Tilemap/VX: Ensure proxy objects don't outlive their parents

Either of these would previously crash (same for VX):

tm = Tilemap.new
at = tm.autotiles
tm = nil
GC.start
at[0] = Bitmap.new(1, 1)

tm = Tilemap.new
at = tm.autotiles
tm.dispose
at[0] = Bitmap.new(1, 1)

Funnily, this makes RMXP itself crash too, but crashing is
never acceptable except for possibly resource exhaustion.

src/tilemap.cpp

@@ -241,7 +241,6 @@ struct TilemapPrivate
 {
 	Viewport *viewport;
 
-	Tilemap::Autotiles autotilesProxy;
 	Bitmap *autotiles[autotileCount];
 
 	Bitmap *tileset;
@@ -1183,6 +1182,9 @@ void ZLayer::finiUpdateZ(ZLayer *prev)
 
 void Tilemap::Autotiles::set(int i, Bitmap *bitmap)
 {
+	if (!p)
+		return;
+
 	if (i < 0 || i > autotileCount-1)
 		return;
 
@@ -1206,6 +1208,9 @@ void Tilemap::Autotiles::set(int i, Bitmap *bitmap)
 
 Bitmap *Tilemap::Autotiles::get(int i) const
 {
+	if (!p)
+		return 0;
+
 	if (i < 0 || i > autotileCount-1)
 		return 0;
 
@@ -1215,7 +1220,7 @@ Bitmap *Tilemap::Autotiles::get(int i) const
 Tilemap::Tilemap(Viewport *viewport)
 {
 	p = new TilemapPrivate(viewport);
-	p->autotilesProxy.p = p;
+	atProxy.p = p;
 }
 
 Tilemap::~Tilemap()
@@ -1244,11 +1249,11 @@ void Tilemap::update()
 		p->tiles.aniIdx = 0;
 }
 
-Tilemap::Autotiles &Tilemap::getAutotiles() const
+Tilemap::Autotiles &Tilemap::getAutotiles()
 {
 	guardDisposed();
 
-	return p->autotilesProxy;
+	return atProxy;
 }
 
 DEF_ATTR_RD_SIMPLE(Tilemap, Viewport, Viewport*, p->viewport)
@@ -1379,4 +1384,5 @@ void Tilemap::setOY(int value)
 void Tilemap::releaseResources()
 {
 	delete p;
+	atProxy.p = 0;
 }

src/tilemap.h

@@ -55,7 +55,7 @@ public:
 
 	void update();
 
-	Autotiles &getAutotiles() const;
+	Autotiles &getAutotiles();
 	Viewport *getViewport() const;
 
 	DECL_ATTR( Tileset,    Bitmap*   )
@@ -68,6 +68,7 @@ public:
 
 private:
 	TilemapPrivate *p;
+	Autotiles atProxy;
 
 	void releaseResources();
 	const char *klassName() const { return "tilemap"; }

src/tilemapvx.cpp

@@ -41,7 +41,6 @@
 
 struct TilemapVXPrivate : public ViewportElement, TileAtlasVX::Reader
 {
-	TilemapVX::BitmapArray bitmapsProxy;
 	Bitmap *bitmaps[BM_COUNT];
 
 	Table *mapData;
@@ -358,6 +357,9 @@ struct TilemapVXPrivate : public ViewportElement, TileAtlasVX::Reader
 
 void TilemapVX::BitmapArray::set(int i, Bitmap *bitmap)
 {
+	if (!p)
+		return;
+
 	if (i < 0 || i >= BM_COUNT)
 		return;
 
@@ -378,6 +380,9 @@ void TilemapVX::BitmapArray::set(int i, Bitmap *bitmap)
 
 Bitmap *TilemapVX::BitmapArray::get(int i) const
 {
+	if (!p)
+		return 0;
+
 	if (i < 0 || i >= BM_COUNT)
 		return 0;
 
@@ -387,7 +392,7 @@ Bitmap *TilemapVX::BitmapArray::get(int i) const
 TilemapVX::TilemapVX(Viewport *viewport)
 {
 	p = new TilemapVXPrivate(viewport);
-	p->bitmapsProxy.p = p;
+	bmProxy.p = p;
 }
 
 TilemapVX::~TilemapVX()
@@ -413,11 +418,11 @@ void TilemapVX::update()
 	p->aniOffset = Vec2(aniIdxA * 2 * 32, aniIdxC * 32);
 }
 
-TilemapVX::BitmapArray &TilemapVX::getBitmapArray() const
+TilemapVX::BitmapArray &TilemapVX::getBitmapArray()
 {
 	guardDisposed();
 
-	return p->bitmapsProxy;
+	return bmProxy;
 }
 
 DEF_ATTR_RD_SIMPLE(TilemapVX, MapData, Table*, p->mapData)
@@ -521,4 +526,5 @@ void TilemapVX::setOY(int value)
 void TilemapVX::releaseResources()
 {
 	delete p;
+	bmProxy.p = 0;
 }

src/tilemapvx.h

@@ -54,7 +54,7 @@ public:
 
 	void update();
 
-	BitmapArray &getBitmapArray() const;
+	BitmapArray &getBitmapArray();
 
 	DECL_ATTR( Viewport,   Viewport* )
 	DECL_ATTR( MapData,    Table*    )
@@ -66,6 +66,7 @@ public:
 
 private:
 	TilemapVXPrivate *p;
+	BitmapArray bmProxy;
 
 	void releaseResources();
 	const char *klassName() const { return "tilemap"; }