* Stopped AnimationManager::drawScene() from marking its own dirtiness.

* Instead, Animation::nextFrame() marks both the old and the new frame dirty. This makes it possible to only update the real screen when the animation changes and results in a pretty big speedup.
* Added utility method Animation::markDirtyRect() which takes a (Surface *) and marks a dirty rect on it for the current frame.
* Fixed artifacts when moving the dragon.

svn-id: r42652

3 files changed, 43 insertions, 29 deletions

diff --git a/engines/draci/animation.cpp b/engines/draci/animation.cpp
index 5b1814f4c4..9cf8f35a8d 100644
--- a/engines/draci/animation.cpp
+++ b/engines/draci/animation.cpp
@@ -50,11 +50,7 @@ bool Animation::isLooping() {
 void Animation::setRelative(int relx, int rely) {
 
 	// Delete the previous frame
-	Common::Rect frameRect;
-
-	frameRect = getFrame()->getRect();
-	frameRect.translate(_relX, _relY);
-	_vm->_screen->getSurface()->markDirtyRect(frameRect);
+	markDirtyRect(_vm->_screen->getSurface());
 
 	_relX = relx;
 	_relY = rely;
@@ -66,6 +62,18 @@ void Animation::setLooping(bool looping) {
 		looping, _id);
 }
 
+void Animation::markDirtyRect(Surface *surface) {
+	// Fetch the current frame's rectangle
+	Drawable *frame = _frames[_currentFrame];
+	Common::Rect frameRect = frame->getRect();			
+
+	// Translate rectangle to compensate for relative coordinates	
+	frameRect.translate(_relX, _relY);
+
+	// Mark the rectangle dirty on the surface
+	surface->markDirtyRect(frameRect);
+}	
+
 void Animation::nextFrame(bool force) {
 
 	// If there's only one or no frames, or if the animation is not playing, return
@@ -73,13 +81,8 @@ void Animation::nextFrame(bool force) {
 		return;
 
 	Drawable *frame = _frames[_currentFrame];
-
-	Common::Rect frameRect;
-	frameRect = frame->getRect();
+	Surface *surface = _vm->_screen->getSurface();
 	
-	// Translate rectangle to compensate for relative coordinates	
-	frameRect.translate(_relX, _relY);
-
 	if (force || (_tick + frame->getDelay() <= _vm->_system->getMillis())) {
 		// If we are at the last frame and not looping, stop the animation
 		// The animation is also restarted to frame zero
@@ -87,9 +90,14 @@ void Animation::nextFrame(bool force) {
 			_currentFrame = 0;
 			setPlaying(false);
 		} else {
-			_vm->_screen->getSurface()->markDirtyRect(frameRect);
+			// Mark old frame dirty so it gets deleted
+			markDirtyRect(surface);
+
 			_currentFrame = nextFrameNum();
 			_tick = _vm->_system->getMillis();
+
+			// Fetch new frame and mark it dirty
+			markDirtyRect(surface);
 		}
 	}
 
@@ -131,7 +139,7 @@ void Animation::drawFrame(Surface *surface) {
 		frame->setY(newY);
 
 		// Draw frame
-		frame->drawScaled(surface, true);
+		frame->drawScaled(surface, false);
 
 		// Revert back to old coordinates
 		frame->setX(x);
@@ -215,6 +223,9 @@ Animation *AnimationManager::addAnimation(int id, uint z, bool playing) {
 void AnimationManager::play(int id) {
 	Animation *anim = getAnimation(id);
 
+	// Mark the first frame dirty so it gets displayed
+	anim->markDirtyRect(_vm->_screen->getSurface());
+
 	if (anim) {
 		anim->setPlaying(true);
 
@@ -226,12 +237,7 @@ void AnimationManager::stop(int id) {
 	Animation *anim = getAnimation(id);
 	
 	// Clean up the last frame that was drawn before stopping
-	Common::Rect frameRect;
-
-	frameRect = anim->getFrame()->getRect();
-
-	frameRect.translate(anim->getRelativeX(), anim->getRelativeY());
-	_vm->_screen->getSurface()->markDirtyRect(frameRect);
+	anim->markDirtyRect(_vm->_screen->getSurface());
 
 	if (anim) {
 		anim->setPlaying(false);
diff --git a/engines/draci/animation.h b/engines/draci/animation.h
index fa28a61599..0e29934699 100644
--- a/engines/draci/animation.h
+++ b/engines/draci/animation.h
@@ -66,6 +66,8 @@ public:
 	int getRelativeX();
 	int getRelativeY();
 
+	void markDirtyRect(Surface *surface);
+
 private:
 	
 	uint nextFrameNum();
diff --git a/engines/draci/game.cpp b/engines/draci/game.cpp
index c01e544986..360375f0b8 100644
--- a/engines/draci/game.cpp
+++ b/engines/draci/game.cpp
@@ -181,7 +181,22 @@ void Game::loop() {
 			double scaleX = _currentRoom._pers0 + _currentRoom._persStep * y;
 			double scaleY = scaleX;
 
-			Drawable *frame;
+			// Set the Z coordinate for the dragon's animation
+			anim->setZ(y+1);
+
+			// Fetch current frame
+			Drawable *frame = anim->getFrame();
+
+			// Fetch base height of the frame
+			uint height = frame->getHeight();
+
+			// We naturally want the dragon to position its feet to the location of the
+			// click but sprites are drawn from their top-left corner so we subtract
+			// the current height of the dragon's sprite
+			// We also need to do this before we change the frames' scaled dimensions
+			// so setRelative() can correctly delete the old frame
+			y -= scaleY * height;
+			anim->setRelative(x, y);
 
 			// Set the scaled dimensions for all frames
 			for (uint i = 0; i < anim->getFramesNum(); ++i) {
@@ -194,15 +209,6 @@ void Game::loop() {
 				frame->setScaled(scaledWidth, scaledHeight);
 			}
 
-			// Set the Z coordinate for the dragon's animation
-			anim->setZ(y+1);
-
-			// We naturally want the dragon to position its feet to the location of the
-			// click but sprites are drawn from their top-left corner so we subtract
-			// the current height of the dragon's sprite
-			y -= frame->getScaledHeight();
-			anim->setRelative(x, y);
-
 			// Play the animation
 			_vm->_anims->play(animID);