Plane, Sprite: Fix Bitmap flushes in draw handler

Comparing the current SceneElement classes to the earlier
written documentation actually immediatelly exposed some
bugs. Yay! :D

src/plane.cpp

@@ -33,6 +33,8 @@
 #include "shader.h"
 #include "glstate.h"
 
+#include <sigc++/connection.h>
+
 struct PlanePrivate
 {
 	Bitmap *bitmap;
@@ -52,6 +54,8 @@ struct PlanePrivate
 
 	EtcTemps tmp;
 
+	sigc::connection prepareCon;
+
 	PlanePrivate()
 	    : bitmap(0),
 	      opacity(255),
@@ -61,7 +65,15 @@ struct PlanePrivate
 	      ox(0), oy(0),
 	      zoomX(1), zoomY(1),
 	      quadSourceDirty(false)
-	{}
+	{
+		prepareCon = shState->prepareDraw.connect
+		        (sigc::mem_fun(this, &PlanePrivate::prepare));
+	}
+
+	~PlanePrivate()
+	{
+		prepareCon.disconnect();
+	}
 
 	void updateQuadSource()
 	{
@@ -73,6 +85,18 @@ struct PlanePrivate
 
 		quad.setTexRect(srcRect);
 	}
+
+	void prepare()
+	{
+		if (quadSourceDirty)
+		{
+			updateQuadSource();
+			quadSourceDirty = false;
+		}
+
+		if (bitmap)
+			bitmap->flush();
+	}
 };
 
 Plane::Plane(Viewport *viewport)
@@ -176,12 +200,6 @@ void Plane::draw()
 	if (!p->opacity)
 		return;
 
-	if (p->quadSourceDirty)
-	{
-		p->updateQuadSource();
-		p->quadSourceDirty = false;
-	}
-
 	ShaderBase *base;
 
 	if (p->color->hasEffect() || p->tone->hasEffect() || p->opacity != 255)
@@ -210,7 +228,6 @@ void Plane::draw()
 
 	glState.blendMode.pushSet(p->blendType);
 
-	p->bitmap->flush();
 	p->bitmap->bindTex(*base);
 	TEX::setRepeat(true);
 

src/sprite.cpp

@@ -59,6 +59,8 @@ struct SpritePrivate
 
 	EtcTemps tmp;
 
+	sigc::connection prepareCon;
+
 	SpritePrivate()
 	    : bitmap(0),
 	      srcRect(&tmp.rect),
@@ -73,11 +75,15 @@ struct SpritePrivate
 
 	{
 		updateSrcRectCon();
+
+		prepareCon = shState->prepareDraw.connect
+		        (sigc::mem_fun(this, &SpritePrivate::prepare));
 	}
 
 	~SpritePrivate()
 	{
 		srcRectCon.disconnect();
+		prepareCon.disconnect();
 	}
 
 	void recomputeBushDepth()
@@ -112,6 +118,12 @@ struct SpritePrivate
 		srcRectCon = srcRect->valueChanged.connect
 				(sigc::mem_fun(this, &SpritePrivate::onSrcRectChange));
 	}
+
+	void prepare()
+	{
+		if (bitmap)
+			bitmap->flush();
+	}
 };
 
 Sprite::Sprite(Viewport *viewport)
@@ -313,8 +325,6 @@ void Sprite::draw()
 	if (emptyFlashFlag)
 		return;
 
-	p->bitmap->flush();
-
 	ShaderBase *base;
 
 	bool renderEffect = p->color->hasEffect() ||