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image/codecs/xan.h

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program 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, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef IMAGE_CODECS_XAN_H
+#define IMAGE_CODECS_XAN_H
+
+#include "image/codecs/codec.h"
+
+namespace Image {
+
+/**
+ * Xan image decoder. (fourcc Xxan)
+ *
+ * Used by Crusader: No Regret AVI files
+ *
+ * This code was created based on the multimedia wiki:
+ * https://wiki.multimedia.cx/index.php/Origin_Xan_Codec
+ * and ffmpeg's libavcodec/xxan.c.
+ * The ffmpeg code is LGPL2 licensed and Copyright (C) 2011
+ * Konstantin Shishkov based on work by Mike Melanson.
+ *
+ * A similar format is used in Wing Commander III (although not in an AVI
+ * container) and IV.
+ */
+class XanDecoder : public Codec {
+public:
+	XanDecoder (int width, int height, int bitsPerPixel);
+	~XanDecoder() override;
+
+	const Graphics::Surface *decodeFrame(Common::SeekableReadStream &stream) override;
+	Graphics::PixelFormat getPixelFormat() const override { return _pixelFormat; }
+	bool setOutputPixelFormat(const Graphics::PixelFormat &format) override {
+		if (format.bytesPerPixel != 2 && format.bytesPerPixel != 4)
+			return false;
+		_pixelFormat = format;
+		return true;
+	}
+
+private:
+	void decodeFrameType0(Common::SeekableReadStream &stream);
+	void decodeFrameType1(Common::SeekableReadStream &stream);
+
+	/** Decompress the huffman table for base luma data */
+	void decompressLuma(Common::SeekableReadStream &stream);
+
+	bool decodeChroma(Common::SeekableReadStream &stream, int chroma_off);
+
+	/** convert the internally expanded YUV to the output RGBA surface */
+	void convertYUVtoRGBSurface();
+
+	/** A buffer to hold the final frame */
+	Graphics::Surface *_surface;
+
+	/** Dest surface width and height */
+	int _width, _height;
+
+	/** Dest surface pixel format */
+	Graphics::PixelFormat _pixelFormat;
+
+	/** If true, decode chroma vals in Wing Commander 4 style (false = No Regret style) */
+	bool _wc4Mode;
+
+	/** A buffer to hold scratch data.  Either chroma data in progress, or
+	 * decompressed delta luma values (5-bit).  Interpretation depends on frame type. */
+	uint8 *_scratchbuf;
+	/** A buffer to hold expanded/interpolated absolute luma values (6-bit) from the values in _scratchbuf.
+	 * These still need to be multiplied out to make 8-bit values. */
+	uint8 *_lumabuf;
+	/** a buffer for uncompressed and multiplied out "y" values (of yuv) */
+	uint8 *_ybuf;
+	/** a buffer for uncompressed "u" values (of yuv) */
+	uint8 *_ubuf;
+	/** a buffer for uncompressed "v" values (of yuv) */
+	uint8 *_vbuf;
+};
+
+} // End of namespace Image
+
+#endif