2001-11-27 00:40:14 +03:00
|
|
|
<HTML>
|
|
|
|
|
<BODY>
|
|
|
|
|
|
1999-01-13 20:48:12 +03:00
|
|
|
<H1 ALIGN=RIGHT><A NAME=basics>2 - FLTK Basics</A></H1>
|
2001-11-27 00:40:14 +03:00
|
|
|
|
|
|
|
|
<P>This chapter teaches you the basics of compiling programs
|
|
|
|
|
that use FLTK.</P>
|
|
|
|
|
|
1998-12-29 17:21:17 +03:00
|
|
|
<H2>Writing Your First FLTK Program</H2>
|
2001-11-27 00:40:14 +03:00
|
|
|
|
|
|
|
|
<P>All programs must include the file <TT><FL/Fl.H></TT>.
|
|
|
|
|
In addition the program must include a header file for each
|
|
|
|
|
FLTK class it uses. Listing 1 shows a simple "Hello,
|
|
|
|
|
World!" program that uses FLTK to display the window.</P>
|
|
|
|
|
|
2000-04-28 22:15:26 +04:00
|
|
|
<UL>
|
|
|
|
|
<P><I>Listing 1 - "hello.cxx"</I>
|
1999-01-13 22:28:54 +03:00
|
|
|
<PRE>
|
|
|
|
|
#include <FL/Fl.H>
|
|
|
|
|
#include <FL/Fl_Window.H>
|
|
|
|
|
#include <FL/Fl_Box.H>
|
1998-12-29 17:21:17 +03:00
|
|
|
|
|
|
|
|
int main(int argc, char **argv) {
|
|
|
|
|
Fl_Window *window = new Fl_Window(300,180);
|
1999-01-31 10:43:16 +03:00
|
|
|
Fl_Box *box = new Fl_Box(20,40,260,100,"Hello, World!");
|
|
|
|
|
box->box(FL_UP_BOX);
|
1999-01-13 22:28:54 +03:00
|
|
|
box->labelsize(36);
|
|
|
|
|
box->labelfont(FL_BOLD+FL_ITALIC);
|
|
|
|
|
box->labeltype(FL_SHADOW_LABEL);
|
|
|
|
|
window->end();
|
|
|
|
|
window->show(argc, argv);
|
1998-12-29 17:21:17 +03:00
|
|
|
return Fl::run();
|
|
|
|
|
}
|
2001-11-27 00:40:14 +03:00
|
|
|
</PRE></UL>
|
|
|
|
|
|
|
|
|
|
<P>After including the required header files, the program then creates a
|
|
|
|
|
window:</P>
|
|
|
|
|
|
|
|
|
|
<UL><PRE>
|
1999-01-13 22:28:54 +03:00
|
|
|
Fl_Window *window = new <A href=Fl_Window.html#Fl_Window>Fl_Window</A>(300,180);
|
2001-11-27 00:40:14 +03:00
|
|
|
</PRE></UL>
|
|
|
|
|
|
|
|
|
|
<P>and a box with the "Hello, World!" string in it:</P>
|
|
|
|
|
|
|
|
|
|
<UL><PRE>
|
1999-01-31 10:43:16 +03:00
|
|
|
Fl_Box *box = new <A href=Fl_Box.html#Fl_Box>Fl_Box</A>(20,40,260,100,"Hello, World!");
|
2001-11-27 00:40:14 +03:00
|
|
|
</PRE></UL>
|
|
|
|
|
|
|
|
|
|
<P>Next, we set the type of box and the size, font, and style of the label:</P>
|
|
|
|
|
|
|
|
|
|
<UL><PRE>
|
1999-01-31 10:43:16 +03:00
|
|
|
box->box(FL_UP_BOX);
|
1999-01-13 22:28:54 +03:00
|
|
|
box-><A href=Fl_Widget.html#Fl_Widget.labelsize>labelsize</A>(36);
|
|
|
|
|
box-><A href=Fl_Widget.html#Fl_Widget.labelfont>labelfont</A>(FL_BOLD+FL_ITALIC);
|
|
|
|
|
box-><A href=Fl_Widget.html#Fl_Widget.labeltype>labeltype</A>(FL_SHADOW_LABEL);
|
2001-11-27 00:40:14 +03:00
|
|
|
</PRE></UL>
|
|
|
|
|
|
|
|
|
|
<P>Finally, we show the window and enter the FLTK event loop:</P>
|
|
|
|
|
|
|
|
|
|
<UL><PRE>
|
1999-01-13 22:28:54 +03:00
|
|
|
window-><A href=Fl_Group.html#Fl_Group.end>end</A>();
|
|
|
|
|
window-><A href=Fl_Window.html#Fl_Window.show>show</A>(argc, argv);
|
|
|
|
|
return <A href=functions.html#run>Fl::run</A>();
|
2001-11-27 00:40:14 +03:00
|
|
|
</PRE></UL>
|
|
|
|
|
|
|
|
|
|
<P>The resulting program will display the window in Figure 2-1.
|
|
|
|
|
You can quit the program by closing the window or pressing the
|
|
|
|
|
<KBD>ESC</KBD>ape key.</P>
|
|
|
|
|
|
|
|
|
|
<P ALIGN="CENTER"><IMG src="hello.C.gif" alt="Hello, World! Window"><BR>
|
|
|
|
|
<I>Figure 2-1: The Hello, World! Window</I></P>
|
|
|
|
|
|
1998-12-29 17:21:17 +03:00
|
|
|
<H3>Creating the Widgets</H3>
|
2001-11-27 00:40:14 +03:00
|
|
|
|
|
|
|
|
<P>The widgets are created using the C++ <TT>new</TT> operator. For
|
|
|
|
|
most widgets the arguments to the constructor are:</P>
|
|
|
|
|
|
|
|
|
|
<UL><PRE>
|
2000-04-28 22:15:26 +04:00
|
|
|
Fl_Widget(x, y, width, height, label)
|
2001-11-27 00:40:14 +03:00
|
|
|
</PRE></UL>
|
|
|
|
|
|
|
|
|
|
<P>The <TT>x</TT> and <TT>y</TT> parameters determine where the
|
|
|
|
|
widget or window is placed on the screen. In FLTK the top left
|
|
|
|
|
corner of the window or screen is the origin (i.e. x = 0, y =
|
|
|
|
|
0) and the units are in pixels.</P>
|
|
|
|
|
|
|
|
|
|
<P>The <TT>width</TT> and <TT>height</TT> parameters determine
|
|
|
|
|
the size of the widget or window in pixels. The maximum widget
|
|
|
|
|
size is typically governed by the underlying window system or
|
|
|
|
|
hardware.</P>
|
|
|
|
|
|
|
|
|
|
<P><tt>label</tt> is a pointer to a character string to label
|
|
|
|
|
the widget with or <tt>NULL</tt>. If not specified the label
|
|
|
|
|
defaults to <tt>NULL</tt>. The label string must be in static
|
|
|
|
|
storage such as a string constant because FLTK does not make a
|
|
|
|
|
copy of it - it just uses the pointer.</P>
|
|
|
|
|
|
1999-01-31 10:43:16 +03:00
|
|
|
<H3>Get/Set Methods</H3>
|
2001-11-27 00:40:14 +03:00
|
|
|
|
|
|
|
|
<P><tt>box->box(FL_UP_BOX)</tt> sets the type of box the
|
|
|
|
|
Fl_Box draws, changing it from the default of
|
|
|
|
|
<tt>FL_NO_BOX</tt>, which means that no box is drawn. In our
|
|
|
|
|
"Hello, World!" example we use <TT>FL_UP_BOX</TT>,
|
|
|
|
|
which means that a raised button border will be drawn around
|
|
|
|
|
the widget. You can learn more about boxtypes in
|
|
|
|
|
<A href="common.html#boytypes">Chapter 3</A>.</P>
|
|
|
|
|
|
|
|
|
|
<P>You could examine the boxtype in by doing
|
|
|
|
|
<tt>box->box()</tt>. FLTK uses method name overloading to make
|
|
|
|
|
short names for get/set methods. A "set" method is always of
|
|
|
|
|
the form "void name(type)", and a "get" method is always
|
|
|
|
|
of the form "type name() const".</P>
|
2000-04-28 22:15:26 +04:00
|
|
|
|
|
|
|
|
<H3>Redrawing After Changing Attributes</H3>
|
2001-11-27 00:40:14 +03:00
|
|
|
|
|
|
|
|
<P>Almost all of the set/get pairs are very fast, short inline
|
|
|
|
|
functions and thus very efficient. However, <i>the "set"
|
|
|
|
|
methods do not call <TT>redraw()</TT></i> - you have to call it
|
|
|
|
|
yourself. This greatly reduces code size and execution time.
|
|
|
|
|
The only common exception is <tt>value()</tt> which calls
|
|
|
|
|
<TT>redraw()</TT> if necessary.</P>
|
2000-04-28 22:15:26 +04:00
|
|
|
|
1998-12-29 17:21:17 +03:00
|
|
|
<H3>Labels</H3>
|
2001-11-27 00:40:14 +03:00
|
|
|
|
|
|
|
|
<P>All widgets support labels. In the case of window widgets,
|
|
|
|
|
the label is used for the label in the title bar. Our example
|
|
|
|
|
program calls the <A href=Fl_Widget.html#Fl_Widget.labelfont>
|
|
|
|
|
<TT>labelfont</TT></A>,
|
|
|
|
|
<A href=Fl_Widget.html#Fl_Widget.labelsize><TT> labelsize</TT></A>,
|
|
|
|
|
and <A href=Fl_Widget.html#Fl_Widget.labeltype><TT>labeltype</TT></A>
|
|
|
|
|
methods.</P>
|
|
|
|
|
|
|
|
|
|
<P>The <TT>labelfont</TT> method sets the typeface and style
|
|
|
|
|
that is used for the label, which for this example we are using
|
|
|
|
|
<TT>FL_BOLD</TT> and <TT>FL_ITALIC</TT>. You can also specify
|
|
|
|
|
typefaces directly. </P> <P>The <TT>labelsize</TT> method sets
|
|
|
|
|
the height of the font in pixels. </P> <P>The <TT>labeltype</TT>
|
|
|
|
|
method sets the type of label. FLTK supports normal, embossed,
|
|
|
|
|
and shadowed labels internally, and more types can be added as
|
|
|
|
|
desired.</P>
|
|
|
|
|
|
|
|
|
|
<P>A complete list of all label options can be found in
|
|
|
|
|
<A href="common.html#labels">Chapter 3</A>.</P>
|
2000-04-28 22:15:26 +04:00
|
|
|
|
1998-12-29 17:21:17 +03:00
|
|
|
<H3>Showing the Window</H3>
|
2001-11-27 00:40:14 +03:00
|
|
|
|
|
|
|
|
<P>The <TT>show()</TT> method shows the widget or window. For windows
|
1999-01-13 22:28:54 +03:00
|
|
|
you can also provide the command-line arguments to allow users to
|
2001-11-27 00:40:14 +03:00
|
|
|
customize the appearance, size, and position of your windows.</P>
|
|
|
|
|
|
1998-12-29 17:21:17 +03:00
|
|
|
<H3>The Main Event Loop</H3>
|
2001-11-27 00:40:14 +03:00
|
|
|
|
|
|
|
|
<P>All FLTK applications (and most GUI applications in general)
|
|
|
|
|
are based on a simple event processing model. User actions such
|
|
|
|
|
as mouse movement, button clicks, and keyboard activity generate
|
|
|
|
|
events that are sent to an application. The application may then
|
|
|
|
|
ignore the events or respond to the user, typically by redrawing
|
|
|
|
|
a button in the "down" position, adding the text to an input
|
|
|
|
|
field, and so forth.</P>
|
|
|
|
|
|
|
|
|
|
<P>FLTK also supports idle, timer, and file pseudo-events that
|
|
|
|
|
cause a function to be called when they occur. Idle functions
|
|
|
|
|
are called when no user input is present and no timers or files
|
|
|
|
|
need to be handled - in short, when the application is not doing
|
|
|
|
|
anything. Idle callbacks are often used to update a 3D display
|
|
|
|
|
or do other background processing.</P>
|
|
|
|
|
|
|
|
|
|
<P>Timer functions are called after a specific amount of time
|
|
|
|
|
has expired. They can be used to pop up a progress dialog after
|
|
|
|
|
a certain amount of time or do other things that need to happen
|
|
|
|
|
at more-or-less regular intervals. FLTK timers are not 100%
|
|
|
|
|
accurate, so they should not be used to measure time intervals,
|
|
|
|
|
for example.</P>
|
|
|
|
|
|
|
|
|
|
<P>File functions are called when data is ready to read or
|
|
|
|
|
write, or when an error condition occurs on a file. They are
|
|
|
|
|
most often used to monitor network connections (sockets) for
|
|
|
|
|
data-driven displays.</P>
|
|
|
|
|
|
|
|
|
|
<P>FLTK applications must periodically check
|
|
|
|
|
(<TT>Fl::check()</TT>) or wait (<TT>Fl::wait()</TT>) for events
|
|
|
|
|
or use the <A href="functions.html#run"><TT>Fl:run()</TT></A>
|
|
|
|
|
method to enter a standard event processing loop. Calling
|
|
|
|
|
<TT>Fl::run()</TT> is equivalent to the following code:</P>
|
|
|
|
|
|
|
|
|
|
<UL><PRE>
|
1998-12-29 17:21:17 +03:00
|
|
|
while (Fl::wait());
|
2001-11-27 00:40:14 +03:00
|
|
|
</PRE></UL>
|
|
|
|
|
|
|
|
|
|
<P><TT>Fl::run()</TT> does not return until all of the windows
|
|
|
|
|
under FLTK control are closed by the user or your program.</P>
|
|
|
|
|
|
|
|
|
|
<H2>Compiling Programs with Standard Compilers</H2>
|
|
|
|
|
|
|
|
|
|
<P>Under UNIX (and under Microsoft Windows when using the GNU development
|
|
|
|
|
tools) you will probably need to tell the compiler where to find the
|
|
|
|
|
header files. This is usually done using the <TT>-I</TT> option:</P>
|
|
|
|
|
|
|
|
|
|
<UL><PRE>
|
|
|
|
|
CC -I/usr/local/include ...
|
|
|
|
|
gcc -I/usr/local/include ...
|
|
|
|
|
</PRE></UL>
|
|
|
|
|
|
|
|
|
|
<P>The <TT>fltk-config</TT> script included with FLTK can be
|
|
|
|
|
used to get the options that are required by your compiler:</P>
|
|
|
|
|
|
|
|
|
|
<UL><PRE>
|
|
|
|
|
CC `fltk-config --cxxflags` ...
|
|
|
|
|
</PRE></UL>
|
|
|
|
|
|
|
|
|
|
<P>Similarly, when linking your application you will need to tell the
|
|
|
|
|
compiler to use the FLTK library:</P>
|
|
|
|
|
|
|
|
|
|
<UL><PRE>
|
|
|
|
|
CC ... -L/usr/local/lib -lfltk -lXext -lX11 -lm
|
|
|
|
|
gcc ... -L/usr/local/lib -lfltk -lXext -lX11 -lm
|
|
|
|
|
</PRE></UL>
|
|
|
|
|
|
|
|
|
|
<P>The <TT>fltk-config</TT> script included with FLTK can be
|
|
|
|
|
used to get the options that are required by your linker:</P>
|
|
|
|
|
|
|
|
|
|
<UL><PRE>
|
|
|
|
|
CC ... `fltk-config --ldflags`
|
|
|
|
|
</PRE></UL>
|
|
|
|
|
|
|
|
|
|
<H2>Compiling Programs with Microsoft Visual C++</H2>
|
|
|
|
|
|
|
|
|
|
<P>In Visual C++ you will need to tell the compiler where to
|
|
|
|
|
find the FLTK header files. This can be done by selecting
|
|
|
|
|
"Settings" from the "Project" menu and then
|
|
|
|
|
changing the "Preprocessor" settings under the
|
|
|
|
|
"C/C++" tab. You will also need to add the FLTK and
|
|
|
|
|
WinSock (WSOCK32.LIB) libraries to the "Link"
|
|
|
|
|
settings.</P>
|
|
|
|
|
|
|
|
|
|
<P>You can build your Microsoft Windows applications as Console or
|
|
|
|
|
WIN32 applications. If you want to use the standard C <TT>main()</TT>
|
|
|
|
|
function as the entry point, FLTK includes a <TT>WinMain()</TT>
|
|
|
|
|
function that will call your <TT>main()</TT> function for you.</P>
|
|
|
|
|
|
|
|
|
|
<P><I>Note: The Visual C++ 5.0 optimizer is known to cause problems with
|
|
|
|
|
many programs. We only recommend using the "Favor Small Code"
|
|
|
|
|
optimization setting.</I> The Visual C++ 6.0 optimizer seems to be much
|
|
|
|
|
better and can be used with the "optimized for speed" setting.</P>
|
|
|
|
|
|
|
|
|
|
<H2>Naming</H2>
|
|
|
|
|
|
|
|
|
|
<P>All public symbols in FLTK start with the characters 'F' and 'L':</P>
|
|
|
|
|
|
|
|
|
|
<UL>
|
|
|
|
|
|
|
|
|
|
<LI>Functions are either <TT>Fl::foo()</TT> or
|
|
|
|
|
<TT>fl_foo()</TT>.</LI>
|
|
|
|
|
|
|
|
|
|
<LI>Class and type names are capitalized:
|
|
|
|
|
<TT>Fl_Foo</TT>.</LI>
|
|
|
|
|
|
|
|
|
|
<LI><A href="enumerations.html">Constants and
|
|
|
|
|
enumerations</A> are uppercase: <TT>FL_FOO</TT>.</LI>
|
|
|
|
|
|
|
|
|
|
<LI>All header files start with <TT><FL/...></TT>.
|
|
|
|
|
</LI>
|
|
|
|
|
|
1999-01-13 22:28:54 +03:00
|
|
|
</UL>
|
2001-11-27 00:40:14 +03:00
|
|
|
|
|
|
|
|
<H2>Header Files</H2>
|
|
|
|
|
|
|
|
|
|
<P>The proper way to include FLTK header files is:</P>
|
|
|
|
|
|
|
|
|
|
<UL><PRE>
|
|
|
|
|
#include <FL/Fl_xyz.H>
|
|
|
|
|
</PRE></UL>
|
|
|
|
|
|
|
|
|
|
<P><B>Microsoft Windows developers please note:</B> case *is*
|
|
|
|
|
significant under other operating systems, and the C standard
|
|
|
|
|
uses the forward slash (/) to separate directories. <i>Do not
|
|
|
|
|
use any of the following include lines:</i></P>
|
|
|
|
|
|
|
|
|
|
<UL><PRE>
|
|
|
|
|
#include <FL\Fl_xyz.H>
|
|
|
|
|
#include <fl/fl_xyz.h>
|
|
|
|
|
#include <Fl/fl_xyz.h>
|
|
|
|
|
</PRE></UL>
|
|
|
|
|
|
2000-04-28 22:15:26 +04:00
|
|
|
</BODY>
|
|
|
|
|
</HTML>
|
