charset masking fixes, mostly for The Dig (hey I think I finally almost understand that part of the code :-)

svn-id: r8248

3 files changed, 20 insertions, 31 deletions

diff --git a/scumm/gfx.cpp b/scumm/gfx.cpp
index e468636f59..0d69ea166b 100644
--- a/scumm/gfx.cpp
+++ b/scumm/gfx.cpp
@@ -447,6 +447,8 @@ void Gdi::drawStripToScreen(VirtScreen *vs, int x, int w, int t, int b) {
 
 void Gdi::clearCharsetMask() {
 	memset(_vm->getResourceAddress(rtBuffer, 9), 0, _imgBufOffs[1]);
+	_mask.top = _mask.left = 32767;
+	_mask.right = _mask.bottom = 0;
 }
 
 /**
@@ -763,10 +765,11 @@ void Scumm::redrawBGStrip(int start, int num) {
 }
 
 void Scumm::restoreCharsetBg() {
-	if (gdi._mask.left != -1) {
+	if (_charset->_hasMask) {
 		restoreBG(gdi._mask);
 		_charset->_hasMask = false;
-		gdi._mask.left = -1;
+		gdi._mask.top = gdi._mask.left = 32767;
+		gdi._mask.right = gdi._mask.bottom = 0;
 		_charset->_str.left = -1;
 		_charset->_left = -1;
 	}
@@ -781,7 +784,7 @@ void Scumm::restoreBG(ScummVM::Rect rect, byte backColor) {
 	byte *backbuff, *bgbak;
 	bool lightsOn;
 
-	if (rect.left == rect.right || rect.top == rect.bottom)
+	if (rect.left >= rect.right || rect.top >= rect.bottom)
 		return;
 	if (rect.top < 0)
 		rect.top = 0;
@@ -846,17 +849,9 @@ void Scumm::restoreBG(ScummVM::Rect rect, byte backColor) {
 }
 
 bool Scumm::hasCharsetMask(int left, int top, int right, int bottom) {
-	// FIXME: I wonder if the <= / >= here shouldn't be replaced by < / >
-	// After all, right/bottom are not actually part of the rects.
-	// That is, the pixels part of the rect range from x = left .. right-1
-	// and y = top .. bottom-1. The 'equal' / '=' cases in the check
-	// would mean that the rects are touching on their borders, but not
-	// actually overlapping.
-	return _charset->_hasMask
-			&& top <= gdi._mask.bottom
-			&& left <= gdi._mask.right
-			&& bottom >= gdi._mask.top
-			&& right >= gdi._mask.left;
+	ScummVM::Rect rect(left, top, right, bottom);
+	
+	return _charset->_hasMask && rect.intersects(gdi._mask);
 }
 
 byte *Scumm::getMaskBuffer(int x, int y, int z) {
diff --git a/scumm/saveload.cpp b/scumm/saveload.cpp
index 791c161411..d22d6347b4 100644
--- a/scumm/saveload.cpp
+++ b/scumm/saveload.cpp
@@ -146,7 +146,9 @@ bool Scumm::loadState(int slot, bool compat, SaveFileManager *mgr) {
 	sb = _screenB;
 	sh = _screenH;
 
-	gdi._mask.left = -1;
+	gdi._mask.top = gdi._mask.left = 32767;
+	gdi._mask.right = gdi._mask.bottom = 0;
+	_charset->_hasMask = false;
 
 	initScreens(0, 0, _screenWidth, _screenHeight);
 
diff --git a/scumm/string.cpp b/scumm/string.cpp
index b96eaec65b..4724394d38 100644
--- a/scumm/string.cpp
+++ b/scumm/string.cpp
@@ -183,6 +183,7 @@ void Scumm::CHARSET_1() {
 
 	if (!_keepText) {
 		if ((_features & GF_AFTER_V2 || _features & GF_AFTER_V3) && _gameId != GID_LOOM) {
+			_charset->_hasMask = true;
 			gdi._mask.left = _string[0].xpos;
 			gdi._mask.top = _string[0].ypos;
 			gdi._mask.bottom = _string[0].ypos + 8;
@@ -331,7 +332,8 @@ void Scumm::CHARSET_1() {
 
 	_charsetBufPos = buffer - _charsetBuffer;
 
-	gdi._mask = _charset->_str;
+	_charset->_hasMask = true;
+	gdi._mask.extend(_charset->_str);
 }
 
 void Scumm::drawDescString(const byte *msg) {
@@ -380,8 +382,9 @@ void Scumm::drawDescString(const byte *msg) {
 
 	// hack: more 8 pixels at width and height while redraw
 	// for proper description redraw while scrolling room
-	gdi._mask = _charset->_str;
-	gdi._mask.grow(8);
+	ScummVM::Rect r(_charset->_str);
+	r.grow(8);
+	gdi._mask.extend(r);
 }
 
 void Scumm::drawString(int a) {
@@ -494,19 +497,8 @@ void Scumm::drawString(int a) {
 
 	if (_features & GF_AFTER_V7) {
 		_charset->_hasMask = true;
-		// FIXME - how is this supposed to ever work, since gdi._mask_left is by default set
-		// to -1 to mark it as invalid. Hence this comparision will always leave it at -1,
-		// which implies that if the mask was marked invalid, it will always stay so. 
-		// That seems odd and not at all to be the intended thing... or is it?
-		if (_charset->_str.left < gdi._mask.left)
-			gdi._mask.left = _charset->_str.left;
-		if (_charset->_str.right > gdi._mask.right)
-			gdi._mask.right = _charset->_str.right;
-		if (_charset->_str.top < gdi._mask.top)
-			gdi._mask.top = _charset->_str.top;
-		if (_charset->_str.bottom > gdi._mask.bottom)
-			gdi._mask.bottom = _charset->_str.bottom;
-	} 
+		gdi._mask.extend(_charset->_str);
+	}
 }
 
 const byte *Scumm::addMessageToStack(const byte *msg) {