RE: Q on performance with 10000 faces

["Drew Adams" <drew.adams@oracle.com>]

    > I guess one alternative would be to insert an image of a
    > complete palette (like the image attached)

    You can construct that image on the fly using eg. XPM format.

Where can I find doc to tell me how to do that? Anything in Emacs about it,
or should I just google for "xpm"?

    To overcome limitations in number of available colors, you could
    construct 100 images covering one line each.

What are the limitations you refer to here? I'm not clear how 100 single-row
images would be better than one 110-row image. Is it because the number of
colors is somehow limited per line?

    Then use the line-height property of the newline character to
    make the display "tight":

          (insert (propertize "\n" 'line-height t)))))

BTW, why does that work for images but not, apparently, for text lines? At
least it didn't seem to work for me - see bug report yesterday.

    Finally, you may use the :map property on images:

    `:map MAP'
         This associates an image map of "hot spots" with this image.

That's what I couldn't find (what I meant by HTML image maps). Thx.

         An image map is an alist where each element has the format `(AREA
         ID PLIST)'.  An AREA is specified as either a rectangle, a circle,
         or a polygon.

         A rectangle is a cons `(rect . ((X0 . Y0) . (X1 . Y1)))' which
         specifies the pixel coordinates of the upper left and bottom right
         corners of the rectangle area.

         A circle is a cons `(circle . ((X0 . Y0) . R))' which specifies
         the center and the radius of the circle; R may be a float or
         integer.

         A polygon is a cons `(poly . [X0 Y0 X1 Y1 ...])' where each pair
         in the vector describes one corner in the polygon.

         When the mouse pointer is above a hot-spot area of an image, the
         PLIST of that hot-spot is consulted; if it contains a `help-echo'
         property it defines a tool-tip for the hot-spot, and if it contains
         a `pointer' property, it defines the shape of the mouse cursor when
         it is over the hot-spot.  *Note Pointer Shape::, for available
         pointer shapes.

         When you click the mouse when the mouse pointer is over a
         hot-spot, an event is composed by combining the ID of the hot-spot
         with the mouse event; for instance, `[area4 mouse-1]' if the
         hot-spot's ID is `area4'.

    Or simply use a common mouse click function and use the x,y coordinates
    of the mouse event to calculate which color is clicked.
    See posn-x-y and posn-object-x-y.

That's what I meant. That would be my next move: just use the image I sent,
knowing that it fits over the character grid I made originally and that I
can record the colors of.