=for comment based on iup-3.5 - http://www.tecgraf.puc-rio.br/iup/en/ctrl/iupcolorbrowser.html

=head1 NAME

IUP::ColorBrowser - [GUI element] color selector via cylindrical projection of the RGB cube

=head1 DESCRIPTION

Creates an element for selecting a color. The selection is done using a
cylindrical projection of the RGB cube. The transformation defines a
coordinate color system called HSI, that is still the RGB color space
but using cylindrical coordinates.

B<H> is for Hue, and it is the angle around the RGB cube diagonal
starting at red (RGB=255 0 0).

B<S> is for Saturation, and it is the normal distance from the color to
the diagonal, normalized by its maximum value at the specified Hue.
This also defines a point at the diagonal used to define B<I>.

B<I> is for Intensity, and it is the distance from the point defined at
the diagonal to black (RGB=0 0 0). B<I> can also be seen as the
projection of the color vector onto the diagonal. But B<I> is not
linear, see L<Notes|#Notes> below.

=begin HTML

<p><img src="http://kmx.github.io/perl-iup/img-3.9/ctrl/iupcolorbrowser.png"></p>

=end HTML

NOTE: For a dialog that simply returns the selected color, you can use
function L<GetColor|IUP/"GetColor()"> or L<IUP::ColorDlg|IUP::ColorDlg>.

=head1 USAGE

=head2 CREATION - new() method

 $colorbrowser = IUP::ColorBrowser->new( RGB=>"100 100 0" );

B<Returns:> the identifier of the created element, or C<undef> if an error occurs.

NOTE: You can pass to C<new()> other C<ATTRIBUTE=E<gt>'value'> or C<CALLBACKNAME=E<gt>\&func> pairs relevant
to this element - see L<IUP::Manual::02_Elements|IUP::Manual::02_Elements/"new()">.

=head2 ATTRIBUTES

For more info about concept of attributes (setting/getting values etc.)
see L<IUP::Manual::03_Attributes|IUP::Manual::03_Attributes>. Attributes specific to this element:

=over

=item L<EXPAND|IUP::Manual::03_Attributes/EXPAND>

The default is "NO".

=item L<RASTERSIZE|IUP::Manual::03_Attributes/RASTERSIZE>

I<(non inheritable)>

The initial size is "181x181". Set to C<undef> to allow the automatic layout
use smaller values.

=item B<RGB>

I<(non inheritable)>

The color selected in the control, in the "r g b" format; r, g and b are integers ranging from 0 to 255.
Default: "255 0 0".

=item B<HSI>

I<(non inheritable)>

The color selected in the control, in the "h s i" format; h, s and i are floating point numbers ranging from
0-360, 0-1 and 0-1 respectively.

=back

The following L<common attributes|IUP::Manual::03_Attributes/Common Attributes> are also accepted:

=over

=item * L<ACTIVE|IUP::Manual::03_Attributes/ACTIVE>,
L<BGCOLOR|IUP::Manual::03_Attributes/BGCOLOR>, L<FONT|IUP::Manual::03_Attributes/FONT>,
L<X|IUP::Manual::03_Attributes/X>, L<Y|IUP::Manual::03_Attributes/Y>,
L<POSITION|IUP::Manual::03_Attributes/POSITION>,
L<MINSIZE|IUP::Manual::03_Attributes/MINSIZE>,
L<MAXSIZE|IUP::Manual::03_Attributes/MAXSIZE>, L<WID|IUP::Manual::03_Attributes/WID>,
L<TIP|IUP::Manual::03_Attributes/TIP>, L<SIZE|IUP::Manual::03_Attributes/SIZE>,
L<ZORDER|IUP::Manual::03_Attributes/ZORDER>,
L<VISIBLE|IUP::Manual::03_Attributes/VISIBLE>

=back

=head2 CALLBACKS

For more info about concept of callbacks (setting callback handlers etc.)
see L<IUP::Manual::04_Callbacks|IUP::Manual::04_Callbacks>. Callbacks specific to this element:

=over

=item B<CHANGE_CB>

Called when the user releases the left mouse button over
the control, defining the selected color.

B<Callback handler prototype:>

 sub change_cb_handler {
   my ($self, $r, $g, $b) = @_;
   #...
 }

=over

B<$self:> reference to the element (IUP::ColorBrowser) that activated the event

B<$r, $g, $b:> color value.

=back

=item B<DRAG_CB>

Called several times while the color is being changed by
dragging the mouse over the control.

B<Callback handler prototype:>

 sub drag_cb_handler {
   my ($self, $r, $g, $b) = @_;
   #...
 }

=over

B<$self:> reference to the element (IUP::ColorBrowser) that activated the event

B<$r, $g, $b:> color value.

=back

=item B<VALUECHANGED_CB>

Called after the value was interactively changed by
the user. It is called whenever a B<CHANGE_CB> or a B<DRAG_CB> would
also be called, it is just called after them. 

B<Callback handler prototype:>

 sub drag_cb_handler {
   my ($self) = @_;
   #...
 }

=over

B<$self:> reference to the element (IUP::ColorBrowser) that activated the event

=back

=back

The following L<common callbacks|IUP::Manual::04_Callbacks/Common Callbacks> are also accepted:

=over

=item * L<MAP_CB|IUP::Manual::04_Callbacks/MAP_CB>,
L<UNMAP_CB|IUP::Manual::04_Callbacks/UNMAP_CB>,
L<GETFOCUS_CB|IUP::Manual::04_Callbacks/GETFOCUS_CB>,
L<KILLFOCUS_CB|IUP::Manual::04_Callbacks/KILLFOCUS_CB>,
L<ENTERWINDOW_CB|IUP::Manual::04_Callbacks/ENTERWINDOW_CB>,
L<LEAVEWINDOW_CB|IUP::Manual::04_Callbacks/LEAVEWINDOW_CB>,
L<K_ANY|IUP::Manual::04_Callbacks/K_ANY>, L<HELP_CB|IUP::Manual::04_Callbacks/HELP_CB>

=back

=head1 NOTES

When the control has the focus the keyboard can be used to change the
color value. Use the arrow keys to move the cursor inside the SI
triangle, and use Home(0), PageUp, PageDn and End(180) keys to move the
cursor inside the Hue circle.

The Hue in the HSI coordinate system defines a plane that it is a
triangle in the RGB cube. But the maximum saturation in this triangle
is different for each Hue because of the geometry of the cube. In
ColorBrowser this point is fixed at the center of the B<I> axis. So the
B<I> axis is not completely linear, it is linear in two parts, one from
0 to 0.5, and another from 0.5 to 1.0. Although the selected values are
linear specified you can notice that when Hue is changed the gray scale
also changes, visually compacting values above or below the B<I>=0.5 line
according to the selected Hue.

=head1 EXAMPLES


The element B<IUP::ColorBrowser> is used in the following sample scripts:

=over

=item * L<0-basic/colorbrowser.pl|https://metacpan.org/source/KMX/IUP-0.303/examples/0-basic/colorbrowser.pl> - IUP::ColorBrowser example

=back 



=head1 SEE ALSO

L<GetColor|IUP/"GetColor()">,
L<IUP::ColorDlg|IUP::ColorDlg>

The original doc: L<iupcolorbrowser.html|http://www.tecgraf.puc-rio.br/iup/en/ctrl/iupcolorbrowser.html>
 

=cut