From cb874522e4fac3108070d5054977696a58ddb510 Mon Sep 17 00:00:00 2001
From: Paul Gilbert
Date: Mon, 16 Mar 2015 23:38:58 -0400
Subject: SHERLOCK: Implement screen clipping for sprite drawing

---
 engines/sherlock/animation.cpp | 22 ++++++++++++----------
 engines/sherlock/graphics.cpp  | 38 ++++++++++++++++++++++++++++++++++++++
 engines/sherlock/graphics.h    |  6 ++++++
 3 files changed, 56 insertions(+), 10 deletions(-)

diff --git a/engines/sherlock/animation.cpp b/engines/sherlock/animation.cpp
index e4ec06b741..581971820d 100644
--- a/engines/sherlock/animation.cpp
+++ b/engines/sherlock/animation.cpp
@@ -101,7 +101,7 @@ bool Animation::playPrologue(const Common::String &filename, int minDelay, int f
 	events.delay(minDelay);
 	if (fade != 0 && fade != 255)
 		screen.fadeToBlack();
-	fade = 0; //***DEBUG****
+
 	if (setPalette) {
 		if (fade != 255)
 			screen.setPalette(sprite._palette);
@@ -112,19 +112,26 @@ bool Animation::playPrologue(const Common::String &filename, int minDelay, int f
 	Common::Point pt;
 	bool skipped = false;
 	while (!_vm->shouldQuit()) {
+		// Get the next sprite to display
 		spriteFrame = stream->readSint16LE();
-		if (spriteFrame != -1) {
+
+		if (spriteFrame == -2) {
+			// End of animation reached
+			break;
+		} else if (spriteFrame != -1) {
+			// Read position from either animation stream or the sprite frame itself
 			if (spriteFrame < 0) {
-				spriteFrame = ABS(spriteFrame);
+				spriteFrame += 32769;
 				pt.x = stream->readUint16LE();
 				pt.y = stream->readUint16LE();
 			} else {
 				pt = sprite[spriteFrame]._position;
 			}
 
-			screen.copyFrom(sprite[spriteFrame]._frame);
-			events.pollEventsAndWait();
+			// Draw the sprite
+			screen.copyFrom(sprite[spriteFrame]._frame, pt);
 		} else {
+			// No sprite to show for this animation frame
 			if (fade == 255) {
 				// Gradual fade in
 				if (screen.equalizePalette(sprite._palette) == 0)
@@ -144,11 +151,6 @@ bool Animation::playPrologue(const Common::String &filename, int minDelay, int f
 			}
 
 			events.delay(speed);
-
-			if (stream->readSint16LE() == -2)
-				// End of animation
-				break;
-			stream->seek(-2, SEEK_CUR);
 		}
 
 		if (events.isKeyPressed()) {
diff --git a/engines/sherlock/graphics.cpp b/engines/sherlock/graphics.cpp
index f4fe6b6b46..fbfd3b7b45 100644
--- a/engines/sherlock/graphics.cpp
+++ b/engines/sherlock/graphics.cpp
@@ -35,6 +35,44 @@ Surface::~Surface() {
     free();
 }
 
+/**
+ * Draws a surface into another
+ */
+void Surface::copyFrom(const Graphics::Surface &src) {
+	copyFrom(src, Common::Point());
+}
+
+/**
+ * Draws a surface at a given position within this surface
+ */
+void Surface::copyFrom(const Graphics::Surface &src, const Common::Point &pt) {
+	Common::Rect drawRect(0, 0, src.w, src.h);
+	Common::Point destPt = pt;
+	
+	if (destPt.x < 0) {
+		drawRect.left += -destPt.x;
+		destPt.x = 0;
+	}
+	if (destPt.y < 0) {
+		drawRect.top += -destPt.y;
+		destPt.y = 0;
+	}
+	int right = destPt.x + src.w;
+	if (right > this->w) {
+		drawRect.right -= (right - this->w);
+	}
+	int bottom = destPt.y + src.h;
+	if (bottom > this->h) {
+		drawRect.bottom -= (bottom - this->h);
+	}
+
+	if (drawRect.isValidRect()) {
+		addDirtyRect(Common::Rect(destPt.x, destPt.y, destPt.x + drawRect.width(),
+			destPt.y + drawRect.height()));
+		copyRectToSurface(src, destPt.x, destPt.y, drawRect);
+	}
+}
+
 void Surface::fillRect(int x1, int y1, int x2, int y2, byte color) {
     Graphics::Surface::fillRect(Common::Rect(x1, y1, x2, y2), color);
 }
diff --git a/engines/sherlock/graphics.h b/engines/sherlock/graphics.h
index c6611db1ce..79cffa839a 100644
--- a/engines/sherlock/graphics.h
+++ b/engines/sherlock/graphics.h
@@ -36,9 +36,15 @@ namespace Sherlock {
 class SherlockEngine;
 
 class Surface : public Graphics::Surface {
+protected:
+	virtual void addDirtyRect(const Common::Rect &r) {}
 public:
     Surface(uint16 width, uint16 height);
     ~Surface();
+
+	void copyFrom(const Graphics::Surface &src);
+	void copyFrom(const Graphics::Surface &src, const Common::Point &pt);
+
 	void fillRect(int x1, int y1, int x2, int y2, byte color);
 	void drawSprite(int x, int y, SpriteFrame *spriteFrame, bool flipped = false, bool altFlag = false);
 };
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