Refactor PNG writing

1 files changed, 75 insertions, 0 deletions

diff --git a/src/PNG.cpp b/src/PNG.cpp
new file mode 100644
index 0000000..1e25712
--- /dev/null
+++ b/src/PNG.cpp
@@ -0,0 +1,75 @@
+/*
+  Copyright (c) 2015, Matthias Schiffer <mschiffer@universe-factory.net>
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions are met:
+
+    1. Redistributions of source code must retain the above copyright notice,
+       this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above copyright notice,
+       this list of conditions and the following disclaimer in the documentation
+       and/or other materials provided with the distribution.
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+
+#include "PNG.hpp"
+
+#include <cerrno>
+#include <cstdio>
+#include <system_error>
+
+#include <png.h>
+
+
+namespace MinedMap {
+
+void writePNG(const char *filename, const uint32_t *data, size_t width, size_t height) {
+	std::FILE *f = std::fopen(filename, "wb");
+	if (!f)
+		throw std::system_error(errno, std::generic_category(), "unable to open output file");
+
+	png_structp png_ptr = png_create_write_struct (PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
+	if (!png_ptr)
+		throw std::runtime_error("unable to create PNG write struct");
+
+	png_infop info_ptr = png_create_info_struct(png_ptr);
+	if (!info_ptr) {
+		png_destroy_write_struct(&png_ptr, nullptr);
+		throw std::runtime_error("unable to create PNG info struct");
+	}
+
+	if (setjmp(png_jmpbuf(png_ptr))) {
+		png_destroy_write_struct(&png_ptr, &info_ptr);
+		std::fclose(f);
+		throw std::runtime_error("unable to write PNG file");
+	}
+
+	png_init_io(png_ptr, f);
+
+	png_set_IHDR(png_ptr, info_ptr, width, height, 8, PNG_COLOR_TYPE_RGB_ALPHA,
+		     PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+
+	uint8_t *row_pointers[height];
+	for (size_t i = 0; i < height; i++)
+		row_pointers[i] = const_cast<uint8_t*>(reinterpret_cast<const uint8_t*>(&data[i*width]));
+
+	png_set_rows(png_ptr, info_ptr, row_pointers);
+	png_write_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL);
+
+	png_destroy_write_struct(&png_ptr, &info_ptr);
+	std::fclose(f);
+}
+
+}