/*

* Copyright 2019-2024 Diligent Graphics LLC

* Copyright 2015-2019 Egor Yusov

*

* Licensed under the Apache License, Version 2.0 (the "License");

* you may not use this file except in compliance with the License.

* You may obtain a copy of the License at

*

* http://www.apache.org/licenses/LICENSE-2.0

*

* Unless required by applicable law or agreed to in writing, software

* distributed under the License is distributed on an "AS IS" BASIS,

* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

* See the License for the specific language governing permissions and

* limitations under the License.

*

* In no event and under no legal theory, whether in tort (including negligence),

* contract, or otherwise, unless required by applicable law (such as deliberate

* and grossly negligent acts) or agreed to in writing, shall any Contributor be

* liable for any damages, including any direct, indirect, special, incidental,

* or consequential damages of any character arising as a result of this License or

* out of the use or inability to use the software (including but not limited to damages

* for loss of goodwill, work stoppage, computer failure or malfunction, or any and

* all other commercial damages or losses), even if such Contributor has been advised

* of the possibility of such damages.

*/

#include <stdlib.h>

#include <string.h>

#include "png.h"

#include "GraphicsTypes.h"

#include "PNGCodec.h"

struct PNGReadFnState

{

const IDataBlob* pPngBits;

size_t Offset;

};

typedef struct PNGReadFnState PNGReadFnState;

static void PngReadCallback(png_structp pngPtr, png_bytep data, png_size_t length)

{

PNGReadFnState* pState = (PNGReadFnState*)(png_get_io_ptr(pngPtr));

const void* pSrcPtr = (const char*)pState->pPngBits + pState->Offset;

memcpy(data, pSrcPtr, length);

pState->Offset += length;

}

DECODE_PNG_RESULT Diligent_DecodePng(const void* pSrcPngBits,

size_t PngDataSize,

IDataBlob* pDstPixels,

ImageDesc* pDstImgDesc)

{

if (!pSrcPngBits || !pDstImgDesc)

return DECODE_PNG_RESULT_INVALID_ARGUMENTS;

// http://www.piko3d.net/tutorials/libpng-tutorial-loading-png-files-from-streams/

// http://www.libpng.org/pub/png/book/chapter13.html#png.ch13.div.10

// https://gist.github.com/niw/5963798

const size_t PngSigSize = 8;

png_const_bytep pngsig = (png_const_bytep)pSrcPngBits;

//Let LibPNG check the signature. If this function returns 0, everything is OK.

if (png_sig_cmp(pngsig, 0, PngSigSize) != 0)

{

return DECODE_PNG_RESULT_INVALID_SIGNATURE;

}

png_structp png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);

if (!png)

{

return DECODE_PNG_RESULT_INITIALIZATION_FAILED;

}

png_infop info = png_create_info_struct(png);

if (!info)

{

png_destroy_read_struct(&png, &info, (png_infopp)0);

return DECODE_PNG_RESULT_INITIALIZATION_FAILED;

}

png_bytep* rowPtrs = NULL;

if (setjmp(png_jmpbuf(png)))

{

if (rowPtrs)

free(rowPtrs);

// When an error occurs during parsing, libPNG will jump to here

png_destroy_read_struct(&png, &info, (png_infopp)0);

return DECODE_PNG_RESULT_DECODING_ERROR;

}

PNGReadFnState ReadState;

ReadState.pPngBits = pSrcPngBits;

ReadState.Offset = 0;

png_set_read_fn(png, (png_voidp)&ReadState, PngReadCallback);

png_read_info(png, info);

png_byte bit_depth = png_get_bit_depth(png, info);

// PNG files store 16-bit pixels in network byte order (big-endian, ie

// most significant bytes first). png_set_swap() shall switch the byte-order

// to little-endian (ie, least significant bits first).

if (bit_depth == 16)

png_set_swap(png);

png_byte color_type = png_get_color_type(png, info);

// See http://www.libpng.org/pub/png/libpng-manual.txt

if (color_type == PNG_COLOR_TYPE_PALETTE)

{

// Transform paletted images into 8-bit rgba

png_set_palette_to_rgb(png);

png_set_filler(png, 0xFF, PNG_FILLER_AFTER);

}

// PNG_COLOR_TYPE_GRAY_ALPHA is always 8 or 16bit depth.

if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)

{

// Expand 1, 2, or 4-bit images to 8-bit

png_set_expand_gray_1_2_4_to_8(png);

}

if (png_get_valid(png, info, PNG_INFO_tRNS))

png_set_tRNS_to_alpha(png);

#if 0

// These color_type don't have an alpha channel then fill it with 0xff.

if( color_type == PNG_COLOR_TYPE_RGB ||

color_type == PNG_COLOR_TYPE_GRAY ||

color_type == PNG_COLOR_TYPE_PALETTE )

png_set_filler( png, 0xFF, PNG_FILLER_AFTER );

if( color_type == PNG_COLOR_TYPE_GRAY ||

color_type == PNG_COLOR_TYPE_GRAY_ALPHA )

png_set_gray_to_rgb( png );

#endif

if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA)

png_set_gray_to_rgb(png);

png_read_update_info(png, info);

bit_depth = png_get_bit_depth(png, info);

pDstImgDesc->Width = png_get_image_width(png, info);

pDstImgDesc->Height = png_get_image_height(png, info);

pDstImgDesc->NumComponents = png_get_channels(png, info);

switch (bit_depth)

{

case 8: pDstImgDesc->ComponentType = VT_UINT8; break;

case 16: pDstImgDesc->ComponentType = VT_UINT16; break;

case 32: pDstImgDesc->ComponentType = VT_UINT32; break;

default:

{

png_destroy_read_struct(&png, &info, (png_infopp)0);

return DECODE_PNG_RESULT_INVALID_BIT_DEPTH;

}

}

if (pDstPixels != NULL)

{

//Array of row pointers. One for every row.

rowPtrs = malloc(sizeof(png_bytep) * pDstImgDesc->Height);

//Allocate a buffer with enough space.

pDstImgDesc->RowStride = pDstImgDesc->Width * (Uint32)bit_depth * pDstImgDesc->NumComponents / 8u;

// Align stride to 4 bytes

pDstImgDesc->RowStride = (pDstImgDesc->RowStride + 3u) & ~3u;

IDataBlob_Resize(pDstPixels, pDstImgDesc->Height * (size_t)pDstImgDesc->RowStride);

png_bytep pRow0 = IDataBlob_GetDataPtr(pDstPixels, 0);

for (size_t i = 0; i < pDstImgDesc->Height; i++)

rowPtrs[i] = pRow0 + i * pDstImgDesc->RowStride;

//Read the imagedata and write it to the addresses pointed to

//by rowptrs (in other words: our image databuffer)

png_read_image(png, rowPtrs);

free(rowPtrs);

}

png_destroy_read_struct(&png, &info, (png_infopp)0);

return DECODE_PNG_RESULT_OK;

}

static void PngWriteCallback(png_structp png_ptr, png_bytep data, png_size_t length)

{

IDataBlob* pEncodedData = (IDataBlob*)png_get_io_ptr(png_ptr);

size_t PrevSize = IDataBlob_GetSize(pEncodedData);

IDataBlob_Resize(pEncodedData, PrevSize + length);

Uint8* pBytes = (Uint8*)IDataBlob_GetDataPtr(pEncodedData, 0);

memcpy(pBytes + PrevSize, data, length);

}

ENCODE_PNG_RESULT Diligent_EncodePng(const Uint8* pSrcPixels,

Uint32 Width,

Uint32 Height,

Uint32 StrideInBytes,

int PngColorType,

IDataBlob* pDstPngBits)

{

if (!pSrcPixels || !pDstPngBits || Width == 0 || Height == 0 || StrideInBytes == 0)

return ENCODE_PNG_RESULT_INVALID_ARGUMENTS;

png_struct* strct = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);

if (!strct)

{

return ENCODE_PNG_RESULT_INITIALIZATION_FAILED;

}

png_info* info = png_create_info_struct(strct);

if (!info)

{

png_destroy_write_struct(&strct, &info);

return ENCODE_PNG_RESULT_INITIALIZATION_FAILED;

}

png_bytep* rowPtrs = NULL;

if (setjmp(png_jmpbuf(strct)) != 0)

{

if (rowPtrs)

free(rowPtrs);

png_destroy_write_struct(&strct, &info);

return ENCODE_PNG_RESULT_INITIALIZATION_FAILED;

}

png_set_IHDR(strct, info, Width, Height, 8,

PngColorType,

PNG_INTERLACE_NONE,

PNG_COMPRESSION_TYPE_DEFAULT,

PNG_FILTER_TYPE_DEFAULT);

//png_set_compression_level(p, 1);

rowPtrs = malloc(sizeof(png_bytep) * Height);

for (size_t y = 0; y < Height; ++y)

rowPtrs[y] = (Uint8*)pSrcPixels + y * StrideInBytes;

png_set_rows(strct, info, rowPtrs);

png_set_write_fn(strct, pDstPngBits, PngWriteCallback, NULL);

png_write_png(strct, info, PNG_TRANSFORM_IDENTITY, NULL);

free(rowPtrs);

png_destroy_write_struct(&strct, &info);

return ENCODE_PNG_RESULT_OK;

}