3 files changed, 148 insertions, 0 deletions
diff --git a/src/spriteloader/grf.cpp b/src/spriteloader/grf.cpp
new file mode 100644
index 000000000..4d412d6ea
--- /dev/null
+++ b/src/spriteloader/grf.cpp
@@ -0,0 +1,96 @@
+#include "../stdafx.h"
+#include "../gfx.h"
+#include "../fileio.h"
+#include "../debug.h"
+#include "grf.hpp"
+
+bool SpriteLoaderGrf::LoadSprite(SpriteLoader::Sprite *sprite, uint32 file_pos)
+{
+	/* Open the right file and go to the correct position */
+	FioSeekToFile(file_pos);
+
+	/* Read the size and type */
+	int num = FioReadWord();
+	byte type = FioReadByte();
+
+	/* Type 0xFF indicates either a colormap or some other non-sprite info; we do not handle them here */
+	if (type == 0xFF) return false;
+
+	sprite->height = FioReadByte();
+	sprite->width  = FioReadWord();
+	sprite->x_offs = FioReadWord();
+	sprite->y_offs = FioReadWord();
+
+	/* 0x02 indicates it is a compressed sprite, so we can't rely on 'num' to be valid.
+	 *  In case it is uncompressed, the size is 'num' - 8 (header-size). */
+	num = (type & 0x02) ? sprite->width * sprite->height : num - 8;
+
+	/* XXX -- We should use a pre-located memory segment for this, malloc/free is pretty expensive */
+	byte *dest_orig = MallocT<byte>(num);
+	byte *dest = dest_orig;
+
+	/* Read the file, which has some kind of compression */
+	while (num > 0) {
+		int8 code = FioReadByte();
+
+		if (code >= 0) {
+			/* Plain bytes to read */
+			int size = (code == 0) ? 0x80 : code;
+			num -= size;
+			for (; size > 0; size--) {
+				*dest = FioReadByte();
+				dest++;
+			}
+		} else {
+			/* Copy bytes from earlier in the sprite */
+			const uint data_offset = ((code & 7) << 8) | FioReadByte();
+			int size = -(code >> 3);
+			num -= size;
+			for (; size > 0; size--) {
+				*dest = *(dest - data_offset);
+				dest++;
+			}
+		}
+	}
+
+	assert(num == 0);
+
+	sprite->data = CallocT<SpriteLoader::CommonPixel>(sprite->width * sprite->height);
+
+	/* When there are transparency pixels, this format has an other trick.. decode it */
+	if (type & 0x08) {
+		for (int y = 0; y < sprite->height; y++) {
+			bool last_item = false;
+			/* Look up in the header-table where the real data is stored for this row */
+			int offset = (dest_orig[y * 2 + 1] << 8) | dest_orig[y * 2];
+			/* Go to that row */
+			dest = &dest_orig[offset];
+
+			do {
+				SpriteLoader::CommonPixel *data;
+				/* Read the header:
+				 *  0 .. 14  - length
+				 *  15       - last_item
+				 *  16 .. 31 - transparency bytes */
+				last_item  = ((*dest) & 0x80) != 0;
+				int length =  (*dest++) & 0x7F;
+				int skip   =   *dest++;
+
+				data = &sprite->data[y * sprite->width + skip];
+
+				for (int x = 0; x < length; x++) {
+					data->m = *dest;
+					dest++;
+					data++;
+				}
+			} while (!last_item);
+		}
+	} else {
+		dest = dest_orig;
+		for (int i = 0; i < sprite->width * sprite->height; i++)
+			sprite->data[i].m = dest[i];
+	}
+
+	free(dest_orig);
+	return true;
+}
diff --git a/src/spriteloader/grf.hpp b/src/spriteloader/grf.hpp
new file mode 100644
index 000000000..27083f993
--- /dev/null
+++ b/src/spriteloader/grf.hpp
@@ -0,0 +1,18 @@
+/* $Id$ */
+
+/** @file grf.hpp */
+
+#ifndef SPRITELOADER_GRF_HPP
+#define SPRITELOADER_GRF_HPP
+
+#include "spriteloader.hpp"
+
+class SpriteLoaderGrf : 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, uint32 file_pos);
+};
+
+#endif /* SPRITELOADER_GRF_HPP */
diff --git a/src/spriteloader/spriteloader.hpp b/src/spriteloader/spriteloader.hpp
new file mode 100644
index 000000000..658277236
--- /dev/null
+++ b/src/spriteloader/spriteloader.hpp
@@ -0,0 +1,34 @@
+/* $Id$ */
+
+/** @file spriteloader.hpp */
+
+#ifndef SPRITELOADER_HPP
+#define SPRITELOADER_HPP
+
+class SpriteLoader {
+public:
+	struct CommonPixel {
+		uint8 r;  ///< Red-channel
+		uint8 g;  ///< Green-channel
+		uint8 b;  ///< Blue-channel
+		uint8 a;  ///< Alpha-channel
+		uint8 m;  ///< Remap-channel
+	};
+
+	struct Sprite {
+		uint16 height;                   ///< Height of the sprite
+		uint16 width;                    ///< Width of the sprite
+		int16 x_offs;                    ///< The x-offset of where the sprite will be drawn
+		int16 y_offs;                    ///< The y-offset of where the sprite will be drawn
+		SpriteLoader::CommonPixel *data; ///< The sprite itself
+	};
+
+	/**
+	 * 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 ~SpriteLoader() { }
+};
+
+#endif /* SPRITELOADER_HPP */