Move Image::as_png() out to image_as_png().

[dcpomatic.git] / src / lib / image_png.cc

diff --git a/src/lib/image_png.cc b/src/lib/image_png.cc
new file mode 100644 (file)
index 0000000..b97ef5a
--- /dev/null
+++ b/src/lib/image_png.cc
@@ -0,0 +1,132 @@
+/*
+    Copyright (C) 2021 Carl Hetherington <cth@carlh.net>
+
+    This file is part of DCP-o-matic.
+
+    DCP-o-matic is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    DCP-o-matic is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+
+#include "dcpomatic_assert.h"
+#include "exceptions.h"
+#include "image.h"
+#include <png.h>
+
+#include "i18n.h"
+
+
+using std::shared_ptr;
+
+
+class Memory
+{
+public:
+       Memory () {}
+       Memory (Memory const&) = delete;
+       Memory& operator= (Memory const&) = delete;
+
+       ~Memory ()
+       {
+               free (data);
+       }
+
+       uint8_t* data = nullptr;
+       size_t size = 0;
+};
+
+
+static void
+png_write_data (png_structp png_ptr, png_bytep data, png_size_t length)
+{
+       auto mem = reinterpret_cast<Memory*>(png_get_io_ptr(png_ptr));
+       size_t size = mem->size + length;
+
+       if (mem->data) {
+               mem->data = reinterpret_cast<uint8_t*>(realloc(mem->data, size));
+       } else {
+               mem->data = reinterpret_cast<uint8_t*>(malloc(size));
+       }
+
+       if (!mem->data) {
+               throw EncodeError (N_("could not allocate memory for PNG"));
+       }
+
+       memcpy (mem->data + mem->size, data, length);
+       mem->size += length;
+}
+
+
+static void
+png_flush (png_structp)
+{
+
+}
+
+
+static void
+png_error_fn (png_structp, char const * message)
+{
+       throw EncodeError (String::compose("Error during PNG write: %1", message));
+}
+
+
+dcp::ArrayData
+image_as_png (shared_ptr<const Image> image)
+{
+       DCPOMATIC_ASSERT (image->bytes_per_pixel(0) == 4);
+       DCPOMATIC_ASSERT (image->planes() == 1);
+       if (image->pixel_format() != AV_PIX_FMT_RGBA) {
+               return image_as_png(image->convert_pixel_format(dcp::YUVToRGB::REC709, AV_PIX_FMT_RGBA, Image::Alignment::PADDED, false));
+       }
+
+       /* error handling? */
+       auto png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, reinterpret_cast<void*>(const_cast<Image*>(image.get())), png_error_fn, 0);
+       if (!png_ptr) {
+               throw EncodeError (N_("could not create PNG write struct"));
+       }
+
+       Memory state;
+
+       png_set_write_fn (png_ptr, &state, png_write_data, png_flush);
+
+       auto info_ptr = png_create_info_struct(png_ptr);
+       if (!info_ptr) {
+               png_destroy_write_struct (&png_ptr, &info_ptr);
+               throw EncodeError (N_("could not create PNG info struct"));
+       }
+
+       int const width = image->size().width;
+       int const height = image->size().height;
+
+       png_set_IHDR (png_ptr, info_ptr, width, height, 8, PNG_COLOR_TYPE_RGBA, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+
+       auto row_pointers = reinterpret_cast<png_byte **>(png_malloc(png_ptr, image->size().height * sizeof(png_byte *)));
+       auto const data = image->data()[0];
+       auto const stride = image->stride()[0];
+       for (int i = 0; i < height; ++i) {
+               row_pointers[i] = reinterpret_cast<png_byte *>(data + i * stride);
+       }
+
+       png_write_info (png_ptr, info_ptr);
+       png_write_image (png_ptr, row_pointers);
+       png_write_end (png_ptr, info_ptr);
+
+       png_destroy_write_struct (&png_ptr, &info_ptr);
+       png_free (png_ptr, row_pointers);
+
+       return dcp::ArrayData (state.data, state.size);
+}
+
+