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authorFabien Costantini <fabien@onepost.net>2008-10-17 11:26:30 +0000
committerFabien Costantini <fabien@onepost.net>2008-10-17 11:26:30 +0000
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+/**
+
+ \page common 3 - Common Widgets and Attributes
+
+This chapter describes many of the widgets that are provided
+with FLTK and covers how to query and set the standard
+attributes.
+
+\section common_buttons Buttons
+
+FLTK provides many types of buttons:
+
+\li Fl_Button - A standard push button.
+
+\li Fl_Check_Button - A button with a check box.
+
+\li Fl_Light_Button - A push button with a light.
+
+\li Fl_Repeat_Button - A push button that repeats when held.
+
+\li Fl_Return_Button - A push button that is activated by the
+ <KBD>Enter</KBD> key.
+
+\li Fl_Round_Button - A button with a radio circle.
+
+\image html buttons.gif "Figure 3-1: FLTK Button Widgets"
+\image latex buttons.eps "FLTK Button Widgets" width=10cm
+All of these buttons just need the corresponding
+<tt><FL/Fl_xyz_Button.H></tt> header file. The constructor
+takes the bounding box of the button and optionally a label
+string:
+
+\code
+Fl_Button *button = new Fl_Button(x, y, width, height, "label");
+Fl_Light_Button *lbutton = new Fl_Light_Button(x, y, width, height);
+Fl_Round_Button *rbutton = new Fl_Round_Button(x, y, width, height, "label");
+\endcode
+
+Each button has an associated <tt>type()</tt> which allows
+it to behave as a push button, toggle button, or radio button:
+
+\code
+button->type(FL_NORMAL_BUTTON);
+lbutton->type(FL_TOGGLE_BUTTON);
+rbutton->type(FL_RADIO_BUTTON);
+\endcode
+
+For toggle and radio buttons, the value() method returns
+the current button state (0 = off, 1 = on). The set() and
+clear() methods can be used on toggle buttons to turn a
+toggle button on or off, respectively.
+Radio buttons can be turned on with the setonly()
+method; this will also turn off other radio buttons in the same
+group.
+
+\section common_text Text
+
+FLTK provides several text widgets for displaying and receiving text:
+
+\li Fl_Input - A one-line text input field.
+
+\li Fl_Output - A one-line text output field.
+
+\li Fl_Multiline_Input - A multi-line text input field.
+
+\li Fl_Multiline_Output - A multi-line text output field.
+
+\li Fl_Text_Display - A multi-line text display widget.
+
+\li Fl_Text_Editor - A multi-line text editing widget.
+
+\li Fl_Help_View - A HTML text display widget.
+
+The <tt>Fl_Output</tt> and <tt>Fl_Multiline_Output</tt>
+widgets allow the user to copy text from the output field but
+not change it.
+
+The <tt>value()</tt> method is used to get or set the
+string that is displayed:
+
+\code
+Fl_Input *input = new Fl_Input(x, y, width, height, "label");
+input->value("Now is the time for all good men...");
+\endcode
+
+The string is copied to the widget's own storage when you set
+the <tt>value()</tt> of the widget.
+
+The <tt>Fl_Text_Display</tt> and <tt>Fl_Text_Editor</tt>
+widgets use an associated <tt>Fl_Text_Buffer</tt> class for the
+value, instead of a simple string.
+
+<!-- NEED 4in -->
+
+\section common_valuators Valuators
+
+Unlike text widgets, valuators keep track of numbers instead of
+strings. FLTK provides the following valuators:
+
+\li Fl_Counter - A widget with arrow buttons that shows the current value.
+
+\li Fl_Dial - A round knob.
+
+\li Fl_Roller - An SGI-like dolly widget.
+
+\li Fl_Scrollbar - A standard scrollbar widget.
+
+\li Fl_Slider - A scrollbar with a knob.
+
+\li Fl_Value_Slider - A slider that shows the current value.
+
+\image html valuators.gif "Figure 3-2: FLTK valuator widgets"
+\image latex valuators.eps "FLTK valuator widgets" width=10cm
+The <tt>value()</tt> method gets and sets the current value
+of the widget. The <tt>minimum()</tt> and <tt>maximum()</tt>
+methods set the range of values that are reported by the
+widget.
+
+<!-- NEED 5in -->
+
+\section common_groups Groups
+
+The <tt>Fl_Group</tt> widget class is used as a general
+purpose "container" widget. Besides grouping radio
+buttons, the groups are used to encapsulate windows, tabs, and
+scrolled windows. The following group classes are available
+with FLTK:
+
+\li Fl_Double_Window - A double-buffered window on the screen.
+
+\li Fl_Gl_Window - An OpenGL window on the screen.
+
+\li Fl_Group - The base container class; can be used to group
+ any widgets together.
+
+\li Fl_Pack - A collection of widgets that are packed into the group area.
+
+\li Fl_Scroll - A scrolled window area.
+
+\li Fl_Tabs - Displays child widgets as tabs.
+
+\li Fl_Tile - A tiled window area.
+
+\li Fl_Window - A window on the screen.
+
+\li Fl_Wizard - Displays one group of widgets at a time.
+
+\section common_sizeposition Setting the Size and Position of Widgets
+
+The size and position of widgets is usually set when you
+create them. You can access them with the <tt>x()</tt>,
+<tt>y()</tt>, <tt>w()</tt>, and <tt>h()</tt> methods.
+
+You can change the size and position by using the
+<tt>position()</tt>, <tt> resize()</tt>, and <tt>size()</tt>
+methods:
+
+\code
+button->position(x, y);
+group->resize(x, y, width, height);
+window->size(width, height);
+\endcode
+
+If you change a widget's size or position after it is
+displayed you will have to call <tt>redraw()</tt> on the
+widget's parent.
+
+<A NAME="colors"></A> <!-- For old HTML links only ! -->
+\section common_colors Colors
+
+FLTK stores the colors of widgets as an 32-bit unsigned
+number that is either an index into a color palette of 256
+colors or a 24-bit RGB color. The color palette is <i>not</i>
+the X or WIN32 colormap, but instead is an internal table with
+fixed contents.
+
+There are symbols for naming some of the more common colors:
+
+\li <tt>FL_BLACK</tt>
+
+\li <tt>FL_RED</tt>
+
+\li <tt>FL_GREEN</tt>
+
+\li <tt>FL_YELLOW</tt>
+
+\li <tt>FL_BLUE</tt>
+
+\li <tt>FL_MAGENTA</tt>
+
+\li <tt>FL_CYAN</tt>
+
+\li <tt>FL_WHITE</tt>
+
+\li FL_WHITE
+
+These symbols are the default colors for all FLTK widgets. They are
+explained in more detail in the chapter
+<A HREF="enumerations.html#colors">Enumerations</A>
+
+\li <tt>FL_FOREGROUND_COLOR</tt>
+
+\li <tt>FL_BACKGROUND_COLOR</tt>
+
+\li <tt>FL_INACTIVE_COLOR</tt>
+
+\li <tt>FL_SELECTION_COLOR</tt>
+
+RGB colors can be set using the <tt>fl_rgb_color()</tt> function:
+
+\code
+Fl_Color c = fl_rgb_color(85, 170, 255);
+\endcode
+
+The widget color is set using the <tt>color()</tt> method:
+
+\code
+button->color(FL_RED);
+\endcode
+
+Similarly, the label color is set using the <tt>labelcolor()</tt>
+method:
+
+\code
+button->labelcolor(FL_WHITE);
+\endcode
+
+<A NAME="boxtypes"></A> <!-- For old HTML links only ! -->
+\section common_boxtypes Box Types
+
+The type <tt>Fl_Boxtype</tt> stored and returned in Fl_Widget::box()
+is an enumeration defined in Enumerations.H.
+
+Figure 3-3 shows the standard box types included with FLTK.
+
+\image html boxtypes.gif "Figure 3-3: FLTK box types"
+\image latex boxtypes.eps "FLTK box types" width=12cm
+<tt>FL_NO_BOX</tt> means nothing is drawn at all, so whatever is
+already on the screen remains. The <tt>FL_..._FRAME</tt> types only
+draw their edges, leaving the interior unchanged. The blue color in
+Figure 3-3 is the area that is not drawn by the frame types.
+
+\subsection common_boxtypes Making Your Own Boxtypes
+
+You can define your own boxtypes by making a small function that draws
+the box and adding it to the table of boxtypes.
+
+<CENTER><TABLE WIDTH="80%" BORDER="1" CELLPADDING="5" CELLSPACING="0" BGCOLOR="#cccccc">
+<TR>
+ <TD><B>Note:</B>
+ <P>This interface has changed in FLTK 2.0!
+ </TD>
+</TR>
+</TABLE></CENTER>
+
+\par The Drawing Function
+
+The drawing function is passed the bounding box and background color
+for the widget:
+
+\code
+void xyz_draw(int x, int y, int w, int h, Fl_Color c) {
+...
+}
+\endcode
+
+<!-- NEED 3in -->
+
+A simple drawing function might fill a rectangle with the
+given color and then draw a black outline:
+
+\code
+void xyz_draw(int x, int y, int w, int h, Fl_Color c) {
+ fl_color(c);
+ fl_rectf(x, y, w, h);
+ fl_color(FL_BLACK);
+ fl_rect(x, y, w, h);
+}
+\endcode
+
+<A name="fl_down"></A> <!-- For old HTML links only ! -->
+\par Fl_Boxtype fl_down(Fl_Boxtype)
+
+<tt>fl_down</tt> returns the "pressed" or "down" version of a box.
+If no "down" version of a given box exists, the behavior of this function
+is undefined and some random box or frame is returned.
+See also: <A HREF="drawing.html#fl_frame">fl_frame drawing</A>.
+
+<A name="fl_frame"></A> <!-- For old HTML links only ! -->
+\par Fl_Boxtype fl_frame(Fl_Boxtype)
+
+<tt>fl_frame</tt> returns the unfilled, frame-only version of a box.
+If no frame version of a given box exists, the behavior of this function
+is undefined and some random box or frame is returned.
+See also: <A HREF="drawing.html#fl_frame">fl_frame drawing</A>.
+
+<A name="fl_box"></A> <!-- For old HTML links only ! -->
+\par Fl_Boxtype fl_box(Fl_Boxtype)
+
+<tt>fl_box</tt> returns the filled version of a frame.
+If no filled version of a given frame exists, the behavior of this function
+is undefined and some random box or frame is returned.
+See also: <tt><A HREF="#fl_frame">fl_frame</A></tt>.
+
+\par Adding Your Box Type
+
+The <tt>Fl::set_boxtype()</tt> method adds or replaces the specified box type:
+
+\code
+#define XYZ_BOX FL_FREE_BOXTYPE
+
+Fl::set_boxtype(XYZ_BOX, xyz_draw, 1, 1, 2, 2);
+\endcode
+The last 4 arguments to <tt>Fl::set_boxtype()</tt> are the
+offsets for the x, y, width, and height values that should be
+subtracted when drawing the label inside the box.
+
+A complete box design contains four box types in this order:
+a filled, neutral box (<tt>UP_BOX</tt>), a filled, depressed box
+(<tt>DOWN_BOX</tt>), and the same as outlines only (<tt>UP_FRAME</tt>
+and <tt>DOWN_FRAME</tt>). The function
+<tt><A HREF="#fl_down">fl_down(Fl_Boxtype)</A></tt>
+expects the neutral design on a boxtype with a numerical
+value evenly divideable by two.
+<tt><A HREF="#fl_frame">fl_frame(Fl_Boxtype)</A></tt>
+expects the <tt>UP_BOX</tt> design at a value divideable by four.
+
+<A NAME="labels"></A> <!-- For old HTML links only ! -->
+\section common_labels Labels and Label Types
+
+The <tt>label()</tt>, <tt>align()</tt>, <tt>labelfont()</tt>,
+<tt>labelsize()</tt>, <tt>labeltype()</tt>, <tt>image()</tt>, and
+<tt>deimage()</tt> methods control the labeling of widgets.
+
+\par label()
+
+The <tt>label()</tt> method sets the string that is displayed
+for the label. Symbols can be included with the label string by
+escaping them using the "@" symbol - "@@" displays a single at
+sign. Figure 3-4 shows the available symbols.
+
+\image html symbols.gif "Figure 3-4: FLTK label symbols"
+
+<!-- NEED 2in -->
+
+The @ sign may also be followed by the following optional
+"formatting" characters, in this order:
+
+\li '#' forces square scaling, rather than distortion to the widget's shape.
+
+\li +[1-9] or -[1-9] tweaks the scaling a little bigger or smaller.
+
+\li '$' flips the symbol horizontaly, '%' flips it verticaly.
+
+\li [0-9] - rotates by a multiple of 45 degrees. '5' and '6' do no rotation
+ while the others point in the direction of that key on a numeric keypad.
+ '0', followed by four more digits rotates the symbol by that amount in
+ degrees.
+
+Thus, to show a very large arrow pointing downward you would use the
+label string "@+92->".
+
+\par align()
+
+The <tt>align()</tt> method positions the label. The following
+constants are defined and may be OR'd together as needed:
+
+\li <tt>FL_ALIGN_CENTER</tt> - center the label in the widget.
+
+\li <tt>FL_ALIGN_TOP</tt> - align the label at the top of the widget.
+
+\li <tt>FL_ALIGN_BOTTOM</tt> - align the label at the bottom of the
+ widget.
+
+\li <tt>FL_ALIGN_LEFT</tt> - align the label to the left of the widget.
+
+\li <tt>FL_ALIGN_RIGHT</tt> - align the label to the right of the
+ widget.
+
+\li <tt>FL_ALIGN_INSIDE</tt> - align the label inside the widget.
+
+\li <tt>FL_ALIGN_CLIP</tt> - clip the label to the widget's bounding
+ box.
+
+\li <tt>FL_ALIGN_WRAP</tt> - wrap the label text as needed.
+
+\li <tt>FL_TEXT_OVER_IMAGE</tt> - show the label text over the image.
+
+\li <tt>FL_IMAGE_OVER_TEXT</tt> - show the label image over the text (default).
+
+<A NAME="labeltypes"></A> <!-- For old HTML links only ! -->
+\par labeltype()
+
+The <tt>labeltype()</tt> method sets the type of the label. The
+following standard label types are included:
+
+\li <tt>FL_NORMAL_LABEL</tt> - draws the text.
+
+\li <tt>FL_NO_LABEL</tt> - does nothing.
+
+\li <tt>FL_SHADOW_LABEL</tt> - draws a drop shadow under the text.
+
+\li <tt>FL_ENGRAVED_LABEL</tt> - draws edges as though the text is engraved.
+
+\li <tt>FL_EMBOSSED_LABEL</tt> - draws edges as thought the text is raised.
+
+\li <tt>FL_ICON_LABEL</tt> - draws the icon associated with the text.
+
+\par image() and deimage()
+
+The <tt>image()</tt> and <tt>deimage()</tt> methods set an image that
+will be displayed with the widget. The <tt>deimage()</tt> method sets the
+image that is shown when the widget is inactive, while the <tt>image()</tt>
+method sets the image that is shown when the widget is active.
+
+To make an image you use a subclass of
+<A HREF="drawing.html#Fl_Image"><tt>Fl_Image</tt></A>.
+
+\par Making Your Own Label Types
+
+Label types are actually indexes into a table of functions
+that draw them. The primary purpose of this is to use this to
+draw the labels in ways inaccessible through the
+<tt>fl_font</tt> mechanisim (e.g. <tt>FL_ENGRAVED_LABEL</tt>) or
+with program-generated letters or symbology.
+
+<CENTER><TABLE WIDTH="80%" BORDER="1" CELLPADDING="5" CELLSPACING="0" BGCOLOR="#cccccc">
+<TR>
+ <TD><B>Note:</B>
+ <P>This interface has changed in FLTK 2.0!
+ </TD>
+</TR>
+</TABLE></CENTER>
+
+\par Label Type Functions
+
+To setup your own label type you will need to write two
+functions: one to draw and one to measure the label. The draw
+function is called with a pointer to a <tt>Fl_Label</tt>
+structure containing the label information, the bounding box for
+the label, and the label alignment:
+
+\code
+void xyz_draw(const Fl_Label *label, int x, int y, int w, int h, Fl_Align align) {
+...
+}
+\endcode
+
+The label should be drawn <I>inside</I> this bounding box,
+even if <tt>FL_ALIGN_INSIDE</tt> is not enabled. The function
+is not called if the label value is <tt>NULL</tt>.
+
+The measure function is called with a pointer to a
+<tt>Fl_Label</tt> structure and references to the width and
+height:
+
+\code
+void xyz_measure(const Fl_Label *label, int &w, int &h) {
+...
+}
+\endcode
+
+The function should measure the size of the label and set
+<tt>w</tt> and <tt>h</tt> to the size it will occupy.
+
+\par Adding Your Label Type
+
+The <tt>Fl::set_labeltype</tt> method creates a label type
+using your draw and measure functions:
+
+\code
+#define XYZ_LABEL FL_FREE_LABELTYPE
+
+Fl::set_labeltype(XYZ_LABEL, xyz_draw, xyz_measure);
+\endcode
+
+The label type number <tt>n</tt> can be any integer value
+starting at the constant <tt>FL_FREE_LABELTYPE</tt>. Once you
+have added the label type you can use the <tt>labeltype()</tt>
+method to select your label type.
+
+The <tt>Fl::set_labeltype</tt> method can also be used to overload
+an existing label type such as <tt>FL_NORMAL_LABEL</tt>.
+
+<A NAME="add_symbol"></A> <!-- For old HTML links only ! -->
+\par Making your own symbols
+
+It is also possible to define your own drawings and add
+them to the symbol list, so they can be rendered as part of
+any label.
+
+To create a new symbol, you implement a drawing function
+<tt>void drawit(Fl_Color c)</tt> which typically uses the
+<a href="drawing.html#complex">complex drawing functions</a>
+to generate a vector shape inside a two-by-two units sized box
+around the origin. This function is then linked into the symbols
+table using <tt>fl_add_symbol</tt>:
+
+\code
+int fl_add_symbol(const char *name, void (*drawit)(Fl_Color), int scalable)
+\endcode
+
+<i>name</i> is the name of the symbol without the "@"; <i>scalable</I>
+must be set to 1 if the symbol is generated using scalable vector drawing
+functions.
+
+\code
+int fl_draw_symbol(const char *name,int x,int y,int w,int h,Fl_Color col)
+\endcode
+
+This function draws a named symbol fitting the given rectangle.
+
+\section common_callbacks Callbacks
+
+Callbacks are functions that are called when the value of a
+widget changes. A callback function is sent a <tt>Fl_Widget</tt>
+pointer of the widget that changed and a pointer to data that
+you provide:
+
+\code
+void xyz_callback(Fl_Widget *w, void *data) {
+...
+}
+\endcode
+
+The <tt>callback()</tt> method sets the callback function for a
+widget. You can optionally pass a pointer to some data needed for the
+callback:
+
+\code
+int xyz_data;
+
+button->callback(xyz_callback, &xyz_data);
+\endcode
+
+Normally callbacks are performed only when the value of the
+widget changes. You can change this using the Fl_Widget::when()
+method:
+
+\code
+button->when(FL_WHEN_NEVER);
+button->when(FL_WHEN_CHANGED);
+button->when(FL_WHEN_RELEASE);
+button->when(FL_WHEN_RELEASE_ALWAYS);
+button->when(FL_WHEN_ENTER_KEY);
+button->when(FL_WHEN_ENTER_KEY_ALWAYS);
+button->when(FL_WHEN_CHANGED | FL_WHEN_NOT_CHANGED);
+\endcode
+
+<CENTER><TABLE WIDTH="80%" BORDER="1" CELLPADDING="5" CELLSPACING="0" BGCOLOR="#cccccc">
+<TR>
+ <TD><B>Note:</B>
+
+ <P>You cannot delete a widget inside a callback, as the
+ widget may still be accessed by FLTK after your callback
+ is completed. Instead, use the Fl::delete_widget()
+ method to mark your widget for deletion when it is safe
+ to do so.
+
+ <p><B>Hint:</B>
+
+ <P>Many programmers new to FLTK or C++ try to use a
+ non-static class method instead of a static class method
+ or function for their callback. Since callbacks are done
+ outside a C++ class, the <tt>this</tt> pointer is not
+ initialized for class methods.
+
+ <P>To work around this problem, define a static method
+ in your class that accepts a pointer to the class, and
+ then have the static method call the class method(s) as
+ needed. The data pointer you provide to the
+ <tt>callback()</tt> method of the widget can be a
+ pointer to the instance of your class.
+
+\code
+class Foo {
+ void my_callback(Fl_Widget *w);
+ static void my_static_callback(Fl_Widget *w, void *f) { ((Foo *)f)->my_callback(w); }
+ ...
+}
+
+...
+
+w->callback(my_static_callback, (void *)this);
+\endcode
+ </TD>
+</TR>
+</TABLE></CENTER>
+
+\section common_shortcuts Shortcuts
+
+Shortcuts are key sequences that activate widgets such as
+buttons or menu items. The <tt>shortcut()</tt> method sets the
+shortcut for a widget:
+
+\code
+button->shortcut(FL_Enter);
+button->shortcut(FL_SHIFT + 'b');
+button->shortcut(FL_CTRL + 'b');
+button->shortcut(FL_ALT + 'b');
+button->shortcut(FL_CTRL + FL_ALT + 'b');
+button->shortcut(0); // no shortcut
+\endcode
+
+The shortcut value is the key event value - the ASCII value
+or one of the special keys like
+<a href="enumerations.html#key_values"><tt>FL_Enter</tt></a> -
+combined with any modifiers like <KBD>Shift</KBD>,
+<KBD>Alt</KBD>, and <KBD>Control</KBD>.
+
+\htmlonly
+<hr>
+<a class="el" href="index.html">[Index]</a> &nbsp;&nbsp;
+<a class="el" href="basics.html">[Previous]&nbsp; 2 - FLTK Basics</a>&nbsp;
+<a class="el" href="editor.html">[Next]&nbsp; 4 - Designing a Simple Text Editor</a>&nbsp;
+
+\endhtmlonly
+*/