Commit ca0d44e4 authored by Glenn Morris's avatar Glenn Morris

* doc/lispref/display.texi (ImageMagick Images): General cleanup.

parent c0468714
2010-09-09 Glenn Morris <rgm@gnu.org>
* display.texi (ImageMagick Images): General cleanup.
2010-09-06 Alexander Klimov <alserkli@inbox.ru> (tiny change)
* files.texi (Directory Names): Use \` rather than ^.
......
......@@ -4468,47 +4468,56 @@ specifying the bounding box of the PostScript image, analogous to the
@node ImageMagick Images
@subsection ImageMagick Images
The Imagemagick library can be used to load many image formats in Emacs.
@cindex ImageMagick images
@cindex images, support for more formats
If you build Emacs with ImageMagick (@url{http://www.imagemagick.org})
support, you can use the ImageMagick library to load many image formats.
@findex imagemagick-types
The function @code{imagemagick-types} returns a list of image file
extensions that your installation of ImageMagick supports. To enable
support, you must call the function @code{imagemagick-register-types}.
@vindex imagemagick-types-inhibit
The variable @code{imagemagick-types-inhibit} specifies a list of
image types that you do @emph{not} want ImageMagick to handle. There
may be overlap between image loaders in your Emacs installation, and
you may prefer to use a different one for a given image type (which
@c FIXME how is this priority determined?
loader will be used in practice depends on the priority of the loaders).
@c FIXME why are these uppercase when image-types is lower-case?
@c FIXME what are the possibe options? Are these actually file extensions?
For example, if you never want to use the ImageMagick loader to use
JPEG files, add @code{JPG} to this list.
@vindex imagemagick-render-type
You can set the variable @code{imagemagick-render-type} to choose
between screen render methods for the ImageMagick loader. The options
are: @code{0}, a conservative method which works with older
@c FIXME details of this "newer method"?
@c Presumably it is faster but may be less "robust"?
ImageMagick versions (it is a bit slow, but robust); and @code{1},
a newer ImageMagick method.
Images loaded with ImageMagick support a few new display specifications:
The function (imagemagick-types) returns a list of image file
extensions that your installation of imagemagick supports.
The function (imagemagick-register-types) will enable the imagemagick
support for the extensions in imagemagick-types minus the types listed
in imagemagick-types-inhibit.
imagemagick-types-inhibit has the value '(C HTML HTM TXT PDF) by
default. There can be overlap between image loaders in your Emacs
installation. If you never want to use the ImageMagick loader to use
Jpeg files, for instance, add 'JPG to imagemagick-types-inhibit. Which
loader that will be used in practice depends on the priority of the
loaders.
imagemagick-render-type is a new variable which can be set to choose
between screen render methods for the ImageMagick loader.
- 0 is a conservative metod which works with older ImageMagick
versions. It is a bit slow, but robust.
- 1 utilizes a newer ImageMagick method
Images loaded with imagemagick will support a couple of new display
specification behaviours:
- if the :width and :height keywords are specified, these values are
used for scaling the image. If only one of :width or :height is
specified, the other one will be calculated so as to preserve the
aspect ratio.If both :width and :height are specified, aspect ratio
will not be preserved.
- :rotation specifies a rotation angle in degrees.
- :index specifies which image inside an image bundle file format, such
as TIFF or DJVM, to view.
The image-metadata function can be used to retrieve the total number
of images in an image bundle. This is simmilar to how GIF files work.
@table @code
@item :width, :height
The @code{:width} and @code{:height} keywords are used for scaling the
image. If only one of them is specified, the other one will be
calculated so as to preserve the aspect ratio. If both are specified,
aspect ratio may not be preserved.
@item :rotation
Specifies a rotation angle in degrees.
@item :index
Specifies which image to view inside an image bundle file format, such
as TIFF or DJVM. You can use the @code{image-metadata} function to
retrieve the total number of images in an image bundle (this is
similar to how GIF files work).
@end table
@node Other Image Types
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