CrystalSpace

Public API Reference

csplugincommon/canvas/draw_line.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_LINE_H__
00021 #define __CS_CSPLUGINCOMMON_CANVAS_DRAW_LINE_H__
00022 
00027 #include "csplugincommon/canvas/draw_common.h"
00028 #include "csqint.h"
00029 
00034 
00035 template<class Tpixel, class Tpixmixer>
00036 class csG2DDrawLine
00037 {
00038 public:
00040   static void DrawLine (csGraphics2D* G2D, float x1, float y1, float x2, float y2,
00041     Tpixel color, uint8 alpha)
00042   {
00043     Tpixmixer mixer (G2D, color, alpha);
00044     unsigned char* Memory = G2D->Memory;
00045     const int* LineAddress = G2D->LineAddress;
00046 
00047     int fx1 = csQint (x1), fx2 = csQint (x2),
00048         fy1 = csQint (y1), fy2 = csQint (y2);
00049     
00050     if (fy1 == fy2)
00051     {
00052       if (fx2 - fx1)
00053       {
00054         if (fx1 > fx2) { int tmp = fx1; fx1 = fx2; fx2 = tmp; }
00055         int count = fx2 - fx1 + 1;
00056         register Tpixel* dest = (Tpixel*)G2D->GetPixelAt (fx1, fy1);
00057         while (count--) mixer.Mix (*dest++);
00058       }
00059       else
00060         mixer.Mix (*((Tpixel*)G2D->GetPixelAt (fx1, fy1)));
00061     }
00062     else if (abs (fx2 - fx1) > abs (fy2 - fy1))
00063     {
00064       // Transform floating-point format to 16.16 fixed-point
00065       fy1 = csQfixed16 (y1); fy2 = csQfixed16 (y2);
00066   
00067       if (fx1 > fx2)
00068       {
00069         int tmp = fx1; fx1 = fx2; fx2 = tmp;
00070         tmp = fy1; fy1 = fy2; fy2 = tmp;
00071       }
00072   
00073       // delta Y can be negative
00074       int deltay = (fy2 - fy1) / (fx2 - fx1 + 1);
00075   
00076       {                                                         
00077         int x, y;                                               
00078         for (x = fx1, y = fy1 + deltay / 2; x <= fx2; x++)      
00079         {                                                               
00080           Tpixel* p = (Tpixel*)(Memory +                        
00081             (x * sizeof (Tpixel) + LineAddress [y >> 16]));     
00082           mixer.Mix (*p); y += deltay;                                  
00083         }                                                               
00084       }
00085     }
00086     else
00087     {
00088       // Transform floating-point format to 16.16 fixed-point
00089       fx1 = csQfixed16 (x1); fx2 = csQfixed16 (x2);
00090   
00091       if (fy1 > fy2)
00092       {
00093         int tmp = fy1; fy1 = fy2; fy2 = tmp;
00094         tmp = fx1; fx1 = fx2; fx2 = tmp;
00095       }
00096   
00097       // delta X can be negative
00098       int deltax = (fx2 - fx1) / (fy2 - fy1 + 1);
00099   
00100       {                             
00101         int x, y; 
00102         for (x = fx1 + deltax / 2, y = fy1; y <= fy2; y++)  
00103         {                               
00104           Tpixel* p = (Tpixel*)(Memory +             
00105             ((x >> 16) * sizeof (Tpixel) + LineAddress [y]));  
00106           mixer.Mix (*p); x += deltax;                  
00107         }                               
00108       }
00109     }
00110     
00111   }
00112 };
00113 
00116 #endif // __CS_CSPLUGINCOMMON_CANVAS_DRAW_LINE_H__

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