If you build Emacs with ImageMagick support, you can use the
ImageMagick library to load many image formats (see File
Conveniences in The GNU Emacs Manual). The image type symbol
for images loaded via ImageMagick is
imagemagick, regardless of
the actual underlying image format.
This function returns a list of image file extensions supported by the
current ImageMagick installation. Each list element is a symbol
representing an internal ImageMagick name for an image type, such as
BMP for .bmp images.
The value of this variable is a list of ImageMagick image types which
Emacs may attempt to render using ImageMagick. Each list element
should be one of the symbols in the list returned by
imagemagick-types, or an equivalent string. Alternatively, a
value of t enables ImageMagick for all possible image types.
Regardless of the value of this variable,
imagemagick-types-inhibit (see below) takes precedence.
The value of this variable lists the ImageMagick image types which should never be rendered using ImageMagick, regardless of the value of imagemagick-enabled-types. A value of t disables ImageMagick entirely.
This variable is an alist mapping image types to file name extensions.
Emacs uses this in conjunction with the
:format image property
(see below) to give a hint to the ImageMagick library as to the type
of an image. Each element has the form
extension), where type is a symbol specifying an image
content-type, and extension is a string that specifies the
associated file name extension.
Images loaded with ImageMagick support the following additional image descriptor properties:
background, if non-
nil, should be a string specifying a
color, which is used as the image’s background color if the image
supports transparency. If the value is
nil, it defaults to the
frame’s background color.
:width width, :height height
: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.
:max-width max-width, :max-height max-height
:max-height keywords are used for
scaling if the size of the image of the image exceeds these values.
:width is set it will have precedence over
:height is set it will have precedence over
max-height, but you can otherwise mix these keywords as you
:max-height will always preserve
the aspect ratio.
The value, type, should be a symbol specifying the type of the image data, as found in image-format-suffixes. This is used when the image does not have an associated file name, to provide a hint to ImageMagick to help it detect the image type.
Specifies a rotation angle in degrees.
See Multi-Frame Images.