mirror of https://github.com/fltk/fltk
56 lines
2.4 KiB
HTML
56 lines
2.4 KiB
HTML
<HTML><BODY>
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<!-- NEW PAGE -->
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<H2><A name=Fl_Overlay_Window>class Fl_Overlay_Window</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_Double_Window.html#Fl_Double_Window>Fl_Double_Window</A>
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+----<B>Fl_Overlay_Window</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_Overlay_Window.H>
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</PRE>
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</UL>
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<H3>Description</H3>
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This window provides double buffering and also the ability to draw the
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"overlay" which is another picture placed on top of the main image. The
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overlay is designed to be a rapidly-changing but simple graphic such as
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a mouse selection box. <TT>Fl_Overlay_Window</TT> uses the overlay
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planes provided by your graphics hardware if they are available.
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<P>If no hardware support is found the overlay is simulated by drawing
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directly into the on-screen copy of the double-buffered window, and
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"erased" by copying the backbuffer over it again. This means the
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overlay will blink if you change the image in the window. </P>
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<H3>Methods</H3>
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<UL>
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<LI><A href=#Fl_Overlay_Window.Fl_Overlay_Window>Fl_Overlay_Window</A></LI>
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<LI><A href=#Fl_Overlay_Window.~Fl_Overlay_Window>~Fl_Overlay_Window</A></LI>
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<LI><A href=#Fl_Overlay_Window.draw_overlay>draw_overlay</A></LI>
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<LI><A href=#Fl_Overlay_Window.redraw_overlay>redraw_overlay</A></LI>
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</UL>
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<H4><A name=Fl_Overlay_Window.Fl_Overlay_Window>
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Fl_Overlay_Window::Fl_Overlay_Window(int x, int y, int w, int h, const
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char *label = 0)</A></H4>
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Creates a new <TT>Fl_Overlay_Window</TT> widget using the given
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position, size, and label (title) string.
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<H4><A name=Fl_Overlay_Window.~Fl_Overlay_Window>virtual
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Fl_Overlay_Window::~Fl_Overlay_Window()</A></H4>
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Destroys the window and all child widgets.
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<H4><A name=Fl_Overlay_Window.draw_overlay>virtual void
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Fl_Overlay_Window::draw_overlay() = 0</A></H4>
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You must subclass <TT>Fl_Overlay_Window</TT> and provide this method.
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It is just like a <TT>draw()</TT> method, except it draws the overlay.
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The overlay will have already been "cleared" when this is called. You
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can use any of the routines described in <A href="drawing.html#drawing"><FL/fl_draw.H></A>.
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<H4><A name=Fl_Overlay_Window.redraw_overlay>void Fl_Overlay_Window::redraw_overlay()</A>
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</H4>
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Call this to indicate that the overlay data has changed and needs to
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be redrawn. The overlay will be clear until the first time this is
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called, so if you want an initial display you must call this after
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calling <TT>show()</TT>. </BODY></HTML>
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