screenshot_png.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD 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, version 2.
 * OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */
 
#include "stdafx.h"
#include "core/math_func.hpp"
#include "debug.h"
#include "fileio_func.h"
#include "screenshot_type.h"
 
#include <png.h>
 
#ifdef PNG_TEXT_SUPPORTED
#include "rev.h"
#include "newgrf_config.h"
#include "ai/ai_info.hpp"
#include "company_base.h"
#include "base_media_base.h"
#endif /* PNG_TEXT_SUPPORTED */
 
#include "safeguards.h"
 
class ScreenshotProvider_Png : public ScreenshotProvider {
public:
  ScreenshotProvider_Png() : ScreenshotProvider("png", "PNG", 0) {}
 
  bool MakeImage(const char *name, ScreenshotCallback *callb, void *userdata, uint w, uint h, int pixelformat, const Colour *palette) override
  {
    png_color rq[256];
    uint i, y, n;
    uint maxlines;
    uint bpp = pixelformat / 8;
    png_structp png_ptr;
    png_infop info_ptr;
 
    /* only implemented for 8bit and 32bit images so far. */
    if (pixelformat != 8 && pixelformat != 32) return false;
 
    auto of = FileHandle::Open(name, "wb");
    if (!of.has_value()) return false;
    auto &f = *of;
 
    png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, const_cast<char *>(name), png_my_error, png_my_warning);
 
    if (png_ptr == nullptr) {
      return false;
    }
 
    info_ptr = png_create_info_struct(png_ptr);
    if (info_ptr == nullptr) {
      png_destroy_write_struct(&png_ptr, (png_infopp)nullptr);
      return false;
    }
 
    if (setjmp(png_jmpbuf(png_ptr))) {
      png_destroy_write_struct(&png_ptr, &info_ptr);
      return false;
    }
 
    png_init_io(png_ptr, f);
 
    png_set_filter(png_ptr, 0, PNG_FILTER_NONE);
 
    png_set_IHDR(png_ptr, info_ptr, w, h, 8, pixelformat == 8 ? PNG_COLOR_TYPE_PALETTE : PNG_COLOR_TYPE_RGB,
      PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
 
#ifdef PNG_TEXT_SUPPORTED
 
    /* Try to add some game metadata to the PNG screenshot so
     * it's more useful for debugging and archival purposes. */
    png_text_struct text[2];
    memset(text, 0, sizeof(text));
    text[0].key = const_cast<char *>("Software");
    text[0].text = const_cast<char *>(_openttd_revision);
    text[0].text_length = strlen(_openttd_revision);
    text[0].compression = PNG_TEXT_COMPRESSION_NONE;
 
    std::string message;
    message.reserve(1024);
    fmt::format_to(std::back_inserter(message), "Graphics set: {} ({})\n", BaseGraphics::GetUsedSet()->name, BaseGraphics::GetUsedSet()->version);
    message += "NewGRFs:\n";
    if (_game_mode != GM_MENU) {
      for (const auto &c : _grfconfig) {
        fmt::format_to(std::back_inserter(message), "{:08X} {} {}\n", std::byteswap(c->ident.grfid), FormatArrayAsHex(c->ident.md5sum), c->filename);
      }
    }
    message += "\nCompanies:\n";
    for (const Company *c : Company::Iterate()) {
      if (c->ai_info == nullptr) {
        fmt::format_to(std::back_inserter(message), "{:2d}: Human\n", c->index);
      } else {
        fmt::format_to(std::back_inserter(message), "{:2d}: {} (v{})\n", c->index, c->ai_info->GetName(), c->ai_info->GetVersion());
      }
    }
    text[1].key = const_cast<char *>("Description");
    text[1].text = const_cast<char *>(message.c_str());
    text[1].text_length = message.size();
    text[1].compression = PNG_TEXT_COMPRESSION_zTXt;
    png_set_text(png_ptr, info_ptr, text, 2);
 
#endif /* PNG_TEXT_SUPPORTED */
 
    if (pixelformat == 8) {
      /* convert the palette to the .PNG format. */
      for (i = 0; i != 256; i++) {
        rq[i].red   = palette[i].r;
        rq[i].green = palette[i].g;
        rq[i].blue  = palette[i].b;
      }
 
      png_set_PLTE(png_ptr, info_ptr, rq, 256);
    }
 
    png_write_info(png_ptr, info_ptr);
    png_set_flush(png_ptr, 512);
 
    if (pixelformat == 32) {
      png_color_8 sig_bit;
 
      /* Save exact colour/alpha resolution */
      sig_bit.alpha = 0;
      sig_bit.blue  = 8;
      sig_bit.green = 8;
      sig_bit.red   = 8;
      sig_bit.gray  = 8;
      png_set_sBIT(png_ptr, info_ptr, &sig_bit);
 
      if constexpr (std::endian::native == std::endian::little) {
        png_set_bgr(png_ptr);
        png_set_filler(png_ptr, 0, PNG_FILLER_AFTER);
      } else {
        png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
      }
    }
 
    /* use by default 64k temp memory */
    maxlines = Clamp(65536 / w, 16, 128);
 
    /* now generate the bitmap bits */
    std::vector<uint8_t> buff(static_cast<size_t>(w) * maxlines * bpp); // by default generate 128 lines at a time.
 
    y = 0;
    do {
      /* determine # lines to write */
      n = std::min(h - y, maxlines);
 
      /* render the pixels into the buffer */
      callb(userdata, buff.data(), y, w, n);
      y += n;
 
      /* write them to png */
      for (i = 0; i != n; i++) {
        png_write_row(png_ptr, (png_bytep)buff.data() + i * w * bpp);
      }
    } while (y != h);
 
    png_write_end(png_ptr, info_ptr);
    png_destroy_write_struct(&png_ptr, &info_ptr);
 
    return true;
  }
 
private:
  static void PNGAPI png_my_error(png_structp png_ptr, png_const_charp message)
  {
    Debug(misc, 0, "[libpng] error: {} - {}", message, (const char *)png_get_error_ptr(png_ptr));
    longjmp(png_jmpbuf(png_ptr), 1);
  }
 
  static void PNGAPI png_my_warning(png_structp png_ptr, png_const_charp message)
  {
    Debug(misc, 1, "[libpng] warning: {} - {}", message, (const char *)png_get_error_ptr(png_ptr));
  }
};
 
static ScreenshotProvider_Png s_screenshot_provider_png;