sdlgraphics.cpp

Linux系统下的《红色警戒》游戏

    
        SDL_UnlockSurface(mTarget);    
    }

    void SDLGraphics::drawVLine(int x, int y1, int y2)
    {
        ClipRectangle top = mClipStack.top();
        x += top.xOffset;
        y1 += top.yOffset;
        y2 += top.yOffset;

        if (x < top.x || x >= top.x + top.width)
            return;
    
        if (y1 > y2)
        {
            y1 ^= y2;
            y2 ^= y1;
            y1 ^= y2;
        }

        if (top.y > y1)
        {
            if (top.y > y2)
            {
                return;
            }
            y1 = top.y;
        }

        if (top.y + top.height <= y2)
        {
            if (top.y + top.height <= y1)
            {
                return;
            }      
            y2 = top.y + top.height - 1;
        }
    
        int bpp = mTarget->format->BytesPerPixel;
    
        SDL_LockSurface(mTarget);
    
        Uint8 *p = (Uint8 *)mTarget->pixels + y1 * mTarget->pitch + x * bpp;
    
        Uint32 pixel = SDL_MapRGB(mTarget->format, mColor.r, mColor.g, mColor.b);
    
        switch(bpp) {
          case 1:
          {
              for (;y1 <= y2; ++y1)
              { 
                  *p = pixel;
                  p += mTarget->pitch;
              }
          } break;
      
          case 2:
          {
              for (;y1 <= y2; ++y1)
              {
                  *(Uint16*)p = pixel;
                  p += mTarget->pitch;
              }
          } break;
        
          case 3:  
          {
              if(SDL_BYTEORDER == SDL_BIG_ENDIAN) {
                  for (;y1 <= y2; ++y1)
                  {
                      p[0] = (pixel >> 16) & 0xff;
                      p[1] = (pixel >> 8) & 0xff;
                      p[2] = pixel & 0xff;
                      p += mTarget->pitch;
                  }
              }
              else
              {
                  for (;y1 <= y2; ++y1)
                  {
                      p[0] = pixel & 0xff;
                      p[1] = (pixel >> 8) & 0xff;
                      p[2] = (pixel >> 16) & 0xff;
                      p += mTarget->pitch;
                  }
              } 
          } break;
  
          case 4:
          {
              for (;y1 <= y2; ++y1)
              {
                  if (mAlpha)
                  {
                      *(Uint32*)p = SDLAlpha32(pixel,*(Uint32*)p,mColor.a);
                  }
                  else
                  {
                      *(Uint32*)p = pixel;
                  }
                  p += mTarget->pitch;
              }
          } break;
        } // end switch
    
        SDL_UnlockSurface(mTarget);
    }

    void SDLGraphics::drawRectangle(const Rectangle& rectangle)
    {
        int x1 = rectangle.x;
        int x2 = rectangle.x + rectangle.width - 1;
        int y1 = rectangle.y;
        int y2 = rectangle.y + rectangle.height - 1;

        drawHLine(x1, y1, x2);
        drawHLine(x1, y2, x2);

        drawVLine(x1, y1, y2);
        drawVLine(x2, y1, y2);    
    }

    void SDLGraphics::drawLine(int x1, int y1, int x2, int y2)
    {
        if (x1 == x2)
        {
            drawVLine(x1, y1, y2);
            return;
        }
        if (y1 == y2)
        {
            drawHLine(x1, y1, x2);
            return;
        }

        ClipRectangle top = mClipStack.top();
        x1 += top.xOffset;
        y1 += top.yOffset;
        x2 += top.xOffset;
        y2 += top.yOffset;

        // Draw a line with Bresenham
        
        int dx = ABS(x2 - x1);
        int dy = ABS(y2 - y1);

        if (dx > dy)
        {
            if (x1 > x2)
            {
                // swap x1, x2
                x1 ^= x2;
                x2 ^= x1;
                x1 ^= x2;

                // swap y1, y2
                y1 ^= y2;
                y2 ^= y1;
                y1 ^= y2;   
            }

            if (y1 < y2)
            {
                int y = y1;
                int p = 0;
            
                for (int x = x1; x <= x2; x++)
                {            
                    if (top.isPointInRect(x, y))
                    {
                        if (mAlpha)
                        {
                            SDLputPixelAlpha(mTarget, x, y, mColor);
                        }
                        else
                        {            
                            SDLputPixel(mTarget, x, y, mColor);
                        }
                    }
                
                    p += dy;
                
                    if (p * 2 >= dx)
                    {
                        y++;
                        p -= dx;
                    }
                }
            }
            else
            {
                int y = y1;
                int p = 0;
            
                for (int x = x1; x <= x2; x++)
                {            
                    if (top.isPointInRect(x, y))
                    {
                        if (mAlpha)
                        {
                            SDLputPixelAlpha(mTarget, x, y, mColor);
                        }
                        else
                        {            
                            SDLputPixel(mTarget, x, y, mColor);
                        }
                    }
                
                    p += dy;
                
                    if (p * 2 >= dx)
                    {
                        y--;
                        p -= dx;
                    }
                }            
            }
        }
        else
        {
            if (y1 > y2)
            {
                // swap y1, y2
                y1 ^= y2;
                y2 ^= y1;
                y1 ^= y2;

                // swap x1, x2
                x1 ^= x2;
                x2 ^= x1;
                x1 ^= x2;   
            }

            if (x1 < x2)
            {
                int x = x1;
                int p = 0;
            
                for (int y = y1; y <= y2; y++)
                {            
                    if (top.isPointInRect(x, y))
                    {
                        if (mAlpha)
                        {
                            SDLputPixelAlpha(mTarget, x, y, mColor);
                        }
                        else
                        {            
                            SDLputPixel(mTarget, x, y, mColor);
                        }
                    }
                
                    p += dx;
                
                    if (p * 2 >= dy)
                    {
                        x++;
                        p -= dy;
                    }
                }
            }
            else
            {
                int x = x1;
                int p = 0;
            
                for (int y = y1; y <= y2; y++)
                {            
                    if (top.isPointInRect(x, y))
                    {
                        if (mAlpha)
                        {
                            SDLputPixelAlpha(mTarget, x, y, mColor);
                        }
                        else
                        {            
                            SDLputPixel(mTarget, x, y, mColor);
                        }
                    }
                
                    p += dx;
                
                    if (p * 2 >= dy)
                    {
                        x--;
                        p -= dy;
                    }
                }            
            }
        }    
    }
    
    void SDLGraphics::setColor(const Color& color)
    {
        mColor = color;    

        mAlpha = color.a != 255;        
    }

    const Color& SDLGraphics::getColor()
    {
        return mColor;    
    }

    void SDLGraphics::drawSDLSurface(SDL_Surface* surface, SDL_Rect source,
                                     SDL_Rect destination)
    {
        ClipRectangle top = mClipStack.top();
        destination.x += top.xOffset;
        destination.y += top.yOffset;
    
        SDL_BlitSurface(surface, &source, mTarget, &destination);        
    }
}