3 files changed, 66 insertions, 0 deletions

diff --git a/image/codecs/codec.h b/image/codecs/codec.h
index d87758e65e..3a2da9ff1e 100644
--- a/image/codecs/codec.h
+++ b/image/codecs/codec.h
@@ -86,6 +86,20 @@ public:
 	 * Does the codec have a dirty palette?
 	 */
 	virtual bool hasDirtyPalette() const { return false; }
+
+	/**
+	 * Can the codec dither down to 8bpp?
+	 *
+	 * @note This should only be used for VFW codecs
+	 */
+	virtual bool canDither() const { return false; }
+
+	/**
+	 * Activate dithering mode with a palette
+	 *
+	 * @note This should only be used for VFW codecs
+	 */
+	virtual void setDither(const byte *palette) {}
 };
 
 /**
diff --git a/video/video_decoder.cpp b/video/video_decoder.cpp
index a4bc5b81a2..217b4c8456 100644
--- a/video/video_decoder.cpp
+++ b/video/video_decoder.cpp
@@ -47,6 +47,7 @@ VideoDecoder::VideoDecoder() {
 	_endTimeSet = false;
 	_nextVideoTrack = 0;
 	_mainAudioTrack = 0;
+	_canSetDither = true;
 
 	// Find the best format for output
 	_defaultHighColorFormat = g_system->getScreenFormat();
@@ -77,6 +78,7 @@ void VideoDecoder::close() {
 	_endTimeSet = false;
 	_nextVideoTrack = 0;
 	_mainAudioTrack = 0;
+	_canSetDither = true;
 }
 
 bool VideoDecoder::loadFile(const Common::String &filename) {
@@ -171,6 +173,7 @@ Graphics::PixelFormat VideoDecoder::getPixelFormat() const {
 
 const Graphics::Surface *VideoDecoder::decodeNextFrame() {
 	_needsUpdate = false;
+	_canSetDither = false;
 
 	readNextPacket();
 
@@ -488,6 +491,23 @@ bool VideoDecoder::seekIntern(const Audio::Timestamp &time) {
 	return true;
 }
 
+bool VideoDecoder::setDitheringPalette(const byte *palette) {
+	// If a frame was already decoded, we can't set it now.
+	if (!_canSetDither)
+		return false;
+
+	bool result = false;
+
+	for (TrackList::iterator it = _tracks.begin(); it != _tracks.end(); it++) {
+		if ((*it)->getTrackType() == Track::kTrackTypeVideo && ((VideoTrack *)*it)->canDither()) {
+			((VideoTrack *)*it)->setDither(palette);
+			result = true;
+		}
+	}
+
+	return result;
+}
+
 VideoDecoder::Track::Track() {
 	_paused = false;
 }
diff --git a/video/video_decoder.h b/video/video_decoder.h
index c3879e9144..eca15e7265 100644
--- a/video/video_decoder.h
+++ b/video/video_decoder.h
@@ -377,6 +377,25 @@ public:
 	 */
 	bool setReverse(bool reverse);
 
+	/**
+	 * Tell the video to dither to a palette.
+	 *
+	 * By default, VideoDecoder will return surfaces in native, or in the case
+	 * of YUV-based videos, the format set by setDefaultHighColorFormat().
+	 * For video formats or codecs that support it, this will start outputting
+	 * its surfaces in 8bpp with this palette.
+	 *
+	 * This should be called after loadStream(), but before a decodeNextFrame()
+	 * call. This is enforced.
+	 *
+	 * The palette will be copied, so you do not need to worry about the pointer
+	 * going out-of-scope.
+	 *
+	 * @param palette The palette to use for dithering
+	 * @return true on success, false otherwise
+	 */
+	bool setDitheringPalette(const byte *palette);
+
 	/////////////////////////////////////////
 	// Audio Control
 	/////////////////////////////////////////
@@ -604,6 +623,16 @@ protected:
 		 * Is the video track set to play in reverse?
 		 */
 		virtual bool isReversed() const { return false; }
+
+		/**
+		 * Can the video track dither?
+		 */
+		virtual bool canDither() const { return false; }
+
+		/**
+		 * Activate dithering mode with a palette
+		 */
+		virtual void setDither(const byte *palette) {}
 	};
 
 	/**
@@ -901,6 +930,9 @@ private:
 	mutable bool _dirtyPalette;
 	const byte *_palette;
 
+	// Enforcement of not being able to set dither
+	bool _canSetDither;
+
 	// Default PixelFormat settings
 	Graphics::PixelFormat _defaultHighColorFormat;