Add support for savepng.c

Makefile.am

@@ -3,7 +3,7 @@ bin_PROGRAMS = hyperrogue
 hyperroguedir = $(datadir)/hyperrogue
 dist_hyperrogue_DATA = music/hyperrogue-music.txt DejaVuSans-Bold.ttf
 dist_doc_DATA = README.md
-hyperrogue_SOURCES = hyper.cpp
+hyperrogue_SOURCES = hyper.cpp savepng.c
 
 # Some definitions used in graph.cpp
 hyperrogue_CPPFLAGS = -DFONTDESTDIR=\"$(pkgdatadir)/DejaVuSans-Bold.ttf\" -DMUSICDESTDIR=\"$(pkgdatadir)/hyperrogue-music.txt\" -O2
@@ -26,6 +26,10 @@ langen_CXXFLAGS = -O0
 language-data.cpp: langen
 	./langen > language-data.cpp
 
+# Generation of savepng
+#noinst_PROGRAMS += savepng
+#savepng_SOURCES = savepng.c 
+
 # Local clean rules
 clean-local:
 	rm -rf language-data.cpp

configure.ac

@@ -34,6 +34,8 @@ AC_CHECK_LIB([SDL_mixer], [main], [], AC_MSG_ERROR([SDL_mixer library was not fo
 AC_CHECK_LIB([SDL_gfx], [main], [], [AS_IF( test ["${host_os#*mingw}" != "$host_os"], [export wincppflags=$wincppflags" dll/SDL_gfx.dll" && AC_MSG_RESULT([Building for windows, ignoring])] ,AC_MSG_ERROR([SDL_gfx library was not found]))])
 # FIXME: Replace `main' with a function in `-lSDL_ttf':
 AC_CHECK_LIB([SDL_ttf], [main], [], [AS_IF( test ["${host_os#*mingw}" != "$host_os"], [export wincppflags=$wincppflags" dll/SDL_ttf.dll" && AC_MSG_RESULT([Building for windows, ignoring])] ,AC_MSG_ERROR([SDL_ttf library was not found]))])
+# Test for libpng
+AC_CHECK_LIB([png], [main], [], AC_MSG_ERROR([png library was not found]))
 
 # Checks for header files.
 AC_CHECK_HEADERS([stdlib.h unistd.h])

savepng.c

@@ -0,0 +1,154 @@
+/*
+ * SDL_SavePNG -- libpng-based SDL_Surface writer.
+ *
+ * This code is free software, available under zlib/libpng license.
+ * http://www.libpng.org/pub/png/src/libpng-LICENSE.txt
+ */
+#include <SDL/SDL.h>
+#include <png.h>
+
+#define SUCCESS 0
+#define ERROR -1
+
+#define USE_ROW_POINTERS
+
+#if SDL_BYTEORDER == SDL_BIG_ENDIAN
+#define rmask 0xFF000000
+#define gmask 0x00FF0000
+#define bmask 0x0000FF00
+#define amask 0x000000FF
+#else
+#define rmask 0x000000FF
+#define gmask 0x0000FF00
+#define bmask 0x00FF0000
+#define amask 0xFF000000
+#endif
+
+/* libpng callbacks */ 
+static void png_error_SDL(png_structp ctx, png_const_charp str)
+{
+	SDL_SetError("libpng: %s\n", str);
+}
+static void png_write_SDL(png_structp png_ptr, png_bytep data, png_size_t length)
+{
+	SDL_RWops *rw = (SDL_RWops*)png_get_io_ptr(png_ptr);
+	SDL_RWwrite(rw, data, sizeof(png_byte), length);
+}
+
+SDL_Surface *SDL_PNGFormatAlpha(SDL_Surface *src) 
+{
+	SDL_Surface *surf;
+	SDL_Rect rect = { 0 };
+
+	/* NO-OP for images < 32bpp and 32bpp images that already have Alpha channel */ 
+	if (src->format->BitsPerPixel <= 24 || src->format->Amask) {
+		src->refcount++;
+		return src;
+	}
+
+	/* Convert 32bpp alpha-less image to 24bpp alpha-less image */
+	rect.w = src->w;
+	rect.h = src->h;
+	surf = SDL_CreateRGBSurface(src->flags, src->w, src->h, 24,
+		src->format->Rmask, src->format->Gmask, src->format->Bmask, 0);
+	SDL_LowerBlit(src, &rect, surf, &rect);
+
+	return surf;
+}
+
+int SDL_SavePNG_RW(SDL_Surface *surface, SDL_RWops *dst, int freedst) 
+{
+	png_structp png_ptr;
+	png_infop info_ptr;
+	png_colorp pal_ptr;
+	SDL_Palette *pal;
+	int i, colortype;
+#ifdef USE_ROW_POINTERS
+	png_bytep *row_pointers;
+#endif
+	/* Initialize and do basic error checking */
+	if (!dst)
+	{
+		SDL_SetError("Argument 2 to SDL_SavePNG_RW can't be NULL, expecting SDL_RWops*\n");
+		return (ERROR);
+	}
+	if (!surface)
+	{
+		SDL_SetError("Argument 1 to SDL_SavePNG_RW can't be NULL, expecting SDL_Surface*\n");
+		if (freedst) SDL_RWclose(dst);
+		return (ERROR);
+	}
+	png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, png_error_SDL, NULL); /* err_ptr, err_fn, warn_fn */
+	if (!png_ptr) 
+	{
+		SDL_SetError("Unable to png_create_write_struct on %s\n", PNG_LIBPNG_VER_STRING);
+		if (freedst) SDL_RWclose(dst);
+		return (ERROR);
+	}
+	info_ptr = png_create_info_struct(png_ptr);
+	if (!info_ptr)
+	{
+		SDL_SetError("Unable to png_create_info_struct\n");
+		png_destroy_write_struct(&png_ptr, NULL);
+		if (freedst) SDL_RWclose(dst);
+		return (ERROR);
+	}
+	if (setjmp(png_jmpbuf(png_ptr)))	/* All other errors, see also "png_error_SDL" */
+	{
+		png_destroy_write_struct(&png_ptr, &info_ptr);
+		if (freedst) SDL_RWclose(dst);
+		return (ERROR);
+	}
+
+	/* Setup our RWops writer */
+	png_set_write_fn(png_ptr, dst, png_write_SDL, NULL); /* w_ptr, write_fn, flush_fn */
+
+	/* Prepare chunks */
+	colortype = PNG_COLOR_MASK_COLOR;
+	if (surface->format->BytesPerPixel > 0
+	&&  surface->format->BytesPerPixel <= 8
+	&& (pal = surface->format->palette))
+	{
+		colortype |= PNG_COLOR_MASK_PALETTE;
+		pal_ptr = (png_colorp)malloc(pal->ncolors * sizeof(png_color));
+		for (i = 0; i < pal->ncolors; i++) {
+			pal_ptr[i].red   = pal->colors[i].r;
+			pal_ptr[i].green = pal->colors[i].g;
+			pal_ptr[i].blue  = pal->colors[i].b;
+		}
+		png_set_PLTE(png_ptr, info_ptr, pal_ptr, pal->ncolors);
+		free(pal_ptr);
+	}
+	else if (surface->format->BytesPerPixel > 3 || surface->format->Amask)
+		colortype |= PNG_COLOR_MASK_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_set_packing(png_ptr);
+
+	/* Allow BGR surfaces */
+	if (surface->format->Rmask == bmask
+	&& surface->format->Gmask == gmask
+	&& surface->format->Bmask == rmask)
+		png_set_bgr(png_ptr);
+
+	/* Write everything */
+	png_write_info(png_ptr, info_ptr);
+#ifdef USE_ROW_POINTERS
+	row_pointers = (png_bytep*) malloc(sizeof(png_bytep)*surface->h);
+	for (i = 0; i < surface->h; i++)
+		row_pointers[i] = (png_bytep)(Uint8*)surface->pixels + i * surface->pitch;
+	png_write_image(png_ptr, row_pointers);
+	free(row_pointers);
+#else
+	for (i = 0; i < surface->h; i++)
+		png_write_row(png_ptr, (png_bytep)(Uint8*)surface->pixels + i * surface->pitch);
+#endif
+	png_write_end(png_ptr, info_ptr);
+
+	/* Done */
+	png_destroy_write_struct(&png_ptr, &info_ptr);
+	if (freedst) SDL_RWclose(dst);
+	return (SUCCESS);
+}