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From Michael Gronager, added support for alpha channel in writing of BMP images

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This commit is contained in:
Robert Osfield
2004-06-28 13:18:10 +00:00
parent 6de63f097b
commit db43e34bce
1 changed files with 34 additions and 11 deletions
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45
src/osgPlugins/bmp/ReaderWriterBMP.cpp
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@@ -228,7 +228,7 @@ int *numComponents_ret)
ncomp = BW; // actually this is a 256 colour, paletted image
inf.Colorbits=8; // so this is how many bits there are per index
//inf.ColorUsed=256; // and number of colours used
if(!inf.ColorUsed) inf.ColorUsed=256; /*the bitmap has 256 colours if ColorUsed = 0 otherwise as many as stored in ColorUsed*/
if(!inf.ColorUsed) inf.ColorUsed=256; /*the bitmap has 256 colours if ColorUsed = 0 otherwise as many as stored in ColorUsed*/
cols=imbuff; // colour palette address - uses 4 bytes/colour
break;
case 2:
@@ -402,7 +402,7 @@ class ReaderWriterBMP : public osgDB::ReaderWriter
inf.YpixPerMeter=1000; //pixels per meter in Y
inf.ColorUsed=0; //number of colors used
inf.Important=0; //number of "important" colors
// inf.os2stuff[6]; // allows os2.1 with 64 bytes to be read. Dont know what these are yet.
// inf.os2stuff[6]; // allows os2.1 with 64 bytes to be read. Dont know what these are yet.
infsize=sizeof(BMPInfo)+sizeof(long);
fwrite(&infsize, sizeof(long), 1, fp);
fwrite(&inf, sizeof(inf), 1, fp); // one dword shorter than the structure defined by MS
@@ -411,17 +411,40 @@ class ReaderWriterBMP : public osgDB::ReaderWriter
osg::notify(osg::INFO) << "sizes "<<size << " "<<infsize <<" "<<sizeof(inf)<< std::endl;
// now output the bitmap
// 1) swap Blue with Red - needed for Windoss.
const unsigned char* data = img.data();
unsigned char *dta=new unsigned char[size];
unsigned char tmp;
memcpy(dta,img.data(),size*sizeof(unsigned char));
for(unsigned int i=0;i<ny;i++) { // per scanline
int ioff=4*wordsPerScan*i;
for(unsigned int j=0;j<nx;j++) {
tmp=dta[3*j+ioff]; // swap r with b, thanks to good ole Bill -
//"Let's use BGR it's more logical than rgb which everyone else uses."
dta[3*j+ioff]=dta[3*j+ioff+2];
dta[3*j+ioff+2]=tmp;
}
// we need to case between different number of components
switch(img.computeNumComponents(img.getPixelFormat()))
{
case(3) :
memcpy(dta,img.data(),size*sizeof(unsigned char));
for(unsigned int i=0;i<ny;i++) { // per scanline
int ioff=4*wordsPerScan*i;
for(unsigned int j=0;j<nx;j++) {
tmp=dta[3*j+ioff]; // swap r with b, thanks to good ole Bill -
//"Let's use BGR it's more logical than rgb which everyone else uses."
dta[3*j+ioff]=dta[3*j+ioff+2];
dta[3*j+ioff+2]=tmp;
}
}
break;
case(4) :
for(unsigned int i=0;i<ny;i++) { // per scanline
int ioff=4*wordsPerScan*i;
for(unsigned int j=0;j<nx;j++) {
// swap r with b, thanks to good ole Bill -
//"Let's use BGR it's more logical than rgb which everyone else uses."
dta[3*j+ioff]=dta[3*j+ioff+2];
dta[3*j+ioff+0]=data[4*(j+i*nx)+2];
dta[3*j+ioff+1]=data[4*(j+i*nx)+1];
dta[3*j+ioff+2]=data[4*(j+i*nx)+0];
}
}
break;
default:
osg::notify(osg::WARN) << "Cannot write images with other number of components than 3 or 4" << std::endl;
break;
}
fwrite(dta, sizeof(unsigned char), size, fp);
delete [] dta;