/// Takes a background image, foreground image, and mask
/// (i.e. the alpha channel for the foreground), and
/// returns an new image where the foreground has been
/// overlaid onto the background using alpha-blending,
/// at location (xoff, yoff).
wxImage *OverlayImage(teBmps eBack, teBmps eForeground,
int xoff, int yoff)
{
wxImage imgBack(theTheme.Image( eBack ));
wxImage imgFore(theTheme.Image( eForeground ));
// TMP: dmazzoni - just so the code runs even though not all of
// our images have transparency...
if (!imgFore.HasAlpha())
return new wxImage(imgBack);
wxASSERT( imgFore.HasAlpha() );
unsigned char *bg = imgBack.GetData();
unsigned char *fg = imgFore.GetData();
unsigned char *mk = imgFore.GetAlpha();
int bgWidth = imgBack.GetWidth();
int bgHeight = imgBack.GetHeight();
int fgWidth = imgFore.GetWidth();
int fgHeight = imgFore.GetHeight();
//Now, determine the dimensions of the images to be masked together
//on top of the background. This should be equal to the area of the
//smaller of the foreground and the mask, as long as it is
//within the area of the background, given the offset.
//Make sure the foreground size is no bigger than the mask
int wCutoff = fgWidth;
int hCutoff = fgHeight;
// If the masked foreground + offset is bigger than the background, masking
// should only occur within these bounds of the foreground image
wCutoff = (bgWidth - xoff > wCutoff) ? wCutoff : bgWidth - xoff;
hCutoff = (bgHeight - yoff > hCutoff) ? hCutoff : bgHeight - yoff;
//Make a new image the size of the background
wxImage * dstImage = new wxImage(bgWidth, bgHeight);
unsigned char *dst = dstImage->GetData();
memcpy(dst, bg, bgWidth * bgHeight * 3);
// Go through the foreground image bit by bit and mask it on to the
// background, at an offset of xoff,yoff.
// BUT...Don't go beyond the size of the background image,
// the foreground image, or the mask
int x, y;
for (y = 0; y < hCutoff; y++) {
unsigned char *bkp = bg + 3 * ((y + yoff) * bgWidth + xoff);
unsigned char *dstp = dst + 3 * ((y + yoff) * bgWidth + xoff);
for (x = 0; x < wCutoff; x++) {
int value = mk[(y * fgWidth + x)];// Don't multiply by 3...
int opp = 255 - value;
for (int c = 0; c < 3; c++)
dstp[x * 3 + c] =
((bkp[x * 3 + c] * opp) +
(fg[3 * (y * fgWidth + x) + c] * value)) / 255;
}
}
return dstImage;
}
/// Takes a background image, foreground image, and mask
/// (i.e. the alpha channel for the foreground), and
/// returns an NEW image where the foreground has been
/// overlaid onto the background using alpha-blending,
/// at location (xoff, yoff).
std::unique_ptr<wxImage> OverlayImage(teBmps eBack, teBmps eForeground,
int xoff, int yoff)
{
wxImage imgBack(theTheme.Image( eBack ));
wxImage imgFore(theTheme.Image( eForeground ));
// TMP: dmazzoni - just so the code runs even though not all of
// our images have transparency...
if (!imgFore.HasAlpha())
return std::make_unique<wxImage>(imgBack);
wxASSERT( imgFore.HasAlpha() );
unsigned char *bg = imgBack.GetData();
unsigned char *fg = imgFore.GetData();
unsigned char *mk = imgFore.GetAlpha();
int bgWidth = imgBack.GetWidth();
int bgHeight = imgBack.GetHeight();
int fgWidth = imgFore.GetWidth();
int fgHeight = imgFore.GetHeight();
//Now, determine the dimensions of the images to be masked together
//on top of the background. This should be equal to the area of the
//smaller of the foreground and the mask, as long as it is
//within the area of the background, given the offset.
//Make sure the foreground size is no bigger than the mask
int wCutoff = fgWidth;
int hCutoff = fgHeight;
// If the masked foreground + offset is bigger than the background, masking
// should only occur within these bounds of the foreground image
wCutoff = (bgWidth - xoff > wCutoff) ? wCutoff : bgWidth - xoff;
hCutoff = (bgHeight - yoff > hCutoff) ? hCutoff : bgHeight - yoff;
//Make a NEW image the size of the background
auto dstImage = std::make_unique<wxImage>(bgWidth, bgHeight);
unsigned char *dst = dstImage->GetData();
memcpy(dst, bg, bgWidth * bgHeight * 3);
// If background image has tranparency, then we want to blend with the
// current backgorund colour.
if( imgBack.HasAlpha() ){
unsigned char *pAlpha = imgBack.GetAlpha();
wxColour c = theTheme.Colour( clrMedium );
unsigned char onePixImage[3];
// GetData() guarantees RGB order [wxWidgets does the ocnversion]
onePixImage[ 0 ] = c.Red();
onePixImage[ 1 ] = c.Green();
onePixImage[ 2 ] = c.Blue();
for( int i=0;i< bgWidth*bgHeight;i++){
unsigned char * pPix = &dst[ 3*i];
float alpha = 1.0 - (pAlpha[i]/255.0);
pPix[0] = pPix[0] + alpha *( (int)onePixImage[0]-(int)pPix[0]);
pPix[1] = pPix[1] + alpha *( (int)onePixImage[1]-(int)pPix[1]);
pPix[2] = pPix[2] + alpha *( (int)onePixImage[2]-(int)pPix[2]);
}
}
// Go through the foreground image bit by bit and mask it on to the
// background, at an offset of xoff,yoff.
// BUT...Don't go beyond the size of the background image,
// the foreground image, or the mask
int x, y;
for (y = 0; y < hCutoff; y++) {
unsigned char *bkp = bg + 3 * ((y + yoff) * bgWidth + xoff);
unsigned char *dstp = dst + 3 * ((y + yoff) * bgWidth + xoff);
for (x = 0; x < wCutoff; x++) {
int value = mk[(y * fgWidth + x)];// Don't multiply by 3...
int opp = 255 - value;
for (int c = 0; c < 3; c++)
dstp[x * 3 + c] =
((bkp[x * 3 + c] * opp) +
(fg[3 * (y * fgWidth + x) + c] * value)) / 255;
}
}
return dstImage;
}
