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FXBackBufferedCanvas.h

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00001 /********************************************************************************
00002 *                                                                               *
00003 *             B a c k  B u f f e r e d  C a n v a s  W i d g e t                *
00004 *                                                                               *
00005 *********************************************************************************
00006 * Copyright (C) 2003 by Davy Durham.  With coding tips from Jeroen van der Zijp *
00007 *********************************************************************************
00008 * This library is free software; you can redistribute it and/or                 *
00009 * modify it under the terms of the GNU Lesser General Public                    *
00010 * License as published by the Free Software Foundation; either                  *
00011 * version 2.1 of the License, or (at your option) any later version.            *
00012 *                                                                               *
00013 * This library is distributed in the hope that it will be useful,               *
00014 * but WITHOUT ANY WARRANTY; without even the implied warranty of                *
00015 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU             *
00016 * Lesser General Public License for more details.                               *
00017 *                                                                               *
00018 * You should have received a copy of the GNU Lesser General Public              *
00019 * License along with this library; if not, write to the Free Software           *
00020 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.    *
00021 ********************************************************************************/
00022 #ifndef FXBACKBUFFEREDCANVAS_H
00023 #define FXBACKBUFFEREDCANVAS_H
00024 
00025 #ifndef FXCANVAS_H
00026 #include <fox/FXCanvas.h>
00027 using namespace FX;
00028 #endif
00029 namespace FXEX {
00030 
00031 
00032 /**
00033  * Back Buffered Canvas, an area drawn by another object, except a little more
00034  * expensive but to reduce flicker
00035  */
00036 class FXAPI FXBackBufferedCanvas : public FXCanvas {
00037   FXDECLARE(FXBackBufferedCanvas)
00038 
00039 private:
00040   FXImage *backBuffer;     // the off-screen buffer
00041   FXDC    *currentDC;      // handle to current FXDC
00042   FXbool   inOnPaintEvent; // figure out if we are in a paint event
00043 
00044 protected:
00045   /// serialisation
00046   FXBackBufferedCanvas();
00047 
00048 public:
00049   long onPaint(FXObject *sender,FXSelector sel,void *ptr);
00050   long onConfigure(FXObject *sender,FXSelector sel,void *ptr);
00051 
00052 public:
00053   /// Construct new back buffered drawing canvas widget
00054   FXBackBufferedCanvas(FXComposite* p,FXObject* tgt=NULL,FXSelector sel=0,FXuint opts=FRAME_NORMAL,FXint x=0,FXint y=0,FXint w=0,FXint h=0);
00055 
00056   /// create resources
00057   void create();
00058 
00059   /*
00060    * - This can be used to set the options of the back buffer to include
00061    * IMAGE_OWNED so that the drawing code can call getBackBufferData()
00062    * and render/modify the back buffer.
00063    * - When IMAGE_OWNED is included in the options, then backBuffer->render()
00064    * will be called just before the backbuffer is blitted to the screen.
00065    */
00066   void setBackBufferOptions(FXint options);
00067 
00068   /// return handle to some backbuffered data
00069   void *getBackBufferData();
00070 
00071   /**
00072    * Normally, the user should wait for the SEL_PAINT event to draw the the canvas, in which case
00073    * the ptr parameter would contain the DC to draw to. 
00074    *
00075    * However, these two methods need to be used if the user is not waiting for the SEL_PAINT event 
00076    * to draw to the canvas since the user should actually be drawing to the back buffer and not the
00077    * actual canvas on screen.  (I suppose much more work could be done to make the use of back
00078    * buffering completly transparent and make it have the same interface as FXCanvas)
00079    */
00080   FXDC *beginPaint();
00081 
00082   /// finish painting
00083   void endPaint();
00084 
00085   /// Save object to stream
00086   virtual void save(FXStream& store) const;
00087 
00088   /// Load object from stream
00089   virtual void load(FXStream& store);
00090 
00091   /// dtor
00092   virtual ~FXBackBufferedCanvas();
00093 
00094   };
00095 
00096 } // namespace FXEX
00097 #endif // FXBACKBUFFEREDCANVAS_H