ImageObject *
CreateDropShadowMask(const ViewportInfo *vpInfo, int offx, int offy, int r)
{
int rx2 = r * 2;
int img_w = vpInfo->file->Width();
int img_h = vpInfo->file->Height();
ImageObject *mask = new ImageObject(
offx + r + img_w, offy + r + img_h, 1);
// Create the blur image
float *blur = new float[rx2 * rx2];
//float root2 = sqrt(2.);
float blurSum = 0.;
for (int i=0; i<rx2; i++)
{
for (int j=0; j<rx2; j++)
{
float u = float(i)/float(rx2-1);
float v = float(j)/float(rx2-1);
float gu = exp(-pow((4*(u - .5)), 2));
float gv = exp(-pow((4*(v - .5)), 2));
float a = gu * gv;
blur[i*rx2+j] = a;
blurSum += a;
}
}
for(int j = 0; j < rx2; ++j)
for(int i = 0; i < rx2; ++i)
blur[j*rx2 + i] /= blurSum;
if(vpInfo->opaqueMode == M_OPAQUE)
{
int white = 255;
mask->SetBlockToColor(offx, offy, offx + img_w, offy + img_h, &white);
}
else if(vpInfo->opaqueMode == M_TRANSPARENT)
{
int gray = int(vpInfo->opacity * 255.);
mask->SetBlockToColor(offx, offy, offx + img_w, offy + img_h, &gray);
}
else
{
unsigned char rr, rg, rb;
rr = vpInfo->transparentColor[0];
rg = vpInfo->transparentColor[1];
rb = vpInfo->transparentColor[2];
// Everywhere that does not match the bg color, color white.
for(int y = 0; y < img_h; ++y)
{
for(int x = 0; x < img_w; ++x)
{
unsigned char *src = vpInfo->file->Pixel(x, y);
unsigned char *dest = mask->Pixel(x+offx, y+offy);
if(src[0] != rr || src[1] != rg || src[2] != rb)
*dest = 255;
}
}
}
// Blur the mask by convolving it with the blur kernel.
for(int y = offy; y < offy + img_h; ++y)
{
for(int x = offx; x < offx + img_w; ++x)
{
int ksrcx = x - r;
int ksrcy = y - r;
float channelSum = 0.;
for(int ky = 0; ky < rx2; ++ky)
{
for(int kx = 0; kx < rx2; ++kx)
{
unsigned char *mask_ptr = mask->Pixel(ksrcx + kx, ksrcy + ky);
channelSum += float(*mask_ptr) * blur[ky*rx2+kx];
}
}
unsigned char *dest = mask->Pixel(x, y);
*dest = (unsigned char)(int)(channelSum);
}
}
if(vpInfo->opaqueMode == M_TRANSPARENT)
{
int black = 0;
mask->SetBlockToColor(0, 0, img_w, img_h, &black);
}
delete [] blur;
return mask;
}
