matplotlib/src/_png.cpp at master · staticfloat/matplotlib · GitHub

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/* -*- mode: c++; c-basic-offset: 4 -*- */

/* For linux, png.h must be imported before Python.h because

png.h needs to be the one to define setjmp.

Undefining _POSIX_C_SOURCE and _XOPEN_SOURCE stops a couple

of harmless warnings.

#ifdef __linux__

# include <png.h>

# ifdef _POSIX_C_SOURCE

# undef _POSIX_C_SOURCE

# endif

# ifdef _XOPEN_SOURCE

# undef _XOPEN_SOURCE

# endif

# include "Python.h"

#else

/* Python API mandates Python.h is included *first* */

# include "Python.h"

# include <png.h>

#endif

// TODO: Un CXX-ify this module

#include "CXX/Extensions.hxx"

#include "numpy/arrayobject.h"

#include "mplutils.h"

// As reported in [3082058] build _png.so on aix

#ifdef _AIX

#undef jmpbuf

#endif

// 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_float,

"read_png(fileobj)");

add_varargs_method("read_png_float", &_png_module::read_png_float,

"read_png_float(fileobj)");

add_varargs_method("read_png_uint8", &_png_module::read_png_uint8,

"read_png_uint8(fileobj)");

initialize("Module to write PNG files");

}

virtual ~_png_module() {}

private:

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

Py::Object read_png_uint8(const Py::Tuple& args);

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

PyObject* _read_png(const Py::Object& py_fileobj, const bool float_result);

};

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)

{

#if PY3K

result = PyObject_CallFunction(write_method, (char *)"y#", data,

length);

#else

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

length);

#endif

}

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 PY3K

int fd = PyObject_AsFileDescriptor(py_fileobj.ptr());

PyErr_Clear();

#endif

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;

}

#if PY3K

else if (fd != -1)

{

fp = fdopen(fd, "w");

}

#else

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

{

fp = PyFile_AsFile(py_fileobj.ptr());

}

#endif

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_jmpbuf(png_ptr)))

{

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 (png_ptr && info_ptr)

{

png_destroy_write_struct(&png_ptr, &info_ptr);

}

delete [] row_pointers;

if (fp && close_file)

{

fclose(fp);

}

/* 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.

throw;

}

png_destroy_write_struct(&png_ptr, &info_ptr);

delete [] row_pointers;

#if PY3K

if (fp)

{

fflush(fp);

}

#endif

if (fp && close_file)

{

fclose(fp);

}

if (PyErr_Occurred()) {

throw Py::Exception();

} else {

return Py::Object();

}

static void _read_png_data(PyObject* py_file_obj, png_bytep data, png_size_t length)

{

PyObject* read_method = PyObject_GetAttrString(py_file_obj, "read");

PyObject* result = NULL;

char *buffer;

Py_ssize_t bufflen;

if (read_method)

{

result = PyObject_CallFunction(read_method, (char *)"i", length);

}

if (PyBytes_AsStringAndSize(result, &buffer, &bufflen) == 0)

{

if (bufflen == (Py_ssize_t)length)

{

memcpy(data, buffer, length);

}

Py_XDECREF(read_method);

Py_XDECREF(result);

}

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

{

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

_read_png_data(py_file_obj, data, length);

}

PyObject*

_png_module::_read_png(const Py::Object& py_fileobj, const bool float_result)

{

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

FILE* fp = NULL;

bool close_file = false;

#if PY3K

int fd = PyObject_AsFileDescriptor(py_fileobj.ptr());

PyErr_Clear();

#endif

if (py_fileobj.isString())

{

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

const char *file_name = fileName.c_str();

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

{

throw Py::RuntimeError(

Printf("Could not open file %s for reading", file_name).str());

}

close_file = true;

}

#if PY3K

else if (fd != -1) {

fp = fdopen(fd, "r");

}

#else

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

{

fp = PyFile_AsFile(py_fileobj.ptr());

}

#endif

else

{

PyObject* read_method = PyObject_GetAttrString(py_fileobj.ptr(), "read");

if (!(read_method && PyCallable_Check(read_method)))

{

Py_XDECREF(read_method);

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

}

Py_XDECREF(read_method);

}

if (fp)

{

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

{

throw Py::RuntimeError(

"_image_module::readpng: error reading PNG header");

}

else

{

_read_png_data(py_fileobj.ptr(), header, 8);

}

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");

}

if (fp)

{

png_init_io(png_ptr, fp);

}

else

{

png_set_read_fn(png_ptr, (void*)py_fileobj.ptr(), &read_png_data);

}

png_set_sig_bytes(png_ptr, 8);

png_read_info(png_ptr, info_ptr);

png_uint_32 width = png_get_image_width(png_ptr, info_ptr);

png_uint_32 height = png_get_image_height(png_ptr, info_ptr);

int bit_depth = png_get_bit_depth(png_ptr, info_ptr);

// Unpack 1, 2, and 4-bit images

if (bit_depth < 8)

png_set_packing(png_ptr);

// If sig bits are set, shift data

png_color_8p sig_bit;

if ((png_get_color_type(png_ptr, info_ptr) != PNG_COLOR_TYPE_PALETTE) &&

png_get_sBIT(png_ptr, info_ptr, &sig_bit))

{

png_set_shift(png_ptr, sig_bit);

}

// Convert big endian to little

if (bit_depth == 16)

{

png_set_swap(png_ptr);

}

// Convert palletes to full RGB

if (png_get_color_type(png_ptr, info_ptr) == PNG_COLOR_TYPE_PALETTE)

{

png_set_palette_to_rgb(png_ptr);

}

// If there's an alpha channel convert gray to RGB

if (png_get_color_type(png_ptr, info_ptr) == PNG_COLOR_TYPE_GRAY_ALPHA)

{

png_set_gray_to_rgb(png_ptr);

}

png_set_interlace_handling(png_ptr);

png_read_update_info(png_ptr, info_ptr);

/* 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

if (png_get_color_type(png_ptr, info_ptr) & PNG_COLOR_MASK_ALPHA)

{

dimensions[2] = 4; //RGBA images

}

else if (png_get_color_type(png_ptr, info_ptr) & PNG_COLOR_MASK_COLOR)

{

dimensions[2] = 3; //RGB images

}

else

{

dimensions[2] = 1; //Greyscale images

}

//For gray, return an x by y array, not an x by y by 1

int num_dims = (png_get_color_type(png_ptr, info_ptr)

& PNG_COLOR_MASK_COLOR) ? 3 : 2;

PyArrayObject *A = NULL;

if (float_result) {

double max_value = (1 << bit_depth) - 1;

A = (PyArrayObject *) PyArray_SimpleNew(num_dims, dimensions, NPY_FLOAT);

if (A == NULL)

{

throw Py::MemoryError("Could not allocate image array");

}

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

{

png_byte* row = row_pointers[y];

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

{

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

if (bit_depth == 16)

{

png_uint_16* ptr = &reinterpret_cast<png_uint_16*>(row)[x * dimensions[2]];

for (png_uint_32 p = 0; p < (png_uint_32)dimensions[2]; p++)

{

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

}

else

{

png_byte* ptr = &(row[x * dimensions[2]]);

for (png_uint_32 p = 0; p < (png_uint_32)dimensions[2]; p++)

{

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

}

} else {

A = (PyArrayObject *) PyArray_SimpleNew(num_dims, dimensions, NPY_UBYTE);

if (A == NULL)

{

throw Py::MemoryError("Could not allocate image array");

}

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

{

png_byte* row = row_pointers[y];

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

{

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

if (bit_depth == 16)

{

png_uint_16* ptr = &reinterpret_cast<png_uint_16*>(row)[x * dimensions[2]];

for (png_uint_32 p = 0; p < (png_uint_32)dimensions[2]; p++)

{

*(png_byte*)(A->data + offset + p*A->strides[2]) = ptr[p] >> 8;

}

else

{

png_byte* ptr = &(row[x * dimensions[2]]);

for (png_uint_32 p = 0; p < (png_uint_32)dimensions[2]; p++)

{

*(png_byte*)(A->data + offset + p*A->strides[2]) = ptr[p];

}

//free the png memory

png_read_end(png_ptr, info_ptr);

#ifndef png_infopp_NULL

png_destroy_read_struct(&png_ptr, &info_ptr, NULL);

#else

png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL);

#endif

if (close_file)

{

fclose(fp);

}

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

{

delete [] row_pointers[row];

}

delete [] row_pointers;

if (PyErr_Occurred()) {

Py_DECREF((PyObject *)A);

return NULL;

} else {

return (PyObject *)A;

}

Py::Object

_png_module::read_png_float(const Py::Tuple& args)

{

args.verify_length(1);

return Py::asObject(_read_png(args[0], true));

}

Py::Object

_png_module::read_png_uint8(const Py::Tuple& args)

{

args.verify_length(1);

return Py::asObject(_read_png(args[0], false));

}

PyMODINIT_FUNC

#if PY3K

PyInit__png(void)

#else

init_png(void)

#endif

{

import_array();

static _png_module* _png = NULL;

_png = new _png_module;

#if PY3K

return _png->module().ptr();

#endif

}

matplotlib/src/_png.cpp at master · staticfloat/matplotlib · GitHub

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