PPresenter
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<TITLE>Portable Presenter; Images</TITLE>

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<TR><TD WIDTH=15% VALIGN=top><IMG SRC=../images/ppresenter.png WIDTH=150 HEIGHT=170></TD>
    <TD ALIGN=center><H1>Images</H1></TD></TR>
<TR><TD VALIGN=top>

<A HREF=../index.html>PPresenter</A><BR>
<A HREF=../manual.html>Manual</A><BR>
<B>Images</B><BR>
<UL>
<LI><A HREF=tkphoto.html>tkPhoto</A>
<LI><A HREF=magick.html>Magick</A>
</UL>
<P>
Options:
<UL>
<LI><A HREF=#general>general</A>
<LI><A HREF=#related>related</A>
</UL>
<P>
<A HREF=#examples>Examples</A>
<P>

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An important part of the design of
<A HREF=../../index.html>Portable Presenter</A> is the requirement for
screen-size independency; fonts and also images are scaled, dependent on
the actual screen-size.
<P>
There are two packages which handle images which you can use:
<UL>
<LI><A HREF=tkphoto.html>Tk::Photo images</A>, which are part of tk, but
    only support a view formats and rather primitive operations;
<LI><A HREF=magick.html>Image::Magick images</A>, which is a package
    available for many operating-systems, capable of processing hardly
    any image format imaginable.<BR>
    See the <A HREF=../download/index.html>download page</A> on how
    to retrieve this optional package.
</UL>
<P>
They way how images work do differ on which package you use: Tk::Photo
images are related to a canvas
(say <A HREF=../viewport/index.html>viewport</A>), while Image::Magick
images are device independent.

<H2><A NAME=general>General</A> Image Options</H2>

<DL>
<DT><B>-file =&gt;</B> <I>filename</I>
<DD>The name of the file to be used.  PPresenter searches the directories in
    the <CODE>imageDirs</CODE> list (see the <CODE>addImageDir</CODE>
    function described below) for the file, except when this is an
    absolute path, of course.
    <P>
    Each file is read only once.  Each images is scaled at most once per
    viewport which shows the image.
    <P>
<DT><B>-sizeBase =&gt;</B> <I>geometry</I>
<DD>Overrules what the show's <CODE>-imageSizeBase</CODE> is defining on what
    screen-size this image is made.  During the presentation, the image
    is scaled to occupy the same amount of screen-space.  Of course only
    when resizing is enabled.
    <P>
<DT><B>-resize =&gt;</B> <I>boolean</I>
<DD>Overrules the show's <CODE>-resize</CODE> (by default on), on whether
    the images should be resized or not.  Resizing can only take place when
    a sizeBase is defined.
    <P>
<DT><B>-enlarge =&gt;</B> <I>boolean</I>
<DD>Overrules the show's <CODE>-enlarge</CODE> (by default off), on whether
    enlarging is allowed when resizing.   This is usually not a good idea,
    because your image quality will be decrease.
    <P>
<DT><B>imageDirs =&gt; [</B>  <I>dir, ...</I> <B>]</B>
<DD>Directories where images can reside.  You shall not change
    anything directly in this list, but only using the function:
<PRE>
$show->addImageDir(<I>dir, ...</I>);
</PRE>
    PPresenter searches all directories from <CODE>@INC</CODE> to find
    the directories you specified, and adds them in from of the
    list in <CODE>imageDirs</CODE>.
    <P>
    At start, the paths "<CODE>PPresenter/images</CODE>" and
    "<CODE>.</CODE>" are added.
</DL>

<H2><A NAME=related>Related Options</A></H2>

Related options of <A HREF=../show/new.html#images>show new()</A>:
<DL>
<DT><B>-imageSizeBase =&gt;</B> <I>geometry</I>
<DT><B>-resizeImages =&gt;</B> <I>boolean</I>
<DT><B>-enlargeImages =&gt;</B> <I>boolean</I>
<DT><B>-scaledImagesDir =&gt;</B> <I>dirname</I>
</DL>
Related options of <A HREF=../decoration/index.html>decoration</A>:
<DL>
<DT><B>-bgcolor</B>
<DD>Determines the color to be used in anti-aliasing while resizing
    transparent images.
<DT><B>-nestImages</B>
</DL>

<H2><A NAME=examples>Examples</A></H2>

<H4>Example 1: Use in the Markup Formatter</H4>

A way to include an image in a show:
<PRE>
   use PPresenter;
   my $show = PPresenter-&gt;new;
   $show-&gt;addSlide(-template =&gt; 'main'
     , -main =&gt; '&lt;IMG SRC=image.gif&gt;');
</PRE>
Options to the <CODE>IMG</CODE> tag of the markup-formatter are
<CODE>RESIZE</CODE> (reflects -resize), <CODE>ENLARGE</CODE> (-enlarge),
<CODE>BASE</CODE> (-sizeBase), and some more for markup.
<P>
If the package Image::Magick is installed, then PPresenter will resize the image with
ImageMagick.  In that case, nearly all imaginable image formats can be
used.  If the package is not installed, the image is read via Tk::Photo,
which supports only a small set of formats (see manual on Tk::Photo).

<H4>Example 2: Same image twice</H4>
If you use the same image for the second time in the same show, those
specified options will be neglected: the first use is defining the image.
<PRE>
   use PPresenter;
   my $show = PPresenter-&gt;new;
   $show-&gt;addSlide(-main =&gt; '&lt;IMG SRC=image.gif RESIZE&gt;');
   $show-&gt;addSlide(-main =&gt; '&lt;IMG SRC=image.gif RESIZE=0&gt;');
</PRE>
In both cases, the resized version of the same image is shown!  For the
second use, I also could have written <CODE>SRC=image</CODE>, because
the basename of the file is an alias for an already defined image.

<H4>Example 3: Predefining images</H4>
The previous example has a hazard: if you run your presentation out of
order: start with the second slide and then the first.  In that case, the
image is not resized.
<P>
To avoid the hazard, but also to improve your possibilities to specify
the images, you can define an image outside a slide:
<PRE>
   use PPresenter;
   my $show = PPresenter->new;
   $show->image(-file =&gt; 'image.gif', -resize =&gt; 0);
   $show-&gt;addSlide(-main =&gt; '&lt;IMG SRC=image&gt;');
   $show-&gt;addSlide(-main =&gt; '&lt;IMG SRC=image&gt;');
</PRE>
Calling the <CODE>image()</CODE> function, you can specify the options
described in this manual-page.  You can refer to the image under its
filename, the basename of the filename, or other aliases (as with all
PPresenter-objects, you may specify an option
<PRE>
    -aliases =&gt; [ 'alias', 'alias2', ... ]
</PRE>

<H4>Example 4: Reading the images yourself</H4>

It is possible to read the images yourself, in your Perl-program, and
then offer it to PPresenter.  The possibilities are different if you want to
use Tk::Photo or Image::Magick;
<A HREF=tkphoto.html>Tk::Photo</A> images are related to a MainWindow
(<A HREF=../viewport/index.html>viewport</A>), while
<A HREF=magick.html>Image::Magick</A> images are not.
Read their manual-pages for more details.
<P>
If you have created you own Photo or Magick image, you can add this to
PPresenter with:
<PRE>
   $object = ...; # create Tk::Photo or Image::Magick object
   $show-&gt;image($object, -name =&gt; 'image');
</PRE>
You do not have to specify a name in case of Image::Magick (the
output filename will be taken by default), but it is clearer this
way.

<HR NOSHADE>
Portable Presenter is written and maintained by
<A HREF=http://mark.overmeer.net>Mark Overmeer</A>.
Copyright (C) 2000-2002, Free Software Foundation FSF.


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