Re: display word wrapping

[Peter Lee]

>>>> Juanma Barranquero writes:

    Juanma> On 26 May 2004 17:06:57 +0200
    Juanma> address@hidden (Kim F. Storm) wrote:

    Juanma> IMO the image support on Windows is still shaky. Current
    Juanma> problems with that (at least, these are the problems I'm
    Juanma> experiencing):

    Juanma>  - There's no single, good, Windows version of the
    Juanma> relevant libraries, so we must try to load each library
    Juanma> with several names, hoping for the best (for example, we
    Juanma> try to load libjpeg.dll, jpeg-62.dll and jpeg.dll, in that
    Juanma> order). That seems fragile.

Indeed.  It took some digging before I discovered the LoadLibrary
calls in image.c.

    Juanma>  - The best-so-far libraries (that I know of) are the
    Juanma> GnuWin32 ones, but (relatively) recent upgrades in some of
    Juanma> them changed some names, so if you try to use them you end
    Juanma> loading several, differently named, zlib DLLs, for
    Juanma> example.

After getting the latest version of the image libraries from gnuwin32,
I had to rename the following files:

jpeg62.dll to jpeg.dll
libtiff3.dll to libtiff.dll
libXpm-noX4.dll to libxpm.dll
zlib1.dll to zlib.dll

    Juanma>  - On MSVC optimized builds, several libraries (most
    Juanma> notably the TIFF one) crash on loading an image. I've
    Juanma> tried to debug it several times, with no success; I'm not
    Juanma> even sure whether is a real Emacs bug hidden somewhere, or
    Juanma> a bug in the MSVC optimizer. Worse, with newest GnuWin32
    Juanma> releases the problem affect more libraries, and some of
    Juanma> them (libpng) don't seem to work at all.

I had this same problem.  I was never able to view images with msvc
build.  At best it would just show an empty box, but usually
crashed.  I always suspected msvc optimization, but I never tried a
non-optimized build.  I just started using mingw.

    Juanma> I'm not entirely sure what to do. Perhaps we could compile
    Juanma> our own graphics libs and distribute them with Emacs,
    Juanma> though that's quite a lot of additional work. But as I
    Juanma> stands, I'd add a section to nt/INSTALL saying: "Don't
    Juanma> compile with image support unless you know what you're
    Juanma> doing and are willing to do some debugging."

I think it would be enough to put a link to gnuwin32 and explain what
libraries are needed for image support.  Which are:
  zlib
  xpm
  libtiff
  libjpeg
  libpng
  libungif
  liburt (needed by ungif)
  fdlibm (needed by ungif)
  libgw32c (needed by ungif)

I'd also note in the nt/INSTALL that the dll's are expected to have
certain names and list those names for each required library.  Then
just explain to the user that after downloading the image binaries
they may need to rename some dll's as well as making sure those dll's
are in the path.

With mingw gcc build and the latest image libs from gnuwin32, I'm
able to view all images supported and have had no real problems.