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Check TGA footer if present to see if attribute channel contains alpha data

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This commit is contained in:
AnyOldName3 2019-05-10 00:04:08 +01:00
parent c9fc6e0f79
commit 33bf30cd8c
1 changed files with 89 additions and 9 deletions
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98
src/osgPlugins/tga/ReaderWriterTGA.cpp
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@ -76,6 +76,15 @@ simage_tga_error(char * buffer, int buflen)
return tgaerror;
}
enum AttributeType
{
NO_ALPHA = 0,
ALPHA_UNDEFINED_IGNORE = 1,
ALPHA_UNDEFINED_KEEP = 2,
ALPHA_PRESENT = 3,
ALPHA_PREMULTIPLIED = 4,
ATTRIBUTE_TYPE_UNSET = 256 // Out of range of values possible in file
};
/* TODO: */
/* - bottom-up images */
@ -133,6 +142,16 @@ convert_32_to_32(const unsigned char * const src, unsigned char * const dest)
dest[3] = src[3];
}
static void
convert_32_to_24(const unsigned char * const src, unsigned char * const dest)
{
/* opengl image format is RGB */
/* TGA image format is BGRA (with A as attribute, not alpha) for 32 bit */
dest[0] = src[2];
dest[1] = src[1];
dest[2] = src[0];
}
static void
convert_data(const unsigned char * const src, unsigned char * const dest,
@ -159,9 +178,16 @@ const int destformat)
}
else
{
assert(srcformat == 4 && destformat == 4);
convert_32_to_32(src+x*srcformat,
dest+x*destformat);
assert(srcformat == 4);
if (destformat == 3)
convert_32_to_24(src + x * srcformat,
dest + x * destformat);
else
{
assert(destformat == 4);
convert_32_to_32(src + x * srcformat,
dest + x * destformat);
}
}
}
@ -296,6 +322,7 @@ int *height_ret,
int *numComponents_ret)
{
unsigned char header[18];
unsigned char footer[26];
int type;
int width;
int height;
@ -313,6 +340,7 @@ int *numComponents_ret)
unsigned char *dest;
int bpr;
int alphaBPP;
AttributeType attributeType = ATTRIBUTE_TYPE_UNSET;
tgaerror = ERR_NO_ERROR; /* clear error */
@ -331,6 +359,37 @@ int *numComponents_ret)
flags = header[17];
alphaBPP = flags & 0x0F;
fin.seekg(-26, std::ios::end);
fin.read((char*)footer, 26);
if (fin.gcount() != 26)
{
tgaerror = ERR_READ;
return NULL;
}
// TGA footer signature is null-terminated, so works like a C string
if (strcmp((char*)&footer[8], "TRUEVISION-XFILE.") == 0)
{
unsigned int extensionAreaOffset = getInt32(&footer[0]);
unsigned int developerAreaOffset = getInt32(&footer[4]);
if (extensionAreaOffset != 0)
{
fin.seekg(extensionAreaOffset + 494);
char attrType;
fin.read(&attrType, 1);
if (fin.gcount() != 1)
{
tgaerror = ERR_READ;
return NULL;
}
attributeType = (AttributeType) attrType;
}
}
fin.seekg(18);
/* check for reasonable values in case this is not a tga file */
if ((type != 1 && type != 2 && type != 10) ||
(width < 0 || width > 4096) ||
@ -365,20 +424,41 @@ int *numComponents_ret)
if (colormapDepth == 2) /* 16 bits */
{
if (alphaBPP == 1) format = 4;
else format = 3;
if (alphaBPP == 1 && (attributeType == ALPHA_PRESENT || attributeType == ALPHA_PREMULTIPLIED || attributeType == ATTRIBUTE_TYPE_UNSET))
format = 4;
else
format = 3;
}
else if (colormapDepth == 3)
format = 3;
else
format = colormapDepth;
{
assert(colormapDepth == 4);
if (attributeType == ALPHA_PRESENT || attributeType == ALPHA_PREMULTIPLIED || attributeType == ATTRIBUTE_TYPE_UNSET)
format = 4;
else
format = 3;
}
}
else
{
if (depth == 2) /* 16 bits */
{
if (flags & 1) format = 4;
else format = 3;
if (alphaBPP == 1 && (attributeType == ALPHA_PRESENT || attributeType == ALPHA_PREMULTIPLIED || attributeType == ATTRIBUTE_TYPE_UNSET))
format = 4;
else
format = 3;
}
else if (depth == 3)
format = 3;
else
{
assert(depth == 4);
if (attributeType == ALPHA_PRESENT || attributeType == ALPHA_PREMULTIPLIED || attributeType == ATTRIBUTE_TYPE_UNSET)
format = 4;
else
format = 3;
}
else format = depth;
}
/* SoDebugError::postInfo("simage_tga_load", "TARGA file: %d %d %d %d %d\n", */