(svn r10143) -Add: store the filename of the grfs opened and allow easy access to the name

-Codechange: store the SpriteID in the spritecache too
-Add: add a PNG loader for graphical files
-Documentation: added a document to explain the PNG format

5 files changed, 201 insertions, 3 deletions

diff --git a/src/spriteloader/grf.cpp b/src/spriteloader/grf.cpp
index 7b72f1ac1..79095e4db 100644
--- a/src/spriteloader/grf.cpp
+++ b/src/spriteloader/grf.cpp
@@ -8,7 +8,7 @@
 #include "../debug.h"
 #include "grf.hpp"
 
-bool SpriteLoaderGrf::LoadSprite(SpriteLoader::Sprite *sprite, uint32 file_pos)
+bool SpriteLoaderGrf::LoadSprite(SpriteLoader::Sprite *sprite, const char *filename, uint32 file_pos)
 {
 	/* Open the right file and go to the correct position */
 	FioSeekToFile(file_pos);
diff --git a/src/spriteloader/grf.hpp b/src/spriteloader/grf.hpp
index 27083f993..e6e67be15 100644
--- a/src/spriteloader/grf.hpp
+++ b/src/spriteloader/grf.hpp
@@ -12,7 +12,7 @@ public:
 	/**
 	 * Load a sprite from the disk and return a sprite struct which is the same for all loaders.
 	 */
-	bool LoadSprite(SpriteLoader::Sprite *sprite, uint32 file_pos);
+	bool LoadSprite(SpriteLoader::Sprite *sprite, const char *filename, uint32 file_pos);
 };
 
 #endif /* SPRITELOADER_GRF_HPP */
diff --git a/src/spriteloader/png.cpp b/src/spriteloader/png.cpp
new file mode 100644
index 000000000..bd735ce43
--- /dev/null
+++ b/src/spriteloader/png.cpp
@@ -0,0 +1,180 @@
+/* $Id$ */
+
+/** @file grf.cpp */
+
+#include "../stdafx.h"
+#include "../gfx.h"
+#include "../fileio.h"
+#include "../variables.h"
+#include "../debug.h"
+#include "png.hpp"
+#include <png.h>
+
+#define PNG_SLOT 62
+
+static void PNGAPI png_my_read(png_structp png_ptr, png_bytep data, png_size_t length)
+{
+	FioReadBlock(data, length);
+}
+
+static void PNGAPI png_my_error(png_structp png_ptr, png_const_charp message)
+{
+	DEBUG(sprite, 0, "ERROR (libpng): %s - %s", message, (char *)png_get_error_ptr(png_ptr));
+	longjmp(png_ptr->jmpbuf, 1);
+}
+
+static void PNGAPI png_my_warning(png_structp png_ptr, png_const_charp message)
+{
+	DEBUG(sprite, 0, "WARNING (libpng): %s - %s", message, (char *)png_get_error_ptr(png_ptr));
+}
+
+static bool OpenPNGFile(const char *filename, uint32 id, bool mask)
+{
+	char png_file[MAX_PATH];
+
+	snprintf(png_file, sizeof(png_file), "sprites" PATHSEP "%s" PATHSEP "%d%s.png", filename, id, mask ? "m" : "");
+	if (FioCheckFileExists(png_file)) {
+		FioOpenFile(PNG_SLOT, png_file);
+		return true;
+	}
+
+	/* TODO -- Add TAR support */
+	return false;
+}
+
+static bool LoadPNG(SpriteLoader::Sprite *sprite, const char *filename, uint32 id, bool mask)
+{
+	png_byte header[8];
+	png_structp png_ptr;
+	png_infop info_ptr, end_info;
+	uint bit_depth, color_type;
+	uint i, pixelsize;
+	png_bytep row_pointer;
+	SpriteLoader::CommonPixel *dst;
+
+	if (!OpenPNGFile(filename, id, mask)) return mask; // If mask is true, and file not found, continue true anyway, as it isn't a show-stopper
+
+	/* Check the header */
+	FioReadBlock(header, 8);
+	if (png_sig_cmp(header, 0, 8) != 0) return false;
+
+	/* Create the reader */
+	png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, (png_voidp)NULL, png_my_error, png_my_warning);
+	if (png_ptr == NULL) return false;
+
+	/* Create initial stuff */
+	info_ptr = png_create_info_struct(png_ptr);
+	if (info_ptr == NULL) {
+		png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
+		return false;
+	}
+	end_info = png_create_info_struct(png_ptr);
+	if (end_info == NULL) {
+		png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
+		return false;
+	}
+
+	/* Make sure that upon error, we can clean up graceful */
+	if (setjmp(png_jmpbuf(png_ptr))) {
+		png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
+		return false;
+	}
+
+	/* Read the file */
+	png_set_read_fn(png_ptr, NULL, png_my_read);
+	png_set_sig_bytes(png_ptr, 8);
+
+	png_read_info(png_ptr, info_ptr);
+
+	if (!mask) {
+		/* Read the text chunks */
+		png_textp text_ptr;
+		int num_text = 0;
+		png_get_text(png_ptr, info_ptr, &text_ptr, &num_text);
+		if (num_text == 0) DEBUG(misc, 0, "Warning: PNG Sprite '%s/%d.png' doesn't have x_offs and y_offs; expect graphical problems", filename, id);
+		for (int i = 0; i < num_text; i++) {
+			/* x_offs and y_offs are in the text-chunk of PNG */
+			if (strcmp("x_offs", text_ptr[i].key) == 0) sprite->x_offs = strtol(text_ptr[i].text, NULL, 0);
+			if (strcmp("y_offs", text_ptr[i].key) == 0) sprite->y_offs = strtol(text_ptr[i].text, NULL, 0);
+		}
+
+		sprite->height = info_ptr->height;
+		sprite->width  = info_ptr->width;
+		sprite->data = CallocT<SpriteLoader::CommonPixel>(sprite->width * sprite->height);
+	}
+
+	bit_depth  = png_get_bit_depth(png_ptr, info_ptr);
+	color_type = png_get_color_type(png_ptr, info_ptr);
+
+	if (mask && (bit_depth != 8 || color_type != PNG_COLOR_TYPE_PALETTE)) {
+		DEBUG(misc, 0, "Ignoring mask for SpriteID %d as it isn't a 8 bit palette image", id);
+		return true;
+	}
+
+	if (!mask) {
+		if (bit_depth == 16) png_set_strip_16(png_ptr);
+
+		if (color_type == PNG_COLOR_TYPE_PALETTE) png_set_palette_to_rgb(png_ptr);
+	/* TODO 32bpp: Convert grayscale to rgb */
+
+#ifdef TTD_LITTLE_ENDIAN
+		png_set_bgr(png_ptr);
+#else
+		if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) png_set_swap_alpha(png_ptr);
+#endif
+
+		if (color_type == PNG_COLOR_TYPE_RGB) {
+#ifdef TTD_LITTLE_ENDIAN
+			png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
+#else
+			png_set_filler(png_ptr, 0xff, PNG_FILLER_BEFORE);
+#endif
+		}
+
+		pixelsize = sizeof(uint32);
+	} else {
+		pixelsize = sizeof(uint8);
+	}
+
+	row_pointer = (png_byte *)malloc(info_ptr->width * pixelsize);
+	if (row_pointer == NULL) {
+		png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
+		return false;
+	}
+
+	for (i = 0; i < info_ptr->height; i++) {
+		png_read_row(png_ptr, row_pointer, NULL);
+
+		dst = sprite->data + i * info_ptr->width;
+
+		for (uint x = 0; x < info_ptr->width; x++) {
+			if (mask) {
+				if (row_pointer[x * sizeof(uint8)] != 0) {
+					dst[x].b = 0;
+					dst[x].g = 0;
+					dst[x].r = 0;
+					/* Alpha channel is used from the original image (to allow transparency in remap colors) */
+					dst[x].m = row_pointer[x * sizeof(uint8)];
+				}
+			} else {
+				dst[x].b = row_pointer[x * sizeof(uint32) + 0];
+				dst[x].g = row_pointer[x * sizeof(uint32) + 1];
+				dst[x].r = row_pointer[x * sizeof(uint32) + 2];
+				dst[x].a = row_pointer[x * sizeof(uint32) + 3];
+				dst[x].m = 0;
+			}
+		}
+	}
+
+	free(row_pointer);
+	png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
+
+	return true;
+}
+
+bool SpriteLoaderPNG::LoadSprite(SpriteLoader::Sprite *sprite, const char *filename, uint32 file_pos)
+{
+	if (!LoadPNG(sprite, filename, file_pos, false)) return false;
+	if (!LoadPNG(sprite, filename, file_pos, true)) return false;
+	return true;
+}
diff --git a/src/spriteloader/png.hpp b/src/spriteloader/png.hpp
new file mode 100644
index 000000000..737501268
--- /dev/null
+++ b/src/spriteloader/png.hpp
@@ -0,0 +1,18 @@
+/* $Id$ */
+
+/** @file png.hpp */
+
+#ifndef SPRITELOADER_PNG_HPP
+#define SPRITELOADER_PNG_HPP
+
+#include "spriteloader.hpp"
+
+class SpriteLoaderPNG : public SpriteLoader {
+public:
+	/**
+	 * Load a sprite from the disk and return a sprite struct which is the same for all loaders.
+	 */
+	bool LoadSprite(SpriteLoader::Sprite *sprite, const char *filename, uint32 file_pos);
+};
+
+#endif /* SPRITELOADER_PNG_HPP */
diff --git a/src/spriteloader/spriteloader.hpp b/src/spriteloader/spriteloader.hpp
index 658277236..fe0e6ab8e 100644
--- a/src/spriteloader/spriteloader.hpp
+++ b/src/spriteloader/spriteloader.hpp
@@ -26,7 +26,7 @@ public:
 	/**
 	 * Load a sprite from the disk and return a sprite struct which is the same for all loaders.
 	 */
-	virtual bool LoadSprite(SpriteLoader::Sprite *sprite, uint32 file_pos) = 0;
+	virtual bool LoadSprite(SpriteLoader::Sprite *sprite, const char *filename, uint32 file_pos) = 0;
 
 	virtual ~SpriteLoader() { }
 };