#include <png.h>

// To remove a gcc warning

#ifdef _POSIX_C_SOURCE

#undef _POSIX_C_SOURCE

#endif

// TODO: Un CXX-ify this module

#include "CXX/Extensions.hxx"

#include "numpy/arrayobject.h"

#include "mplutils.h"

// the extension module

class _png_module : public Py::ExtensionModule<_png_module>

{

public:

_png_module()

: Py::ExtensionModule<_png_module>( "_png" )

{

add_varargs_method("write_png", &_png_module::write_png,

"write_png(buffer, width, height, fileobj, dpi=None)");

add_varargs_method("read_png", &_png_module::read_png,

"read_png(fileobj)");

initialize("Module to write PNG files");

}

virtual ~_png_module() {}

private:

Py::Object write_png(const Py::Tuple& args);

Py::Object read_png(const Py::Tuple& args);

};

static void write_png_data(png_structp png_ptr, png_bytep data, png_size_t length) {

PyObject* py_file_obj = (PyObject*)png_get_io_ptr(png_ptr);

PyObject* write_method = PyObject_GetAttrString(py_file_obj, "write");

PyObject* result = NULL;

if (write_method)

result = PyObject_CallFunction(write_method, (char *)"s#", data, length);

Py_XDECREF(write_method);

Py_XDECREF(result);

}

static void flush_png_data(png_structp png_ptr) {

PyObject* py_file_obj = (PyObject*)png_get_io_ptr(png_ptr);

PyObject* flush_method = PyObject_GetAttrString(py_file_obj, "flush");

PyObject* result = NULL;

if (flush_method)

result = PyObject_CallFunction(flush_method, (char *)"");

Py_XDECREF(flush_method);

Py_XDECREF(result);

}

// this code is heavily adapted from the paint license, which is in

// the file paint.license (BSD compatible) included in this

// distribution. TODO, add license file to MANIFEST.in and CVS

Py::Object _png_module::write_png(const Py::Tuple& args)

{

args.verify_length(4, 5);

FILE *fp = NULL;

bool close_file = false;

Py::Object buffer_obj = Py::Object(args[0]);

PyObject* buffer = buffer_obj.ptr();

if (!PyObject_CheckReadBuffer(buffer)) {

throw Py::TypeError("First argument must be an rgba buffer.");

}

const void* pixBufferPtr = NULL;

Py_ssize_t pixBufferLength = 0;

if (PyObject_AsReadBuffer(buffer, &pixBufferPtr, &pixBufferLength)) {

throw Py::ValueError("Couldn't get data from read buffer.");

}

png_byte* pixBuffer = (png_byte*)pixBufferPtr;

int width = (int)Py::Int(args[1]);

int height = (int)Py::Int(args[2]);

if (pixBufferLength < width * height * 4) {

throw Py::ValueError("Buffer and width, height don't seem to match.");

}

Py::Object py_fileobj = Py::Object(args[3]);

if (py_fileobj.isString()) {

std::string fileName = Py::String(py_fileobj);

const char *file_name = fileName.c_str();

if ((fp = fopen(file_name, "wb")) == NULL)

throw Py::RuntimeError( Printf("Could not open file %s", file_name).str() );

close_file = true;

} else if (PyFile_CheckExact(py_fileobj.ptr())) {

fp = PyFile_AsFile(py_fileobj.ptr());

}

else {

PyObject* write_method = PyObject_GetAttrString(py_fileobj.ptr(), "write");

if (!(write_method && PyCallable_Check(write_method))) {

Py_XDECREF(write_method);

throw Py::TypeError("Object does not appear to be a 8-bit string path or a Python file-like object");

}

Py_XDECREF(write_method);

}

png_bytep *row_pointers = NULL;

png_structp png_ptr = NULL;

png_infop info_ptr = NULL;

try {

struct png_color_8_struct sig_bit;

png_uint_32 row;

row_pointers = new png_bytep[height];

for (row = 0; row < (png_uint_32)height; ++row) {

row_pointers[row] = pixBuffer + row * width * 4;

}

png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);

if (png_ptr == NULL) {

throw Py::RuntimeError("Could not create write struct");

}

info_ptr = png_create_info_struct(png_ptr);

if (info_ptr == NULL) {

throw Py::RuntimeError("Could not create info struct");

}

if (setjmp(png_ptr->jmpbuf)) {

throw Py::RuntimeError("Error building image");

}

if (fp) {

png_init_io(png_ptr, fp);

} else {

png_set_write_fn(png_ptr, (void*)py_fileobj.ptr(),

&write_png_data, &flush_png_data);

}

png_set_IHDR(png_ptr, info_ptr,

width, height, 8,

PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,

PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);

// Save the dpi of the image in the file

if (args.size() == 5) {

double dpi = Py::Float(args[4]);

size_t dots_per_meter = (size_t)(dpi / (2.54 / 100.0));

png_set_pHYs(png_ptr, info_ptr, dots_per_meter, dots_per_meter, PNG_RESOLUTION_METER);

}

// this a a color image!

sig_bit.gray = 0;

sig_bit.red = 8;

sig_bit.green = 8;

sig_bit.blue = 8;

/* if the image has an alpha channel then */

sig_bit.alpha = 8;

png_set_sBIT(png_ptr, info_ptr, &sig_bit);

png_write_info(png_ptr, info_ptr);

png_write_image(png_ptr, row_pointers);

png_write_end(png_ptr, info_ptr);

} catch (...) {

if (fp && close_file) fclose(fp);

delete [] row_pointers;

/* Changed calls to png_destroy_write_struct to follow

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

This ensures the info_ptr memory is released.

*/

if (png_ptr && info_ptr) png_destroy_write_struct(&png_ptr, &info_ptr);

throw;

}

png_destroy_write_struct(&png_ptr, &info_ptr);

delete [] row_pointers;

if (fp && close_file) fclose(fp);

return Py::Object();

}

Py::Object

_png_module::read_png(const Py::Tuple& args) {

args.verify_length(1);

std::string fname = Py::String(args[0]);

png_byte header[8]; // 8 is the maximum size that can be checked

FILE *fp = fopen(fname.c_str(), "rb");

if (!fp)

throw Py::RuntimeError(Printf("_image_module::readpng could not open PNG file %s for reading", fname.c_str()).str());

if (fread(header, 1, 8, fp) != 8)

throw Py::RuntimeError("_image_module::readpng: error reading PNG header");

if (png_sig_cmp(header, 0, 8))

throw Py::RuntimeError("_image_module::readpng: file not recognized as a PNG file");

/* initialize stuff */

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

if (!png_ptr)

throw Py::RuntimeError("_image_module::readpng: png_create_read_struct failed");

png_infop info_ptr = png_create_info_struct(png_ptr);

if (!info_ptr)

throw Py::RuntimeError("_image_module::readpng: png_create_info_struct failed");

if (setjmp(png_jmpbuf(png_ptr)))

throw Py::RuntimeError("_image_module::readpng: error during init_io");

png_init_io(png_ptr, fp);

png_set_sig_bytes(png_ptr, 8);

png_read_info(png_ptr, info_ptr);

png_uint_32 width = info_ptr->width;

png_uint_32 height = info_ptr->height;

bool do_gray_conversion = (info_ptr->bit_depth < 8 &&

info_ptr->color_type == PNG_COLOR_TYPE_GRAY);

int bit_depth = info_ptr->bit_depth;

if (bit_depth == 16) {

png_set_strip_16(png_ptr);

} else if (bit_depth < 8) {

png_set_packing(png_ptr);

}

// convert misc color types to rgb for simplicity

if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY ||

info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {

png_set_gray_to_rgb(png_ptr);

} else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) {

png_set_palette_to_rgb(png_ptr);

}

png_set_interlace_handling(png_ptr);

png_read_update_info(png_ptr, info_ptr);

bool rgba = info_ptr->color_type == PNG_COLOR_TYPE_RGBA;

if ( (info_ptr->color_type != PNG_COLOR_TYPE_RGB) && !rgba) {

std::cerr << "Found color type " << (int)info_ptr->color_type << std::endl;

throw Py::RuntimeError("_image_module::readpng: cannot handle color_type");

}

/* read file */

if (setjmp(png_jmpbuf(png_ptr)))

throw Py::RuntimeError("_image_module::readpng: error during read_image");

png_bytep *row_pointers = new png_bytep[height];

png_uint_32 row;

for (row = 0; row < height; row++)

row_pointers[row] = new png_byte[png_get_rowbytes(png_ptr,info_ptr)];

png_read_image(png_ptr, row_pointers);

npy_intp dimensions[3];

dimensions[0] = height; //numrows

dimensions[1] = width; //numcols

dimensions[2] = 4;

PyArrayObject *A = (PyArrayObject *) PyArray_SimpleNew(3, dimensions, PyArray_FLOAT);

if (do_gray_conversion) {

float max_value = (float)((1L << bit_depth) - 1);

for (png_uint_32 y = 0; y < height; y++) {

png_byte* row = row_pointers[y];

for (png_uint_32 x = 0; x < width; x++) {

float value = row[x] / max_value;

size_t offset = y*A->strides[0] + x*A->strides[1];

*(float*)(A->data + offset + 0*A->strides[2]) = value;

*(float*)(A->data + offset + 1*A->strides[2]) = value;

*(float*)(A->data + offset + 2*A->strides[2]) = value;

*(float*)(A->data + offset + 3*A->strides[2]) = 1.0f;

}

}

} else {

for (png_uint_32 y = 0; y < height; y++) {

png_byte* row = row_pointers[y];

for (png_uint_32 x = 0; x < width; x++) {

png_byte* ptr = (rgba) ? &(row[x*4]) : &(row[x*3]);

size_t offset = y*A->strides[0] + x*A->strides[1];

*(float*)(A->data + offset + 0*A->strides[2]) = (float)(ptr[0]/255.0);

*(float*)(A->data + offset + 1*A->strides[2]) = (float)(ptr[1]/255.0);

*(float*)(A->data + offset + 2*A->strides[2]) = (float)(ptr[2]/255.0);

*(float*)(A->data + offset + 3*A->strides[2]) = rgba ? (float)(ptr[3]/255.0) : 1.0f;

}

}

}

//free the png memory

png_read_end(png_ptr, info_ptr);

png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL);

fclose(fp);

for (row = 0; row < height; row++)

delete [] row_pointers[row];

delete [] row_pointers;

return Py::asObject((PyObject*)A);

}

extern "C"

DL_EXPORT(void)

init_png(void)

{

import_array();

static _png_module* _png = NULL;

_png = new _png_module;

}