# 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.

### X11 Geometry Specifications

X11 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 or right and top and bottom 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 right edge of the object is to be placed xoffset pixels in from the right 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 bottom edge of the object is to be yoffset pixels above the bottom 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. Objects can be placed in the four corners of the image using the following specifications:

+0+0 | upper left hand corner.
-0+0 | upper right hand corner.
-0-0 | lower right hand corner.
+0-0 | lower left hand corner.

### ImageMagick Extensions To X11 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 contructor 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 |  | unsigned int width_, unsigned int height_, unsigned int xOff_ = 0, unsigned int yOff_ = 0, bool xNegative_ = false, bool yNegative_ = false | Construct X11 geometry via explicit parameters.
const string geometry_ | Construct geometry from C++ string
const char * geometry_ | Construct geometry from C string
width | void | unsigned int width_ | Width
unsigned int | void
height | void | unsigned int height_ | Height
unsigned int | void
xOff | void | unsigned int xOff_ | X offset from origin
int | void
yOff | void | unsigned int yOff_ | Y offset from origin
int | void
xNegative | void | bool xNegative_ | Sign of X offset negative? (X origin at right)
bool | void
yNegative | void | bool yNegative_ | Sign of Y offset negative? (Y origin at bottom)
bool | void
percent | void | bool percent_ | Width and height are expressed as percentages
bool | void
aspect | void | bool aspect_ | Resize without preserving aspect ratio (!)
bool | void
greater | void | bool greater_ | Resize if image is greater than size (>)
bool | void
less | void | bool less_ | Resize if image is less than size (<)
bool | void
isValid | void | bool isValid_ | Does object contain valid geometry?
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
operator<< | ostream& | ostream& stream_, const Geometry& geometry_ | Stream onto ostream