/*---------------------------------------------------------------------------
Loads a PNG file.
Image : Image will be returned there.
Path : Path to image file, relative to the current working directory.
Gamma : Display gamma to apply on textures, 2.2 is typical.
---------------------------------------------------------------------------*/
void PNG::Load(Texture &Image, const std::string &Path, float Gamma)
{
Destroy();
//Important - set class to reading mode
Mode = PNG::ModeRead;
#if defined (WINDOWS)
if (fopen_s(&File, Path.c_str(), "rb") != 0)
{throw dexception("Failed to open file: %s.", Path.c_str());}
#else
File = fopen(Path.c_str(), "rb");
if (File == nullptr) {throw dexception("Failed to open file: %s.", Path.c_str());}
#endif
uint8 Header[PNG::HeaderSize];
if (fread((png_bytep)Header, 1, PNG::HeaderSize, File) == 0)
{throw dexception("fread( ) failed.");}
if (!png_check_sig(Header, PNG::HeaderSize))
{throw dexception("Not a valid PNG file.");}
PngPtr = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
if (PngPtr == nullptr) {throw dexception("png_create_read_struct( ) failed.");}
InfoPtr = png_create_info_struct(PngPtr);
if (InfoPtr == nullptr) {throw dexception("png_create_info_struct( ) failed.");}
if (setjmp(png_jmpbuf(PngPtr)))
{throw dexception("setjmp( ) failed.");}
//Read into structures
png_init_io(PngPtr, File);
png_set_sig_bytes(PngPtr, PNG::HeaderSize);
png_read_info(PngPtr, InfoPtr);
//Determine image attributes
vector2<png_uint_32> Res;
int BitDepth, ColourType;
png_get_IHDR(PngPtr, InfoPtr, &Res.U, &Res.V, &BitDepth, &ColourType, nullptr, nullptr, nullptr);
Texture::TexType Type = Texture::TypeRGB;
switch (ColourType)
{
case PNG_COLOR_TYPE_GRAY :
if (BitDepth < 8)
{
Type = Texture::TypeLum;
png_set_expand_gray_1_2_4_to_8(PngPtr);
}
else if (BitDepth == 16)
{
Type = Texture::TypeDepth;
}
break;
case PNG_COLOR_TYPE_GRAY_ALPHA :
Type = Texture::TypeRGBA;
png_set_gray_to_rgb(PngPtr);
break;
case PNG_COLOR_TYPE_PALETTE :
Type = Texture::TypeRGB;
png_set_palette_to_rgb(PngPtr);
break;
case PNG_COLOR_TYPE_RGB :
Type = Texture::TypeRGB;
png_set_strip_alpha(PngPtr); //If libpng reports RGB, make sure we completely strip alpha
break;
case PNG_COLOR_TYPE_RGB_ALPHA :
Type = Texture::TypeRGBA;
break;
default : throw dexception("Unknown colour type.");
}
//Convert palette alpha into a separate alpha channel
if (png_get_valid(PngPtr, InfoPtr, PNG_INFO_tRNS))
{
png_set_tRNS_to_alpha(PngPtr);
if (ColourType == PNG_COLOR_TYPE_PALETTE) {Type = Texture::TypeRGBA;}
}
//Force 8 bit per channel
if (BitDepth >= 16)
{
if (Type != Texture::TypeDepth) {png_set_strip_16(PngPtr);}
}
else if (BitDepth < 8)
{
png_set_packing(PngPtr);
}
//Specify display and file gamma (assume 0.45455 for missing file gamma)
double FileGamma;
if (!png_get_gAMA(PngPtr, InfoPtr, &FileGamma)) {FileGamma = 0.45455;}
png_set_gamma(PngPtr, Gamma, FileGamma);
//Swap byte order for int16 values on big endian machines
if ((BitDepth >= 16) && !Math::MachineLittleEndian())
{png_set_swap(PngPtr);}
//Apply the above transformation settings
png_read_update_info(PngPtr, InfoPtr);
//Allocate image
Image.Create(cast_vector2(uint, Res), Type);
if (Image.GetBytesPerLine() < (usize)png_get_rowbytes(PngPtr, InfoPtr))
{throw dexception("Incorrect scan line size for allocated image.");}
//Populate row pointer array
Rows.Create((usize)Res.V);
for (uiter I = 0; I < (usize)Res.V; I++)
{
Rows[I] = Image.Address(0, I);
}
//Decode
png_read_image(PngPtr, Rows.Pointer());
png_read_end(PngPtr, InfoPtr);
//Clean up
Destroy();
}
/*---------------------------------------------------------------------------
Saves a PNG file.
Image : Image to save.
Path : Path to image file, relative to the current working directory.
Compress : Specifies the compression level to use for encoding.
---------------------------------------------------------------------------*/
void PNG::Save(const Texture &Image, const std::string &Path, CompLevel Compress)
{
Destroy();
//Important - set class to writing mode
Mode = PNG::ModeWrite;
vector2u Res = Image.Resolution();
if (Res.U < 1 || Res.V < 1) {return;}
#if defined (WINDOWS)
if (fopen_s(&File, Path.c_str(), "wb") != 0)
{throw dexception("Failed to open file: %s.", Path.c_str());}
#else
File = fopen(Path.c_str(), "wb");
if (File == nullptr) {throw dexception("Failed to open file: %s.", Path.c_str());}
#endif
PngPtr = png_create_write_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
if (PngPtr == nullptr) {throw dexception("png_create_write_struct( ) failed.");}
InfoPtr = png_create_info_struct(PngPtr);
if (InfoPtr == nullptr) {throw dexception("png_create_info_struct( ) failed.");}
if (setjmp(png_jmpbuf(PngPtr)))
{throw dexception("setjmp( ) failed.");}
png_init_io(PngPtr, File);
png_set_compression_level(PngPtr, (int)Compress);
int BitDepth, ColourType;
switch (Image.DataType())
{
case Texture::TypeAlpha : BitDepth = 8; ColourType = PNG_COLOR_TYPE_GRAY; break;
case Texture::TypeLum : BitDepth = 8; ColourType = PNG_COLOR_TYPE_GRAY; break;
case Texture::TypeDepth : BitDepth = 16; ColourType = PNG_COLOR_TYPE_GRAY; break;
case Texture::TypeRGB : BitDepth = 8; ColourType = PNG_COLOR_TYPE_RGB; break;
case Texture::TypeRGBA : BitDepth = 8; ColourType = PNG_COLOR_TYPE_RGB_ALPHA; break;
default : throw dexception("Unsupported image type."); break;
}
png_set_IHDR(PngPtr, InfoPtr, (png_uint_32)Res.U, (png_uint_32)Res.V, BitDepth, ColourType, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
png_set_sRGB(PngPtr, InfoPtr, PNG_sRGB_INTENT_ABSOLUTE);
png_set_sRGB_gAMA_and_cHRM(PngPtr, InfoPtr, PNG_sRGB_INTENT_ABSOLUTE);
png_color_16 BackGnd;
BackGnd.red = 0;
BackGnd.green = 0;
BackGnd.blue = 0;
png_set_bKGD(PngPtr, InfoPtr, &BackGnd);
png_text PngText[2];
memset(PngText, 0, sizeof(PngText));
PngText[0].compression = PNG_TEXT_COMPRESSION_NONE;
PngText[0].key = const_cast<png_charp>("Software");
PngText[0].text = const_cast<png_charp>(AppName);
PngText[0].text_length = strlen(PngText[0].text);
PngText[1].compression = PNG_TEXT_COMPRESSION_NONE;
PngText[1].key = const_cast<png_charp>("Author");
PngText[1].text = const_cast<png_charp>(AppAuthor);
PngText[1].text_length = strlen(PngText[1].text);
png_set_text(PngPtr, InfoPtr, PngText, 2);
png_write_info(PngPtr, InfoPtr);
//Populate row pointer array
Rows.Create((usize)Res.V);
for (uiter I = 0; I < (usize)Res.V; I++)
{
Rows[I] = Image.Address(0, I);
}
//Encode
png_write_image(PngPtr, Rows.Pointer());
png_write_end(PngPtr, nullptr);
//Clean up
Destroy();
}
