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image/codecs/msrle.cpp

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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/>.
+ *
+ */
+
+// Based off ffmpeg's msrledec.c
+
+#include "image/codecs/msrle.h"
+#include "common/stream.h"
+#include "common/textconsole.h"
+
+namespace Image {
+
+MSRLEDecoder::MSRLEDecoder(uint16 width, uint16 height, byte bitsPerPixel) {
+	_surface = new Graphics::Surface();
+	_surface->create(width, height, Graphics::PixelFormat::createFormatCLUT8());
+	_bitsPerPixel = bitsPerPixel;
+}
+
+MSRLEDecoder::~MSRLEDecoder() {
+	_surface->free();
+	delete _surface;
+}
+
+const Graphics::Surface *MSRLEDecoder::decodeFrame(Common::SeekableReadStream &stream) {
+	if (_bitsPerPixel == 8) {
+		decode8(stream);
+	} else
+		error("Unhandled %d bit Microsoft RLE encoding", _bitsPerPixel);
+
+	return _surface;
+}
+
+void MSRLEDecoder::decode8(Common::SeekableReadStream &stream) {
+
+	int x = 0;
+	int y = _surface->h - 1;
+
+	byte *data = (byte *) _surface->getPixels();
+	uint16 width  = _surface->w;
+	uint16 height = _surface->h;
+	uint16 pitch = _surface->pitch;
+
+	byte *output     = data + ((height - 1) * pitch);
+	byte *output_end = data + ((height)     * pitch) - (pitch - width);
+
+	while (!stream.eos()) {
+		byte count = stream.readByte();
+		byte value = stream.readByte();
+
+		if (count == 0) {
+			if (value == 0) {
+				// End of line
+
+				x = 0;
+				y--;
+				output = data + (y * pitch);
+
+			} else if (value == 1) {
+				// End of image
+				return;
+
+			} else if (value == 2) {
+				// Skip
+
+				count = stream.readByte();
+				value = stream.readByte();
+
+				y -= value;
+				x += count;
+
+				if (y < 0) {
+					warning("MS RLE Codec: Skip beyond picture bounds");
+					return;
+				}
+
+				output = data + ((y * pitch) + x);
+
+			} else {
+				// Copy data
+				if (y < 0) {
+					warning("MS RLE Codec: Copy data is beyond picture bounds");
+					return;
+				}
+
+				if (output + value > output_end) {
+					if (stream.pos() + value >= stream.size())
+						break;
+					else
+						stream.skip(value);
+					continue;
+				}
+
+				for (int i = 0; i < value; i++)
+					*output++ = stream.readByte();
+
+				if (value & 1)
+					stream.skip(1);
+
+				x += value;
+			}
+
+		} else {
+			// Run data
+			if (y < 0) {
+				warning("MS RLE Codec: Run data is beyond picture bounds");
+				return;
+			}
+
+			if (output + count > output_end)
+				continue;
+
+			for (int i = 0; i < count; i++, x++)
+				*output++ = value;
+		}
+
+	}
+
+	warning("MS RLE Codec: No end-of-picture code");
+}
+
+} // End of namespace Image