ZVISION: Handle rlf frame transitions internally

Animations use incremental frame changes. That is, only a few frames
are complete (I-frames), the rest are just the pixels that change between the current
frame and both the previous frame and the next frame (B-frames). See
https://en.wikipedia.org/wiki/Video_compression_picture_types

3 files changed, 93 insertions, 26 deletions

diff --git a/engines/zvision/animation.cpp b/engines/zvision/animation.cpp
index 7c41c23a06..8ca892dfda 100644
--- a/engines/zvision/animation.cpp
+++ b/engines/zvision/animation.cpp
@@ -31,8 +31,6 @@
 namespace ZVision {
 
 void ZVision::playAnimation(RlfAnimation *animation, uint16 x, uint16 y, DisposeAfterUse::Flag disposeAfterUse) {
-	uint currentFrame = 0;
-	uint lastFrame = animation->frameCount();
 	bool skip = false;
 	uint32 frameTime = animation->frameTime();
 	uint width = animation->width();
@@ -44,7 +42,7 @@ void ZVision::playAnimation(RlfAnimation *animation, uint16 x, uint16 y, Dispose
 	uint32 accumulatedTime = 0;
 
 	// Only continue while the video is still playing
-	while (!shouldQuit() && !skip && currentFrame < lastFrame) {
+	while (!shouldQuit() && !skip && !animation->endOfAnimation()) {
 		_clock.update();
 		uint32 currentTime = _clock.getLastMeasuredTime();
 		accumulatedTime += _clock.getDeltaTime();
@@ -69,11 +67,10 @@ void ZVision::playAnimation(RlfAnimation *animation, uint16 x, uint16 y, Dispose
 			}
 		}
 
-		if (accumulatedTime >= frameTime) {
+		while (accumulatedTime >= frameTime && !animation->endOfAnimation()) {
 			accumulatedTime -= frameTime;
 
-			_system->copyRectToScreen(animation->getFrameData(currentFrame), width * sizeof(uint16), newX, newY, width, height);
-			currentFrame++;
+			_system->copyRectToScreen(animation->getNextFrame(), width * sizeof(uint16), newX, newY, width, height);
 		}
 
 		// Always update the screen so the mouse continues to render
diff --git a/engines/zvision/rlf_animation.cpp b/engines/zvision/rlf_animation.cpp
index 26ce2e217c..90086e9bd0 100644
--- a/engines/zvision/rlf_animation.cpp
+++ b/engines/zvision/rlf_animation.cpp
@@ -34,7 +34,14 @@
 namespace ZVision {
 
 RlfAnimation::RlfAnimation(const Common::String &fileName) 
-		: _frames(0) {
+		: _frameCount(0),
+		  _width(0),
+		  _height(0),
+		  _frameTime(0),
+		  _frames(0),
+		  _currentFrameBuffer(0),
+		  _currentFrame(-1),
+		  _frameBufferByteSize(0) {
 	Common::File file;
 	if (!file.open(fileName)) {
 		warning("RLF animation file %s could not be opened", fileName.c_str());
@@ -87,8 +94,11 @@ RlfAnimation::RlfAnimation(const Common::String &fileName)
 	file.readUint32LE();                    // Unknown11
 	_frameTime = file.readUint32LE() / 10;  // Frame time in microseconds
 
+	_frames = new Frame[_frameCount];
+	_currentFrameBuffer = new uint16[_width * _height];
+	_frameBufferByteSize = _width * _height * sizeof(uint16);
+
 	// Read in each frame
-	_frames = new uint16 *[_frameCount];
 	for (uint i = 0; i < _frameCount; i++) {
 		file.readUint32BE();                        // Magic number MARF
 		uint32 size = file.readUint32LE();          // Size
@@ -98,27 +108,19 @@ RlfAnimation::RlfAnimation(const Common::String &fileName)
 		uint32 headerSize = file.readUint32LE();    // Offset from the beginning of this frame to the frame data. Should always be 28
 		file.readUint32LE();                        // Unknown3
 
-		int8 *buffer = new int8[size - headerSize];
-		file.read(buffer, size - headerSize);
-
-		_frames[i] = new uint16[_width * _height];
-		uint frameByteSize = _width * _height * sizeof(uint16);
-		memset(_frames[i], 0x7C00, frameByteSize);
-		// Decode the data
-		debug("Decoding frame %u", i);
+		_frames[i].encodedSize = size - headerSize;
+		_frames[i].encodedData = new int8[_frames[i].encodedSize];
+		file.read(_frames[i].encodedData, _frames[i].encodedSize);
+		
 		if (type == MKTAG('E', 'L', 'H', 'D')) {
-			debug("Decoding with masked RLE");
-			decodeMaskedRunLengthEncoding(buffer, (int8 *)_frames[i], size - headerSize, frameByteSize);
+			_frames[i].type = Masked;
 		} else if (type == MKTAG('E', 'L', 'R', 'H')) {
-			debug("Decoding with simple RLE");
-			decodeSimpleRunLengthEncoding(buffer, (int8 *)_frames[i], size - headerSize, frameByteSize);
+			_frames[i].type = Simple;
+			_completeFrames.push_back(i);
 		} else {
 			warning("Frame %u of %s doesn't have type that can be decoded", i, fileName.c_str());
 			return;
 		}
-
-		// Cleanup
-		delete[] buffer;
 	}
 };
 
@@ -126,9 +128,58 @@ RlfAnimation::~RlfAnimation() {
 	if (_frames != 0) {
 		delete[] _frames;
 	}
+	if (_currentFrameBuffer != 0) {
+		delete[] _currentFrameBuffer;
+	}
+}
+
+const uint16 *RlfAnimation::getFrameData(uint frameNumber) {
+	assert(frameNumber < _frameCount && frameNumber >= 0);
+
+	if (frameNumber == _currentFrame) {
+		return _currentFrameBuffer;
+	}
+
+	uint closestFrame = _currentFrame;
+	uint distance = ABS(_currentFrame - frameNumber);
+	for (Common::List<uint>::const_iterator iter = _completeFrames.begin(); iter != _completeFrames.end(); iter++) {
+		uint newDistance = ABS((*iter) - frameNumber);
+		if (closestFrame == -1 || newDistance < distance) {
+			closestFrame = (*iter);
+			distance = newDistance;
+		}
+	}
+
+	bool forwards = frameNumber > closestFrame;
+	if (forwards) {
+		for (uint i = closestFrame; i <= frameNumber; i++) {
+			applyFrameToCurrent(i);
+		}
+	} else {
+		for (uint i = closestFrame; i >= frameNumber; i--) {
+			applyFrameToCurrent(i);
+		}
+	}
+
+	return _currentFrameBuffer;
 }
 
+const uint16 *RlfAnimation::getNextFrame() {
+	assert(_currentFrame + 1 < _frameCount);
 
+	applyFrameToCurrent(_currentFrame + 1);
+	return _currentFrameBuffer;
+}
+
+void RlfAnimation::applyFrameToCurrent(uint frameNumber) {
+	if (_frames[frameNumber].type == Masked) {
+		decodeMaskedRunLengthEncoding(_frames[frameNumber].encodedData, (int8 *)_currentFrameBuffer, _frames[frameNumber].encodedSize, _frameBufferByteSize);
+	} else if (_frames[frameNumber].type == Simple) {
+		decodeSimpleRunLengthEncoding(_frames[frameNumber].encodedData, (int8 *)_currentFrameBuffer, _frames[frameNumber].encodedSize, _frameBufferByteSize);
+	}
+
+	_currentFrame = frameNumber;
+}
 
 void RlfAnimation::decodeMaskedRunLengthEncoding(int8 *source, int8 *dest, uint32 sourceSize, uint32 destSize) const {
 	uint32 sourceOffset = 0;
@@ -226,5 +277,4 @@ void RlfAnimation::decodeSimpleRunLengthEncoding(int8 *source, int8 *dest, uint3
 	}
 }
 
-
 } // End of namespace ZVision
diff --git a/engines/zvision/rlf_animation.h b/engines/zvision/rlf_animation.h
index 7ece4e5063..e204a50090 100644
--- a/engines/zvision/rlf_animation.h
+++ b/engines/zvision/rlf_animation.h
@@ -36,21 +36,41 @@ public:
 	~RlfAnimation();
 
 private:
+	enum EncodingType {
+		Masked,
+		Simple
+	};
+
+	struct Frame {
+		EncodingType type;
+		int8 *encodedData;
+		uint32 encodedSize;
+	};
+
 private:
 	uint _frameCount;
 	uint _width;
 	uint _height;
 	uint32 _frameTime; // In milliseconds
-	uint16 **_frames;
+	Frame *_frames;
+	Common::List<uint> _completeFrames;
+
+	int _currentFrame;
+	uint16 *_currentFrameBuffer;
+	uint32 _frameBufferByteSize;
 
 public:
 	uint frameCount() { return _frameCount; }
 	uint width() { return _width; }
 	uint height() { return _height; }
 	uint32 frameTime() { return _frameTime; }
-	const uint16 *getFrameData(uint frameNumber) const { return _frames[frameNumber]; }
+	const uint16 *getFrameData(uint frameNumber);
+	const uint16 *getNextFrame();
+	bool endOfAnimation() { return _currentFrame == _frameCount - 1; }
 
 private:
+	void applyFrameToCurrent(uint frameNumber);
+
 	void decodeMaskedRunLengthEncoding(int8 *source, int8 *dest, uint32 sourceSize, uint32 destSize) const;
 	void decodeSimpleRunLengthEncoding(int8 *source, int8 *dest, uint32 sourceSize, uint32 destSize) const;
 };