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svn path=/trunk/matplotlib/; revision=5472
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‎src/_png.cpp‎

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#include <png.h>
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// To remove a gcc warning
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#ifdef _POSIX_C_SOURCE
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#undef _POSIX_C_SOURCE
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#endif
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// TODO: Un CXX-ify this module
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#include "CXX/Extensions.hxx"
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#include "numpy/arrayobject.h"
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#include "mplutils.h"
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// the extension module
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class _png_module : public Py::ExtensionModule<_png_module>
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{
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public:
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_png_module()
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: Py::ExtensionModule<_png_module>( "_png" )
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{
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add_varargs_method("write_png", &_png_module::write_png,
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"write_png(buffer, width, height, fileobj, dpi=None)");
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add_varargs_method("read_png", &_png_module::write_png,
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"read_png(fileobj)");
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initialize("Module to write PNG files");
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}
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virtual ~_png_module() {}
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private:
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Py::Object write_png(const Py::Tuple& args);
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Py::Object read_png(const Py::Tuple& args);
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};
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static void write_png_data(png_structp png_ptr, png_bytep data, png_size_t length) {
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printf("%x %x %d %x\n", png_ptr, data, *data, length);
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PyObject* py_file_obj = (PyObject*)png_get_io_ptr(png_ptr);
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PyObject* write_method = PyObject_GetAttrString(py_file_obj, "write");
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PyObject* result = NULL;
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if (write_method)
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result = PyObject_CallFunction(write_method, (char *)"s#", data, length);
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Py_XDECREF(write_method);
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Py_XDECREF(result);
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}
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static void flush_png_data(png_structp png_ptr) {
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PyObject* py_file_obj = (PyObject*)png_get_io_ptr(png_ptr);
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PyObject* flush_method = PyObject_GetAttrString(py_file_obj, "flush");
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PyObject* result = NULL;
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if (flush_method)
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result = PyObject_CallFunction(flush_method, (char *)"");
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Py_XDECREF(flush_method);
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Py_XDECREF(result);
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}
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// this code is heavily adapted from the paint license, which is in
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// the file paint.license (BSD compatible) included in this
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// distribution. TODO, add license file to MANIFEST.in and CVS
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Py::Object _png_module::write_png(const Py::Tuple& args)
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{
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args.verify_length(4, 5);
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FILE *fp = NULL;
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bool close_file = false;
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Py::Object buffer_obj = Py::Object(args[0]);
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PyObject* buffer = buffer_obj.ptr();
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if (!PyObject_CheckReadBuffer(buffer)) {
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throw Py::TypeError("First argument must be an rgba buffer.");
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}
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const void* pixBufferPtr = NULL;
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Py_ssize_t pixBufferLength = 0;
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if (PyObject_AsReadBuffer(buffer, &pixBufferPtr, &pixBufferLength)) {
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throw Py::ValueError("Couldn't get data from read buffer.");
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}
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png_byte* pixBuffer = (png_byte*)pixBufferPtr;
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int width = (int)Py::Int(args[1]);
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int height = (int)Py::Int(args[2]);
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if (pixBufferLength < width * height * 4) {
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throw Py::ValueError("Buffer and width, height don't seem to match.");
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}
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Py::Object py_fileobj = Py::Object(args[3]);
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if (py_fileobj.isString()) {
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std::string fileName = Py::String(py_fileobj);
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const char *file_name = fileName.c_str();
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if ((fp = fopen(file_name, "wb")) == NULL)
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throw Py::RuntimeError( Printf("Could not open file %s", file_name).str() );
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close_file = true;
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} else if (PyFile_CheckExact(py_fileobj.ptr())) {
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fp = PyFile_AsFile(py_fileobj.ptr());
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}
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else {
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PyObject* write_method = PyObject_GetAttrString(py_fileobj.ptr(), "write");
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if (!(write_method && PyCallable_Check(write_method))) {
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Py_XDECREF(write_method);
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throw Py::TypeError("Object does not appear to be a 8-bit string path or a Python file-like object");
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}
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Py_XDECREF(write_method);
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}
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png_bytep *row_pointers = NULL;
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png_structp png_ptr = NULL;
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png_infop info_ptr = NULL;
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try {
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struct png_color_8_struct sig_bit;
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png_uint_32 row;
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row_pointers = new png_bytep[height];
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for (row = 0; row < (png_uint_32)height; ++row) {
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row_pointers[row] = pixBuffer + row * width * 4;
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}
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png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
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if (png_ptr == NULL) {
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throw Py::RuntimeError("Could not create write struct");
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}
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info_ptr = png_create_info_struct(png_ptr);
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if (info_ptr == NULL) {
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throw Py::RuntimeError("Could not create info struct");
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}
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if (setjmp(png_ptr->jmpbuf)) {
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throw Py::RuntimeError("Error building image");
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}
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if (fp) {
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png_init_io(png_ptr, fp);
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} else {
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png_set_write_fn(png_ptr, (void*)py_fileobj.ptr(),
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&write_png_data, &flush_png_data);
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}
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png_set_IHDR(png_ptr, info_ptr,
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width, height, 8,
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PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
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PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
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// Save the dpi of the image in the file
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if (args.size() == 5) {
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double dpi = Py::Float(args[4]);
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size_t dots_per_meter = (size_t)(dpi / (2.54 / 100.0));
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png_set_pHYs(png_ptr, info_ptr, dots_per_meter, dots_per_meter, PNG_RESOLUTION_METER);
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}
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// this a a color image!
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sig_bit.gray = 0;
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sig_bit.red = 8;
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sig_bit.green = 8;
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sig_bit.blue = 8;
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/* if the image has an alpha channel then */
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sig_bit.alpha = 8;
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png_set_sBIT(png_ptr, info_ptr, &sig_bit);
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png_write_info(png_ptr, info_ptr);
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png_write_image(png_ptr, row_pointers);
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png_write_end(png_ptr, info_ptr);
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} catch (...) {
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if (fp && close_file) fclose(fp);
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delete [] row_pointers;
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/* Changed calls to png_destroy_write_struct to follow
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http://www.libpng.org/pub/png/libpng-manual.txt.
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This ensures the info_ptr memory is released.
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*/
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if (png_ptr && info_ptr) png_destroy_write_struct(&png_ptr, &info_ptr);
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throw;
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}
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png_destroy_write_struct(&png_ptr, &info_ptr);
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delete [] row_pointers;
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if (fp && close_file) fclose(fp);
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return Py::Object();
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}
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Py::Object
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_png_module::read_png(const Py::Tuple& args) {
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args.verify_length(1);
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std::string fname = Py::String(args[0]);
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png_byte header[8]; // 8 is the maximum size that can be checked
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FILE *fp = fopen(fname.c_str(), "rb");
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if (!fp)
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throw Py::RuntimeError(Printf("_image_module::readpng could not open PNG file %s for reading", fname.c_str()).str());
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if (fread(header, 1, 8, fp) != 8)
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throw Py::RuntimeError("_image_module::readpng: error reading PNG header");
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if (png_sig_cmp(header, 0, 8))
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throw Py::RuntimeError("_image_module::readpng: file not recognized as a PNG file");
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/* initialize stuff */
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png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
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if (!png_ptr)
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throw Py::RuntimeError("_image_module::readpng: png_create_read_struct failed");
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png_infop info_ptr = png_create_info_struct(png_ptr);
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if (!info_ptr)
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throw Py::RuntimeError("_image_module::readpng: png_create_info_struct failed");
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if (setjmp(png_jmpbuf(png_ptr)))
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throw Py::RuntimeError("_image_module::readpng: error during init_io");
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png_init_io(png_ptr, fp);
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png_set_sig_bytes(png_ptr, 8);
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png_read_info(png_ptr, info_ptr);
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png_uint_32 width = info_ptr->width;
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png_uint_32 height = info_ptr->height;
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// convert misc color types to rgb for simplicity
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if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY ||
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info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
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png_set_gray_to_rgb(png_ptr);
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else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
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png_set_palette_to_rgb(png_ptr);
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int bit_depth = info_ptr->bit_depth;
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if (bit_depth == 16) png_set_strip_16(png_ptr);
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png_set_interlace_handling(png_ptr);
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png_read_update_info(png_ptr, info_ptr);
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bool rgba = info_ptr->color_type == PNG_COLOR_TYPE_RGBA;
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if ( (info_ptr->color_type != PNG_COLOR_TYPE_RGB) && !rgba) {
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std::cerr << "Found color type " << (int)info_ptr->color_type << std::endl;
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throw Py::RuntimeError("_image_module::readpng: cannot handle color_type");
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}
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/* read file */
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if (setjmp(png_jmpbuf(png_ptr)))
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throw Py::RuntimeError("_image_module::readpng: error during read_image");
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png_bytep *row_pointers = new png_bytep[height];
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png_uint_32 row;
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for (row = 0; row < height; row++)
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row_pointers[row] = new png_byte[png_get_rowbytes(png_ptr,info_ptr)];
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png_read_image(png_ptr, row_pointers);
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int dimensions[3];
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dimensions[0] = height; //numrows
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dimensions[1] = width; //numcols
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dimensions[2] = 4;
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PyArrayObject *A = (PyArrayObject *) PyArray_FromDims(3, dimensions, PyArray_FLOAT);
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for (png_uint_32 y = 0; y < height; y++) {
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png_byte* row = row_pointers[y];
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for (png_uint_32 x = 0; x < width; x++) {
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png_byte* ptr = (rgba) ? &(row[x*4]) : &(row[x*3]);
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size_t offset = y*A->strides[0] + x*A->strides[1];
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//if ((y<10)&&(x==10)) std::cout << "r = " << ptr[0] << " " << ptr[0]/255.0 << std::endl;
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*(float*)(A->data + offset + 0*A->strides[2]) = (float)(ptr[0]/255.0f);
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*(float*)(A->data + offset + 1*A->strides[2]) = (float)(ptr[1]/255.0f);
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*(float*)(A->data + offset + 2*A->strides[2]) = (float)(ptr[2]/255.0f);
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*(float*)(A->data + offset + 3*A->strides[2]) = rgba ? (float)(ptr[3]/255.0f) : 1.0f;
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}
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}
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//free the png memory
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png_read_end(png_ptr, info_ptr);
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png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL);
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fclose(fp);
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for (row = 0; row < height; row++)
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delete [] row_pointers[row];
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delete [] row_pointers;
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return Py::asObject((PyObject*)A);
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}
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extern "C"
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DL_EXPORT(void)
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init_png(void)
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{
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import_array();
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static _png_module* _png = NULL;
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_png = new _png_module;
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}

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