transparent_painter.cpp

// transparent_painter.cpp

// Copyright (C) 2004 Steven Weiß (steven11@gmx.de)
//
// Permission to copy, use, sell and distribute this software is granted
// provided this copyright notice appears in all copies.
// Permission to modify the code and to distribute modified code is granted
// provided this copyright notice appears in all copies, and a notice
// that the code was modified is included with the copyright notice.
//
// This software is provided "as is" without express or implied warranty,
// and with no claim as to its suitability for any purpose.


#include <background_wnd/painters/transparent_painter.hpp>


namespace win32 { namespace gui {

transparent_painter::transparent_painter(param0 crTransparent) : crTransparent_(crTransparent)
{}

transparent_painter* transparent_painter::clone() const
{
     return new transparent_painter(*this);
}

void transparent_painter::draw(HDC hDC, int cx, int cy)
{    
     if (cx <= 0 || cy <= 0)
          return;

     if (painter_available()) {
          // prepare mem dc
          painter_base& painter = get_painter();                                
          HDC hPainterDC = CreateCompatibleDC(hDC);         
          HBITMAP hBmp   = CreateCompatibleBitmap(hDC, cx, cy);
          HBITMAP hOldBmp = (HBITMAP) SelectObject(hPainterDC, hBmp);      
          
          // FIXED:
          // first fill with transparent color
          RECT rc = { 0, 0, cx, cy };
          HBRUSH hbr = CreateSolidBrush(crTransparent_);         
          FillRect(hPainterDC, &rc, hbr);
          DeleteObject(hbr);
        
          // draw the painter
          painter.draw(hPainterDC, cx, cy);       

          #if (!defined WINVER || WINVER < 0x0500)
               SelectObject(hPainterDC, hOldBmp);
               DeleteDC(hPainterDC);
                         
               // create the mask
               HBITMAP hMaskBmp = prepare_mask(hBmp, cx, cy);

               // draw transparently
               HDC hTemp = CreateCompatibleDC(NULL);
               hOldBmp = (HBITMAP) SelectObject(hTemp, hBmp);
               draw_transparent_bitmap(hDC, hTemp, hMaskBmp, cx, cy);

               // clean up              
               SelectObject(hTemp, hOldBmp);
               DeleteObject(hBmp);
               DeleteObject(hMaskBmp);
               DeleteDC(hTemp);
          #else
               TransparentBlt(hDC, 0, 0, cx, cy, hPainterDC, 0, 0, cx, cy, crTransparent_);
                              
               // clean up
               SelectObject(hPainterDC, hOldBmp);
               DeleteObject(hBmp);
               DeleteDC(hPainterDC);
          #endif
     }
}

// only use our implementation on Win98 or below (TransparentBlt() has a resource leak on those OSes)
#if (!defined WINVER || WINVER < 0x0500)
     // This code is based on the Raja Segar's article at codeproject.com. Thx!
     HBITMAP transparent_painter::prepare_mask(HBITMAP hSourceBmp, int cx, int cy)                         
     {   
          // create the mask bitmap   
          HBITMAP hMaskBmp = CreateBitmap(cx, cy, 1, 1, NULL);
             
          // load the bitmaps into the DCs
          HDC hSourceDC = CreateCompatibleDC(NULL);
          HDC hMaskDC = CreateCompatibleDC(NULL);   
          HBITMAP hOldSourceBmp = (HBITMAP) SelectObject(hSourceDC, hSourceBmp);
          HBITMAP hOldMaskBmp   = (HBITMAP) SelectObject(hMaskDC, hMaskBmp);
                
          // create the mask
          COLORREF clrSaveBk  = SetBkColor(hSourceDC, crTransparent_);
          BitBlt(hMaskDC, 0, 0, cx, cy, hSourceDC, 0, 0, SRCCOPY);
             
          // transparent color -> black
          COLORREF crOldText = SetTextColor(hSourceDC, RGB(255, 255, 255));
          SetBkColor(hSourceDC, RGB(0, 0, 0));
          BitBlt(hSourceDC, 0, 0, cx, cy, hMaskDC, 0, 0, SRCAND);

          // clean up
          SetTextColor(hSourceDC, crOldText);
          SetBkColor(hSourceDC,   clrSaveBk);
          SelectObject(hSourceDC, hOldSourceBmp);
          SelectObject(hMaskDC,   hOldMaskBmp);
          DeleteDC(hSourceDC);
          DeleteDC(hMaskDC);

          return hMaskBmp;
     }

     void transparent_painter::draw_transparent_bitmap(HDC hDC, HDC hSourceDC, HBITMAP hMaskBmp, int cx, int cy)
     {    
          HDC hMaskDC = CreateCompatibleDC(NULL);
          HBITMAP hOldMaskBmp = (HBITMAP) SelectObject(hMaskDC, hMaskBmp);

          // blit
          BitBlt(hDC, 0, 0, cx, cy, hMaskDC, 0, 0, SRCAND);   
          BitBlt(hDC, 0, 0, cx, cy, hSourceDC, 0, 0, SRCPAINT);

          // clean up
          SelectObject(hMaskDC, hOldMaskBmp);
          DeleteDC(hMaskDC);
     }
#endif    // #ifndef WINVER || WINVER < 0x0500


void transparent_painter::transparent_color(COLORREF crTransparent)
{
     crTransparent_ = crTransparent;
}

COLORREF transparent_painter::transparent_color() const
{
     return crTransparent_;
}

} }  // namespace win32::gui

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