SCI32: Enable optional explicit memory management of hunk entries

Bitmaps in ScrollWindow and Robot code are managed by the kernel
and not by game scripts, although they must be able to be
referenced through a reg_t. To prevent incorrect GC of bitmaps
that are in use but not referenced by any game script, explicit
memory management of hunk entries can be enabled.

6 files changed, 29 insertions, 18 deletions

diff --git a/engines/sci/engine/gc.cpp b/engines/sci/engine/gc.cpp
index b229490570..e0467e9461 100644
--- a/engines/sci/engine/gc.cpp
+++ b/engines/sci/engine/gc.cpp
@@ -143,23 +143,30 @@ AddrSet *findAllActiveReferences(EngineState *s) {
 	const Common::Array<SegmentObj *> &heap = s->_segMan->getSegments();
 	uint heapSize = heap.size();
 
-	// Init: Explicitly loaded scripts
 	for (uint i = 1; i < heapSize; i++) {
-		if (heap[i] && heap[i]->getType() == SEG_TYPE_SCRIPT) {
-			Script *script = (Script *)heap[i];
+		if (heap[i]) {
+			// Init: Explicitly loaded scripts
+			if (heap[i]->getType() == SEG_TYPE_SCRIPT) {
+				Script *script = (Script *)heap[i];
 
-			if (script->getLockers()) { // Explicitly loaded?
-				wm.pushArray(script->listObjectReferences());
+				if (script->getLockers()) { // Explicitly loaded?
+					wm.pushArray(script->listObjectReferences());
+				}
+			}
+
+			// Init: Explicitly opted-out hunks
+			else if (heap[i]->getType() == SEG_TYPE_HUNK) {
+				HunkTable *ht = static_cast<HunkTable *>(heap[i]);
+
+				for (uint j = 0; j < ht->_table.size(); j++) {
+					if (!ht->_table[j].data.gc) {
+						wm.push(make_reg(i, j));
+					}
+				}
 			}
 		}
 	}
 
-#ifdef ENABLE_SCI32
-	// Init: ScrollWindows
-	if (g_sci->_gfxControls32)
-		wm.pushArray(g_sci->_gfxControls32->listObjectReferences());
-#endif
-
 	debugC(kDebugLevelGC, "[GC] -- Finished explicitly loaded scripts, done with root set");
 
 	processWorkList(s->_segMan, wm, heap);
diff --git a/engines/sci/engine/kgraphics32.cpp b/engines/sci/engine/kgraphics32.cpp
index 9cfe53255b..b8682b3f47 100644
--- a/engines/sci/engine/kgraphics32.cpp
+++ b/engines/sci/engine/kgraphics32.cpp
@@ -195,14 +195,14 @@ reg_t kCreateTextBitmap(EngineState *s, int argc, reg_t *argv) {
 
 	if (subop == 0) {
 		TextAlign alignment = (TextAlign)readSelectorValue(segMan, object, SELECTOR(mode));
-		return g_sci->_gfxText32->createFontBitmap(width, height, rect, text, foreColor, backColor, skipColor, fontId, alignment, borderColor, dimmed, true);
+		return g_sci->_gfxText32->createFontBitmap(width, height, rect, text, foreColor, backColor, skipColor, fontId, alignment, borderColor, dimmed, true, true);
 	} else {
 		CelInfo32 celInfo;
 		celInfo.type = kCelTypeView;
 		celInfo.resourceId = readSelectorValue(segMan, object, SELECTOR(view));
 		celInfo.loopNo = readSelectorValue(segMan, object, SELECTOR(loop));
 		celInfo.celNo = readSelectorValue(segMan, object, SELECTOR(cel));
-		return g_sci->_gfxText32->createFontBitmap(celInfo, rect, text, foreColor, backColor, fontId, skipColor, borderColor, dimmed);
+		return g_sci->_gfxText32->createFontBitmap(celInfo, rect, text, foreColor, backColor, fontId, skipColor, borderColor, dimmed, true);
 	}
 }
 
@@ -534,7 +534,7 @@ reg_t kBitmapCreate(EngineState *s, int argc, reg_t *argv) {
 	int16 scaledHeight = argc > 5 ? argv[5].toSint16() : g_sci->_gfxText32->_scaledHeight;
 	bool useRemap = argc > 6 ? argv[6].toSint16() : false;
 
-	BitmapResource bitmap(s->_segMan, width, height, skipColor, 0, 0, scaledWidth, scaledHeight, 0, useRemap);
+	BitmapResource bitmap(s->_segMan, width, height, skipColor, 0, 0, scaledWidth, scaledHeight, 0, useRemap, true);
 	memset(bitmap.getPixels(), backColor, width * height);
 	return bitmap.getObject();
 }
@@ -604,7 +604,7 @@ reg_t kBitmapDrawText(EngineState *s, int argc, reg_t *argv) {
 	// Then clips. But this seems stupid.
 	textRect.clip(Common::Rect(bitmap.getWidth(), bitmap.getHeight()));
 
-	reg_t textBitmapObject = g_sci->_gfxText32->createFontBitmap(textRect.width(), textRect.height(), Common::Rect(textRect.width(), textRect.height()), text, foreColor, backColor, skipColor, fontId, alignment, borderColor, dimmed, false);
+	reg_t textBitmapObject = g_sci->_gfxText32->createFontBitmap(textRect.width(), textRect.height(), Common::Rect(textRect.width(), textRect.height()), text, foreColor, backColor, skipColor, fontId, alignment, borderColor, dimmed, false, false);
 	CelObjMem textCel(textBitmapObject);
 	textCel.draw(bitmap.getBuffer(), textRect, Common::Point(textRect.left, textRect.top), false);
 	s->_segMan->freeHunkEntry(textBitmapObject);
diff --git a/engines/sci/engine/kscripts.cpp b/engines/sci/engine/kscripts.cpp
index 6fd130bceb..42e7a2028f 100644
--- a/engines/sci/engine/kscripts.cpp
+++ b/engines/sci/engine/kscripts.cpp
@@ -40,7 +40,7 @@ reg_t kLoad(EngineState *s, int argc, reg_t *argv) {
 
 	// Request to dynamically allocate hunk memory for later use
 	if (restype == kResourceTypeMemory)
-		return s->_segMan->allocateHunkEntry("kLoad()", resnr);
+		return s->_segMan->allocateHunkEntry("kLoad()", resnr, true);
 
 	return make_reg(0, ((restype << 11) | resnr)); // Return the resource identifier as handle
 }
diff --git a/engines/sci/engine/seg_manager.cpp b/engines/sci/engine/seg_manager.cpp
index 95e3cd15f9..e6692060b6 100644
--- a/engines/sci/engine/seg_manager.cpp
+++ b/engines/sci/engine/seg_manager.cpp
@@ -393,7 +393,7 @@ void SegManager::freeHunkEntry(reg_t addr) {
 	ht->freeEntryContents(addr.getOffset());
 }
 
-reg_t SegManager::allocateHunkEntry(const char *hunk_type, int size) {
+reg_t SegManager::allocateHunkEntry(const char *hunk_type, int size, bool gc) {
 	HunkTable *table;
 	int offset;
 
@@ -412,6 +412,7 @@ reg_t SegManager::allocateHunkEntry(const char *hunk_type, int size) {
 	h->mem = malloc(size);
 	h->size = size;
 	h->type = hunk_type;
+	h->gc = gc;
 
 	return addr;
 }
diff --git a/engines/sci/engine/seg_manager.h b/engines/sci/engine/seg_manager.h
index 9da7e58770..ba2ba33a6a 100644
--- a/engines/sci/engine/seg_manager.h
+++ b/engines/sci/engine/seg_manager.h
@@ -225,9 +225,11 @@ public:
 	 * @param[in] size		Number of bytes to allocate for the hunk entry
 	 * @param[in] hunk_type	A descriptive string for the hunk entry, for
 	 *						debugging purposes
+	 * @param[in] gc        Whether to make the hunk eligible for garbage
+	 *                      collection
 	 * @return				The offset of the freshly allocated hunk entry
 	 */
-	reg_t allocateHunkEntry(const char *hunk_type, int size);
+	reg_t allocateHunkEntry(const char *hunk_type, int size, bool gc);
 
 	/**
 	 * Deallocates a hunk entry
diff --git a/engines/sci/engine/segment.h b/engines/sci/engine/segment.h
index 50c77d0538..6c94c24ff9 100644
--- a/engines/sci/engine/segment.h
+++ b/engines/sci/engine/segment.h
@@ -205,6 +205,7 @@ struct Hunk {
 	void *mem;
 	uint32 size;
 	const char *type;
+	bool gc;
 };
 
 template<typename T>