Merge pull request #10143 from Pokechu22/png-compression-level

Add option for setting the PNG zlib compression level

Source/Core/Common/CMakeLists.txt

@@ -64,6 +64,8 @@ add_library(common
   HttpRequest.h
   Image.cpp
   Image.h
+  ImageC.c
+  ImageC.h
   IniFile.cpp
   IniFile.h
   Inline.h

Source/Core/Common/Image.cpp

@@ -10,6 +10,9 @@
 
 #include "Common/CommonTypes.h"
 #include "Common/IOFile.h"
+#include "Common/ImageC.h"
+#include "Common/Logging/Log.h"
+#include "Common/Timer.h"
 
 namespace Common
 {
@@ -39,23 +42,28 @@ bool LoadPNG(const std::vector<u8>& input, std::vector<u8>* data_out, u32* width
   return true;
 }
 
-bool SavePNG(const std::string& path, const u8* input, ImageByteFormat format, u32 width,
-             u32 height, int stride)
+static void WriteCallback(png_structp png_ptr, png_bytep data, size_t length)
 {
-  png_image png = {};
-  png.version = PNG_IMAGE_VERSION;
-  png.width = width;
-  png.height = height;
+  std::vector<u8>* buffer = static_cast<std::vector<u8>*>(png_get_io_ptr(png_ptr));
+  buffer->insert(buffer->end(), data, data + length);
+}
+
+bool SavePNG(const std::string& path, const u8* input, ImageByteFormat format, u32 width,
+             u32 height, int stride, int level)
+{
+  Common::Timer timer;
+  timer.Start();
 
   size_t byte_per_pixel;
+  int png_format;
   switch (format)
   {
   case ImageByteFormat::RGB:
-    png.format = PNG_FORMAT_RGB;
+    png_format = PNG_FORMAT_RGB;
     byte_per_pixel = 3;
     break;
   case ImageByteFormat::RGBA:
-    png.format = PNG_FORMAT_RGBA;
+    png_format = PNG_FORMAT_RGBA;
     byte_per_pixel = 4;
     break;
   default:
@@ -64,30 +72,47 @@ bool SavePNG(const std::string& path, const u8* input, ImageByteFormat format, u
 
   // libpng doesn't handle non-ASCII characters in path, so write in two steps:
   // first to memory, then to file
-  std::vector<u8> buffer(byte_per_pixel * width * height);
-  png_alloc_size_t size = buffer.size();
-  int success = png_image_write_to_memory(&png, buffer.data(), &size, 0, input, stride, nullptr);
-  if (!success && size > buffer.size())
-  {
-    // initial buffer size guess was too small, set to the now-known size and retry
-    buffer.resize(size);
-    png.warning_or_error = 0;
-    success = png_image_write_to_memory(&png, buffer.data(), &size, 0, input, stride, nullptr);
-  }
-  if (!success || (png.warning_or_error & PNG_IMAGE_ERROR) != 0)
-    return false;
+  std::vector<u8> buffer;
+  buffer.reserve(byte_per_pixel * width * height);
 
-  File::IOFile outfile(path, "wb");
-  if (!outfile)
-    return false;
-  return outfile.WriteBytes(buffer.data(), size);
+  std::vector<const u8*> rows;
+  rows.reserve(height);
+  for (u32 row = 0; row < height; row++)
+  {
+    rows.push_back(&input[row * stride]);
+  }
+
+  png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
+  png_infop info_ptr = png_create_info_struct(png_ptr);
+
+  bool success = false;
+  if (png_ptr != nullptr && info_ptr != nullptr)
+  {
+    success = SavePNG0(png_ptr, info_ptr, png_format, width, height, level, &buffer, WriteCallback,
+                       const_cast<u8**>(rows.data()));
+  }
+  png_destroy_write_struct(&png_ptr, &info_ptr);
+
+  if (success)
+  {
+    File::IOFile outfile(path, "wb");
+    if (!outfile)
+      return false;
+    success = outfile.WriteBytes(buffer.data(), buffer.size());
+
+    timer.Stop();
+    INFO_LOG_FMT(FRAMEDUMP, "{} byte {} by {} image saved to {} at level {} in {}", buffer.size(),
+                 width, height, path, level, timer.GetTimeElapsedFormatted());
+  }
+
+  return success;
 }
 
 bool ConvertRGBAToRGBAndSavePNG(const std::string& path, const u8* input, u32 width, u32 height,
-                                int stride)
+                                int stride, int level)
 {
   const std::vector<u8> data = RGBAToRGB(input, width, height, stride);
-  return SavePNG(path, data.data(), ImageByteFormat::RGB, width, height);
+  return SavePNG(path, data.data(), ImageByteFormat::RGB, width, height, width * 3, level);
 }
 
 std::vector<u8> RGBAToRGB(const u8* input, u32 width, u32 height, int row_stride)

Source/Core/Common/Image.h

@@ -20,9 +20,9 @@ enum class ImageByteFormat
 };
 
 bool SavePNG(const std::string& path, const u8* input, ImageByteFormat format, u32 width,
-             u32 height, int stride = 0);
+             u32 height, int stride, int level = 6);
 bool ConvertRGBAToRGBAndSavePNG(const std::string& path, const u8* input, u32 width, u32 height,
-                                int stride = 0);
+                                int stride, int level);
 
 std::vector<u8> RGBAToRGB(const u8* input, u32 width, u32 height, int row_stride = 0);
 

Source/Core/Common/ImageC.c

@@ -0,0 +1,27 @@
+// Copyright 2021 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "Common/ImageC.h"
+
+// Since libpng requires use of setjmp, and setjmp interacts poorly with destructors and other C++
+// features, this is in a separate C file.
+
+// The main purpose of this function is to allow specifying the compression level, which
+// png_image_write_to_memory does not allow.  row_pointers is not modified by libpng, but also isn't
+// const for some reason.
+bool SavePNG0(png_structp png_ptr, png_infop info_ptr, int png_format, png_uint_32 width,
+              png_uint_32 height, int level, png_voidp io_ptr, png_rw_ptr write_fn,
+              png_bytepp row_pointers)
+{
+  if (setjmp(png_jmpbuf(png_ptr)) != 0)
+    return false;
+
+  png_set_compression_level(png_ptr, level);
+  png_set_IHDR(png_ptr, info_ptr, width, height, 8, png_format, PNG_INTERLACE_NONE,
+               PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+  png_set_rows(png_ptr, info_ptr, row_pointers);
+  png_set_write_fn(png_ptr, io_ptr, write_fn, NULL);
+  png_write_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL);
+
+  return true;
+}

Source/Core/Common/ImageC.h

@@ -0,0 +1,15 @@
+// Copyright 2021 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <png.h>
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C"
+#endif
+    bool
+    SavePNG0(png_structp png_ptr, png_infop info_ptr, int png_format, png_uint_32 width,
+             png_uint_32 height, int level, png_voidp io_ptr, png_rw_ptr write_fn,
+             png_bytepp row_pointers);