CrystalSpace

Public API Reference

csplugincommon/canvas/draw_common.h

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00001 /*
00002     Copyright (C) 2004 by Jorrit Tyberghein
00003               (C) 2004 by Frank Richter
00004 
00005     This library is free software; you can redistribute it and/or
00006     modify it under the terms of the GNU Library General Public
00007     License as published by the Free Software Foundation; either
00008     version 2 of the License, or (at your option) any later version.
00009 
00010     This library is distributed in the hope that it will be useful,
00011     but WITHOUT ANY WARRANTY; without even the implied warranty of
00012     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013     Library General Public License for more details.
00014 
00015     You should have received a copy of the GNU Library General Public
00016     License along with this library; if not, write to the Free
00017     Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00018 */
00019 
00020 #ifndef __CS_CSPLUGINCOMMON_CANVAS_DRAW_COMMON_H__
00021 #define __CS_CSPLUGINCOMMON_CANVAS_DRAW_COMMON_H__
00022 
00027 #include "csplugincommon/canvas/graph2d.h"
00028 
00033 
00034 template<class Tpixel>
00035 static void SplitAlpha (const int color, Tpixel& colorPart, uint8& alphaPart)
00036 {
00037   colorPart = color ^ 0xff000000;
00038   alphaPart = 255 - (color >> 24);
00039 }
00040 
00042 template<class Tpixel>
00043 class csPixMixerCopy
00044 {
00045   Tpixel color;
00046 public:
00047   csPixMixerCopy (csGraphics2D* /*G2D*/, Tpixel color, uint8 /*alpha*/)
00048   {
00049     csPixMixerCopy::color = color;
00050   }
00051   inline void Mix (Tpixel& dest)
00052   {
00053     dest = color;
00054   }
00055 };
00056 
00058 template<class Tpixel>
00059 class csPixMixerRGBA
00060 {
00061   uint32 rbMask, gaMask;
00062   int intAlphaInv;
00063   uint32 intRB, intGA;
00064   int gShift, gShift2;
00065   int alphaPrec;
00066 public:
00067   csPixMixerRGBA (csGraphics2D* G2D, Tpixel color, uint8 alpha)
00068   {
00069     alphaPrec = G2D->pfmt.GreenBits;
00070     const int alphaShift = 8 - alphaPrec;
00071     const int intAlpha = (alpha + 1) >> alphaShift;
00072     intAlphaInv = (255 - alpha + 1) >> alphaShift;
00073     gShift = G2D->pfmt.GreenShift;
00074     gShift2 = alphaPrec - gShift;
00075     // Makes the assumption that colors are laid out ARGB ...
00076     rbMask = G2D->pfmt.RedMask | G2D->pfmt.BlueMask;
00077     intRB = ((color & rbMask) * intAlpha) >> alphaPrec;
00078     gaMask = G2D->pfmt.GreenMask | G2D->pfmt.AlphaMask;
00079     intGA = (((color & gaMask) >> gShift) * intAlpha) >> gShift2;
00080   }
00081   inline void Mix (Tpixel& dest) const
00082   {
00083     const Tpixel destCol = dest;
00084     const Tpixel newRB = 
00085       ((intRB + (((destCol & rbMask) * intAlphaInv) >> alphaPrec)) & rbMask);
00086     const Tpixel newGA = 
00087       ((intGA + (((((destCol & gaMask) >> gShift) * intAlphaInv)) >> gShift2)) 
00088         & gaMask);
00089     dest = newRB | newGA;
00090   }
00091 };
00092 
00094 template<class Tpixel>
00095 class csPixMixerNoop
00096 {
00097 public:
00098   csPixMixerNoop (csGraphics2D* /*G2D*/, Tpixel /*color*/, uint8 /*alpha*/)
00099   { }
00100   inline void Mix (Tpixel& /*dest*/)
00101   { }
00102 };
00103 
00106 #endif // __CS_CSPLUGINCOMMON_CANVAS_DRAW_COMMON_H__

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