mirror of https://github.com/fltk/fltk
100 lines
4.7 KiB
HTML
100 lines
4.7 KiB
HTML
<HTML><BODY>
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<!-- NEW PAGE -->
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<H2><A name=Fl_Scroll>class Fl_Scroll</A></H2>
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<HR>
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<H3>Class Hierarchy</H3>
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<UL>
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<PRE>
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<A href=Fl_Group.html#Fl_Group>Fl_Group</A>
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+----<B>Fl_Scroll</B>
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</PRE>
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</UL>
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<H3>Include Files</H3>
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<UL>
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<PRE>
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#include <FL/Fl_Scroll.H>
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</PRE>
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</UL>
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<H3>Description</H3>
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This container widget lets you maneuver around a set of widgets much
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larger than your window. If the child widgets are larger than the size
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of this object then scrollbars will appear so that you can scroll over
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to them:
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<P ALIGN=CENTER><IMG src="Fl_Scroll.gif" ALT="Fl_Scroll widget."></P>
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<P>If all of the child widgets are packed together into a solid
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rectangle then you want to set <TT>box()</TT> to <TT>FL_NO_BOX</TT> or
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one of the <TT>_FRAME</TT> types. This will result in the best output.
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However, if the child widgets are a sparse arrangment you must set <TT>
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box()</TT> to a real <TT>_BOX</TT> type. This can result in some
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blinking during redrawing, but that can be solved by using a <TT>
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Fl_Double_Window</TT>. </P>
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<P>This widget can also be used to pan around a single child widget
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"canvas". This child widget should be of your own class, with a <TT>
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draw()</TT> method that draws the contents. The scrolling is done by
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changing the <TT>x()</TT> and <TT>y()</TT> of the widget, so this child
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must use the <TT>x()</TT> and <TT>y()</TT> to position it's drawing.
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To speed up drawing it should test <A href=drawing.html#fl_push_clip><TT>fl_push_clip()</TT></A>
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. </P>
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<P>Another very useful child is a single <A href=Fl_Pack.html#Fl_Pack><TT>
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Fl_Pack</TT></A>, which is itself a group that packs it's children
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together and changes size to surround them. Filling the <TT>Fl_Pack</TT>
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with <A href=Fl_Tabs.html#Fl_Tabs><TT>Fl_Tabs</TT></A> groups (and then putting
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normal widgets inside those) gives you a very powerful scrolling list
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of individually-openable panels. </P>
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<P>Fluid lets you create these, but you can only lay out objects that
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fit inside the <TT>Fl_Scroll</TT> without scrolling. Be sure to leave
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space for the scrollbars, as Fluid won't show these either. </P>
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<P><I>You cannot use <TT>Fl_Window</TT> as a child of this since the
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clipping is not conveyed to it when drawn, and it will draw over the
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scrollbars and neighboring objects.</I></P>
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<H3>Methods</H3>
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<UL>
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<LI><A href=#Fl_Scroll.Fl_Scroll>Fl_Scroll</A></LI>
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<LI><A href=#Fl_Scroll.~Fl_Scroll>~Fl_Scroll</A></LI>
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<LI><A href=#Fl_Scroll.align>align</A></LI>
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<LI><A href=#Fl_Scroll.position>position</A></LI>
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<LI><A href=#Fl_Scroll.type>type</A></LI>
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<LI><A href=#Fl_Scroll.xposition>xposition</A></LI>
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<LI><A href=#Fl_Scroll.yposition>yposition</A></LI>
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</UL>
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<H4><A name=Fl_Scroll.Fl_Scroll>Fl_Scroll::Fl_Scroll(int x, int y, int
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w, int h, const char *label = 0)</A></H4>
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Creates a new <TT>Fl_Scroll</TT> widget using the given position,
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size, and label string. The default boxtype is <TT>FL_NO_BOX</TT>.
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<H4><A name=Fl_Scroll.~Fl_Scroll>virtual Fl_Scroll::~Fl_Scroll()</A></H4>
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The destructor <I>also deletes all the children</I>. This allows a
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whole tree to be deleted at once, without having to keep a pointer to
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all the children in the user code. A kludge has been done so the <TT>
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Fl_Scroll</TT> and all of it's children can be automatic (local)
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variables, but you must declare the <TT>Fl_Scroll</TT><I>first</I>, so
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that it is destroyed last.
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<H4><A name=Fl_Scroll.type>void Fl_Widget::type(int)</A></H4>
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By default you can scroll in both directions, and the scrollbars
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disappear if the data will fit in the area of the scroll. <TT>type()</TT>
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can change this:
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<UL>
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<LI><TT>0</TT> - No scrollbars </LI>
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<LI><TT>Fl_Scroll::HORIZONTAL</TT> - Only a horizontal scrollbar. </LI>
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<LI><TT>Fl_Scroll::VERTICAL</TT> - Only a vertical scrollbar. </LI>
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<LI><TT>Fl_Scroll::BOTH</TT> - The default is both scrollbars. </LI>
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<LI><TT>Fl_Scroll::HORIZONTAL_ALWAYS</TT> - Horizontal scrollbar
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always on, vertical always off. </LI>
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<LI><TT>Fl_Scroll::VERTICAL_ALWAYS</TT> - Vertical scrollbar always on,
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horizontal always off. </LI>
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<LI><TT>Fl_Scroll::BOTH_ALWAYS</TT> - Both always on. </LI>
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</UL>
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<H4><A name=Fl_Scroll.align>void Fl_Scroll::scrollbar.align(int)
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<BR> void Fl_Scroll::hscrollbar.align(int)</A></H4>
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This is used to change what side the scrollbars are drawn on. If the <TT>
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FL_ALIGN_LEFT</TT> bit is on, the vertical scrollbar is on the left.
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If the <TT>FL_ALIGN_TOP</TT> bit is on, the horizontal scrollbar is on
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the top.
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<H4><A name=Fl_Scroll.xposition>int Fl_Scroll::xposition() const</A></H4>
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Gets the current horizontal scrolling position.
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<H4><A name=Fl_Scroll.yposition>int Fl_Scroll::yposition() const</A></H4>
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Gets the current vertical scrolling position.
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<H4><A name=Fl_Scroll.position>void Fl_Scroll::position(int w, int h)</A>
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</H4>
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Sets the upper-lefthand corner of the scrolling region. </BODY></HTML>
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