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implemented fallback for AlphaBlend() for the systems not supporting it

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git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@20199 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Vadim Zeitlin 2003-04-13 15:59:49 +00:00
parent cc37ebe090
commit 878711c01c
1 changed files with 76 additions and 9 deletions
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85
src/msw/dc.cpp
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@ -44,6 +44,7 @@
#include "wx/dcprint.h"
#include "wx/module.h"
#include "wx/dynload.h"
#include "wx/rawbmp.h"
#include <string.h>
#include <math.h>
@ -58,6 +59,10 @@
#include <print.h>
#endif
#ifndef AC_SRC_ALPHA
#define AC_SRC_ALPHA 1
#endif
/* Quaternary raster codes */
#ifndef MAKEROP4
#define MAKEROP4(fore,back) (DWORD)((((back) << 8) & 0xFF000000) | (fore))
@ -109,6 +114,10 @@ static const int MM_METRIC = 10;
// convert degrees to radians
static inline double DegToRad(double deg) { return (deg * M_PI) / 180.0; }
// our (limited) AlphaBlend() replacement
static void
wxAlphaBlend(wxDC& dc, int x, int y, int w, int h, const wxBitmap& bmp);
// ----------------------------------------------------------------------------
// private classes
// ----------------------------------------------------------------------------
@ -983,10 +992,6 @@ void wxDC::DoDrawBitmap( const wxBitmap &bmp, wxCoord x, wxCoord y, bool useMask
MemoryHDC hdcMem;
SelectInHDC select(hdcMem, GetHbitmapOf(bmp));
#ifndef AC_SRC_ALPHA
#define AC_SRC_ALPHA 1
#endif
BLENDFUNCTION bf;
bf.BlendOp = AC_SRC_OVER;
bf.BlendFlags = 0;
@ -999,10 +1004,13 @@ void wxDC::DoDrawBitmap( const wxBitmap &bmp, wxCoord x, wxCoord y, bool useMask
{
wxLogLastError(_T("AlphaBlend"));
}
return;
}
//else: AlphaBlend() not available
else // use our own (probably much slower) implementation
{
wxAlphaBlend(*this, x, y, width, height, bmp);
}
return;
}
#endif // defined(AC_SRC_OVER)
@ -2146,6 +2154,10 @@ void wxDC::SetLogicalScale(double x, double y)
m_logicalScaleY = y;
}
// ----------------------------------------------------------------------------
// DC caching
// ----------------------------------------------------------------------------
#if wxUSE_DC_CACHEING
/*
@ -2281,6 +2293,61 @@ private:
IMPLEMENT_DYNAMIC_CLASS(wxDCModule, wxModule)
#endif
// wxUSE_DC_CACHEING
#endif // wxUSE_DC_CACHEING
// ----------------------------------------------------------------------------
// wxAlphaBlend: our fallback if ::AlphaBlend() is unavailable
// ----------------------------------------------------------------------------
static void
wxAlphaBlend(wxDC& dc, int xDst, int yDst, int w, int h, const wxBitmap& bmpSrc)
{
// get the destination DC pixels
wxBitmap bmpDst(w, h, 32);
MemoryHDC hdcMem;
SelectInHDC select(hdcMem, GetHbitmapOf(bmpDst));
if ( !::BitBlt(hdcMem, 0, 0, w, h, GetHdcOf(dc), 0, 0, SRCCOPY) )
{
wxLogLastError(_T("BitBlt"));
}
// combine them with the source bitmap using alpha
wxRawBitmapData dataDst(bmpDst),
dataSrc(bmpSrc);
wxRawBitmapIterator pDst(dataDst),
pSrc(dataSrc);
for ( int y = 0; y < h; y++ )
{
wxRawBitmapIterator pDstRowStart = pDst,
pSrcRowStart = pSrc;
for ( int x = 0; x < w; x++ )
{
// note that source bitmap uses premultiplied alpha (as required by
// the real AlphaBlend)
const unsigned beta = 255 - pSrc.Alpha();
pDst.Red() = pSrc.Red() + (beta * pDst.Red() + 127) / 255;
pDst.Blue() = pSrc.Blue() + (beta * pDst.Blue() + 127) / 255;
pDst.Green() = pSrc.Green() + (beta * pDst.Green() + 127) / 255;
++pDst;
++pSrc;
}
pDst = pDstRowStart;
pSrc = pSrcRowStart;
pDst.OffsetY(1);
pSrc.OffsetY(1);
}
// and finally blit them back to the destination DC
if ( !::BitBlt(GetHdcOf(dc), xDst, yDst, w, h, hdcMem, 0, 0, SRCCOPY) )
{
wxLogLastError(_T("BitBlt"));
}
}