Module: Axon::PNG

Defined in:
ext/axon/png.c

Defined Under Namespace

Classes: Reader

Class Method Summary collapse

Class Method Details

.write(image_in, io_out) ⇒ Integer

Writes the given image image_in to io_out as compressed PNG data. Returns the number of bytes written.

image = Axon::Solid.new(200, 300)
io = File.open("test.jpg", "w")
Axon::PNG.write(image, io)     #=> 1234

Returns:

  • (Integer) 


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# File 'ext/axon/png.c', line 178

static VALUE
write_png(VALUE self, VALUE image_in, VALUE io_out)
{
    VALUE ensure_args[3];
    png_structp png_ptr;
    png_infop info_ptr;
    struct io_write data;

    png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, (png_voidp)NULL,
              (png_error_ptr)png_error_fn,
              (png_error_ptr)png_warning_fn);

    if (png_ptr == NULL)
  rb_raise(rb_eRuntimeError, "unable to allocate a png object");

    info_ptr = png_create_info_struct(png_ptr);
    if (info_ptr == NULL) {
  png_destroy_write_struct(&png_ptr, (png_info **)NULL);
  rb_raise(rb_eRuntimeError, "unable to allocate a png info object");
    }

    data.io = io_out;
    data.total = 0;
    png_set_write_fn(png_ptr, (void *)&data, write_data, flush_data);

    ensure_args[0] = (VALUE)png_ptr;
    ensure_args[1] = (VALUE)info_ptr;
    ensure_args[2] = image_in;

    return rb_ensure(write_png2, (VALUE)ensure_args, write_png2_ensure,
                     (VALUE)ensure_args);
}