wxBitmap ConvertTo24Bit( wxColor bgColor, wxBitmap front ) {
if( front.GetDepth() == 24 ) return front;
wxBitmap result( front.GetWidth(), front.GetHeight(), 24 );
front.UseAlpha();
wxImage im_front = front.ConvertToImage();
wxImage im_result = result.ConvertToImage();
unsigned char *presult = im_result.GetData();
unsigned char *pfront = im_front.GetData();
unsigned char *afront = NULL;
if( im_front.HasAlpha() )
afront = im_front.GetAlpha();
for( int i = 0; i < result.GetWidth(); i++ ) {
for( int j = 0; j < result.GetHeight(); j++ ) {
double alphaF = (double) ( *afront++ ) / 256.0;
unsigned char r = *pfront++ * alphaF + bgColor.Red() * ( 1.0 - alphaF );
*presult++ = r;
unsigned char g = *pfront++ * alphaF + bgColor.Green() * ( 1.0 - alphaF );
*presult++ = g;
unsigned char b = *pfront++ * alphaF + bgColor.Blue() * ( 1.0 - alphaF );
*presult++ = b;
}
}
result = wxBitmap( im_result );
return result;
}
wxBitmap MergeBitmaps( wxBitmap back, wxBitmap front, wxSize offset )
{
wxBitmap merged( back.GetWidth(), back.GetHeight(), back.GetDepth() );
// If the front bitmap has no alpha channel, then merging will accomplish nothing
// So, simply return the bitmap intact
wxImage im_front = front.ConvertToImage();
if(!im_front.HasAlpha())
return front;
#if !wxCHECK_VERSION(2,9,4)
// Manual alpha blending for broken wxWidgets alpha bitmap support, pervasive in wx2.8.
merged.UseAlpha();
back.UseAlpha();
front.UseAlpha();
// wxImage im_front = front.ConvertToImage();
wxImage im_back = back.ConvertToImage();
wxImage im_result = back.ConvertToImage();// Only way to make result have alpha channel in wxW 2.8.
unsigned char *presult = im_result.GetData();
unsigned char *pback = im_back.GetData();
unsigned char *pfront = im_front.GetData();
unsigned char *afront = NULL;
if( im_front.HasAlpha() )
afront = im_front.GetAlpha();
unsigned char *aback = NULL;
if( im_back.HasAlpha() )
aback = im_back.GetAlpha();
unsigned char *aresult = NULL;
if( im_result.HasAlpha() )
aresult = im_result.GetAlpha();
// Do alpha blending, associative version of "over" operator.
if(presult && pback && pfront){
for( int i = 0; i < back.GetHeight(); i++ ) {
for( int j = 0; j < back.GetWidth(); j++ ) {
int fX = j - offset.x;
int fY = i - offset.y;
bool inFront = true;
if( fX < 0 || fY < 0 ) inFront = false;
if( fX >= front.GetWidth() ) inFront = false;
if( fY >= front.GetHeight() ) inFront = false;
if( inFront ) {
double alphaF = (double) ( *afront++ ) / 256.0;
double alphaB = (double) ( *aback++ ) / 256.0;
double alphaRes = alphaF + alphaB * ( 1.0 - alphaF );
unsigned char a = alphaRes * 256;
*aresult++ = a;
unsigned char r = (*pfront++ * alphaF + *pback++ * alphaB * ( 1.0 - alphaF )) / alphaRes;
*presult++ = r;
unsigned char g = (*pfront++ * alphaF + *pback++ * alphaB * ( 1.0 - alphaF )) / alphaRes;
*presult++ = g;
unsigned char b = (*pfront++ * alphaF + *pback++ * alphaB * ( 1.0 - alphaF )) / alphaRes;
*presult++ = b;
} else {
*aresult++ = *aback++;
*presult++ = *pback++;
*presult++ = *pback++;
*presult++ = *pback++;
}
}
}
}
merged = wxBitmap( im_result );
#else
wxMemoryDC mdc( merged );
mdc.DrawBitmap( back, 0, 0, true );
mdc.DrawBitmap( front, offset.x, offset.y, true );
mdc.SelectObject( wxNullBitmap );
#endif
return merged;
}
wxBitmap MergeBitmaps( wxBitmap back, wxBitmap front, wxSize offset )
{
wxBitmap merged( back.GetWidth(), back.GetHeight(), back.GetDepth() );
#if (defined(__WXGTK__) || defined(__WXMAC__))
// Manual alpha blending for broken wxWidgets platforms.
merged.UseAlpha();
back.UseAlpha();
front.UseAlpha();
wxImage im_front = front.ConvertToImage();
wxImage im_back = back.ConvertToImage();
wxImage im_result = back.ConvertToImage();// Only way to make result have alpha channel in wxW 2.8.
unsigned char *presult = im_result.GetData();
unsigned char *pback = im_back.GetData();
unsigned char *pfront = im_front.GetData();
unsigned char *afront = NULL;
if( im_front.HasAlpha() )
afront = im_front.GetAlpha();
unsigned char *aback = NULL;
if( im_back.HasAlpha() )
aback = im_back.GetAlpha();
unsigned char *aresult = NULL;
if( im_result.HasAlpha() )
aresult = im_result.GetAlpha();
// Do alpha blending, associative version of "over" operator.
for( int i = 0; i < back.GetHeight(); i++ ) {
for( int j = 0; j < back.GetWidth(); j++ ) {
int fX = j - offset.x;
int fY = i - offset.y;
bool inFront = true;
if( fX < 0 || fY < 0 ) inFront = false;
if( fX >= front.GetWidth() ) inFront = false;
if( fY >= front.GetHeight() ) inFront = false;
if( inFront ) {
double alphaF = (double) ( *afront++ ) / 256.0;
double alphaB = (double) ( *aback++ ) / 256.0;
double alphaRes = alphaF + alphaB * ( 1.0 - alphaF );
unsigned char a = alphaRes * 256;
*aresult++ = a;
unsigned char r = (*pfront++ * alphaF + *pback++ * alphaB * ( 1.0 - alphaF )) / alphaRes;
*presult++ = r;
unsigned char g = (*pfront++ * alphaF + *pback++ * alphaB * ( 1.0 - alphaF )) / alphaRes;
*presult++ = g;
unsigned char b = (*pfront++ * alphaF + *pback++ * alphaB * ( 1.0 - alphaF )) / alphaRes;
*presult++ = b;
} else {
*aresult++ = *aback++;
*presult++ = *pback++;
*presult++ = *pback++;
*presult++ = *pback++;
}
}
}
merged = wxBitmap( im_result );
#else
wxMemoryDC mdc( merged );
mdc.DrawBitmap( back, 0, 0, true );
mdc.DrawBitmap( front, offset.x, offset.y, true );
mdc.SelectObject( wxNullBitmap );
#endif
return merged;
}
