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Documentation: Icons and Images
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<center><img src='art/foxstart.png'>
<BR><B>Documentation: Icons and Images</B>
</center>
<p>
<p>
<b>Icons and Images</b>
<hr>
Icons and Images are part an parcel of attractive, user-friendly Graphical
User Interfaces these days. Consequently, considerable effort has
been expended in designing FOX to allow icon- and image-rich applications
to be developed with the greatest ease.
<P>In FOX, Images and Icons are objects that represent picture data.
Images are simple pictures, whereas Icons are pictures with a <I>shape
mask</I> that may be used to effectively mask out a certain area of the
picture, and allow part the background to peek through as if the picture
were transparent in some areas.
<P>Both Icons and Images may have <B>Client</B> <B>side</B> <B><I>pixel
data</I></B> as well as an <B>X Server side</B> <B><I>pixmap</I></B> representation.
The typical application will construct the client-side pixel data by filling
the Icon or Image with a picture, then create the server-side representation
[after contact with the X Server has been established] by calling i<TT>con->create()</TT>,
which creates an server side <I>pixmap</I> and uses a call to <TT>icon->render()</TT>
to fill the pixmap with the pixel data .
<P>Note that this is a two-step process which is very similar to that of
constructing and creating regular FOX Widgets. This is no accident.
The FOX philosophy is to construct [client-side] data structures such as
Widgets and Icons and Images etc., then with all the information available,
create their X Server side representation in one fell swoop by calling
<TT>app->create()</TT>.
<P>When you have given Buttons or Labels or other FOX Widgets icons, a
call to that Widget's <TT>create()</TT> member function will also automatically
call its icon <TT>create()</TT>. To allow icons to be shared by multiple
Widgets, it is specifically allowed to call <TT>create()</TT> more than
once on an icon or image.
<P>In many cases, after calling an icon's create() member function, there
is no need to keep the client-side pixel data around; thus, FOX icons will
in most cases release the memory taken up by the pixel data. Should
you want to repeatedly change the pixel data, however, FXIcon and FXImage
have an option <B>IMAGE_KEEP</B> to allow you to hang on to the pixel data
in the client. After making changes to the pixel data, you can call
<TT>icon->render()</TT>
again to render it into the pixmap.
<p>
<p>
<b>Image Formats Supported</b>
<hr>Currently, FOX supports <B>GIF</B>, <B>BMP</B>, <B>PNG</B>, <B>JPEG</B>, <B>XPM</B>, <B>TIFF</B>, <B>ICO</B>
and <B>PCX</B> based icons/images.
In the near future, <B>PPM</B> will be added as a convenience. The
most preferred format is GIF, as it is about 10 times more compact than
XPM, and about 2 times more compact than BMP. This is of some concern,
as applications may have lots of icons [some analysis of our own applications
revealed than one application's executable had about 1MB worth of XPM icons;
with GIF, this would have been less than a 100kB].
<p>
<p>
<b>Incorporating Icons and Images into an Application</b>
<hr>
One crucial problem with icon-rich applications is where to keep all
those icons; obviously, keeping icons in separate files allows end-users
to substitute icons and perhaps change them with an Icon Editor program.
However, such a scenario also poses a maintainance problem:- software becomes
extraordinarily dependent on specifics of a user installation, and end-users
may actually break software by substituting corrupted icon files by accident,
or perhaps other applications may overwrite them. Another common
problem is the need for end-users to set paths and environment variables.
<P>To eliminate these problems, the FOX approach is to <B><I>embed</I></B>
all icons and images right into the application's executable. This
is done by simply by compiling the icons into the code in the form of C
data statements, and then linking them in.
<P>For XPM icons or images, the image files can be directly included into
the code, as the XPM format is basically a C/C++ data array.
<P>Other image formats need to be transformed into a C/C++ data
array with a small build-time utility called <A NAME="RESWRAP"></A><B><I>reswrap</I></B>,
which is provided in the FOX distribution.
<P>
Reswrap allows you to generate the C/C++ data arrays automatically from the
icons during the build process of your application; simply add a few rules
into your Makefile, or, under VC++, use the reswrap program in a so-called
<em>Utility Project</em>.
<P>For example, given as input a GIF file image such as below:
<BR>
<BR>
<BR>
<BR>
<BR>
<BR>
<CENTER>
<P><IMG SRC="art/bigpenguin.png" HEIGHT=57 WIDTH=48>
<BR>Figure 1. Linux Penguin from file <I>bigpenguin.gif</I>.</CENTER>
<BR>
<P><BR>
<BR>
<BR>
<BR>
<BR>
<BR>
<BR>
<P> After processing this file, reswrap generates a C data statement
such as:
<BR>
<CENTER><TABLE BORDER CELLSPACING=0 COLS=1 WIDTH="90%" BGCOLOR="#FFF8E1" NOSAVE >
<TR>
<TD><TT>/* Generated by reswrap from file <I>bigpenguin.gif</I> */</TT>
<BR><TT>const unsigned char bigpenguin[]={</TT>
<BR><TT> 0x47,0x49,0x46,0x38,0x37,0x61,0x30,0x00,0x39,0x00,0xf3,0x00,0x00,0xb2,0xc0,0xdc,</TT>
<BR><TT> ...............................................................................</TT>
<BR><TT> ...............................................................................</TT>
<BR><TT> 0xf4,0xe0,0x63,0x90,0x7c,0x7d,0x40,0xc5,0x92,0x0c,0x34,0x39,0x41,0x04,0x00,0x3b</TT>
<BR><TT> };</TT></TD>
</TR>
</TABLE></CENTER>
<P>This can then be subsequently compiled into an object file, and linked
in with the executable. To make use of such an icon, FOX supports
deserialization from a <I>memory stream</I>.
<BR>The icon data above could be used as follows to create an Icon:
<BR>
<CENTER><TABLE BORDER CELLSPACING=0 COLS=1 WIDTH="90%" BGCOLOR="#FFF8E1" NOSAVE >
<TR>
<TD>
<BLOCKQUOTE><TT></TT>
<BR><TT>FXIcon *tux_icon = new FXGIFIcon(application,bigpenguin);</TT></BLOCKQUOTE>
</TD>
</TR>
</TABLE></CENTER>
<P>Wait! Is that all? Yes it is! This <I>one</I> statement creates
an icon object, then <I>deserializes</I> the icon data from the GIF stream
to build the icon's internal pixel data. A subsequent call:
<BLOCKQUOTE><TT>tux_icon->create();</TT></BLOCKQUOTE>
Will create an X pixmap, render the icon into it, and subsequently release
the pixel data after it is no longer needed. If you had created the
icon with the IMAGE_KEEP option, the pixel data would have been kept around
for subsequent manipulation by your application, and perhaps repeated rendering.
<P>To draw the icon in a window, simply:
<BR>
<BLOCKQUOTE><TT>window->drawIcon(tux_icon,x,y);</TT></BLOCKQUOTE>
will do the job.
<p>
<p>
<b>Bitmaps</b>
<hr>
Bitmaps in FOX behave very much like Images. Except, unlike Images
which are always 24 bits, and in color, Bitmaps are only one bit, or blank
and white. Typical uses for Bitmaps are the creation of patterns
and stipples, or shape masks against which other primitives are clipped.
<BR>In terms of constructing and using Bitmaps in FOX, it is completely
analoguous:
<BR>
<BR>
<CENTER><TABLE BORDER CELLSPACING=0 COLS=1 WIDTH="90%" BGCOLOR="#FFF8E1" NOSAVE >
<TR>
<TD>
<BR>// Bitmap Data, in XBM Format
<P>#define gray_width 32
<BR>#define gray_height 2
<BR>static unsigned char gray_bits[] = {0x55, 0x55, 0x55, 0x55, 0xaa, 0xaa,
0xaa, 0xaa};
<P>// Construct a bitmap object
<BR>FXBitmap *grayBitmap=new FXBitmap(application, gray_bits, 0, gray_width,
gray_height);</TD>
</TR>
</TABLE></CENTER>
<P>In terms of using Bitmaps for subsequent tiling and stippling operations,
remember that MS-Windows has certain size limits such patterns; X-Windows
has no such limit, but presumably smaller patterns are more efficient.
It is probably a good idea to keep so widths such as 8,16, or 32.
<p>
<p>
<b>Cursors</b>
<hr>
Cursors can be constructed in FOX to change the shape of the mouse-cursor.
Constructing Cursors is very similar to constructing Bitmaps, except that
Cursors comprise two bitmaps, a picture and a shape mask; also, Cursors
have a so-called hot-spot, the point inside the cursor-glyph which is ``pointer
to'' by the mouse.
<BR>Besides defining your own ``custom'' cursors, FOX also allows you to
simply create a ``stock'' cursor, i.e. a cursor whose shape has already
been predefined by the system.
<P>To create a custom Cursor:
<BR>
<BR>
<CENTER><TABLE BORDER CELLSPACING=0 COLS=1 WIDTH="90%" BGCOLOR="#FFF8E1" NOSAVE >
<TR>
<TD>
<BR>// Picture bits, in XBM Format
<BR>#define resize_width 32
<BR>#define resize_height 32
<BR>#define resize_x_hot 9
<BR>#define resize_y_hot 9
<BR>static unsigned char resize_bits[] = {
<BR> 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xfc,
0x00, 0x00, 0x00,
<BR> ....
<BR> 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00};
<P>// Shape bits, in XBM Format
<BR>#define resize_mask_width 32
<BR>#define resize_mask_height 32
<BR>#define resize_mask_x_hot 9
<BR>#define resize_mask_y_hot 9
<BR>static unsigned char resize_mask_bits[] = {
<BR> 0x00, 0x00, 0x00, 0x00, 0xfe, 0x01, 0x00, 0x00, 0xfe,
0x01, 0x00, 0x00,
<BR> ....
<BR> 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00};
<BR>
<P> // Resize corner
<BR> resizeCursor=new FXCursor(application,resize_bits,resize_mask_bits,resize_width,resize_height,resize_x_hot,resize_y_hot);
<BR> </TD>
</TR>
</TABLE></CENTER>
<P>To create a stock Cursor:
<BR>
<BR>
<CENTER><TABLE BORDER CELLSPACING=0 COLS=1 WIDTH="90%" BGCOLOR="#FFF8E1" NOSAVE >
<TR>
<TD>
<BR> // Text Cursor
<BR> IBeamCursor=new FXCursor(application,CURSOR_IBEAM);
<BR> </TD>
</TR>
</TABLE></CENTER>
<P>If you define your own Custom Cursors, make sure the size is exactly
32x32. MS-Windows does not support any other sizes. Also, the shape
and the picture will have to be the same size.
<p>
<p>
<b>If Icons Look Funny...</b>
<hr>Sometimes, your icons may look funny. This is usually because
FOX Icon routines determine the wrong value for the transparency color.
FOX can handle images with a true alpha-channel, or images with a special
transparency color. The latter is the more common approach, as many
file formats do not support true alpha channels.
<BR>Different image formats guess the transparency color in different ways.
<P>For <B><I>GIF</I></B> Images, FOX uses the following algorithm:
<BR>
<UL>
<LI>
If a transparent color is found in the GIF file, that color is used.</LI>
<LI>
If not, the background color is used.</LI>
<LI>
If the option IMAGE_ALPHACOLOR is used when constructing the icon, the
specified color is used.</LI>
<LI>
Finally, if the option IMAGE_OPAQUE is used, the icon is forced to be non-transparent.</LI>
</UL>
<P><BR>For <B><I>BMP</I></B> images, there is no background or transparency
color in the image file format; the algorithm is simpler:
<BR>
<UL>
<LI>
The assumed transparency color is the same as the default GUI background
color, which is FXRGB(192,192,192).</LI>
<LI>
If the option IMAGE_ALPHACOLOR is used when constructing the icon, the
specified color is used.</LI>
<LI>
Finally, if the option IMAGE_OPAQUE is used, the icon is forced to be non-transparent.</LI>
</UL>
<P><BR>In most cases, you will create your icons simply as below:
<BR>
<BLOCKQUOTE><FONT FACE="Courier New,Courier">new FXGIFIcon(app,picture_data);</FONT></BLOCKQUOTE>
<P><BR>In some cases, when you want to override the transparency color,
construct your icons as:
<BR>
<BLOCKQUOTE><FONT FACE="Courier New,Courier">new FXGIFIcon(app,picture_data,FXRGB(192,192,192),IMAGE_ALPHACOLOR);</FONT></BLOCKQUOTE>
<P><BR>To create an completely opaque icon:
<BLOCKQUOTE>
<BR><FONT FACE="Courier New,Courier">new FXGIFIcon(app,picture_data,0,IMAGE_OPQUE);</FONT></BLOCKQUOTE>
<P><BR>For more information on graphics file formats and their idiosyncracies,
see the <A HREF="http://www.dcs.ed.ac.uk/~mxr/gfx/index-hi.html">Graphics
File Format Web Site</A>.
<BR>
<BR>
<P><A NAME="RESWRAPDOC"></A>
<p>
<p>
<b>More on Reswrap</b>
<hr>
The reswrap tool has a number of options to make it convenient to build
C source and header files automatically from image files as a part of your
regular project build process. Reswrap is normally invoked as follows:
<BR>
<BR>
<BLOCKQUOTE><TT><B>reswrap</B> [options] [-o[a] outfile] files....</TT></BLOCKQUOTE>
Invoking reswrap with <TT>-o outfile</TT> will make reswrap write its output
on the file <B><I>outfile</I></B>. With <TT>-oa outfile</TT>, reswrap
will append additional data at the end of <B><I>outfile</I></B>.
<BR>Any number of input files may be specified. Reswrap typically
produces one data statement for each of the input files specified on the
command line.
<P>Reswrap understands a few additional options:
<P><B><I>-h</I></B>
<BLOCKQUOTE>Will print out a summary of the supported options.</BLOCKQUOTE>
<B><I>-v</I></B>
<BLOCKQUOTE>Will print out the version number.</BLOCKQUOTE>
<B><I>-d</I></B>
<BLOCKQUOTE>Reswrap normally generates its output as hexadecimal numbers;
the -d option will make reswrap generate decimal numbers.</BLOCKQUOTE>
<B><I>-x</I></B>
<BLOCKQUOTE>Forces reswrap to generate hexadecimal numbers [the default].</BLOCKQUOTE>
<B><I>-e</I></B>
<BLOCKQUOTE>Places the storage modifier <B><TT>extern</TT></B> in front
of the data array, ensuring that the data array can be linked with other
compilation units.</BLOCKQUOTE>
<B><I>-i</I></B>
<BLOCKQUOTE>Instead of a data array statement, reswrap will generate a
declaration only. For example,</BLOCKQUOTE>
<BLOCKQUOTE><TT> reswrap -i bigpenguin.gif</TT></BLOCKQUOTE>
<BLOCKQUOTE>will produce the output:</BLOCKQUOTE>
<BLOCKQUOTE><TT> /* Generated by reswrap from file bigpenguin.gif
*/</TT>
<BR><TT> extern const unsigned char bigpenguin[];</TT>
<BR>
<P>Which you could include as a header file into whichever source file
needs access to the data.</BLOCKQUOTE>
<B><I>-s</I></B>
<BLOCKQUOTE>This option suppresses comments inserted by reswrap to indicate
the original file name from which the data statement was generated.</BLOCKQUOTE>
<B><I>-n name</I></B>
<BLOCKQUOTE>Instead of taking the filename less the extension, reswrap
substitutes <I>name</I> for the name of the resource.</BLOCKQUOTE>
<B><I>-c cols</I></B>
<BLOCKQUOTE>Uses <I>cols</I> columns instead of the default 16 columns
in the data statements generated by reswrap.</BLOCKQUOTE>
<B><I>-ppm</I></B>
<BLOCKQUOTE>Assumes the source file is a Portable Pixmap (ppm) file.
Reswrap will output a simple rgb array.</BLOCKQUOTE>
Example of using reswrap in your Application's Makefile:
<BR>
<BR>
<BLOCKQUOTE><TT>OBJECTS = icons.o myapp.o</TT></BLOCKQUOTE>
<BLOCKQUOTE><TT>ICONS = bigpenguin.gif applogo.gif</TT></BLOCKQUOTE>
<BLOCKQUOTE><TT>icons.h: $(ICONS)</TT>
<BR><TT> reswrap -e -o icons.h $(ICONS)</TT>
<P><TT>icons.cc: $(ICONS)</TT>
<BR><TT> reswrap -o icons.cc $(ICONS)</TT>
<P><TT>myapp: $(OBJECTS)</TT>
<BR><TT> gcc -o myapp $(OBJECTS) -lFOX -lm -lSM -lICE -lXext
-lX11</TT>
<P><TT>myapp.o: myapp.cc icons.h</TT>
<BR> </BLOCKQUOTE>
This will cause make to generate two files, <TT>icons.h</TT> and <TT>icons.cc</TT>
which contain the declarations and definitions respectively for all the
reswrapped icons listed in the ICONS variable.
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<address>Copyright 1997-2002 <a href=mailto:jeroen@fox-toolkit.org>Jeroen van der Zijp</a></address>
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