0'.

	Note: In the run-up to 0.91 the ''Inkscape Document unit'' was sometimes used incorrectly ~~to indicate~~ the ''SVG scale'' resulting in a number of bugs.		Note: In the run-up to 0.91 the ''Inkscape Document unit'' was sometimes used incorrectly as the ''SVG scale factor'' resulting in a number of bugs.


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	: The page size is defined by the SVG 'width'/'height' attributes. Pre-0.91 the scale is 'user unit' == 1px with the assumption of 90dpi. To correct for 96dpi, set the 'width' and 'height' attributes using 'mm' or 'in' and add a 'viewBox' calculated at 90dpi. In 0.91, one can set the 'viewBox' to define the 'user unit' to be 1px, 1mm, 1in, etc.		: The page size is defined by the SVG 'width'/'height' attributes. Pre-0.91 the scale is 'user unit' == 1px with the assumption of 90dpi. To correct for 96dpi, set the 'width' and 'height' attributes using 'mm' or 'in' and add a 'viewBox' calculated at 90dpi. In 0.91, one can set the 'viewBox' to define the 'user unit' to be 1px, 1mm, 1in, etc.
	; Scaled drawings		; Scaled drawings
	:Scaling determined by document size and viewBox~~. Need to add GUI to define document scale~~.		:Scaling determined by document size and viewBox.

	== Page Size/Scale Changes ==		== Page Size/Scale Changes ==

	* Page size is determined by SVG root 'width' and 'height'.		* Page size is determined by SVG root 'width' and 'height'.
	* 'viewBox' defined in 'user units'.		* 'viewBox' defined in 'user units' with the values: (x offset,y-offset, width, height).
	* Document scale is determined by ratio of 'width'/'height' to 'viewBox'.		* Document scale is determined by ratio of 'width'/'height' to 'viewBox'.

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	: Change 'width'/'height' in GUI, 'viewBox' changed to keep scale. Grids/guides do not need any change.		: Change 'width'/'height' in GUI, 'viewBox' changed to keep scale. Grids/guides do not need any change.
	; Change document scale		; Change document scale
	: Change ~~'viewBox'~~ via '~~Scale factor~~' in GUI. ~~Preset~~ 'mm', 'in' ~~scales~~.		: Change via a 'Scaling' section in GUI which changes the 'viewBox'. Include a preset with common values ('mm', 'in', etc. to 1 'user unit') and a (normally hidden) custom 'viewBox' entry box.


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	; Grids		; Grids
	: Pre 0.91 grids are defined in 'external units'. A 'unit identifier' is permitted (in fact, required) thus there will be a problem if real units were used (e.g. 'cm') to define the grid with the 90dpi to 96dpi conversion. No code has been added to trunk yet to handle this case. Unit identifiers should not be used ~~put~~ have been available at least since 0.48.		: Pre 0.91 grids are defined in 'external units'. A 'unit identifier' is permitted (in fact, required) thus there will be a problem if real units were used (e.g. 'cm') to define the grid with the 90dpi to 96dpi conversion. No code has been added to trunk yet to handle this case. Unit identifiers should not be used but have been available at least since 0.48.

	; Perspective (3D boxes)		; Perspective (3D boxes)
	: Needs same treatment as guides.		: Needs same treatment as guides. Code is already in trunk. It needs to be back-ported to 0.91.

	; Other		; Other

Tavmjong: /* Example */

2014-12-05T14:43:50Z

Example

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	:# The width of '10in' could be equivalently written as '25.4cm', '254mm', etc.		:# The width of '10in' could be equivalently written as '25.4cm', '254mm', etc.
	:# The width could also be written as '960' or '960px' using the CSS/SVG defined value of 96 pixels per inch.		:# The width could also be written as '960' or '960px' using the CSS/SVG defined value of 96 pixels per inch.
	:#* If a 'unit identifier' is missing or 'px', the length is interpreted to be in 'user units'. CSS requires the use of a 'unit identifier'.		:#* If a 'unit identifier' is missing or 'px', the length is interpreted to be in 'user units'. CSS requires the use of a 'unit identifier'. Thus while one can write 'font-size="20"' (an SVG presentation attribute), one must write 'style="font-size:20px" (a CSS style value).
	:#* Inkscape 0.91 and earlier used a value of 90 pixels per inch.		:#* Inkscape 0.91 and earlier used a value of 90 pixels per inch.

Tavmjong: /* Example */

2014-12-05T14:38:28Z

Example

← Older revision		Revision as of 14:38, 5 December 2014
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	; Drawing size		; Drawing size
	:# This is a nominal 10x6 inch drawing. The actual size of the drawing when displayed depends on how it is displayed. It is very unlikely to be the nominal size when displayed on a digital screen.		: This is a nominal 10x6 inch drawing.
			:#The actual size of the drawing when displayed depends on how it is displayed. It is very unlikely to be the nominal size when displayed on a digital screen.
	:# The width of '10in' could be equivalently written as '25.4cm', '254mm', etc.		:# The width of '10in' could be equivalently written as '25.4cm', '254mm', etc.
	:# The width could also be written as '960' or '960px' using the CSS/SVG defined value of 96 pixels per inch.		:# The width could also be written as '960' or '960px' using the CSS/SVG defined value of 96 pixels per inch.
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	; SVG scale factor		; SVG scale factor
	: The scale factor is 0.2 inches per initial 'user unit'. (10 inches/50 'user units). SVG allows for different ~~scaling~~ factors in 'x' and 'y'.		: The scale factor is 0.2 inches per initial 'user unit'. (10 inches/50 'user units). SVG allows for different scale factors in 'x' and 'y'.

	=Inkscape & Units=		=Inkscape & Units=

Tavmjong: /* Generic SVG */

2014-12-05T14:35:48Z

Generic SVG

← Older revision		Revision as of 14:35, 5 December 2014
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	; SVG Scale Factor		; SVG Scale Factor
	: A scale factor determined by SVG root 'width'/'height' and the 'viewBox'. It serves to map 'user units' inside ~~and~~ SVG document to the ''real world''.		: A scale factor determined by SVG root 'width'/'height' and the 'viewBox'. It serves to map 'user units' inside an SVG document to the ''real world''.

	== Inkscape specific ==		== Inkscape specific ==

Tavmjong: /* Generic SVG */

2014-12-05T14:35:12Z

Generic SVG

← Older revision		Revision as of 14:35, 5 December 2014
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	; SVG Scale Factor		; SVG Scale Factor
	: A scale factor determined by SVG root 'width'/'height' and the 'viewBox'.		: A scale factor determined by SVG root 'width'/'height' and the 'viewBox'. It serves to map 'user units' inside and SVG document to the ''real world''.

	== Inkscape specific ==		== Inkscape specific ==

Tavmjong: /* Definitions */

2014-12-05T10:21:15Z

Definitions

← Older revision		Revision as of 10:21, 5 December 2014
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	To better understand the following discussion it is necessary to have well defined terms to describe which ''unit'' is being talked about. Often ''unit'' is used when one should use ''unit identifier''.		To better understand the following discussion it is necessary to have well defined terms to describe which ''unit'' is being talked about. Often ''unit'' is used when one should use ''unit identifier''.

			== Generic SVG==

	; User Unit		; User Unit
	: A term defined by the SVG specification: [http://www.w3.org/TR/SVG/coords.html#Units a ~~value~~ in the current user coordinate system].		: A term defined by the SVG specification: [http://www.w3.org/TR/SVG/coords.html#Units a unit length in the current user coordinate system].

	; ~~External~~ Unit Identifier		; Unit Identifier
	: The unit ~~identifier~~ in ~~the root SVG~~ ''~~width~~'' or ''~~height~~'' ~~attribute~~. ~~If the~~ ''~~width~~'' ~~is '10in~~', ~~the External Unit Identifier is~~ 'in'.		: The part of a length value that expresses the units used to interpret the length. In SVG there are six '[http://www.w3.org/TR/css3-values/#absolute-lengths' absolute]' unit identifiers: 'mm', 'cm', 'in', 'pt', 'pc', 'px' and several '[http://www.w3.org/TR/css3-values/#relative-lengths relative]' unit identifiers: 'em', 'ex', '%', ...

	; ~~External Unit~~		; SVG Scale Factor
	: A ~~length of 1 as expressed with the External Unit Identifier. If the '~~'width'' ~~is '10in~~', the ~~External Unit is~~ '~~1in~~'.		: A scale factor determined by SVG root 'width'/'height' and the 'viewBox'.

	~~; Internal Unit~~		== Inkscape specific ==
	: The basic SVG unit. Never used with a unit identifier. It is the initial value of the User Unit. The real world value of the Internal Unit is determined by the 'SVG scale' determined from the root SVG ''width''/''height'' attributes and the ''viewBox''.

	; GUI Unit Identifier ('inkscape:document-units')		; GUI Unit Identifier ('inkscape:document-units')
	: The unit identifier displayed in the GUI. It should not be used when storing numerical values inside the SVG file (e.g. a width may be displayed in ''mm'' in the GUI but should be stored in user units). ~~It is read~~ in as SPNamedView->doc_units. This value is returned in 0.91 by getDefaultUnit() and in trunk by getDisplayUnit(). (Renamed to avoid confusion.)~~<br/>During the run-up to 0.91 it was used in some places to represent the "SVG Scale". <br/>Directly read~~ in sp-namedview.cpp, read and written in ui/dialog/document-properties.cpp, metafile-inout.cpp, test_reassemble.c.		: The unit identifier displayed in the GUI.
			: It should not be used when storing numerical values inside the SVG file (e.g. a width may be displayed in ''mm'' in the GUI but should be stored in 'user units').
			: During the run-up to 0.91 it was used in some places to represent the "SVG Scale".
			: Read in as SPNamedView->doc_units. This value is returned in 0.91 by getDefaultUnit() and in trunk by getDisplayUnit(). (Renamed to avoid confusion.)
			: Read in sp-namedview.cpp, read and written in ui/dialog/document-properties.cpp, metafile-inout.cpp, test_reassemble.c.

			;Page Size Unit Identifier (namedview 'units')
			: The unit identifier displayed in the page size widget.
			: It's only use is to set the default unit in the page-sizer widget. The variable has been renamed to 'page_size_units' in trunk.
			: Read in as SPNamedView->units. Only used in ui/widget/page-sizer.cpp.


			== Example ==

			Consider an SVG with the following SVG root element:

			<svg width="10in" height="6in" viewBox="0 0 50 30">

			; Drawing size
			:# This is a nominal 10x6 inch drawing. The actual size of the drawing when displayed depends on how it is displayed. It is very unlikely to be the nominal size when displayed on a digital screen.
			:# The width of '10in' could be equivalently written as '25.4cm', '254mm', etc.
			:# The width could also be written as '960' or '960px' using the CSS/SVG defined value of 96 pixels per inch.
			:#* If a 'unit identifier' is missing or 'px', the length is interpreted to be in 'user units'. CSS requires the use of a 'unit identifier'.
			:#* Inkscape 0.91 and earlier used a value of 90 pixels per inch.

	;~~Page size~~ units (~~namedview~~ 'units')		; Initial 'user unit'
	: ~~Actually a Unit Identifier. Read in as SPNamedView~~->units.~~<br/>Only used in ui/widget/page-sizer~~.~~cpp. It~~'~~s only~~ use is ~~to set~~ the ~~default unit in~~ the ~~page-sizer widget~~. The ~~variable~~ has ~~been renamed to~~ '~~page_size_units~~' ~~in trunk~~.		: The 'viewBox' defines the drawing to be 50 'user units' wide and 30 'user units' high (with no offset of the origin).
			:# A rectangle with 'width="10"' is 10 'user units' wide which would correspond to 2 inches at the nominal drawing size (if no scaling transforms are applied).
			:# A rectangle with 'width="1in"' is 96 'user-units' wide, corresponding to a width of 19.2 inches at the nominal drawing size. This is ''not'' what one would naively expect and is the reason the use of 'unit identifiers' is not recommended inside the SVG document (other than on the root 'width' and 'height'.
			:# The 'user unit' can be scaled by a transform. For example, if a group has a scaling transform of 0.5 ('transform="scale(0.5,0.5)'), the 'user unit' is half the length of the initial 'user unit' and objects inside the group are drawn at half their nominal size.

	;SVG ~~Scale~~		; SVG scale factor
	: ~~This is/will be a Geom::Scale variable that reflects the current~~ scale factor ~~between the SVG root~~ '~~width~~'/'~~height~~' and ~~the~~ '~~viewBox~~'.		: The scale factor is 0.2 inches per initial 'user unit'. (10 inches/50 'user units). SVG allows for different scaling factors in 'x' and 'y'.

	=Inkscape & Units=		=Inkscape & Units=

Tavmjong: /* Notes */

2014-12-03T16:10:54Z

Notes

← Older revision		Revision as of 16:10, 3 December 2014
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	See [http://tavmjong.free.fr/INKSCAPE/UNITS/ Test Files]		See [http://tavmjong.free.fr/INKSCAPE/UNITS/ Test Files]

	~~=Notes=~~

	The outer SVG width/height, viewBox, and document-units should not be changed in the XML Editor. Use the Page tab of the Document Properties to change the document size or document unit to avoid the risk of them becoming inconsistent.