Magick::Geometry

Geometry provides a convenient means to specify a geometry argument. The object may be initialized from a C string or C++ string containing a geometry specification. It may also be initialized by more efficient parameterized constructors.

Geometry Specifications

Geometry specifications are in the form "<width>x<height>{+-}<xoffset>{+-}<yoffset>" (where width, height, xoffset, and yoffset are numbers) for specifying the size and placement location for an object.

The width and height parts of the geometry specification are measured in pixels. The xoffset and yoffset parts are also measured in pixels and are used to specify the distance of the placement coordinate from the left and top and edges of the image, respectively. Both types of offsets are measured from the indicated edge of the object to the corresponding edge of the image. The X offset may be specified in the following ways:

+xoffset	The left edge of the object is to be placed xoffset pixels in from the left edge of the image.
-xoffset	The left edge of the object is to be placed outside the image, xoffset pixels out from the left edge of the image.

The Y offset has similar meanings:

+yoffset	The top edge of the object is to be yoffset pixels below the top edge of the image.
-yoffset	The top edge of the object is to be yoffset pixels above the top edge of the image.

Offsets must be given as pairs; in other words, in order to specify either xoffset or yoffset both must be present.

ImageMagick Extensions To Geometry Specifications

ImageMagick has added a number of qualifiers to the standard geometry string for use when resizing images. The form of an extended geometry string is "<width>x<height>{+-}<xoffset>{+-}<yoffset>{%}{!}{<}{>}". Extended geometry strings should only be used when resizing an image. Using an extended geometry string for other applications may cause the API call to fail. The available qualifiers are shown in the following table:

ImageMagick Geometry Qualifiers

Qualifier	Description
%	Interpret width and height as a percentage of the current size.
!	Resize to width and height exactly, loosing original aspect ratio.
<	Resize only if the image is smaller than the geometry specification.
>	Resize only if the image is greater than the geometry specification.

Postscript Page Size Extension To Geometry Specifications

Any geometry string specification supplied to the Geometry constructor is considered to be a Postscript page size nickname if the first character is not numeric. The Geometry constructor converts these page size specifications into the equivalent numeric geometry string specification (preserving any offset component) prior to conversion to the internal object format. Postscript page size specifications are short-hand for the pixel geometry required to fill a page of that size. Since the 11x17 inch page size used in the US starts with a digit, it is not supported as a Postscript page size nickname. Instead, substitute the geometry specification "792x1224>" when 11x17 output is desired.

An example of a Postscript page size specification is "letter+43+43>".

Postscript Page Size Nicknames

Postscript Page Size Nickname	Equivalent Extended Geometry Specification
Ledger	1224x792>
Legal	612x1008>
Letter	612x792>
LetterSmall	612x792>
ArchE	2592x3456>
ArchD	1728x2592>
ArchC	1296x1728>
ArchB	864x1296>
ArchA	648x864>
A0	2380x3368>
A1	1684x2380>
A2	1190x1684>
A3	842x1190>
A4	595x842>
A4Small	595x842>
A5	421x595>
A6	297x421>
A7	210x297>
A8	148x210>
A9	105x148>
A10	74x105>
B0	2836x4008>
B1	2004x2836>
B2	1418x2004>
B3	1002x1418>
B4	709x1002>
B5	501x709>
C0	2600x3677>
C1	1837x2600>
C2	1298x1837>
C3	918x1298>
C4	649x918>
C5	459x649>
C6	323x459>
Flsa	612x936>
Flse	612x936>
HalfLetter	396x612>

Geometry Methods

Geometry provides methods to initialize its value from strings, from a set of parameters, or via attributes. The methods available for use in Geometry are shown in the following table:

Geometry Methods

Method	Return Type	Signature(s)	Description
Geometry		size_t width_, size_t height_, ssize_t xOff_ = 0, ssize_t yOff_ = 0, bool xNegative_ = false, bool yNegative_ = false	Construct geometry via explicit parameters.
		const string geometry_	Construct geometry from C++ string
		const char * geometry_	Construct geometry from C string
width	void	size_t width_	Width
width	size_t	void	Width
height	void	size_t height_	Height
height	size_t	void	Height
xOff	void	ssize_t xOff_	X offset from origin
xOff	ssize_t	void	X offset from origin
yOff	void	ssize_t yOff_	Y offset from origin
yOff	size_t	void	Y offset from origin
xNegative	void	bool xNegative_	Sign of X offset negative? (X origin at right)
xNegative	bool	void	Sign of X offset negative? (X origin at right)
yNegative	void	bool yNegative_	Sign of Y offset negative? (Y origin at bottom)
yNegative	bool	void	Sign of Y offset negative? (Y origin at bottom)
percent	void	bool percent_	Width and height are expressed as percentages
percent	bool	void	Width and height are expressed as percentages
aspect	void	bool aspect_	Resize without preserving aspect ratio (!)
aspect	bool	void	Resize without preserving aspect ratio (!)
greater	void	bool greater_	Resize if image is greater than size (>)
greater	bool	void	Resize if image is greater than size (>)
less	void	bool less_	Resize if image is less than size (<)
less	bool	void	Resize if image is less than size (<)
isValid	void	bool isValid_	Does object contain a valid geometry? May be set to false in order to invalidate an existing geometry object.
isValid	bool	void
operator =	const Geometry&	const string geometry_	Set geometry via C++ string
operator =	const Geometry&	const char * geometry_	Set geometry via C string
operator string	string	Geometry&	Obtain C++ string representation of geometry

In addition, we support these yet to be documented geometry flags: the fill area flag ('^') and the pixel area count limit flag ('@').