Fix memory leak when disposing a high-res Bitmap

src/display/bitmap.cpp

@@ -805,6 +805,8 @@ Bitmap::Bitmap(SDL_Surface *imgSurf, SDL_Surface *imgSurfHires, bool forceMega)
 Bitmap::~Bitmap()
 {
     dispose();
+
+    loresDispCon.disconnect();
 }
 
 void Bitmap::initFromSurface(SDL_Surface *imgSurf, Bitmap *hiresBitmap, bool forceMega)
@@ -897,6 +899,7 @@ void Bitmap::setLores(Bitmap *lores) {
     guardDisposed();
 
     p->selfLores = lores;
+    loresDispCon = lores->wasDisposed.connect(&Bitmap::loresDisposal, this);
 }
 
 bool Bitmap::isMega() const{
@@ -2603,3 +2606,9 @@ void Bitmap::releaseResources()
 
     delete p;
 }
+
+void Bitmap::loresDisposal()
+{
+    loresDispCon.disconnect();
+    dispose();
+}

src/display/bitmap.h

@@ -171,9 +171,12 @@ class Bitmap : public Disposable
 
 private:
 	void releaseResources();
+	sigslot::connection loresDispCon;
 	const char *klassName() const { return "bitmap"; }
 
 	BitmapPrivate *p;
+
+	void loresDisposal();
 };
 
 #endif // BITMAP_H

tests/hires-bitmap/hires-bitmap-test.rb

@@ -395,6 +395,25 @@ def dump(bmp, spr, desc)
 
 # TODO: Animation tests, if we can find a good way to test them.
 
+bmp = Bitmap.new(640, 480)
+fnt = Font.new("Liberation Sans", 100)
+fnt.out_color = Color.new(0, 255, 0)
+bmp.font = fnt
+bmp.draw_text(100, 200, 450, 300, "Now testing dispose for memory leaks...", 1)
+dump(bmp, spr, "memory-leak")
+
+def allocate()
+	bmp_allocate = Bitmap.new("Graphics/Pictures/children-alpha")
+	bmp_allocate.dispose
+end
+
+for i in (1...100)
+	for j in (1...10)
+		allocate
+	end
+	System::puts("Memory leak test #{i}/100")
+end
+
 # Tests are finished, show exit screen
 
 bmp = Bitmap.new(640, 480)