3 files changed, 49 insertions, 11 deletions
diff --git a/engines/sherlock/animation.cpp b/engines/sherlock/animation.cpp
index 581971820d..0e932b6dd2 100644
--- a/engines/sherlock/animation.cpp
+++ b/engines/sherlock/animation.cpp
@@ -129,7 +129,7 @@ bool Animation::playPrologue(const Common::String &filename, int minDelay, int f
 			}
 
 			// Draw the sprite
-			screen.copyFrom(sprite[spriteFrame]._frame, pt);
+			screen.transBlitFrom(sprite[spriteFrame]._frame, pt);
 		} else {
 			// No sprite to show for this animation frame
 			if (fade == 255) {
diff --git a/engines/sherlock/graphics.cpp b/engines/sherlock/graphics.cpp
index 23d3b443e8..2bce822707 100644
--- a/engines/sherlock/graphics.cpp
+++ b/engines/sherlock/graphics.cpp
@@ -36,16 +36,9 @@ Surface::~Surface() {
 }
 
 /**
- * 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) {
+void Surface::blitFrom(const Graphics::Surface &src, const Common::Point &pt) {
 	Common::Rect drawRect(0, 0, src.w, src.h);
 	Common::Point destPt = pt;
 	
@@ -73,6 +66,51 @@ void Surface::copyFrom(const Graphics::Surface &src, const Common::Point &pt) {
 	}
 }
 
+
+/**
+* Draws a surface at a given position within this surface with transparency
+*/
+void Surface::transBlitFrom(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())
+		return;
+
+	addDirtyRect(Common::Rect(destPt.x, destPt.y, destPt.x + drawRect.width(),
+		destPt.y + drawRect.height()));
+
+	// Draw loop
+	const int TRANSPARENCY = 0xFF;
+	for (int yp = 0; yp < drawRect.height(); ++yp) {
+		const byte *srcP = (const byte *)src.getBasePtr(drawRect.left, drawRect.top + yp);
+		byte *destP = (byte *)getBasePtr(destPt.x, destPt.y + yp);
+
+		for (int xp = 0; xp < drawRect.width(); ++xp, ++srcP, ++destP) {
+			if (*srcP != TRANSPARENCY)
+				*destP = *srcP;
+		}
+	}
+}
+
+
 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 1765cf04ae..983a22a790 100644
--- a/engines/sherlock/graphics.h
+++ b/engines/sherlock/graphics.h
@@ -35,8 +35,8 @@ public:
     Surface(uint16 width, uint16 height);
     ~Surface();
 
-	void copyFrom(const Graphics::Surface &src);
-	void copyFrom(const Graphics::Surface &src, const Common::Point &pt);
+	void blitFrom(const Graphics::Surface &src, const Common::Point &pt);
+	void transBlitFrom(const Graphics::Surface &src, const Common::Point &pt);
 
 	void fillRect(int x1, int y1, int x2, int y2, byte color);
 };