PngLib Namespace Reference

Functions
bool	writePNG (SDL_Surface *const surface, const std::string &filename)

Function Documentation

writePNG()

bool PngLib::writePNG	(	SDL_Surface *const	surface,
		const std::string &	filename
	)

< Surface is in video memory

< Use asynchronous blits if possible

< Surface is RLE encoded

< Surface is in video memory

< Use asynchronous blits if possible

< Surface is RLE encoded

Definition at line 37 of file pnglib.cpp.

{
    if (surface == nullptr)
        return false;
 
 
    if (SDL_MUSTLOCK(surface))
        SDL_LockSurface(surface);
 
    png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
        nullptr, nullptr, nullptr);
    if (png_ptr == nullptr)
    {
        reportAlways("Had trouble creating png_structp")
        return false;
    }
 
    png_infop info_ptr = png_create_info_struct(png_ptr);
    if (info_ptr == nullptr)
    {
        png_destroy_write_struct(&png_ptr, static_cast<png_infopp>(nullptr));
        reportAlways("Could not create png_info")
        return false;
    }
 
    if (setjmp(png_jmpbuf(png_ptr)))
    {
        png_destroy_write_struct(&png_ptr, &info_ptr);
        reportAlways("problem writing to %s", filename.c_str())
        return false;
    }
 
    FILE *const fp = fopen(filename.c_str(), "wb");
    if (fp == nullptr)
    {
        reportAlways("could not open file %s for writing",
            filename.c_str())
        return false;
    }
 
    png_init_io(png_ptr, fp);
 
    const int colortype = (surface->format->BitsPerPixel == 24) ?
        PNG_COLOR_TYPE_RGB : PNG_COLOR_TYPE_RGB_ALPHA;
 
    png_set_IHDR(png_ptr, info_ptr, surface->w, surface->h, 8, colortype,
        PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,
        PNG_FILTER_TYPE_DEFAULT);
 
    png_write_info(png_ptr, info_ptr);
 
    png_set_packing(png_ptr);
 
    png_bytep *const row_pointers
        = new png_bytep[CAST_SIZE(surface->h)];
 
    for (int i = 0; i < surface->h; i++)
    {
        row_pointers[i] = static_cast<png_bytep>(static_cast<uint8_t *>(
            surface->pixels) + CAST_SIZE(i * surface->pitch));
    }
 
    png_write_image(png_ptr, row_pointers);
    png_write_end(png_ptr, info_ptr);
 
    fclose(fp);
 
    delete [] row_pointers;
 
    png_destroy_write_struct(&png_ptr,
        &info_ptr);
 
    if (SDL_MUSTLOCK(surface))
        SDL_UnlockSurface(surface);
 
    return true;
}

References CAST_SIZE, and reportAlways.

Referenced by main(), and Game::saveScreenshot().