The first step for an RTL UI:

1. The main change is in font.cpp

2. It is currently conditioned on the WANT_RTL environment variable

3. All clipping areas passed to draw_text* should be fixed for this to
   work.

4. The following calls has been fixed:
   - widgets/button.cpp
   - widgets/label.cpp
   - show_dialog.cpp

src/font.cpp

@@ -345,6 +345,9 @@ public:
 	void measure() const;
 	size_t width() const;
 	size_t height() const;
+#ifdef	HAVE_FRIBIDI
+	bool is_rtl() const { return is_rtl_; }	// Right-To-Left alignment
+#endif
 	std::vector<surface> const & get_surfaces() const;
 
 	bool operator==(text_surface const &t) const {
@@ -362,14 +365,18 @@ private:
 	mutable bool initialized_;
 	mutable std::vector<text_chunk> chunks_;
 	mutable std::vector<surface> surfs_;
+#ifdef	HAVE_FRIBIDI
+	bool is_rtl_;
+	void bidi_cvt();
+#endif
 	void hash();
 };
 
 #ifdef	HAVE_FRIBIDI
-static std::string bidi_cvt(std::string const &str)
+void text_surface::bidi_cvt()
 {
-	char		*c_str = const_cast<char *>(str.c_str());	// fribidi forgot const...
-	int		len = str.length();
+	char		*c_str = const_cast<char *>(str_.c_str());	// fribidi forgot const...
+	int		len = str_.length();
 	FriBidiChar	bidi_logical[len + 2];
 	FriBidiChar	bidi_visual[len + 2];
 	char		utf8str[len + 1];
@@ -379,16 +386,18 @@ static std::string bidi_cvt(std::string const &str)
 	n = fribidi_utf8_to_unicode (c_str, len, bidi_logical);
 	fribidi_log2vis(bidi_logical, n, &base_dir, bidi_visual, NULL, NULL, NULL);
 	fribidi_unicode_to_utf8 (bidi_visual, n, utf8str);
-	return std::string(utf8str);
+	is_rtl_ = base_dir == FRIBIDI_TYPE_RTL;
+	str_ = std::string(utf8str);
 }
-#else
-#	define	bidi_cvt(x)	(x)
 #endif
 
 text_surface::text_surface(std::string const &str, int size, SDL_Color color, int style)
-  : font_size_(size), color_(color), style_(style), w_(-1), h_(-1), str_(bidi_cvt(str)),
+  : font_size_(size), color_(color), style_(style), w_(-1), h_(-1), str_(str),
   initialized_(false)
 {
+#ifdef	HAVE_FRIBIDI
+	bidi_cvt();
+#endif
 	hash();
 }
 
@@ -402,7 +411,10 @@ void text_surface::set_text(std::string const &str)
 	initialized_ = false;
 	w_ = -1;
 	h_ = -1;
-	str_ = bidi_cvt(str);
+	str_ = str;
+#ifdef	HAVE_FRIBIDI
+	bidi_cvt();
+#endif
 	hash();
 }
 
@@ -673,9 +685,17 @@ SDL_Rect draw_text_line(surface gui_surface, const SDL_Rect& area, int size,
 	}
 
 	SDL_Rect dest;
-	if(x!=-1)
+	if(x!=-1) {
 		dest.x = x;
-	else
+#ifdef	HAVE_FRIBIDI
+		// Oron -- Conditional, until all draw_text_line calls have fixed area parameter
+		if(getenv("WANT_RTL")) {
+			bool is_rtl = text_cache::find(text_surface(text, size, colour, style)).is_rtl();
+			if(is_rtl)
+				dest.x = area.x + area.w - surface->w - (x - area.x);
+		}
+#endif
+	} else
 		dest.x = (area.w/2)-(surface->w/2);
 	if(y!=-1)
 		dest.y = y;

src/show_dialog.cpp

@@ -633,9 +633,12 @@ int show_dialog(display& disp, surface image,
 		menu_.set_location(menu_xpos,menu_ypos);
 	}
 
+	text_size.x = xloc + left_padding;
+	text_size.y = yloc + top_padding + caption_size.h;
 	if(image != NULL) {
 		const int x = xloc + left_padding;
 		const int y = yloc + top_padding;
+		text_size.x += image_width + image_h_padding;
 
 		screen.blit_surface(x,y,image);
 
@@ -645,7 +648,7 @@ int show_dialog(display& disp, surface image,
 		                yloc+top_padding);
 	}
 
-	font::draw_text(&screen, clipRect, message_font_size,
+	font::draw_text(&screen, text_size, message_font_size,
 	                font::NORMAL_COLOUR, message,
 	                xloc+image_width+left_padding+image_h_padding,
 	                yloc+top_padding+caption_size.h);

src/widgets/button.cpp

@@ -189,15 +189,17 @@ void button::draw_contents()
 		break;
 	}
 
-	SDL_Rect const &clipArea = screen_area();
 	SDL_Rect const &loc = location();
+	SDL_Rect clipArea = loc;
 	const int texty = loc.y + loc.h / 2 - textRect_.h / 2 + offset;
 	int textx;
 
 	if (type_ != TYPE_CHECK)
 		textx = loc.x + image->w / 2 - textRect_.w / 2 + offset;
-	else
+	else {
+		clipArea.w += image_w + checkbox_horizontal_padding;
 		textx = loc.x + image_w + checkbox_horizontal_padding / 2;
+	}
 
 	SDL_Color button_colour = font::BUTTON_COLOUR;
 
@@ -208,6 +210,10 @@ void button::draw_contents()
 
 	video().blit_surface(loc.x, loc.y, image);
 	if (type_ != TYPE_IMAGE){
+		clipArea.x += offset;
+		clipArea.y += offset;
+		clipArea.w -= 2*offset;
+		clipArea.h -= 2*offset;
 		font::draw_text(&video(), clipArea, font_size, button_colour, label_, textx, texty);
 	}
 

src/widgets/label.cpp

@@ -67,7 +67,7 @@ const SDL_Color& label::get_colour() const
 
 void label::draw_contents()
 {
-	font::draw_text(&video(), screen_area(), size_, colour_, text_, location().x, location().y);
+	font::draw_text(&video(), location(), size_, colour_, text_, location().x, location().y);
 }
 
 void label::update_label_size()