Merge pull request #29874 from ibrahn/rework-png-loadsave

PNG driver reworked to use libpng 1.6 simplified API

5 files changed, 306 insertions, 448 deletions

diff --git a/drivers/png/image_loader_png.cpp b/drivers/png/image_loader_png.cpp
index 0bf432c78a..f257fafd93 100644
--- a/drivers/png/image_loader_png.cpp
+++ b/drivers/png/image_loader_png.cpp
@@ -32,186 +32,26 @@
 
 #include "core/os/os.h"
 #include "core/print_string.h"
+#include "drivers/png/png_driver_common.h"
 
 #include <string.h>
 
-void ImageLoaderPNG::_read_png_data(png_structp png_ptr, png_bytep data, png_size_t p_length) {
-
-	FileAccess *f = (FileAccess *)png_get_io_ptr(png_ptr);
-	f->get_buffer((uint8_t *)data, p_length);
-}
-
-/*
-png_structp png_ptr = png_create_read_struct_2
-    (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
-     user_error_fn, user_warning_fn, (png_voidp)
-     user_mem_ptr, user_malloc_fn, user_free_fn);
-*/
-static png_voidp _png_malloc_fn(png_structp png_ptr, png_size_t size) {
-
-	return memalloc(size);
-}
-
-static void _png_free_fn(png_structp png_ptr, png_voidp ptr) {
-
-	memfree(ptr);
-}
-
-static void _png_error_function(png_structp, png_const_charp text) {
-
-	ERR_PRINT(text);
-}
-
-static void _png_warn_function(png_structp, png_const_charp text) {
-#ifdef TOOLS_ENABLED
-	if (Engine::get_singleton()->is_editor_hint()) {
-		if (String(text).begins_with("iCCP")) return; // silences annoying spam emitted to output every time the user opened assetlib
-	}
-#endif
-	WARN_PRINT(text);
-}
-
-typedef void(PNGAPI *png_error_ptr) PNGARG((png_structp, png_const_charp));
-
-Error ImageLoaderPNG::_load_image(void *rf_up, png_rw_ptr p_func, Ref<Image> p_image) {
-
-	png_structp png;
-	png_infop info;
-
-	//png = png_create_read_struct(PNG_LIBPNG_VER_STRING, (png_voidp)NULL, NULL, NULL);
-
-	png = png_create_read_struct_2(PNG_LIBPNG_VER_STRING, (png_voidp)NULL, _png_error_function, _png_warn_function, (png_voidp)NULL,
-			_png_malloc_fn, _png_free_fn);
-
-	ERR_FAIL_COND_V(!png, ERR_OUT_OF_MEMORY);
-
-	info = png_create_info_struct(png);
-	if (!info) {
-		png_destroy_read_struct(&png, NULL, NULL);
-		ERR_PRINT("Out of Memory");
-		return ERR_OUT_OF_MEMORY;
-	}
-
-	if (setjmp(png_jmpbuf(png))) {
-
-		png_destroy_read_struct(&png, NULL, NULL);
-		ERR_PRINT("PNG Corrupted");
-		return ERR_FILE_CORRUPT;
-	}
-
-	png_set_read_fn(png, (void *)rf_up, p_func);
-
-	png_uint_32 width, height;
-	int depth, color;
-
-	png_read_info(png, info);
-	png_get_IHDR(png, info, &width, &height, &depth, &color, NULL, NULL, NULL);
-
-	//https://svn.gov.pt/projects/ccidadao/repository/middleware-offline/trunk/_src/eidmw/FreeImagePTEiD/Source/FreeImage/PluginPNG.cpp
-	//png_get_text(png,info,)
-	/*
-	printf("Image width:%i\n", width);
-	printf("Image Height:%i\n", height);
-	printf("Bit depth:%i\n", depth);
-	printf("Color type:%i\n", color);
-	*/
-
-	bool update_info = false;
-
-	if (depth < 8) { //only bit dept 8 per channel is handled
-
-		png_set_packing(png);
-		update_info = true;
-	};
-
-	if (png_get_color_type(png, info) == PNG_COLOR_TYPE_PALETTE) {
-		png_set_palette_to_rgb(png);
-		update_info = true;
-	}
-
-	if (depth > 8) {
-		png_set_strip_16(png);
-		update_info = true;
-	}
-
-	if (png_get_valid(png, info, PNG_INFO_tRNS)) {
-		//png_set_expand_gray_1_2_4_to_8(png);
-		png_set_tRNS_to_alpha(png);
-		update_info = true;
-	}
-
-	if (update_info) {
-		png_read_update_info(png, info);
-		png_get_IHDR(png, info, &width, &height, &depth, &color, NULL, NULL, NULL);
-	}
-
-	int components = 0;
-
-	Image::Format fmt;
-	switch (color) {
-
-		case PNG_COLOR_TYPE_GRAY: {
-
-			fmt = Image::FORMAT_L8;
-			components = 1;
-		} break;
-		case PNG_COLOR_TYPE_GRAY_ALPHA: {
-
-			fmt = Image::FORMAT_LA8;
-			components = 2;
-		} break;
-		case PNG_COLOR_TYPE_RGB: {
-
-			fmt = Image::FORMAT_RGB8;
-			components = 3;
-		} break;
-		case PNG_COLOR_TYPE_RGB_ALPHA: {
-
-			fmt = Image::FORMAT_RGBA8;
-			components = 4;
-		} break;
-		default: {
+Error ImageLoaderPNG::load_image(Ref<Image> p_image, FileAccess *f, bool p_force_linear, float p_scale) {
 
-			ERR_PRINT("INVALID PNG TYPE");
-			png_destroy_read_struct(&png, &info, NULL);
-			return ERR_UNAVAILABLE;
-		} break;
+	const size_t buffer_size = f->get_len();
+	PoolVector<uint8_t> file_buffer;
+	Error err = file_buffer.resize(buffer_size);
+	if (err) {
+		f->close();
+		return err;
 	}
-
-	//int rowsize = png_get_rowbytes(png, info);
-	int rowsize = components * width;
-
-	PoolVector<uint8_t> dstbuff;
-
-	dstbuff.resize(rowsize * height);
-
-	PoolVector<uint8_t>::Write dstbuff_write = dstbuff.write();
-
-	uint8_t *data = dstbuff_write.ptr();
-
-	uint8_t **row_p = memnew_arr(uint8_t *, height);
-
-	for (unsigned int i = 0; i < height; i++) {
-		row_p[i] = &data[components * width * i];
+	{
+		PoolVector<uint8_t>::Write writer = file_buffer.write();
+		f->get_buffer(writer.ptr(), buffer_size);
+		f->close();
 	}
-
-	png_read_image(png, (png_bytep *)row_p);
-
-	memdelete_arr(row_p);
-
-	p_image->create(width, height, 0, fmt, dstbuff);
-
-	png_destroy_read_struct(&png, &info, NULL);
-
-	return OK;
-}
-
-Error ImageLoaderPNG::load_image(Ref<Image> p_image, FileAccess *f, bool p_force_linear, float p_scale) {
-
-	Error err = _load_image(f, _read_png_data, p_image);
-	f->close();
-
-	return err;
+	PoolVector<uint8_t>::Read reader = file_buffer.read();
+	return PNGDriverCommon::png_to_image(reader.ptr(), buffer_size, p_image);
 }
 
 void ImageLoaderPNG::get_recognized_extensions(List<String> *p_extensions) const {
@@ -219,178 +59,53 @@ void ImageLoaderPNG::get_recognized_extensions(List<String> *p_extensions) const
 	p_extensions->push_back("png");
 }
 
-struct PNGReadStatus {
-
-	uint32_t offset;
-	uint32_t size;
-	const unsigned char *image;
-};
-
-static void user_read_data(png_structp png_ptr, png_bytep data, png_size_t p_length) {
-
-	PNGReadStatus *rstatus;
-	rstatus = (PNGReadStatus *)png_get_io_ptr(png_ptr);
-
-	png_size_t to_read = MIN(p_length, rstatus->size - rstatus->offset);
-	memcpy(data, &rstatus->image[rstatus->offset], to_read);
-	rstatus->offset += to_read;
-
-	if (to_read < p_length) {
-		memset(&data[to_read], 0, p_length - to_read);
-	}
-}
-
-static Ref<Image> _load_mem_png(const uint8_t *p_png, int p_size) {
-
-	PNGReadStatus prs;
-	prs.image = p_png;
-	prs.offset = 0;
-	prs.size = p_size;
+Ref<Image> ImageLoaderPNG::load_mem_png(const uint8_t *p_png, int p_size) {
 
 	Ref<Image> img;
 	img.instance();
-	Error err = ImageLoaderPNG::_load_image(&prs, user_read_data, img);
+
+	Error err = PNGDriverCommon::png_to_image(p_png, p_size, img);
 	ERR_FAIL_COND_V(err, Ref<Image>());
 
 	return img;
 }
 
-static Ref<Image> _lossless_unpack_png(const PoolVector<uint8_t> &p_data) {
+Ref<Image> ImageLoaderPNG::lossless_unpack_png(const PoolVector<uint8_t> &p_data) {
 
-	int len = p_data.size();
+	const int len = p_data.size();
 	ERR_FAIL_COND_V(len < 4, Ref<Image>());
 	PoolVector<uint8_t>::Read r = p_data.read();
 	ERR_FAIL_COND_V(r[0] != 'P' || r[1] != 'N' || r[2] != 'G' || r[3] != ' ', Ref<Image>());
-	return _load_mem_png(&r[4], len - 4);
-}
-
-static void _write_png_data(png_structp png_ptr, png_bytep data, png_size_t p_length) {
-
-	PoolVector<uint8_t> &v = *(PoolVector<uint8_t> *)png_get_io_ptr(png_ptr);
-	int vs = v.size();
-
-	v.resize(vs + p_length);
-	PoolVector<uint8_t>::Write w = v.write();
-	copymem(&w[vs], data, p_length);
+	return load_mem_png(&r[4], len - 4);
 }
 
-static PoolVector<uint8_t> _lossless_pack_png(const Ref<Image> &p_image) {
-
-	Ref<Image> img = p_image->duplicate();
-
-	if (img->is_compressed())
-		img->decompress();
-
-	ERR_FAIL_COND_V(img->is_compressed(), PoolVector<uint8_t>());
-
-	png_structp png_ptr;
-	png_infop info_ptr;
-	png_bytep *row_pointers;
-
-	/* initialize stuff */
-	png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+PoolVector<uint8_t> ImageLoaderPNG::lossless_pack_png(const Ref<Image> &p_image) {
 
-	ERR_FAIL_COND_V(!png_ptr, PoolVector<uint8_t>());
+	PoolVector<uint8_t> out_buffer;
 
-	info_ptr = png_create_info_struct(png_ptr);
-
-	ERR_FAIL_COND_V(!info_ptr, PoolVector<uint8_t>());
-
-	if (setjmp(png_jmpbuf(png_ptr))) {
+	// add Godot's own "PNG " prefix
+	if (out_buffer.resize(4) != OK) {
 		ERR_FAIL_V(PoolVector<uint8_t>());
 	}
-	PoolVector<uint8_t> ret;
-	ret.push_back('P');
-	ret.push_back('N');
-	ret.push_back('G');
-	ret.push_back(' ');
 
-	png_set_write_fn(png_ptr, &ret, _write_png_data, NULL);
-
-	/* write header */
-	if (setjmp(png_jmpbuf(png_ptr))) {
-		ERR_FAIL_V(PoolVector<uint8_t>());
+	// scope for writer lifetime
+	{
+		// must be closed before call to image_to_png
+		PoolVector<uint8_t>::Write writer = out_buffer.write();
+		copymem(writer.ptr(), "PNG ", 4);
 	}
 
-	int pngf = 0;
-	int cs = 0;
-
-	switch (img->get_format()) {
-
-		case Image::FORMAT_L8: {
-
-			pngf = PNG_COLOR_TYPE_GRAY;
-			cs = 1;
-		} break;
-		case Image::FORMAT_LA8: {
-
-			pngf = PNG_COLOR_TYPE_GRAY_ALPHA;
-			cs = 2;
-		} break;
-		case Image::FORMAT_RGB8: {
-
-			pngf = PNG_COLOR_TYPE_RGB;
-			cs = 3;
-		} break;
-		case Image::FORMAT_RGBA8: {
-
-			pngf = PNG_COLOR_TYPE_RGB_ALPHA;
-			cs = 4;
-		} break;
-		default: {
-
-			if (img->detect_alpha()) {
-
-				img->convert(Image::FORMAT_RGBA8);
-				pngf = PNG_COLOR_TYPE_RGB_ALPHA;
-				cs = 4;
-			} else {
-
-				img->convert(Image::FORMAT_RGB8);
-				pngf = PNG_COLOR_TYPE_RGB;
-				cs = 3;
-			}
-		}
-	}
-
-	int w = img->get_width();
-	int h = img->get_height();
-	png_set_IHDR(png_ptr, info_ptr, w, h,
-			8, pngf, PNG_INTERLACE_NONE,
-			PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
-
-	png_write_info(png_ptr, info_ptr);
-
-	/* write bytes */
-	if (setjmp(png_jmpbuf(png_ptr))) {
+	Error err = PNGDriverCommon::image_to_png(p_image, out_buffer);
+	if (err) {
 		ERR_FAIL_V(PoolVector<uint8_t>());
 	}
 
-	PoolVector<uint8_t>::Read r = img->get_data().read();
-
-	row_pointers = (png_bytep *)memalloc(sizeof(png_bytep) * h);
-	for (int i = 0; i < h; i++) {
-
-		row_pointers[i] = (png_bytep)&r[i * w * cs];
-	}
-	png_write_image(png_ptr, row_pointers);
-
-	memfree(row_pointers);
-
-	/* end write */
-	if (setjmp(png_jmpbuf(png_ptr))) {
-
-		ERR_FAIL_V(PoolVector<uint8_t>());
-	}
-
-	png_write_end(png_ptr, NULL);
-
-	return ret;
+	return out_buffer;
 }
 
 ImageLoaderPNG::ImageLoaderPNG() {
 
-	Image::_png_mem_loader_func = _load_mem_png;
-	Image::lossless_unpacker = _lossless_unpack_png;
-	Image::lossless_packer = _lossless_pack_png;
+	Image::_png_mem_loader_func = load_mem_png;
+	Image::lossless_unpacker = lossless_unpack_png;
+	Image::lossless_packer = lossless_pack_png;
 }
diff --git a/drivers/png/image_loader_png.h b/drivers/png/image_loader_png.h
index c3951979c3..cc789f95d6 100644
--- a/drivers/png/image_loader_png.h
+++ b/drivers/png/image_loader_png.h
@@ -33,17 +33,16 @@
 
 #include "core/io/image_loader.h"
 
-#include <png.h>
-
 /**
 	@author Juan Linietsky <reduzio@gmail.com>
 */
 class ImageLoaderPNG : public ImageFormatLoader {
-
-	static void _read_png_data(png_structp png_ptr, png_bytep data, png_size_t p_length);
+private:
+	static PoolVector<uint8_t> lossless_pack_png(const Ref<Image> &p_image);
+	static Ref<Image> lossless_unpack_png(const PoolVector<uint8_t> &p_data);
+	static Ref<Image> load_mem_png(const uint8_t *p_png, int p_size);
 
 public:
-	static Error _load_image(void *rf_up, png_rw_ptr p_func, Ref<Image> p_image);
 	virtual Error load_image(Ref<Image> p_image, FileAccess *f, bool p_force_linear, float p_scale);
 	virtual void get_recognized_extensions(List<String> *p_extensions) const;
 	ImageLoaderPNG();
diff --git a/drivers/png/png_driver_common.cpp b/drivers/png/png_driver_common.cpp
new file mode 100644
index 0000000000..0e849bf2fe
--- /dev/null
+++ b/drivers/png/png_driver_common.cpp
@@ -0,0 +1,205 @@
+/*************************************************************************/
+/*  png_driver_common.cpp                                                */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2019 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2019 Godot Engine contributors (cf. AUTHORS.md)    */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "png_driver_common.h"
+
+#include "core/os/os.h"
+
+#include <png.h>
+#include <string.h>
+
+namespace PNGDriverCommon {
+
+// Print any warnings.
+// On error, set explain and return true.
+// Call should be wrapped in ERR_FAIL_COND
+static bool check_error(const png_image &image) {
+	const png_uint_32 failed = PNG_IMAGE_FAILED(image);
+	if (failed & PNG_IMAGE_ERROR) {
+		ERR_EXPLAINC(image.message);
+		return true;
+	} else if (failed) {
+#ifdef TOOLS_ENABLED
+		// suppress this warning, to avoid log spam when opening assetlib
+		const static char *const noisy = "iCCP: known incorrect sRGB profile";
+		const Engine *const eng = Engine::get_singleton();
+		if (eng && eng->is_editor_hint() && !strcmp(image.message, noisy)) {
+			return false;
+		}
+#endif
+		WARN_PRINT(image.message);
+	}
+	return false;
+}
+
+Error png_to_image(const uint8_t *p_source, size_t p_size, Ref<Image> p_image) {
+
+	png_image png_img;
+	zeromem(&png_img, sizeof(png_img));
+	png_img.version = PNG_IMAGE_VERSION;
+
+	// fetch image properties
+	int success = png_image_begin_read_from_memory(&png_img, p_source, p_size);
+	ERR_FAIL_COND_V(check_error(png_img), ERR_FILE_CORRUPT);
+	ERR_FAIL_COND_V(!success, ERR_FILE_CORRUPT);
+
+	// flags to be masked out of input format to give target format
+	const png_uint_32 format_mask = ~(
+			// convert component order to RGBA
+			PNG_FORMAT_FLAG_BGR | PNG_FORMAT_FLAG_AFIRST
+			// convert 16 bit components to 8 bit
+			| PNG_FORMAT_FLAG_LINEAR
+			// convert indexed image to direct color
+			| PNG_FORMAT_FLAG_COLORMAP);
+
+	png_img.format &= format_mask;
+
+	Image::Format dest_format;
+	switch (png_img.format) {
+		case PNG_FORMAT_GRAY:
+			dest_format = Image::FORMAT_L8;
+			break;
+		case PNG_FORMAT_GA:
+			dest_format = Image::FORMAT_LA8;
+			break;
+		case PNG_FORMAT_RGB:
+			dest_format = Image::FORMAT_RGB8;
+			break;
+		case PNG_FORMAT_RGBA:
+			dest_format = Image::FORMAT_RGBA8;
+			break;
+		default:
+			png_image_free(&png_img); // only required when we return before finish_read
+			ERR_PRINT("Unsupported png format");
+			return ERR_UNAVAILABLE;
+	}
+
+	const png_uint_32 stride = PNG_IMAGE_ROW_STRIDE(png_img);
+	PoolVector<uint8_t> buffer;
+	Error err = buffer.resize(PNG_IMAGE_BUFFER_SIZE(png_img, stride));
+	if (err) {
+		png_image_free(&png_img); // only required when we return before finish_read
+		return err;
+	}
+	PoolVector<uint8_t>::Write writer = buffer.write();
+
+	// read image data to buffer and release libpng resources
+	success = png_image_finish_read(&png_img, NULL, writer.ptr(), stride, NULL);
+	ERR_FAIL_COND_V(check_error(png_img), ERR_FILE_CORRUPT);
+	ERR_FAIL_COND_V(!success, ERR_FILE_CORRUPT);
+
+	p_image->create(png_img.width, png_img.height, 0, dest_format, buffer);
+
+	return OK;
+}
+
+Error image_to_png(const Ref<Image> &p_image, PoolVector<uint8_t> &p_buffer) {
+
+	Ref<Image> source_image = p_image->duplicate();
+
+	if (source_image->is_compressed())
+		source_image->decompress();
+
+	ERR_FAIL_COND_V(source_image->is_compressed(), FAILED);
+
+	png_image png_img;
+	zeromem(&png_img, sizeof(png_img));
+	png_img.version = PNG_IMAGE_VERSION;
+	png_img.width = source_image->get_width();
+	png_img.height = source_image->get_height();
+
+	switch (source_image->get_format()) {
+		case Image::FORMAT_L8:
+			png_img.format = PNG_FORMAT_GRAY;
+			break;
+		case Image::FORMAT_LA8:
+			png_img.format = PNG_FORMAT_GA;
+			break;
+		case Image::FORMAT_RGB8:
+			png_img.format = PNG_FORMAT_RGB;
+			break;
+		case Image::FORMAT_RGBA8:
+			png_img.format = PNG_FORMAT_RGBA;
+			break;
+		default:
+			if (source_image->detect_alpha()) {
+				source_image->convert(Image::FORMAT_RGBA8);
+				png_img.format = PNG_FORMAT_RGBA;
+			} else {
+				source_image->convert(Image::FORMAT_RGB8);
+				png_img.format = PNG_FORMAT_RGB;
+			}
+	}
+
+	const PoolVector<uint8_t> image_data = source_image->get_data();
+	const PoolVector<uint8_t>::Read reader = image_data.read();
+
+	// we may be passed a buffer with existing content we're expected to append to
+	const int buffer_offset = p_buffer.size();
+
+	const size_t png_size_estimate = PNG_IMAGE_PNG_SIZE_MAX(png_img);
+
+	// try with estimated size
+	size_t compressed_size = png_size_estimate;
+	int success = 0;
+	{ // scope writer lifetime
+		Error err = p_buffer.resize(buffer_offset + png_size_estimate);
+		ERR_FAIL_COND_V(err, err);
+
+		PoolVector<uint8_t>::Write writer = p_buffer.write();
+		success = png_image_write_to_memory(&png_img, &writer[buffer_offset],
+				&compressed_size, 0, reader.ptr(), 0, NULL);
+		ERR_FAIL_COND_V(check_error(png_img), FAILED);
+	}
+	if (!success) {
+		if (compressed_size <= png_size_estimate) {
+			// buffer was big enough, must be some other error
+			ERR_FAIL_V(FAILED);
+		}
+
+		// write failed due to buffer size, resize and retry
+		Error err = p_buffer.resize(buffer_offset + compressed_size);
+		ERR_FAIL_COND_V(err, err);
+
+		PoolVector<uint8_t>::Write writer = p_buffer.write();
+		success = png_image_write_to_memory(&png_img, &writer[buffer_offset],
+				&compressed_size, 0, reader.ptr(), 0, NULL);
+		ERR_FAIL_COND_V(check_error(png_img), FAILED);
+		ERR_FAIL_COND_V(!success, FAILED);
+	}
+
+	// trim buffer size to content
+	Error err = p_buffer.resize(buffer_offset + compressed_size);
+	ERR_FAIL_COND_V(err, err);
+
+	return OK;
+}
+
+} // namespace PNGDriverCommon
diff --git a/drivers/png/png_driver_common.h b/drivers/png/png_driver_common.h
new file mode 100644
index 0000000000..3ff87759fb
--- /dev/null
+++ b/drivers/png/png_driver_common.h
@@ -0,0 +1,48 @@
+/*************************************************************************/
+/*  png_driver_common.h                                                  */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2019 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2019 Godot Engine contributors (cf. AUTHORS.md)    */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef PNG_DRIVER_COMMON_H
+#define PNG_DRIVER_COMMON_H
+
+#include "core/image.h"
+#include "core/pool_vector.h"
+
+namespace PNGDriverCommon {
+
+// Attempt to load png from buffer (p_source, p_size) into p_image
+Error png_to_image(const uint8_t *p_source, size_t p_size, Ref<Image> p_image);
+
+// Append p_image, as a png, to p_buffer.
+// Contents of p_buffer is unspecified if error returned.
+Error image_to_png(const Ref<Image> &p_image, PoolVector<uint8_t> &p_buffer);
+
+} // namespace PNGDriverCommon
+
+#endif
diff --git a/drivers/png/resource_saver_png.cpp b/drivers/png/resource_saver_png.cpp
index 9e8043cbea..89e8ee32cc 100644
--- a/drivers/png/resource_saver_png.cpp
+++ b/drivers/png/resource_saver_png.cpp
@@ -32,17 +32,9 @@
 
 #include "core/image.h"
 #include "core/os/file_access.h"
-#include "core/project_settings.h"
+#include "drivers/png/png_driver_common.h"
 #include "scene/resources/texture.h"
 
-#include <png.h>
-
-static void _write_png_data(png_structp png_ptr, png_bytep data, png_size_t p_length) {
-
-	FileAccess *f = (FileAccess *)png_get_io_ptr(png_ptr);
-	f->store_buffer((const uint8_t *)data, p_length);
-}
-
 Error ResourceSaverPNG::save(const String &p_path, const RES &p_resource, uint32_t p_flags) {
 
 	Ref<ImageTexture> texture = p_resource;
@@ -55,129 +47,27 @@ Error ResourceSaverPNG::save(const String &p_path, const RES &p_resource, uint32
 
 	Error err = save_image(p_path, img);
 
-	if (err == OK) {
-	}
-
 	return err;
 };
 
 Error ResourceSaverPNG::save_image(const String &p_path, const Ref<Image> &p_img) {
 
-	Ref<Image> img = p_img->duplicate();
-
-	if (img->is_compressed())
-		img->decompress();
-
-	ERR_FAIL_COND_V(img->is_compressed(), ERR_INVALID_PARAMETER);
-
-	png_structp png_ptr;
-	png_infop info_ptr;
-	png_bytep *row_pointers;
-
-	/* initialize stuff */
-	png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
-
-	ERR_FAIL_COND_V(!png_ptr, ERR_CANT_CREATE);
+	PoolVector<uint8_t> buffer;
+	Error err = PNGDriverCommon::image_to_png(p_img, buffer);
+	ERR_FAIL_COND_V(err, err);
+	FileAccess *file = FileAccess::open(p_path, FileAccess::WRITE, &err);
+	ERR_FAIL_COND_V(err, err);
 
-	info_ptr = png_create_info_struct(png_ptr);
+	PoolVector<uint8_t>::Read reader = buffer.read();
 
-	ERR_FAIL_COND_V(!info_ptr, ERR_CANT_CREATE);
-
-	if (setjmp(png_jmpbuf(png_ptr))) {
-		ERR_FAIL_V(ERR_CANT_OPEN);
-	}
-	//change this
-	Error err;
-	FileAccess *f = FileAccess::open(p_path, FileAccess::WRITE, &err);
-	if (err) {
-		ERR_FAIL_V(err);
-	}
-
-	png_set_write_fn(png_ptr, f, _write_png_data, NULL);
-
-	/* write header */
-	if (setjmp(png_jmpbuf(png_ptr))) {
-		ERR_FAIL_V(ERR_CANT_OPEN);
+	file->store_buffer(reader.ptr(), buffer.size());
+	if (file->get_error() != OK && file->get_error() != ERR_FILE_EOF) {
+		memdelete(file);
+		return ERR_CANT_CREATE;
 	}
 
-	int pngf = 0;
-	int cs = 0;
-
-	switch (img->get_format()) {
-
-		case Image::FORMAT_L8: {
-
-			pngf = PNG_COLOR_TYPE_GRAY;
-			cs = 1;
-		} break;
-		case Image::FORMAT_LA8: {
-
-			pngf = PNG_COLOR_TYPE_GRAY_ALPHA;
-			cs = 2;
-		} break;
-		case Image::FORMAT_RGB8: {
-
-			pngf = PNG_COLOR_TYPE_RGB;
-			cs = 3;
-		} break;
-		case Image::FORMAT_RGBA8: {
-
-			pngf = PNG_COLOR_TYPE_RGB_ALPHA;
-			cs = 4;
-		} break;
-		default: {
-
-			if (img->detect_alpha()) {
-
-				img->convert(Image::FORMAT_RGBA8);
-				pngf = PNG_COLOR_TYPE_RGB_ALPHA;
-				cs = 4;
-			} else {
-
-				img->convert(Image::FORMAT_RGB8);
-				pngf = PNG_COLOR_TYPE_RGB;
-				cs = 3;
-			}
-		}
-	}
-
-	int w = img->get_width();
-	int h = img->get_height();
-	png_set_IHDR(png_ptr, info_ptr, w, h,
-			8, pngf, PNG_INTERLACE_NONE,
-			PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
-
-	png_write_info(png_ptr, info_ptr);
-
-	/* write bytes */
-	if (setjmp(png_jmpbuf(png_ptr))) {
-		memdelete(f);
-		ERR_FAIL_V(ERR_CANT_OPEN);
-	}
-
-	PoolVector<uint8_t>::Read r = img->get_data().read();
-
-	row_pointers = (png_bytep *)memalloc(sizeof(png_bytep) * h);
-	for (int i = 0; i < h; i++) {
-
-		row_pointers[i] = (png_bytep)&r[i * w * cs];
-	}
-	png_write_image(png_ptr, row_pointers);
-
-	memfree(row_pointers);
-
-	/* end write */
-	if (setjmp(png_jmpbuf(png_ptr))) {
-
-		memdelete(f);
-		ERR_FAIL_V(ERR_CANT_OPEN);
-	}
-
-	png_write_end(png_ptr, NULL);
-	memdelete(f);
-
-	/* cleanup heap allocation */
-	png_destroy_write_struct(&png_ptr, &info_ptr);
+	file->close();
+	memdelete(file);
 
 	return OK;
 }
@@ -186,6 +76,7 @@ bool ResourceSaverPNG::recognize(const RES &p_resource) const {
 
 	return (p_resource.is_valid() && p_resource->is_class("ImageTexture"));
 }
+
 void ResourceSaverPNG::get_recognized_extensions(const RES &p_resource, List<String> *p_extensions) const {
 
 	if (Object::cast_to<Texture>(*p_resource)) {