Merge from origin/emacs-25

[gnu-emacs] / doc / lispref / display.texi

diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index 323895927a9933c18521f5a3e62833eb6620f704..26f3de40e919904a784460b8a1d953e146cc6c15 100644 (file)
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -5198,6 +5198,14 @@ and if @code{:height} is set it will have precedence over
 wish.  @code{:max-width} and @code{:max-height} will always preserve
 the aspect ratio.
 
+@item :scale @var{scale}
+This should be a number, where values higher than 1 means to increase
+the size, and lower means to decrease the size.  For instance, a value
+of 0.25 will make the image a quarter size of what it originally was.
+If the scaling makes the image larger than specified by
+@code{:max-width} or @code{:max-height}, the resulting size will not
+exceed those two values.
+
 @item :format @var{type}
 The value, @var{type}, should be a symbol specifying the type of the
 image data, as found in @code{image-format-suffixes}.  This is used
@@ -5384,6 +5392,13 @@ Here is an example of using @code{image-load-path-for-library}:
 @end example
 @end defun
 
+@vindex image-scaling-factor
+Images are automatically scaled when created based on the
+@code{image-scaling-factor} variable.  The value is either a floating
+point number (where numbers higher than 1 means to increase the size
+and lower means to shrink the size), or the symbol @code{auto}, which
+will compute a scaling factor based on the font pixel size.
+
 @node Showing Images
 @subsection Showing Images
 @cindex show image
@@ -5493,6 +5508,26 @@ cache, it can always be displayed, even if the value of
 @code{max-image-size} is subsequently changed (@pxref{Image Cache}).
 @end defvar
 
+Images inserted with the insertion functions above also get a local
+keymap installed in the text properties (or overlays) that span the
+displayed image.  This keymap defines the following commands:
+
+@table @kbd
+@item +
+Increase the image size (@code{image-increase-size}).  A prefix value
+of @samp{4} means to increase the size by 40%.  The default is 20%.
+
+@item -
+Decrease the image size (@code{image-increase-size}).  A prefix value
+of @samp{4} means to decrease the size by 40%.  The default is 20%.
+
+@item r
+Rotate the image by 90 degrees (@code{image-rotate}).
+
+@item o
+Save the image to a file (@code{image-save}).
+@end table
+
 @node Multi-Frame Images
 @subsection Multi-Frame Images
 @cindex multi-frame images